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src/backend/access/transam/xact.c
6 506 строк
186 KB
Amit Langote
Hardwire RI fast-path end-of-xact cleanup into xact.c
29 июн 2026, 04:24
29 июн 2026, 04:24
6f4bac8
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/*------------------------------------------------------------------------- * * xact.c * top level transaction system support routines * * See src/backend/access/transam/README for more information. * * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * src/backend/access/transam/xact.c * *------------------------------------------------------------------------- */ #include "postgres.h" #include <time.h> #include <unistd.h> #include "access/commit_ts.h" #include "access/multixact.h" #include "access/parallel.h" #include "access/subtrans.h" #include "access/transam.h" #include "access/twophase.h" #include "access/xact.h" #include "access/xlog.h" #include "access/xloginsert.h" #include "access/xlogrecovery.h" #include "access/xlogutils.h" #include "access/xlogwait.h" #include "catalog/index.h" #include "catalog/namespace.h" #include "catalog/pg_enum.h" #include "catalog/storage.h" #include "commands/async.h" #include "commands/tablecmds.h" #include "commands/trigger.h" #include "common/pg_prng.h" #include "executor/spi.h" #include "libpq/be-fsstubs.h" #include "libpq/pqsignal.h" #include "miscadmin.h" #include "pg_trace.h" #include "pgstat.h" #include "replication/logical.h" #include "replication/logicallauncher.h" #include "replication/logicalworker.h" #include "replication/origin.h" #include "replication/snapbuild.h" #include "replication/syncrep.h" #include "storage/aio_subsys.h" #include "storage/condition_variable.h" #include "storage/fd.h" #include "storage/lmgr.h" #include "storage/md.h" #include "storage/predicate.h" #include "storage/proc.h" #include "storage/procarray.h" #include "storage/sinvaladt.h" #include "storage/smgr.h" #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" #include "utils/snapmgr.h" #include "utils/timeout.h" #include "utils/timestamp.h" #include "utils/typcache.h" #include "utils/wait_event.h" /* * User-tweakable parameters */ int DefaultXactIsoLevel = XACT_READ_COMMITTED; int XactIsoLevel = XACT_READ_COMMITTED; bool DefaultXactReadOnly = false; bool XactReadOnly; bool DefaultXactDeferrable = false; bool XactDeferrable; int synchronous_commit = SYNCHRONOUS_COMMIT_ON; /* * CheckXidAlive is a xid value pointing to a possibly ongoing (sub) * transaction. Currently, it is used in logical decoding. It's possible * that such transactions can get aborted while the decoding is ongoing in * which case we skip decoding that particular transaction. To ensure that we * check whether the CheckXidAlive is aborted after fetching the tuple from * system tables. We also ensure that during logical decoding we never * directly access the tableam or heap APIs because we are checking for the * concurrent aborts only in systable_* APIs. */ TransactionId CheckXidAlive = InvalidTransactionId; bool bsysscan = false; /* * When running as a parallel worker, we place only a single * TransactionStateData on the parallel worker's state stack, and the XID * reflected there will be that of the *innermost* currently-active * subtransaction in the backend that initiated parallelism. However, * GetTopTransactionId() and TransactionIdIsCurrentTransactionId() * need to return the same answers in the parallel worker as they would have * in the user backend, so we need some additional bookkeeping. * * XactTopFullTransactionId stores the XID of our toplevel transaction, which * will be the same as TopTransactionStateData.fullTransactionId in an * ordinary backend; but in a parallel backend, which does not have the entire * transaction state, it will instead be copied from the backend that started * the parallel operation. * * nParallelCurrentXids will be 0 and ParallelCurrentXids NULL in an ordinary * backend, but in a parallel backend, nParallelCurrentXids will contain the * number of XIDs that need to be considered current, and ParallelCurrentXids * will contain the XIDs themselves. This includes all XIDs that were current * or sub-committed in the parent at the time the parallel operation began. * The XIDs are stored sorted in numerical order (not logical order) to make * lookups as fast as possible. */ static FullTransactionId XactTopFullTransactionId = {InvalidTransactionId}; static int nParallelCurrentXids = 0; static TransactionId *ParallelCurrentXids; /* * Miscellaneous flag bits to record events which occur on the top level * transaction. These flags are only persisted in MyXactFlags and are intended * so we remember to do certain things later on in the transaction. This is * globally accessible, so can be set from anywhere in the code that requires * recording flags. */ int MyXactFlags; /* * transaction states - transaction state from server perspective */ typedef enum TransState { TRANS_DEFAULT, /* idle */ TRANS_START, /* transaction starting */ TRANS_INPROGRESS, /* inside a valid transaction */ TRANS_COMMIT, /* commit in progress */ TRANS_ABORT, /* abort in progress */ TRANS_PREPARE, /* prepare in progress */ } TransState; /* * transaction block states - transaction state of client queries * * Note: the subtransaction states are used only for non-topmost * transactions; the others appear only in the topmost transaction. */ typedef enum TBlockState { /* not-in-transaction-block states */ TBLOCK_DEFAULT, /* idle */ TBLOCK_STARTED, /* running single-query transaction */ /* transaction block states */ TBLOCK_BEGIN, /* starting transaction block */ TBLOCK_INPROGRESS, /* live transaction */ TBLOCK_IMPLICIT_INPROGRESS, /* live transaction after implicit BEGIN */ TBLOCK_PARALLEL_INPROGRESS, /* live transaction inside parallel worker */ TBLOCK_END, /* COMMIT received */ TBLOCK_ABORT, /* failed xact, awaiting ROLLBACK */ TBLOCK_ABORT_END, /* failed xact, ROLLBACK received */ TBLOCK_ABORT_PENDING, /* live xact, ROLLBACK received */ TBLOCK_PREPARE, /* live xact, PREPARE received */ /* subtransaction states */ TBLOCK_SUBBEGIN, /* starting a subtransaction */ TBLOCK_SUBINPROGRESS, /* live subtransaction */ TBLOCK_SUBRELEASE, /* RELEASE received */ TBLOCK_SUBCOMMIT, /* COMMIT received while TBLOCK_SUBINPROGRESS */ TBLOCK_SUBABORT, /* failed subxact, awaiting ROLLBACK */ TBLOCK_SUBABORT_END, /* failed subxact, ROLLBACK received */ TBLOCK_SUBABORT_PENDING, /* live subxact, ROLLBACK received */ TBLOCK_SUBRESTART, /* live subxact, ROLLBACK TO received */ TBLOCK_SUBABORT_RESTART, /* failed subxact, ROLLBACK TO received */ } TBlockState; /* * transaction state structure * * Note: parallelModeLevel counts the number of unmatched EnterParallelMode * calls done at this transaction level. parallelChildXact is true if any * upper transaction level has nonzero parallelModeLevel. */ typedef struct TransactionStateData { FullTransactionId fullTransactionId; /* my FullTransactionId */ SubTransactionId subTransactionId; /* my subxact ID */ char *name; /* savepoint name, if any */ int savepointLevel; /* savepoint level */ TransState state; /* low-level state */ TBlockState blockState; /* high-level state */ int nestingLevel; /* transaction nesting depth */ int gucNestLevel; /* GUC context nesting depth */ MemoryContext curTransactionContext; /* my xact-lifetime context */ ResourceOwner curTransactionOwner; /* my query resources */ MemoryContext priorContext; /* CurrentMemoryContext before xact started */ TransactionId *childXids; /* subcommitted child XIDs, in XID order */ int nChildXids; /* # of subcommitted child XIDs */ int maxChildXids; /* allocated size of childXids[] */ Oid prevUser; /* previous CurrentUserId setting */ int prevSecContext; /* previous SecurityRestrictionContext */ bool prevXactReadOnly; /* entry-time xact r/o state */ bool startedInRecovery; /* did we start in recovery? */ bool didLogXid; /* has xid been included in WAL record? */ int parallelModeLevel; /* Enter/ExitParallelMode counter */ bool parallelChildXact; /* is any parent transaction parallel? */ bool chain; /* start a new block after this one */ bool topXidLogged; /* for a subxact: is top-level XID logged? */ struct TransactionStateData *parent; /* back link to parent */ } TransactionStateData; typedef TransactionStateData *TransactionState; /* * Serialized representation used to transmit transaction state to parallel * workers through shared memory. */ typedef struct SerializedTransactionState { int xactIsoLevel; bool xactDeferrable; FullTransactionId topFullTransactionId; FullTransactionId currentFullTransactionId; CommandId currentCommandId; int nParallelCurrentXids; TransactionId parallelCurrentXids[FLEXIBLE_ARRAY_MEMBER]; } SerializedTransactionState; /* The size of SerializedTransactionState, not including the final array. */ #define SerializedTransactionStateHeaderSize \ offsetof(SerializedTransactionState, parallelCurrentXids) /* * CurrentTransactionState always points to the current transaction state * block. It will point to TopTransactionStateData when not in a * transaction at all, or when in a top-level transaction. */ static TransactionStateData TopTransactionStateData = { .state = TRANS_DEFAULT, .blockState = TBLOCK_DEFAULT, .topXidLogged = false, }; /* * unreportedXids holds XIDs of all subtransactions that have not yet been * reported in an XLOG_XACT_ASSIGNMENT record. */ static int nUnreportedXids; static TransactionId unreportedXids[PGPROC_MAX_CACHED_SUBXIDS]; static TransactionState CurrentTransactionState = &TopTransactionStateData; /* * The subtransaction ID and command ID assignment counters are global * to a whole transaction, so we do not keep them in the state stack. */ static SubTransactionId currentSubTransactionId; static CommandId currentCommandId; static bool currentCommandIdUsed; /* * xactStartTimestamp is the value of transaction_timestamp(). * stmtStartTimestamp is the value of statement_timestamp(). * xactStopTimestamp is the time at which we log a commit / abort WAL record, * or if that was skipped, the time of the first subsequent * GetCurrentTransactionStopTimestamp() call. * * These do not change as we enter and exit subtransactions, so we don't * keep them inside the TransactionState stack. */ static TimestampTz xactStartTimestamp; static TimestampTz stmtStartTimestamp; static TimestampTz xactStopTimestamp; /* * GID to be used for preparing the current transaction. This is also * global to a whole transaction, so we don't keep it in the state stack. */ static char *prepareGID; /* * Some commands want to force synchronous commit. */ static bool forceSyncCommit = false; /* Flag for logging statements in a transaction. */ bool xact_is_sampled = false; /* * Private context for transaction-abort work --- we reserve space for this * at startup to ensure that AbortTransaction and AbortSubTransaction can work * when we've run out of memory. */ static MemoryContext TransactionAbortContext = NULL; /* * List of add-on start- and end-of-xact callbacks */ typedef struct XactCallbackItem { struct XactCallbackItem *next; XactCallback callback; void *arg; } XactCallbackItem; static XactCallbackItem *Xact_callbacks = NULL; /* * List of add-on start- and end-of-subxact callbacks */ typedef struct SubXactCallbackItem { struct SubXactCallbackItem *next; SubXactCallback callback; void *arg; } SubXactCallbackItem; static SubXactCallbackItem *SubXact_callbacks = NULL; /* local function prototypes */ static void AssignTransactionId(TransactionState s); static void AbortTransaction(void); static void AtAbort_Memory(void); static void AtCleanup_Memory(void); static void AtAbort_ResourceOwner(void); static void AtCCI_LocalCache(void); static void AtCommit_Memory(void); static void AtStart_Cache(void); static void AtStart_Memory(void); static void AtStart_ResourceOwner(void); static void CallXactCallbacks(XactEvent event); static void CallSubXactCallbacks(SubXactEvent event, SubTransactionId mySubid, SubTransactionId parentSubid); static void CleanupTransaction(void); static void CheckTransactionBlock(bool isTopLevel, bool throwError, const char *stmtType); static void CommitTransaction(void); static TransactionId RecordTransactionAbort(bool isSubXact); static void StartTransaction(void); static bool CommitTransactionCommandInternal(void); static bool AbortCurrentTransactionInternal(void); static void StartSubTransaction(void); static void CommitSubTransaction(void); static void AbortSubTransaction(void); static void CleanupSubTransaction(void); static void PushTransaction(void); static void PopTransaction(void); static void AtSubAbort_Memory(void); static void AtSubCleanup_Memory(void); static void AtSubAbort_ResourceOwner(void); static void AtSubCommit_Memory(void); static void AtSubStart_Memory(void); static void AtSubStart_ResourceOwner(void); static void ShowTransactionState(const char *str); static void ShowTransactionStateRec(const char *str, TransactionState s); static const char *BlockStateAsString(TBlockState blockState); static const char *TransStateAsString(TransState state); /* ---------------------------------------------------------------- * transaction state accessors * ---------------------------------------------------------------- */ /* * IsTransactionState * * This returns true if we are inside a valid transaction; that is, * it is safe to initiate database access, take heavyweight locks, etc. */ bool IsTransactionState(void) { TransactionState s = CurrentTransactionState; /* * TRANS_DEFAULT and TRANS_ABORT are obviously unsafe states. However, we * also reject the startup/shutdown states TRANS_START, TRANS_COMMIT, * TRANS_PREPARE since it might be too soon or too late within those * transition states to do anything interesting. Hence, the only "valid" * state is TRANS_INPROGRESS. */ return (s->state == TRANS_INPROGRESS); } /* * IsAbortedTransactionBlockState * * This returns true if we are within an aborted transaction block. */ bool IsAbortedTransactionBlockState(void) { TransactionState s = CurrentTransactionState; if (s->blockState == TBLOCK_ABORT || s->blockState == TBLOCK_SUBABORT) return true; return false; } /* * GetTopTransactionId * * This will return the XID of the main transaction, assigning one if * it's not yet set. Be careful to call this only inside a valid xact. */ TransactionId GetTopTransactionId(void) { if (!FullTransactionIdIsValid(XactTopFullTransactionId)) AssignTransactionId(&TopTransactionStateData); return XidFromFullTransactionId(XactTopFullTransactionId); } /* * GetTopTransactionIdIfAny * * This will return the XID of the main transaction, if one is assigned. * It will return InvalidTransactionId if we are not currently inside a * transaction, or inside a transaction that hasn't yet been assigned an XID. */ TransactionId GetTopTransactionIdIfAny(void) { return XidFromFullTransactionId(XactTopFullTransactionId); } /* * GetCurrentTransactionId * * This will return the XID of the current transaction (main or sub * transaction), assigning one if it's not yet set. Be careful to call this * only inside a valid xact. */ TransactionId GetCurrentTransactionId(void) { TransactionState s = CurrentTransactionState; if (!FullTransactionIdIsValid(s->fullTransactionId)) AssignTransactionId(s); return XidFromFullTransactionId(s->fullTransactionId); } /* * GetCurrentTransactionIdIfAny * * This will return the XID of the current sub xact, if one is assigned. * It will return InvalidTransactionId if we are not currently inside a * transaction, or inside a transaction that hasn't been assigned an XID yet. */ TransactionId GetCurrentTransactionIdIfAny(void) { return XidFromFullTransactionId(CurrentTransactionState->fullTransactionId); } /* * GetTopFullTransactionId * * This will return the FullTransactionId of the main transaction, assigning * one if it's not yet set. Be careful to call this only inside a valid xact. */ FullTransactionId GetTopFullTransactionId(void) { if (!FullTransactionIdIsValid(XactTopFullTransactionId)) AssignTransactionId(&TopTransactionStateData); return XactTopFullTransactionId; } /* * GetTopFullTransactionIdIfAny * * This will return the FullTransactionId of the main transaction, if one is * assigned. It will return InvalidFullTransactionId if we are not currently * inside a transaction, or inside a transaction that hasn't yet been assigned * one. */ FullTransactionId GetTopFullTransactionIdIfAny(void) { return XactTopFullTransactionId; } /* * GetCurrentFullTransactionId * * This will return the FullTransactionId of the current transaction (main or * sub transaction), assigning one if it's not yet set. Be careful to call * this only inside a valid xact. */ FullTransactionId GetCurrentFullTransactionId(void) { TransactionState s = CurrentTransactionState; if (!FullTransactionIdIsValid(s->fullTransactionId)) AssignTransactionId(s); return s->fullTransactionId; } /* * GetCurrentFullTransactionIdIfAny * * This will return the FullTransactionId of the current sub xact, if one is * assigned. It will return InvalidFullTransactionId if we are not currently * inside a transaction, or inside a transaction that hasn't been assigned one * yet. */ FullTransactionId GetCurrentFullTransactionIdIfAny(void) { return CurrentTransactionState->fullTransactionId; } /* * MarkCurrentTransactionIdLoggedIfAny * * Remember that the current xid - if it is assigned - now has been wal logged. */ void MarkCurrentTransactionIdLoggedIfAny(void) { if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId)) CurrentTransactionState->didLogXid = true; } /* * IsSubxactTopXidLogPending * * This is used to decide whether we need to WAL log the top-level XID for * operation in a subtransaction. We require that for logical decoding, see * LogicalDecodingProcessRecord. * * This returns true if effective_wal_level is logical and we are inside * a valid subtransaction, for which the assignment was not yet written to * any WAL record. */ bool IsSubxactTopXidLogPending(void) { /* check whether it is already logged */ if (CurrentTransactionState->topXidLogged) return false; /* effective_wal_level has to be logical */ if (!XLogLogicalInfoActive()) return false; /* we need to be in a transaction state */ if (!IsTransactionState()) return false; /* it has to be a subtransaction */ if (!IsSubTransaction()) return false; /* the subtransaction has to have a XID assigned */ if (!TransactionIdIsValid(GetCurrentTransactionIdIfAny())) return false; return true; } /* * MarkSubxactTopXidLogged * * Remember that the top transaction id for the current subtransaction is WAL * logged now. */ void MarkSubxactTopXidLogged(void) { Assert(IsSubxactTopXidLogPending()); CurrentTransactionState->topXidLogged = true; } /* * GetStableLatestTransactionId * * Get the transaction's XID if it has one, else read the next-to-be-assigned * XID. Once we have a value, return that same value for the remainder of the * current transaction. This is meant to provide the reference point for the * age(xid) function, but might be useful for other maintenance tasks as well. */ TransactionId GetStableLatestTransactionId(void) { static LocalTransactionId lxid = InvalidLocalTransactionId; static TransactionId stablexid = InvalidTransactionId; if (lxid != MyProc->vxid.lxid) { lxid = MyProc->vxid.lxid; stablexid = GetTopTransactionIdIfAny(); if (!TransactionIdIsValid(stablexid)) stablexid = ReadNextTransactionId(); } Assert(TransactionIdIsValid(stablexid)); return stablexid; } /* * AssignTransactionId * * Assigns a new permanent FullTransactionId to the given TransactionState. * We do not assign XIDs to transactions until/unless this is called. * Also, any parent TransactionStates that don't yet have XIDs are assigned * one; this maintains the invariant that a child transaction has an XID * following its parent's. */ static void AssignTransactionId(TransactionState s) { bool isSubXact = (s->parent != NULL); ResourceOwner currentOwner; bool log_unknown_top = false; /* Assert that caller didn't screw up */ Assert(!FullTransactionIdIsValid(s->fullTransactionId)); Assert(s->state == TRANS_INPROGRESS); /* * Workers synchronize transaction state at the beginning of each parallel * operation, so we can't account for new XIDs at this point. */ if (IsInParallelMode() || IsParallelWorker()) ereport(ERROR, (errcode(ERRCODE_INVALID_TRANSACTION_STATE), errmsg("cannot assign transaction IDs during a parallel operation"))); /* * Ensure parent(s) have XIDs, so that a child always has an XID later * than its parent. Mustn't recurse here, or we might get a stack * overflow if we're at the bottom of a huge stack of subtransactions none * of which have XIDs yet. */ if (isSubXact && !FullTransactionIdIsValid(s->parent->fullTransactionId)) { TransactionState p = s->parent; TransactionState *parents; size_t parentOffset = 0; parents = palloc_array(TransactionState, s->nestingLevel); while (p != NULL && !FullTransactionIdIsValid(p->fullTransactionId)) { parents[parentOffset++] = p; p = p->parent; } /* * This is technically a recursive call, but the recursion will never * be more than one layer deep. */ while (parentOffset != 0) AssignTransactionId(parents[--parentOffset]); pfree(parents); } /* * When effective_wal_level is logical, guarantee that a subtransaction's * xid can only be seen in the WAL stream if its toplevel xid has been * logged before. If necessary we log an xact_assignment record with fewer * than PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't * set for a transaction even though it appears in a WAL record, we just * might superfluously log something. That can happen when an xid is * included somewhere inside a wal record, but not in XLogRecord->xl_xid, * like in xl_standby_locks. */ if (isSubXact && XLogLogicalInfoActive() && !TopTransactionStateData.didLogXid) log_unknown_top = true; /* * Generate a new FullTransactionId and record its xid in PGPROC and * pg_subtrans. * * NB: we must make the subtrans entry BEFORE the Xid appears anywhere in * shared storage other than PGPROC; because if there's no room for it in * PGPROC, the subtrans entry is needed to ensure that other backends see * the Xid as "running". See GetNewTransactionId. */ s->fullTransactionId = GetNewTransactionId(isSubXact); if (!isSubXact) XactTopFullTransactionId = s->fullTransactionId; if (isSubXact) SubTransSetParent(XidFromFullTransactionId(s->fullTransactionId), XidFromFullTransactionId(s->parent->fullTransactionId)); /* * If it's a top-level transaction, the predicate locking system needs to * be told about it too. */ if (!isSubXact) RegisterPredicateLockingXid(XidFromFullTransactionId(s->fullTransactionId)); /* * Acquire lock on the transaction XID. (We assume this cannot block.) We * have to ensure that the lock is assigned to the transaction's own * ResourceOwner. */ currentOwner = CurrentResourceOwner; CurrentResourceOwner = s->curTransactionOwner; XactLockTableInsert(XidFromFullTransactionId(s->fullTransactionId)); CurrentResourceOwner = currentOwner; /* * Every PGPROC_MAX_CACHED_SUBXIDS assigned transaction ids within each * top-level transaction we issue a WAL record for the assignment. We * include the top-level xid and all the subxids that have not yet been * reported using XLOG_XACT_ASSIGNMENT records. * * This is required to limit the amount of shared memory required in a hot * standby server to keep track of in-progress XIDs. See notes for * RecordKnownAssignedTransactionIds(). * * We don't keep track of the immediate parent of each subxid, only the * top-level transaction that each subxact belongs to. This is correct in * recovery only because aborted subtransactions are separately WAL * logged. * * This is correct even for the case where several levels above us didn't * have an xid assigned as we recursed up to them beforehand. */ if (isSubXact && XLogStandbyInfoActive()) { unreportedXids[nUnreportedXids] = XidFromFullTransactionId(s->fullTransactionId); nUnreportedXids++; /* * ensure this test matches similar one in * RecoverPreparedTransactions() */ if (nUnreportedXids >= PGPROC_MAX_CACHED_SUBXIDS || log_unknown_top) { xl_xact_assignment xlrec; /* * xtop is always set by now because we recurse up transaction * stack to the highest unassigned xid and then come back down */ xlrec.xtop = GetTopTransactionId(); Assert(TransactionIdIsValid(xlrec.xtop)); xlrec.nsubxacts = nUnreportedXids; XLogBeginInsert(); XLogRegisterData(&xlrec, MinSizeOfXactAssignment); XLogRegisterData(unreportedXids, nUnreportedXids * sizeof(TransactionId)); (void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT); nUnreportedXids = 0; /* mark top, not current xact as having been logged */ TopTransactionStateData.didLogXid = true; } } } /* * GetCurrentSubTransactionId */ SubTransactionId GetCurrentSubTransactionId(void) { TransactionState s = CurrentTransactionState; return s->subTransactionId; } /* * SubTransactionIsActive * * Test if the specified subxact ID is still active. Note caller is * responsible for checking whether this ID is relevant to the current xact. */ bool SubTransactionIsActive(SubTransactionId subxid) { TransactionState s; for (s = CurrentTransactionState; s != NULL; s = s->parent) { if (s->state == TRANS_ABORT) continue; if (s->subTransactionId == subxid) return true; } return false; } /* * GetCurrentCommandId * * "used" must be true if the caller intends to use the command ID to mark * inserted/updated/deleted tuples. false means the ID is being fetched * for read-only purposes (ie, as a snapshot validity cutoff). See * CommandCounterIncrement() for discussion. */ CommandId GetCurrentCommandId(bool used) { /* this is global to a transaction, not subtransaction-local */ if (used) { /* * Forbid setting currentCommandIdUsed in a parallel worker, because * we have no provision for communicating this back to the leader. We * could relax this restriction when currentCommandIdUsed was already * true at the start of the parallel operation. */ if (IsParallelWorker()) ereport(ERROR, (errcode(ERRCODE_INVALID_TRANSACTION_STATE), errmsg("cannot modify data in a parallel worker"))); currentCommandIdUsed = true; } return currentCommandId; } /* * SetParallelStartTimestamps * * In a parallel worker, we should inherit the parent transaction's * timestamps rather than setting our own. The parallel worker * infrastructure must call this to provide those values before * calling StartTransaction() or SetCurrentStatementStartTimestamp(). */ void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts) { Assert(IsParallelWorker()); xactStartTimestamp = xact_ts; stmtStartTimestamp = stmt_ts; } /* * GetCurrentTransactionStartTimestamp */ TimestampTz GetCurrentTransactionStartTimestamp(void) { return xactStartTimestamp; } /* * GetCurrentStatementStartTimestamp */ TimestampTz GetCurrentStatementStartTimestamp(void) { return stmtStartTimestamp; } /* * GetCurrentTransactionStopTimestamp * * If the transaction stop time hasn't already been set, which can happen if * we decided we don't need to log an XLOG record, set xactStopTimestamp. */ TimestampTz GetCurrentTransactionStopTimestamp(void) { TransactionState s PG_USED_FOR_ASSERTS_ONLY = CurrentTransactionState; /* should only be called after commit / abort processing */ Assert(s->state == TRANS_DEFAULT || s->state == TRANS_COMMIT || s->state == TRANS_ABORT || s->state == TRANS_PREPARE); if (xactStopTimestamp == 0) xactStopTimestamp = GetCurrentTimestamp(); return xactStopTimestamp; } /* * SetCurrentStatementStartTimestamp * * In a parallel worker, this should already have been provided by a call * to SetParallelStartTimestamps(). */ void SetCurrentStatementStartTimestamp(void) { if (!IsParallelWorker()) stmtStartTimestamp = GetCurrentTimestamp(); else Assert(stmtStartTimestamp != 0); } /* * GetCurrentTransactionNestLevel * * Note: this will return zero when not inside any transaction, one when * inside a top-level transaction, etc. */ int GetCurrentTransactionNestLevel(void) { TransactionState s = CurrentTransactionState; return s->nestingLevel; } /* * TransactionIdIsCurrentTransactionId */ bool TransactionIdIsCurrentTransactionId(TransactionId xid) { TransactionState s; /* * We always say that BootstrapTransactionId is "not my transaction ID" * even when it is (ie, during bootstrap). Along with the fact that * transam.c always treats BootstrapTransactionId as already committed, * this causes the heapam_visibility.c routines to see all tuples as * committed, which is what we need during bootstrap. (Bootstrap mode * only inserts tuples, it never updates or deletes them, so all tuples * can be presumed good immediately.) * * Likewise, InvalidTransactionId and FrozenTransactionId are certainly * not my transaction ID, so we can just return "false" immediately for * any non-normal XID. */ if (!TransactionIdIsNormal(xid)) return false; if (TransactionIdEquals(xid, GetTopTransactionIdIfAny())) return true; /* * In parallel workers, the XIDs we must consider as current are stored in * ParallelCurrentXids rather than the transaction-state stack. Note that * the XIDs in this array are sorted numerically rather than according to * transactionIdPrecedes order. */ if (nParallelCurrentXids > 0) { int low, high; low = 0; high = nParallelCurrentXids - 1; while (low <= high) { int middle; TransactionId probe; middle = low + (high - low) / 2; probe = ParallelCurrentXids[middle]; if (probe == xid) return true; else if (probe < xid) low = middle + 1; else high = middle - 1; } return false; } /* * We will return true for the Xid of the current subtransaction, any of * its subcommitted children, any of its parents, or any of their * previously subcommitted children. However, a transaction being aborted * is no longer "current", even though it may still have an entry on the * state stack. */ for (s = CurrentTransactionState; s != NULL; s = s->parent) { int low, high; if (s->state == TRANS_ABORT) continue; if (!FullTransactionIdIsValid(s->fullTransactionId)) continue; /* it can't have any child XIDs either */ if (TransactionIdEquals(xid, XidFromFullTransactionId(s->fullTransactionId))) return true; /* As the childXids array is ordered, we can use binary search */ low = 0; high = s->nChildXids - 1; while (low <= high) { int middle; TransactionId probe; middle = low + (high - low) / 2; probe = s->childXids[middle]; if (TransactionIdEquals(probe, xid)) return true; else if (TransactionIdPrecedes(probe, xid)) low = middle + 1; else high = middle - 1; } } return false; } /* * TransactionStartedDuringRecovery * * Returns true if the current transaction started while recovery was still * in progress. Recovery might have ended since so RecoveryInProgress() might * return false already. */ bool TransactionStartedDuringRecovery(void) { return CurrentTransactionState->startedInRecovery; } /* * GetTopReadOnlyTransactionNestLevel * * Note: this will return zero when not inside any transaction or when neither * a top-level transaction nor subtransactions are read-only, one when the * top-level transaction is read-only, two when one level of subtransaction is * read-only, etc. * * Note: subtransactions of the topmost read-only transaction are also * read-only, because they inherit read-only mode from the transaction, and * thus can't change to read-write mode (see check_transaction_read_only). */ int GetTopReadOnlyTransactionNestLevel(void) { TransactionState s = CurrentTransactionState; if (!XactReadOnly) return 0; while (s->nestingLevel > 1) { if (!s->prevXactReadOnly) return s->nestingLevel; s = s->parent; } return s->nestingLevel; } /* * EnterParallelMode */ void EnterParallelMode(void) { TransactionState s = CurrentTransactionState; Assert(s->parallelModeLevel >= 0); ++s->parallelModeLevel; } /* * ExitParallelMode */ void ExitParallelMode(void) { TransactionState s = CurrentTransactionState; Assert(s->parallelModeLevel > 0); Assert(s->parallelModeLevel > 1 || s->parallelChildXact || !ParallelContextActive()); --s->parallelModeLevel; } /* * IsInParallelMode * * Are we in a parallel operation, as either the leader or a worker? Check * this to prohibit operations that change backend-local state expected to * match across all workers. Mere caches usually don't require such a * restriction. State modified in a strict push/pop fashion, such as the * active snapshot stack, is often fine. * * We say we are in parallel mode if we are in a subxact of a transaction * that's initiated a parallel operation; for most purposes that context * has all the same restrictions. */ bool IsInParallelMode(void) { TransactionState s = CurrentTransactionState; return s->parallelModeLevel != 0 || s->parallelChildXact; } /* * CommandCounterIncrement */ void CommandCounterIncrement(void) { /* * If the current value of the command counter hasn't been "used" to mark * tuples, we need not increment it, since there's no need to distinguish * a read-only command from others. This helps postpone command counter * overflow, and keeps no-op CommandCounterIncrement operations cheap. */ if (currentCommandIdUsed) { /* * Workers synchronize transaction state at the beginning of each * parallel operation, so we can't account for new commands after that * point. */ if (IsInParallelMode() || IsParallelWorker()) ereport(ERROR, (errcode(ERRCODE_INVALID_TRANSACTION_STATE), errmsg("cannot start commands during a parallel operation"))); currentCommandId += 1; if (currentCommandId == InvalidCommandId) { currentCommandId -= 1; ereport(ERROR, (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), errmsg("cannot have more than 2^32-2 commands in a transaction"))); } currentCommandIdUsed = false; /* Propagate new command ID into static snapshots */ SnapshotSetCommandId(currentCommandId); /* * Make any catalog changes done by the just-completed command visible * in the local syscache. We obviously don't need to do this after a * read-only command. (But see hacks in inval.c to make real sure we * don't think a command that queued inval messages was read-only.) */ AtCCI_LocalCache(); } } /* * ForceSyncCommit * * Interface routine to allow commands to force a synchronous commit of the * current top-level transaction. Currently, two-phase commit does not * persist and restore this variable. So long as all callers use * PreventInTransactionBlock(), that omission has no consequences. */ void ForceSyncCommit(void) { forceSyncCommit = true; } /* ---------------------------------------------------------------- * StartTransaction stuff * ---------------------------------------------------------------- */ /* * AtStart_Cache */ static void AtStart_Cache(void) { AcceptInvalidationMessages(); } /* * AtStart_Memory */ static void AtStart_Memory(void) { TransactionState s = CurrentTransactionState; /* * Remember the memory context that was active prior to transaction start. */ s->priorContext = CurrentMemoryContext; /* * If this is the first time through, create a private context for * AbortTransaction to work in. By reserving some space now, we can * insulate AbortTransaction from out-of-memory scenarios. Like * ErrorContext, we set it up with slow growth rate and a nonzero minimum * size, so that space will be reserved immediately. */ if (TransactionAbortContext == NULL) TransactionAbortContext = AllocSetContextCreate(TopMemoryContext, "TransactionAbortContext", 32 * 1024, 32 * 1024, 32 * 1024); /* * Likewise, if this is the first time through, create a top-level context * for transaction-local data. This context will be reset at transaction * end, and then re-used in later transactions. */ if (TopTransactionContext == NULL) TopTransactionContext = AllocSetContextCreate(TopMemoryContext, "TopTransactionContext", ALLOCSET_DEFAULT_SIZES); /* * In a top-level transaction, CurTransactionContext is the same as * TopTransactionContext. */ CurTransactionContext = TopTransactionContext; s->curTransactionContext = CurTransactionContext; /* Make the CurTransactionContext active. */ MemoryContextSwitchTo(CurTransactionContext); } /* * AtStart_ResourceOwner */ static void AtStart_ResourceOwner(void) { TransactionState s = CurrentTransactionState; /* * We shouldn't have a transaction resource owner already. */ Assert(TopTransactionResourceOwner == NULL); /* * Create a toplevel resource owner for the transaction. */ s->curTransactionOwner = ResourceOwnerCreate(NULL, "TopTransaction"); TopTransactionResourceOwner = s->curTransactionOwner; CurTransactionResourceOwner = s->curTransactionOwner; CurrentResourceOwner = s->curTransactionOwner; } /* ---------------------------------------------------------------- * StartSubTransaction stuff * ---------------------------------------------------------------- */ /* * AtSubStart_Memory */ static void AtSubStart_Memory(void) { TransactionState s = CurrentTransactionState; Assert(CurTransactionContext != NULL); /* * Remember the context that was active prior to subtransaction start. */ s->priorContext = CurrentMemoryContext; /* * Create a CurTransactionContext, which will be used to hold data that * survives subtransaction commit but disappears on subtransaction abort. * We make it a child of the immediate parent's CurTransactionContext. */ CurTransactionContext = AllocSetContextCreate(CurTransactionContext, "CurTransactionContext", ALLOCSET_DEFAULT_SIZES); s->curTransactionContext = CurTransactionContext; /* Make the CurTransactionContext active. */ MemoryContextSwitchTo(CurTransactionContext); } /* * AtSubStart_ResourceOwner */ static void AtSubStart_ResourceOwner(void) { TransactionState s = CurrentTransactionState; Assert(s->parent != NULL); /* * Create a resource owner for the subtransaction. We make it a child of * the immediate parent's resource owner. */ s->curTransactionOwner = ResourceOwnerCreate(s->parent->curTransactionOwner, "SubTransaction"); CurTransactionResourceOwner = s->curTransactionOwner; CurrentResourceOwner = s->curTransactionOwner; } /* ---------------------------------------------------------------- * CommitTransaction stuff * ---------------------------------------------------------------- */ /* * RecordTransactionCommit * * Returns latest XID among xact and its children, or InvalidTransactionId * if the xact has no XID. (We compute that here just because it's easier.) * * If you change this function, see RecordTransactionCommitPrepared also. */ static TransactionId RecordTransactionCommit(void) { TransactionId xid = GetTopTransactionIdIfAny(); bool markXidCommitted = TransactionIdIsValid(xid); TransactionId latestXid = InvalidTransactionId; int nrels; RelFileLocator *rels; int nchildren; TransactionId *children; int ndroppedstats = 0; xl_xact_stats_item *droppedstats = NULL; int nmsgs = 0; SharedInvalidationMessage *invalMessages = NULL; bool RelcacheInitFileInval = false; bool wrote_xlog; /* * Log pending invalidations for logical decoding of in-progress * transactions. Normally for DDLs, we log this at each command end, * however, for certain cases where we directly update the system table * without a transaction block, the invalidations are not logged till this * time. */ if (XLogLogicalInfoActive()) LogLogicalInvalidations(); /* Get data needed for commit record */ nrels = smgrGetPendingDeletes(true, &rels); nchildren = xactGetCommittedChildren(&children); ndroppedstats = pgstat_get_transactional_drops(true, &droppedstats); if (XLogStandbyInfoActive()) nmsgs = xactGetCommittedInvalidationMessages(&invalMessages, &RelcacheInitFileInval); wrote_xlog = (XactLastRecEnd != 0); /* * If we haven't been assigned an XID yet, we neither can, nor do we want * to write a COMMIT record. */ if (!markXidCommitted) { /* * We expect that every RelationDropStorage is followed by a catalog * update, and hence XID assignment, so we shouldn't get here with any * pending deletes. Same is true for dropping stats. * * Use a real test not just an Assert to check this, since it's a bit * fragile. */ if (nrels != 0 || ndroppedstats != 0) elog(ERROR, "cannot commit a transaction that deleted files but has no xid"); /* Can't have child XIDs either; AssignTransactionId enforces this */ Assert(nchildren == 0); /* * Transactions without an assigned xid can contain invalidation * messages. While inplace updates do this, this is not known to be * necessary; see comment at inplace CacheInvalidateHeapTuple(). * Extensions might still rely on this capability, and standbys may * need to process those invals. We can't emit a commit record * without an xid, and we don't want to force assigning an xid, * because that'd be problematic for e.g. vacuum. Hence we emit a * bespoke record for the invalidations. We don't want to use that in * case a commit record is emitted, so they happen synchronously with * commits (besides not wanting to emit more WAL records). * * XXX Every known use of this capability is a defect. Since an XID * isn't controlling visibility of the change that prompted invals, * other sessions need the inval even if this transactions aborts. * * ON COMMIT DELETE ROWS does a nontransactional index_build(), which * queues a relcache inval, including in transactions without an xid * that had read the (empty) table. Standbys don't need any ON COMMIT * DELETE ROWS invals, but we've not done the work to withhold them. */ if (nmsgs != 0) { LogStandbyInvalidations(nmsgs, invalMessages, RelcacheInitFileInval); wrote_xlog = true; /* not strictly necessary */ } /* * If we didn't create XLOG entries, we're done here; otherwise we * should trigger flushing those entries the same as a commit record * would. This will primarily happen for HOT pruning and the like; we * want these to be flushed to disk in due time. */ if (!wrote_xlog) goto cleanup; } else { bool replorigin; /* * Are we using the replication origins feature? Or, in other words, * are we replaying remote actions? */ replorigin = (replorigin_xact_state.origin != InvalidReplOriginId && replorigin_xact_state.origin != DoNotReplicateId); /* * Mark ourselves as within our "commit critical section". This * forces any concurrent checkpoint to wait until we've updated * pg_xact. Without this, it is possible for the checkpoint to set * REDO after the XLOG record but fail to flush the pg_xact update to * disk, leading to loss of the transaction commit if the system * crashes a little later. * * Note: we could, but don't bother to, set this flag in * RecordTransactionAbort. That's because loss of a transaction abort * is noncritical; the presumption would be that it aborted, anyway. * * It's safe to change the delayChkptFlags flag of our own backend * without holding the ProcArrayLock, since we're the only one * modifying it. This makes checkpoint's determination of which xacts * are delaying the checkpoint a bit fuzzy, but it doesn't matter. * * Note, it is important to get the commit timestamp after marking the * transaction in the commit critical section. See * RecordTransactionCommitPrepared. */ Assert((MyProc->delayChkptFlags & DELAY_CHKPT_IN_COMMIT) == 0); START_CRIT_SECTION(); MyProc->delayChkptFlags |= DELAY_CHKPT_IN_COMMIT; Assert(xactStopTimestamp == 0); /* * Ensures the DELAY_CHKPT_IN_COMMIT flag write is globally visible * before commit time is written. */ pg_write_barrier(); /* * Insert the commit XLOG record. */ XactLogCommitRecord(GetCurrentTransactionStopTimestamp(), nchildren, children, nrels, rels, ndroppedstats, droppedstats, nmsgs, invalMessages, RelcacheInitFileInval, MyXactFlags, InvalidTransactionId, NULL /* plain commit */ ); if (replorigin) /* Move LSNs forward for this replication origin */ replorigin_session_advance(replorigin_xact_state.origin_lsn, XactLastRecEnd); /* * Record commit timestamp. The value comes from plain commit * timestamp if there's no replication origin; otherwise, the * timestamp was already set in replorigin_xact_state.origin_timestamp * by replication. * * We don't need to WAL-log anything here, as the commit record * written above already contains the data. */ if (!replorigin || replorigin_xact_state.origin_timestamp == 0) replorigin_xact_state.origin_timestamp = GetCurrentTransactionStopTimestamp(); TransactionTreeSetCommitTsData(xid, nchildren, children, replorigin_xact_state.origin_timestamp, replorigin_xact_state.origin); } /* * Check if we want to commit asynchronously. We can allow the XLOG flush * to happen asynchronously if synchronous_commit=off, or if the current * transaction has not performed any WAL-logged operation or didn't assign * an xid. The transaction can end up not writing any WAL, even if it has * an xid, if it only wrote to temporary and/or unlogged tables. It can * end up having written WAL without an xid if it did HOT pruning. In * case of a crash, the loss of such a transaction will be irrelevant; * temp tables will be lost anyway, unlogged tables will be truncated and * HOT pruning will be done again later. (Given the foregoing, you might * think that it would be unnecessary to emit the XLOG record at all in * this case, but we don't currently try to do that. It would certainly * cause problems at least in Hot Standby mode, where the * KnownAssignedXids machinery requires tracking every XID assignment. It * might be OK to skip it only when wal_level < replica, but for now we * don't.) * * However, if we're doing cleanup of any non-temp rels or committing any * command that wanted to force sync commit, then we must flush XLOG * immediately. (We must not allow asynchronous commit if there are any * non-temp tables to be deleted, because we might delete the files before * the COMMIT record is flushed to disk. We do allow asynchronous commit * if all to-be-deleted tables are temporary though, since they are lost * anyway if we crash.) */ if ((wrote_xlog && markXidCommitted && synchronous_commit > SYNCHRONOUS_COMMIT_OFF) || forceSyncCommit || nrels > 0) { XLogFlush(XactLastRecEnd); /* * Now we may update the CLOG, if we wrote a COMMIT record above */ if (markXidCommitted) TransactionIdCommitTree(xid, nchildren, children); } else { /* * Asynchronous commit case: * * This enables possible committed transaction loss in the case of a * postmaster crash because WAL buffers are left unwritten. Ideally we * could issue the WAL write without the fsync, but some * wal_sync_methods do not allow separate write/fsync. * * Report the latest async commit LSN, so that the WAL writer knows to * flush this commit. */ XLogSetAsyncXactLSN(XactLastRecEnd); /* * We must not immediately update the CLOG, since we didn't flush the * XLOG. Instead, we store the LSN up to which the XLOG must be * flushed before the CLOG may be updated. */ if (markXidCommitted) TransactionIdAsyncCommitTree(xid, nchildren, children, XactLastRecEnd); } /* * If we entered a commit critical section, leave it now, and let * checkpoints proceed. */ if (markXidCommitted) { MyProc->delayChkptFlags &= ~DELAY_CHKPT_IN_COMMIT; END_CRIT_SECTION(); } /* Compute latestXid while we have the child XIDs handy */ latestXid = TransactionIdLatest(xid, nchildren, children); /* * Wait for synchronous replication, if required. Similar to the decision * above about using committing asynchronously we only want to wait if * this backend assigned an xid and wrote WAL. No need to wait if an xid * was assigned due to temporary/unlogged tables or due to HOT pruning. * * Note that at this stage we have marked clog, but still show as running * in the procarray and continue to hold locks. */ if (wrote_xlog && markXidCommitted) SyncRepWaitForLSN(XactLastRecEnd, true); /* remember end of last commit record */ XactLastCommitEnd = XactLastRecEnd; /* Reset XactLastRecEnd until the next transaction writes something */ XactLastRecEnd = 0; cleanup: /* Clean up local data */ if (rels) pfree(rels); if (ndroppedstats) pfree(droppedstats); return latestXid; } /* * AtCCI_LocalCache */ static void AtCCI_LocalCache(void) { /* * Make any pending relation map changes visible. We must do this before * processing local sinval messages, so that the map changes will get * reflected into the relcache when relcache invals are processed. */ AtCCI_RelationMap(); /* * Make catalog changes visible to me for the next command. */ CommandEndInvalidationMessages(); } /* * AtCommit_Memory */ static void AtCommit_Memory(void) { TransactionState s = CurrentTransactionState; /* * Return to the memory context that was current before we started the * transaction. (In principle, this could not be any of the contexts we * are about to delete. If it somehow is, assertions in mcxt.c will * complain.) */ MemoryContextSwitchTo(s->priorContext); /* * Release all transaction-local memory. TopTransactionContext survives * but becomes empty; any sub-contexts go away. */ Assert(TopTransactionContext != NULL); MemoryContextReset(TopTransactionContext); /* * Clear these pointers as a pro-forma matter. (Notionally, while * TopTransactionContext still exists, it's currently not associated with * this TransactionState struct.) */ CurTransactionContext = NULL; s->curTransactionContext = NULL; } /* ---------------------------------------------------------------- * CommitSubTransaction stuff * ---------------------------------------------------------------- */ /* * AtSubCommit_Memory */ static void AtSubCommit_Memory(void) { TransactionState s = CurrentTransactionState; Assert(s->parent != NULL); /* Return to parent transaction level's memory context. */ CurTransactionContext = s->parent->curTransactionContext; MemoryContextSwitchTo(CurTransactionContext); /* * Ordinarily we cannot throw away the child's CurTransactionContext, * since the data it contains will be needed at upper commit. However, if * there isn't actually anything in it, we can throw it away. This avoids * a small memory leak in the common case of "trivial" subxacts. */ if (MemoryContextIsEmpty(s->curTransactionContext)) { MemoryContextDelete(s->curTransactionContext); s->curTransactionContext = NULL; } } /* * AtSubCommit_childXids * * Pass my own XID and my child XIDs up to my parent as committed children. */ static void AtSubCommit_childXids(void) { TransactionState s = CurrentTransactionState; int new_nChildXids; Assert(s->parent != NULL); /* * The parent childXids array will need to hold my XID and all my * childXids, in addition to the XIDs already there. */ new_nChildXids = s->parent->nChildXids + s->nChildXids + 1; /* Allocate or enlarge the parent array if necessary */ if (s->parent->maxChildXids < new_nChildXids) { int new_maxChildXids; TransactionId *new_childXids; /* * Make it 2x what's needed right now, to avoid having to enlarge it * repeatedly. But we can't go above MaxAllocSize. (The latter limit * is what ensures that we don't need to worry about integer overflow * here or in the calculation of new_nChildXids.) */ new_maxChildXids = Min(new_nChildXids * 2, (int) (MaxAllocSize / sizeof(TransactionId))); if (new_maxChildXids < new_nChildXids) ereport(ERROR, (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), errmsg("maximum number of committed subtransactions (%d) exceeded", (int) (MaxAllocSize / sizeof(TransactionId))))); /* * We keep the child-XID arrays in TopTransactionContext; this avoids * setting up child-transaction contexts for what might be just a few * bytes of grandchild XIDs. */ if (s->parent->childXids == NULL) new_childXids = MemoryContextAlloc(TopTransactionContext, new_maxChildXids * sizeof(TransactionId)); else new_childXids = repalloc(s->parent->childXids, new_maxChildXids * sizeof(TransactionId)); s->parent->childXids = new_childXids; s->parent->maxChildXids = new_maxChildXids; } /* * Copy all my XIDs to parent's array. * * Note: We rely on the fact that the XID of a child always follows that * of its parent. By copying the XID of this subtransaction before the * XIDs of its children, we ensure that the array stays ordered. Likewise, * all XIDs already in the array belong to subtransactions started and * subcommitted before us, so their XIDs must precede ours. */ s->parent->childXids[s->parent->nChildXids] = XidFromFullTransactionId(s->fullTransactionId); if (s->nChildXids > 0) memcpy(&s->parent->childXids[s->parent->nChildXids + 1], s->childXids, s->nChildXids * sizeof(TransactionId)); s->parent->nChildXids = new_nChildXids; /* Release child's array to avoid leakage */ if (s->childXids != NULL) pfree(s->childXids); /* We must reset these to avoid double-free if fail later in commit */ s->childXids = NULL; s->nChildXids = 0; s->maxChildXids = 0; } /* ---------------------------------------------------------------- * AbortTransaction stuff * ---------------------------------------------------------------- */ /* * RecordTransactionAbort * * Returns latest XID among xact and its children, or InvalidTransactionId * if the xact has no XID. (We compute that here just because it's easier.) */ static TransactionId RecordTransactionAbort(bool isSubXact) { TransactionId xid = GetCurrentTransactionIdIfAny(); TransactionId latestXid; int nrels; RelFileLocator *rels; int ndroppedstats = 0; xl_xact_stats_item *droppedstats = NULL; int nchildren; TransactionId *children; TimestampTz xact_time; bool replorigin; /* * If we haven't been assigned an XID, nobody will care whether we aborted * or not. Hence, we're done in that case. It does not matter if we have * rels to delete (note that this routine is not responsible for actually * deleting 'em). We cannot have any child XIDs, either. */ if (!TransactionIdIsValid(xid)) { /* Reset XactLastRecEnd until the next transaction writes something */ if (!isSubXact) XactLastRecEnd = 0; return InvalidTransactionId; } /* * We have a valid XID, so we should write an ABORT record for it. * * We do not flush XLOG to disk here, since the default assumption after a * crash would be that we aborted, anyway. For the same reason, we don't * need to worry about interlocking against checkpoint start. */ /* * Check that we haven't aborted halfway through RecordTransactionCommit. */ if (TransactionIdDidCommit(xid)) elog(PANIC, "cannot abort transaction %u, it was already committed", xid); /* * Are we using the replication origins feature? Or, in other words, are * we replaying remote actions? */ replorigin = (replorigin_xact_state.origin != InvalidReplOriginId && replorigin_xact_state.origin != DoNotReplicateId); /* Fetch the data we need for the abort record */ nrels = smgrGetPendingDeletes(false, &rels); nchildren = xactGetCommittedChildren(&children); ndroppedstats = pgstat_get_transactional_drops(false, &droppedstats); /* XXX do we really need a critical section here? */ START_CRIT_SECTION(); /* Write the ABORT record */ if (isSubXact) xact_time = GetCurrentTimestamp(); else { xact_time = GetCurrentTransactionStopTimestamp(); } XactLogAbortRecord(xact_time, nchildren, children, nrels, rels, ndroppedstats, droppedstats, MyXactFlags, InvalidTransactionId, NULL); if (replorigin) /* Move LSNs forward for this replication origin */ replorigin_session_advance(replorigin_xact_state.origin_lsn, XactLastRecEnd); /* * Report the latest async abort LSN, so that the WAL writer knows to * flush this abort. There's nothing to be gained by delaying this, since * WALWriter may as well do this when it can. This is important with * streaming replication because if we don't flush WAL regularly we will * find that large aborts leave us with a long backlog for when commits * occur after the abort, increasing our window of data loss should * problems occur at that point. */ if (!isSubXact) XLogSetAsyncXactLSN(XactLastRecEnd); /* * Mark the transaction aborted in clog. This is not absolutely necessary * but we may as well do it while we are here; also, in the subxact case * it is helpful because XactLockTableWait makes use of it to avoid * waiting for already-aborted subtransactions. It is OK to do it without * having flushed the ABORT record to disk, because in event of a crash * we'd be assumed to have aborted anyway. */ TransactionIdAbortTree(xid, nchildren, children); END_CRIT_SECTION(); /* Compute latestXid while we have the child XIDs handy */ latestXid = TransactionIdLatest(xid, nchildren, children); /* * If we're aborting a subtransaction, we can immediately remove failed * XIDs from PGPROC's cache of running child XIDs. We do that here for * subxacts, because we already have the child XID array at hand. For * main xacts, the equivalent happens just after this function returns. */ if (isSubXact) XidCacheRemoveRunningXids(xid, nchildren, children, latestXid); /* Reset XactLastRecEnd until the next transaction writes something */ if (!isSubXact) XactLastRecEnd = 0; /* And clean up local data */ if (rels) pfree(rels); if (ndroppedstats) pfree(droppedstats); return latestXid; } /* * AtAbort_Memory */ static void AtAbort_Memory(void) { /* * Switch into TransactionAbortContext, which should have some free space * even if nothing else does. We'll work in this context until we've * finished cleaning up. * * It is barely possible to get here when we've not been able to create * TransactionAbortContext yet; if so use TopMemoryContext. */ if (TransactionAbortContext != NULL) MemoryContextSwitchTo(TransactionAbortContext); else MemoryContextSwitchTo(TopMemoryContext); } /* * AtSubAbort_Memory */ static void AtSubAbort_Memory(void) { Assert(TransactionAbortContext != NULL); MemoryContextSwitchTo(TransactionAbortContext); } /* * AtAbort_ResourceOwner */ static void AtAbort_ResourceOwner(void) { /* * Make sure we have a valid ResourceOwner, if possible (else it will be * NULL, which is OK) */ CurrentResourceOwner = TopTransactionResourceOwner; } /* * AtSubAbort_ResourceOwner */ static void AtSubAbort_ResourceOwner(void) { TransactionState s = CurrentTransactionState; /* Make sure we have a valid ResourceOwner */ CurrentResourceOwner = s->curTransactionOwner; } /* * AtSubAbort_childXids */ static void AtSubAbort_childXids(void) { TransactionState s = CurrentTransactionState; /* * We keep the child-XID arrays in TopTransactionContext (see * AtSubCommit_childXids). This means we'd better free the array * explicitly at abort to avoid leakage. */ if (s->childXids != NULL) pfree(s->childXids); s->childXids = NULL; s->nChildXids = 0; s->maxChildXids = 0; /* * We could prune the unreportedXids array here. But we don't bother. That * would potentially reduce number of XLOG_XACT_ASSIGNMENT records but it * would likely introduce more CPU time into the more common paths, so we * choose not to do that. */ } /* ---------------------------------------------------------------- * CleanupTransaction stuff * ---------------------------------------------------------------- */ /* * AtCleanup_Memory */ static void AtCleanup_Memory(void) { TransactionState s = CurrentTransactionState; /* Should be at top level */ Assert(s->parent == NULL); /* * Return to the memory context that was current before we started the * transaction. (In principle, this could not be any of the contexts we * are about to delete. If it somehow is, assertions in mcxt.c will * complain.) */ MemoryContextSwitchTo(s->priorContext); /* * Clear the special abort context for next time. */ if (TransactionAbortContext != NULL) MemoryContextReset(TransactionAbortContext); /* * Release all transaction-local memory, the same as in AtCommit_Memory, * except we must cope with the possibility that we didn't get as far as * creating TopTransactionContext. */ if (TopTransactionContext != NULL) MemoryContextReset(TopTransactionContext); /* * Clear these pointers as a pro-forma matter. (Notionally, while * TopTransactionContext still exists, it's currently not associated with * this TransactionState struct.) */ CurTransactionContext = NULL; s->curTransactionContext = NULL; } /* ---------------------------------------------------------------- * CleanupSubTransaction stuff * ---------------------------------------------------------------- */ /* * AtSubCleanup_Memory */ static void AtSubCleanup_Memory(void) { TransactionState s = CurrentTransactionState; Assert(s->parent != NULL); /* * Return to the memory context that was current before we started the * subtransaction. (In principle, this could not be any of the contexts * we are about to delete. If it somehow is, assertions in mcxt.c will * complain.) */ MemoryContextSwitchTo(s->priorContext); /* Update CurTransactionContext (might not be same as priorContext) */ CurTransactionContext = s->parent->curTransactionContext; /* * Clear the special abort context for next time. */ if (TransactionAbortContext != NULL) MemoryContextReset(TransactionAbortContext); /* * Delete the subxact local memory contexts. Its CurTransactionContext can * go too (note this also kills CurTransactionContexts from any children * of the subxact). */ if (s->curTransactionContext) MemoryContextDelete(s->curTransactionContext); s->curTransactionContext = NULL; } /* ---------------------------------------------------------------- * interface routines * ---------------------------------------------------------------- */ /* * StartTransaction */ static void StartTransaction(void) { TransactionState s; VirtualTransactionId vxid; /* * Let's just make sure the state stack is empty */ s = &TopTransactionStateData; CurrentTransactionState = s; Assert(!FullTransactionIdIsValid(XactTopFullTransactionId)); /* check the current transaction state */ Assert(s->state == TRANS_DEFAULT); /* * Set the current transaction state information appropriately during * start processing. Note that once the transaction status is switched * this process cannot fail until the user ID and the security context * flags are fetched below. */ s->state = TRANS_START; s->fullTransactionId = InvalidFullTransactionId; /* until assigned */ /* Determine if statements are logged in this transaction */ xact_is_sampled = log_xact_sample_rate != 0 && (log_xact_sample_rate == 1 || pg_prng_double(&pg_global_prng_state) <= log_xact_sample_rate); /* * initialize current transaction state fields * * note: prevXactReadOnly is not used at the outermost level */ s->nestingLevel = 1; s->gucNestLevel = 1; s->childXids = NULL; s->nChildXids = 0; s->maxChildXids = 0; /* * Once the current user ID and the security context flags are fetched, * both will be properly reset even if transaction startup fails. */ GetUserIdAndSecContext(&s->prevUser, &s->prevSecContext); /* SecurityRestrictionContext should never be set outside a transaction */ Assert(s->prevSecContext == 0); /* * Make sure we've reset xact state variables * * If recovery is still in progress, mark this transaction as read-only. * We have lower level defences in XLogInsert and elsewhere to stop us * from modifying data during recovery, but this gives the normal * indication to the user that the transaction is read-only. */ if (RecoveryInProgress()) { s->startedInRecovery = true; XactReadOnly = true; } else { s->startedInRecovery = false; XactReadOnly = DefaultXactReadOnly; } XactDeferrable = DefaultXactDeferrable; XactIsoLevel = DefaultXactIsoLevel; forceSyncCommit = false; MyXactFlags = 0; /* * reinitialize within-transaction counters */ s->subTransactionId = TopSubTransactionId; currentSubTransactionId = TopSubTransactionId; currentCommandId = FirstCommandId; currentCommandIdUsed = false; /* * initialize reported xid accounting */ nUnreportedXids = 0; s->didLogXid = false; /* * must initialize resource-management stuff first */ AtStart_Memory(); AtStart_ResourceOwner(); /* * Assign a new LocalTransactionId, and combine it with the proc number to * form a virtual transaction id. */ vxid.procNumber = MyProcNumber; vxid.localTransactionId = GetNextLocalTransactionId(); /* * Lock the virtual transaction id before we announce it in the proc array */ VirtualXactLockTableInsert(vxid); /* * Advertise it in the proc array. We assume assignment of * localTransactionId is atomic, and the proc number should be set * already. */ Assert(MyProc->vxid.procNumber == vxid.procNumber); MyProc->vxid.lxid = vxid.localTransactionId; TRACE_POSTGRESQL_TRANSACTION_START(vxid.localTransactionId); /* * set transaction_timestamp() (a/k/a now()). Normally, we want this to * be the same as the first command's statement_timestamp(), so don't do a * fresh GetCurrentTimestamp() call (which'd be expensive anyway). But * for transactions started inside procedures (i.e., nonatomic SPI * contexts), we do need to advance the timestamp. Also, in a parallel * worker, the timestamp should already have been provided by a call to * SetParallelStartTimestamps(). */ if (!IsParallelWorker()) { if (!SPI_inside_nonatomic_context()) xactStartTimestamp = stmtStartTimestamp; else xactStartTimestamp = GetCurrentTimestamp(); } else Assert(xactStartTimestamp != 0); pgstat_report_xact_timestamp(xactStartTimestamp); /* Mark xactStopTimestamp as unset. */ xactStopTimestamp = 0; /* * initialize other subsystems for new transaction */ AtStart_GUC(); AtStart_Cache(); AfterTriggerBeginXact(); /* * done with start processing, set current transaction state to "in * progress" */ s->state = TRANS_INPROGRESS; /* Schedule transaction timeout */ if (TransactionTimeout > 0) enable_timeout_after(TRANSACTION_TIMEOUT, TransactionTimeout); ShowTransactionState("StartTransaction"); } /* * CommitTransaction * * NB: if you change this routine, better look at PrepareTransaction too! */ static void CommitTransaction(void) { TransactionState s = CurrentTransactionState; TransactionId latestXid; bool is_parallel_worker; is_parallel_worker = (s->blockState == TBLOCK_PARALLEL_INPROGRESS); /* Enforce parallel mode restrictions during parallel worker commit. */ if (is_parallel_worker) EnterParallelMode(); ShowTransactionState("CommitTransaction"); /* * check the current transaction state */ if (s->state != TRANS_INPROGRESS) elog(WARNING, "CommitTransaction while in %s state", TransStateAsString(s->state)); Assert(s->parent == NULL); /* * Do pre-commit processing that involves calling user-defined code, such * as triggers. SECURITY_RESTRICTED_OPERATION contexts must not queue an * action that would run here, because that would bypass the sandbox. * Since closing cursors could queue trigger actions, triggers could open * cursors, etc, we have to keep looping until there's nothing left to do. */ for (;;) { /* * Fire all currently pending deferred triggers. */ AfterTriggerFireDeferred(); /* * Close open portals (converting holdable ones into static portals). * If there weren't any, we are done ... otherwise loop back to check * if they queued deferred triggers. Lather, rinse, repeat. */ if (!PreCommit_Portals(false)) break; } /* * The remaining actions cannot call any user-defined code, so it's safe * to start shutting down within-transaction services. But note that most * of this stuff could still throw an error, which would switch us into * the transaction-abort path. */ CallXactCallbacks(is_parallel_worker ? XACT_EVENT_PARALLEL_PRE_COMMIT : XACT_EVENT_PRE_COMMIT); /* * If this xact has started any unfinished parallel operation, clean up * its workers, warning about leaked resources. (But we don't actually * reset parallelModeLevel till entering TRANS_COMMIT, a bit below. This * keeps parallel mode restrictions active as long as possible in a * parallel worker.) */ AtEOXact_Parallel(true); if (is_parallel_worker) { if (s->parallelModeLevel != 1) elog(WARNING, "parallelModeLevel is %d not 1 at end of parallel worker transaction", s->parallelModeLevel); } else { if (s->parallelModeLevel != 0) elog(WARNING, "parallelModeLevel is %d not 0 at end of transaction", s->parallelModeLevel); } /* Shut down the deferred-trigger manager */ AfterTriggerEndXact(true); /* * Let ON COMMIT management do its thing (must happen after closing * cursors, to avoid dangling-reference problems) */ PreCommit_on_commit_actions(); /* * Synchronize files that are created and not WAL-logged during this * transaction. This must happen before AtEOXact_RelationMap(), so that we * don't see committed-but-broken files after a crash. */ smgrDoPendingSyncs(true, is_parallel_worker); /* close large objects before lower-level cleanup */ AtEOXact_LargeObject(true); /* * Insert notifications sent by NOTIFY commands into the queue. This * should be late in the pre-commit sequence to minimize time spent * holding the notify-insertion lock. However, this could result in * creating a snapshot, so we must do it before serializable cleanup. */ PreCommit_Notify(); /* * Mark serializable transaction as complete for predicate locking * purposes. This should be done as late as we can put it and still allow * errors to be raised for failure patterns found at commit. This is not * appropriate in a parallel worker however, because we aren't committing * the leader's transaction and its serializable state will live on. */ if (!is_parallel_worker) PreCommit_CheckForSerializationFailure(); /* Prevent cancel/die interrupt while cleaning up */ HOLD_INTERRUPTS(); /* Commit updates to the relation map --- do this as late as possible */ AtEOXact_RelationMap(true, is_parallel_worker); /* * set the current transaction state information appropriately during * commit processing */ s->state = TRANS_COMMIT; s->parallelModeLevel = 0; s->parallelChildXact = false; /* should be false already */ /* Disable transaction timeout */ if (TransactionTimeout > 0) disable_timeout(TRANSACTION_TIMEOUT, false); if (!is_parallel_worker) { /* * We need to mark our XIDs as committed in pg_xact. This is where we * durably commit. */ latestXid = RecordTransactionCommit(); } else { /* * We must not mark our XID committed; the parallel leader is * responsible for that. */ latestXid = InvalidTransactionId; /* * Make sure the leader will know about any WAL we wrote before it * commits. */ ParallelWorkerReportLastRecEnd(XactLastRecEnd); } TRACE_POSTGRESQL_TRANSACTION_COMMIT(MyProc->vxid.lxid); /* * Let others know about no transaction in progress by me. Note that this * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ ProcArrayEndTransaction(MyProc, latestXid); /* * This is all post-commit cleanup. Note that if an error is raised here, * it's too late to abort the transaction. This should be just * noncritical resource releasing. * * The ordering of operations is not entirely random. The idea is: * release resources visible to other backends (eg, files, buffer pins); * then release locks; then release backend-local resources. We want to * release locks at the point where any backend waiting for us will see * our transaction as being fully cleaned up. * * Resources that can be associated with individual queries are handled by * the ResourceOwner mechanism. The other calls here are for backend-wide * state. */ CallXactCallbacks(is_parallel_worker ? XACT_EVENT_PARALLEL_COMMIT : XACT_EVENT_COMMIT); CurrentResourceOwner = NULL; ResourceOwnerRelease(TopTransactionResourceOwner, RESOURCE_RELEASE_BEFORE_LOCKS, true, true); AtEOXact_Aio(true); /* Check we've released all buffer pins */ AtEOXact_Buffers(true); /* Clean up the relation cache */ AtEOXact_RelationCache(true); /* Clean up the type cache */ AtEOXact_TypeCache(); /* * Make catalog changes visible to all backends. This has to happen after * relcache references are dropped (see comments for * AtEOXact_RelationCache), but before locks are released (if anyone is * waiting for lock on a relation we've modified, we want them to know * about the catalog change before they start using the relation). */ AtEOXact_Inval(true); AtEOXact_MultiXact(); ResourceOwnerRelease(TopTransactionResourceOwner, RESOURCE_RELEASE_LOCKS, true, true); ResourceOwnerRelease(TopTransactionResourceOwner, RESOURCE_RELEASE_AFTER_LOCKS, true, true); /* * Likewise, dropping of files deleted during the transaction is best done * after releasing relcache and buffer pins. (This is not strictly * necessary during commit, since such pins should have been released * already, but this ordering is definitely critical during abort.) Since * this may take many seconds, also delay until after releasing locks. * Other backends will observe the attendant catalog changes and not * attempt to access affected files. */ smgrDoPendingDeletes(true); /* * Send out notification signals to other backends (and do other * post-commit NOTIFY cleanup). This must not happen until after our * transaction is fully done from the viewpoint of other backends. */ AtCommit_Notify(); /* * Everything after this should be purely internal-to-this-backend * cleanup. */ AtEOXact_GUC(true, 1); AtEOXact_SPI(true); AtEOXact_Enum(); AtEOXact_on_commit_actions(true); AtEOXact_Namespace(true, is_parallel_worker); AtEOXact_SMgr(); AtEOXact_Files(true); AtEOXact_ComboCid(); AtEOXact_HashTables(true); AtEOXact_RI(true); AtEOXact_PgStat(true, is_parallel_worker); AtEOXact_Snapshot(true, false); AtEOXact_ApplyLauncher(true); AtEOXact_LogicalRepWorkers(true); AtEOXact_LogicalCtl(); pgstat_report_xact_timestamp(0); ResourceOwnerDelete(TopTransactionResourceOwner); s->curTransactionOwner = NULL; CurTransactionResourceOwner = NULL; TopTransactionResourceOwner = NULL; AtCommit_Memory(); s->fullTransactionId = InvalidFullTransactionId; s->subTransactionId = InvalidSubTransactionId; s->nestingLevel = 0; s->gucNestLevel = 0; s->childXids = NULL; s->nChildXids = 0; s->maxChildXids = 0; XactTopFullTransactionId = InvalidFullTransactionId; nParallelCurrentXids = 0; /* * done with commit processing, set current transaction state back to * default */ s->state = TRANS_DEFAULT; RESUME_INTERRUPTS(); } /* * PrepareTransaction * * NB: if you change this routine, better look at CommitTransaction too! */ static void PrepareTransaction(void) { TransactionState s = CurrentTransactionState; FullTransactionId fxid = GetCurrentFullTransactionId(); GlobalTransaction gxact; TimestampTz prepared_at; Assert(!IsInParallelMode()); ShowTransactionState("PrepareTransaction"); /* * check the current transaction state */ if (s->state != TRANS_INPROGRESS) elog(WARNING, "PrepareTransaction while in %s state", TransStateAsString(s->state)); Assert(s->parent == NULL); /* * Do pre-commit processing that involves calling user-defined code, such * as triggers. Since closing cursors could queue trigger actions, * triggers could open cursors, etc, we have to keep looping until there's * nothing left to do. */ for (;;) { /* * Fire all currently pending deferred triggers. */ AfterTriggerFireDeferred(); /* * Close open portals (converting holdable ones into static portals). * If there weren't any, we are done ... otherwise loop back to check * if they queued deferred triggers. Lather, rinse, repeat. */ if (!PreCommit_Portals(true)) break; } CallXactCallbacks(XACT_EVENT_PRE_PREPARE); /* * The remaining actions cannot call any user-defined code, so it's safe * to start shutting down within-transaction services. But note that most * of this stuff could still throw an error, which would switch us into * the transaction-abort path. */ /* Shut down the deferred-trigger manager */ AfterTriggerEndXact(true); /* * Let ON COMMIT management do its thing (must happen after closing * cursors, to avoid dangling-reference problems) */ PreCommit_on_commit_actions(); /* * Synchronize files that are created and not WAL-logged during this * transaction. This must happen before EndPrepare(), so that we don't see * committed-but-broken files after a crash and COMMIT PREPARED. */ smgrDoPendingSyncs(true, false); /* close large objects before lower-level cleanup */ AtEOXact_LargeObject(true); /* NOTIFY requires no work at this point */ /* * Mark serializable transaction as complete for predicate locking * purposes. This should be done as late as we can put it and still allow * errors to be raised for failure patterns found at commit. */ PreCommit_CheckForSerializationFailure(); /* * Don't allow PREPARE TRANSACTION if we've accessed a temporary table in * this transaction. Having the prepared xact hold locks on another * backend's temp table seems a bad idea --- for instance it would prevent * the backend from exiting. There are other problems too, such as how to * clean up the source backend's local buffers and ON COMMIT state if the * prepared xact includes a DROP of a temp table. * * Other objects types, like functions, operators or extensions, share the * same restriction as they should not be created, locked or dropped as * this can mess up with this session or even a follow-up session trying * to use the same temporary namespace. * * We must check this after executing any ON COMMIT actions, because they * might still access a temp relation. * * XXX In principle this could be relaxed to allow some useful special * cases, such as a temp table created and dropped all within the * transaction. That seems to require much more bookkeeping though. */ if ((MyXactFlags & XACT_FLAGS_ACCESSEDTEMPNAMESPACE)) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot PREPARE a transaction that has operated on temporary objects"))); /* * Likewise, don't allow PREPARE after pg_export_snapshot. This could be * supported if we added cleanup logic to twophase.c, but for now it * doesn't seem worth the trouble. */ if (XactHasExportedSnapshots()) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot PREPARE a transaction that has exported snapshots"))); /* Prevent cancel/die interrupt while cleaning up */ HOLD_INTERRUPTS(); /* * set the current transaction state information appropriately during * prepare processing */ s->state = TRANS_PREPARE; /* Disable transaction timeout */ if (TransactionTimeout > 0) disable_timeout(TRANSACTION_TIMEOUT, false); prepared_at = GetCurrentTimestamp(); /* * Reserve the GID for this transaction. This could fail if the requested * GID is invalid or already in use. */ gxact = MarkAsPreparing(fxid, prepareGID, prepared_at, GetUserId(), MyDatabaseId); prepareGID = NULL; /* * Collect data for the 2PC state file. Note that in general, no actual * state change should happen in the called modules during this step, * since it's still possible to fail before commit, and in that case we * want transaction abort to be able to clean up. (In particular, the * AtPrepare routines may error out if they find cases they cannot * handle.) State cleanup should happen in the PostPrepare routines * below. However, some modules can go ahead and clear state here because * they wouldn't do anything with it during abort anyway. * * Note: because the 2PC state file records will be replayed in the same * order they are made, the order of these calls has to match the order in * which we want things to happen during COMMIT PREPARED or ROLLBACK * PREPARED; in particular, pay attention to whether things should happen * before or after releasing the transaction's locks. */ StartPrepare(gxact); AtPrepare_Notify(); AtPrepare_Locks(); AtPrepare_PredicateLocks(); AtPrepare_PgStat(); AtPrepare_MultiXact(); AtPrepare_RelationMap(); /* * Here is where we really truly prepare. * * We have to record transaction prepares even if we didn't make any * updates, because the transaction manager might get confused if we lose * a global transaction. */ EndPrepare(gxact); /* * Now we clean up backend-internal state and release internal resources. */ /* Reset XactLastRecEnd until the next transaction writes something */ XactLastRecEnd = 0; /* * Transfer our locks to a dummy PGPROC. This has to be done before * ProcArrayClearTransaction(). Otherwise, a GetLockConflicts() would * conclude "xact already committed or aborted" for our locks. */ PostPrepare_Locks(fxid); /* * Let others know about no transaction in progress by me. This has to be * done *after* the prepared transaction has been marked valid, else * someone may think it is unlocked and recyclable. */ ProcArrayClearTransaction(MyProc); /* * In normal commit-processing, this is all non-critical post-transaction * cleanup. When the transaction is prepared, however, it's important * that the locks and other per-backend resources are transferred to the * prepared transaction's PGPROC entry. Note that if an error is raised * here, it's too late to abort the transaction. XXX: This probably should * be in a critical section, to force a PANIC if any of this fails, but * that cure could be worse than the disease. */ CallXactCallbacks(XACT_EVENT_PREPARE); ResourceOwnerRelease(TopTransactionResourceOwner, RESOURCE_RELEASE_BEFORE_LOCKS, true, true); AtEOXact_Aio(true); /* Check we've released all buffer pins */ AtEOXact_Buffers(true); /* Clean up the relation cache */ AtEOXact_RelationCache(true); /* Clean up the type cache */ AtEOXact_TypeCache(); /* notify doesn't need a postprepare call */ PostPrepare_PgStat(); PostPrepare_Inval(); PostPrepare_smgr(); PostPrepare_MultiXact(fxid); PostPrepare_PredicateLocks(fxid); ResourceOwnerRelease(TopTransactionResourceOwner, RESOURCE_RELEASE_LOCKS, true, true); ResourceOwnerRelease(TopTransactionResourceOwner, RESOURCE_RELEASE_AFTER_LOCKS, true, true); /* * Allow another backend to finish the transaction. After * PostPrepare_Twophase(), the transaction is completely detached from our * backend. The rest is just non-critical cleanup of backend-local state. */ PostPrepare_Twophase(); /* PREPARE acts the same as COMMIT as far as GUC is concerned */ AtEOXact_GUC(true, 1); AtEOXact_SPI(true); AtEOXact_Enum(); AtEOXact_on_commit_actions(true); AtEOXact_Namespace(true, false); AtEOXact_SMgr(); AtEOXact_Files(true); AtEOXact_ComboCid(); AtEOXact_HashTables(true); AtEOXact_RI(true); /* don't call AtEOXact_PgStat here; we fixed pgstat state above */ AtEOXact_Snapshot(true, true); /* we treat PREPARE as ROLLBACK so far as waking workers goes */ AtEOXact_ApplyLauncher(false); AtEOXact_LogicalRepWorkers(false); AtEOXact_LogicalCtl(); pgstat_report_xact_timestamp(0); CurrentResourceOwner = NULL; ResourceOwnerDelete(TopTransactionResourceOwner); s->curTransactionOwner = NULL; CurTransactionResourceOwner = NULL; TopTransactionResourceOwner = NULL; AtCommit_Memory(); s->fullTransactionId = InvalidFullTransactionId; s->subTransactionId = InvalidSubTransactionId; s->nestingLevel = 0; s->gucNestLevel = 0; s->childXids = NULL; s->nChildXids = 0; s->maxChildXids = 0; XactTopFullTransactionId = InvalidFullTransactionId; nParallelCurrentXids = 0; /* * done with 1st phase commit processing, set current transaction state * back to default */ s->state = TRANS_DEFAULT; RESUME_INTERRUPTS(); } /* * AbortTransaction */ static void AbortTransaction(void) { TransactionState s = CurrentTransactionState; TransactionId latestXid; bool is_parallel_worker; /* Prevent cancel/die interrupt while cleaning up */ HOLD_INTERRUPTS(); /* Disable transaction timeout */ if (TransactionTimeout > 0) disable_timeout(TRANSACTION_TIMEOUT, false); /* Make sure we have a valid memory context and resource owner */ AtAbort_Memory(); AtAbort_ResourceOwner(); /* * Release any LW locks we might be holding as quickly as possible. * (Regular locks, however, must be held till we finish aborting.) * Releasing LW locks is critical since we might try to grab them again * while cleaning up! */ LWLockReleaseAll(); /* * Cleanup waiting for LSN if any. */ WaitLSNCleanup(); /* Clear wait information and command progress indicator */ pgstat_report_wait_end(); pgstat_progress_end_command(); pgaio_error_cleanup(); /* Clean up buffer content locks, too */ UnlockBuffers(); /* Reset WAL record construction state */ XLogResetInsertion(); /* Cancel condition variable sleep */ ConditionVariableCancelSleep(); /* * Also clean up any open wait for lock, since the lock manager will choke * if we try to wait for another lock before doing this. */ LockErrorCleanup(); /* * If any timeout events are still active, make sure the timeout interrupt * is scheduled. This covers possible loss of a timeout interrupt due to * longjmp'ing out of the SIGINT handler (see notes in handle_sig_alarm). * We delay this till after LockErrorCleanup so that we don't uselessly * reschedule lock or deadlock check timeouts. */ reschedule_timeouts(); /* * Re-enable signals, in case we got here by longjmp'ing out of a signal * handler. We do this fairly early in the sequence so that the timeout * infrastructure will be functional if needed while aborting. */ sigprocmask(SIG_SETMASK, &UnBlockSig, NULL); /* * check the current transaction state */ is_parallel_worker = (s->blockState == TBLOCK_PARALLEL_INPROGRESS); if (s->state != TRANS_INPROGRESS && s->state != TRANS_PREPARE) elog(WARNING, "AbortTransaction while in %s state", TransStateAsString(s->state)); Assert(s->parent == NULL); /* * set the current transaction state information appropriately during the * abort processing */ s->state = TRANS_ABORT; /* * Reset user ID which might have been changed transiently. We need this * to clean up in case control escaped out of a SECURITY DEFINER function * or other local change of CurrentUserId; therefore, the prior value of * SecurityRestrictionContext also needs to be restored. * * (Note: it is not necessary to restore session authorization or role * settings here because those can only be changed via GUC, and GUC will * take care of rolling them back if need be.) */ SetUserIdAndSecContext(s->prevUser, s->prevSecContext); /* Forget about any active REINDEX. */ ResetReindexState(s->nestingLevel); /* Reset logical streaming state. */ ResetLogicalStreamingState(); /* Reset snapshot export state. */ SnapBuildResetExportedSnapshotState(); /* * If this xact has started any unfinished parallel operation, clean up * its workers and exit parallel mode. Don't warn about leaked resources. */ AtEOXact_Parallel(false); s->parallelModeLevel = 0; s->parallelChildXact = false; /* should be false already */ /* * do abort processing */ AfterTriggerEndXact(false); /* 'false' means it's abort */ AtAbort_Portals(); smgrDoPendingSyncs(false, is_parallel_worker); AtEOXact_LargeObject(false); AtAbort_Notify(); AtEOXact_RelationMap(false, is_parallel_worker); AtAbort_Twophase(); /* * Advertise the fact that we aborted in pg_xact (assuming that we got as * far as assigning an XID to advertise). But if we're inside a parallel * worker, skip this; the user backend must be the one to write the abort * record. */ if (!is_parallel_worker) latestXid = RecordTransactionAbort(false); else { latestXid = InvalidTransactionId; /* * Since the parallel leader won't get our value of XactLastRecEnd in * this case, we nudge WAL-writer ourselves in this case. See related * comments in RecordTransactionAbort for why this matters. */ XLogSetAsyncXactLSN(XactLastRecEnd); } TRACE_POSTGRESQL_TRANSACTION_ABORT(MyProc->vxid.lxid); /* * Let others know about no transaction in progress by me. Note that this * must be done _before_ releasing locks we hold and _after_ * RecordTransactionAbort. */ ProcArrayEndTransaction(MyProc, latestXid); /* * Post-abort cleanup. See notes in CommitTransaction() concerning * ordering. We can skip all of it if the transaction failed before * creating a resource owner. */ if (TopTransactionResourceOwner != NULL) { if (is_parallel_worker) CallXactCallbacks(XACT_EVENT_PARALLEL_ABORT); else CallXactCallbacks(XACT_EVENT_ABORT); ResourceOwnerRelease(TopTransactionResourceOwner, RESOURCE_RELEASE_BEFORE_LOCKS, false, true); AtEOXact_Aio(false); AtEOXact_Buffers(false); AtEOXact_RelationCache(false); AtEOXact_TypeCache(); AtEOXact_Inval(false); AtEOXact_MultiXact(); ResourceOwnerRelease(TopTransactionResourceOwner, RESOURCE_RELEASE_LOCKS, false, true); ResourceOwnerRelease(TopTransactionResourceOwner, RESOURCE_RELEASE_AFTER_LOCKS, false, true); smgrDoPendingDeletes(false); AtEOXact_GUC(false, 1); AtEOXact_SPI(false); AtEOXact_Enum(); AtEOXact_on_commit_actions(false); AtEOXact_Namespace(false, is_parallel_worker); AtEOXact_SMgr(); AtEOXact_Files(false); AtEOXact_ComboCid(); AtEOXact_HashTables(false); AtEOXact_RI(false); AtEOXact_PgStat(false, is_parallel_worker); AtEOXact_ApplyLauncher(false); AtEOXact_LogicalRepWorkers(false); AtEOXact_LogicalCtl(); pgstat_report_xact_timestamp(0); } /* * State remains TRANS_ABORT until CleanupTransaction(). */ RESUME_INTERRUPTS(); } /* * CleanupTransaction */ static void CleanupTransaction(void) { TransactionState s = CurrentTransactionState; /* * State should still be TRANS_ABORT from AbortTransaction(). */ if (s->state != TRANS_ABORT) elog(FATAL, "CleanupTransaction: unexpected state %s", TransStateAsString(s->state)); /* * do abort cleanup processing */ AtCleanup_Portals(); /* now safe to release portal memory */ AtEOXact_Snapshot(false, true); /* and release the transaction's snapshots */ CurrentResourceOwner = NULL; /* and resource owner */ if (TopTransactionResourceOwner) ResourceOwnerDelete(TopTransactionResourceOwner); s->curTransactionOwner = NULL; CurTransactionResourceOwner = NULL; TopTransactionResourceOwner = NULL; AtCleanup_Memory(); /* and transaction memory */ s->fullTransactionId = InvalidFullTransactionId; s->subTransactionId = InvalidSubTransactionId; s->nestingLevel = 0; s->gucNestLevel = 0; s->childXids = NULL; s->nChildXids = 0; s->maxChildXids = 0; s->parallelModeLevel = 0; s->parallelChildXact = false; XactTopFullTransactionId = InvalidFullTransactionId; nParallelCurrentXids = 0; /* * done with abort processing, set current transaction state back to * default */ s->state = TRANS_DEFAULT; } /* * StartTransactionCommand */ void StartTransactionCommand(void) { TransactionState s = CurrentTransactionState; switch (s->blockState) { /* * if we aren't in a transaction block, we just do our usual start * transaction. */ case TBLOCK_DEFAULT: StartTransaction(); s->blockState = TBLOCK_STARTED; break; /* * We are somewhere in a transaction block or subtransaction and * about to start a new command. For now we do nothing, but * someday we may do command-local resource initialization. (Note * that any needed CommandCounterIncrement was done by the * previous CommitTransactionCommand.) */ case TBLOCK_INPROGRESS: case TBLOCK_IMPLICIT_INPROGRESS: case TBLOCK_SUBINPROGRESS: break; /* * Here we are in a failed transaction block (one of the commands * caused an abort) so we do nothing but remain in the abort * state. Eventually we will get a ROLLBACK command which will * get us out of this state. (It is up to other code to ensure * that no commands other than ROLLBACK will be processed in these * states.) */ case TBLOCK_ABORT: case TBLOCK_SUBABORT: break; /* These cases are invalid. */ case TBLOCK_STARTED: case TBLOCK_BEGIN: case TBLOCK_PARALLEL_INPROGRESS: case TBLOCK_SUBBEGIN: case TBLOCK_END: case TBLOCK_SUBRELEASE: case TBLOCK_SUBCOMMIT: case TBLOCK_ABORT_END: case TBLOCK_SUBABORT_END: case TBLOCK_ABORT_PENDING: case TBLOCK_SUBABORT_PENDING: case TBLOCK_SUBRESTART: case TBLOCK_SUBABORT_RESTART: case TBLOCK_PREPARE: elog(ERROR, "StartTransactionCommand: unexpected state %s", BlockStateAsString(s->blockState)); break; } /* * We must switch to CurTransactionContext before returning. This is * already done if we called StartTransaction, otherwise not. */ Assert(CurTransactionContext != NULL); MemoryContextSwitchTo(CurTransactionContext); } /* * Simple system for saving and restoring transaction characteristics * (isolation level, read only, deferrable). We need this for transaction * chaining, so that we can set the characteristics of the new transaction to * be the same as the previous one. (We need something like this because the * GUC system resets the characteristics at transaction end, so for example * just skipping the reset in StartTransaction() won't work.) */ void SaveTransactionCharacteristics(SavedTransactionCharacteristics *s) { s->save_XactIsoLevel = XactIsoLevel; s->save_XactReadOnly = XactReadOnly; s->save_XactDeferrable = XactDeferrable; } void RestoreTransactionCharacteristics(const SavedTransactionCharacteristics *s) { XactIsoLevel = s->save_XactIsoLevel; XactReadOnly = s->save_XactReadOnly; XactDeferrable = s->save_XactDeferrable; } /* * CommitTransactionCommand -- a wrapper function handling the * loop over subtransactions to avoid a potentially dangerous recursion * in CommitTransactionCommandInternal(). */ void CommitTransactionCommand(void) { /* * Repeatedly call CommitTransactionCommandInternal() until all the work * is done. */ while (!CommitTransactionCommandInternal()) { } } /* * CommitTransactionCommandInternal - a function doing an iteration of work * regarding handling the commit transaction command. In the case of * subtransactions more than one iterations could be required. Returns * true when no more iterations required, false otherwise. */ static bool CommitTransactionCommandInternal(void) { TransactionState s = CurrentTransactionState; SavedTransactionCharacteristics savetc; /* Must save in case we need to restore below */ SaveTransactionCharacteristics(&savetc); switch (s->blockState) { /* * These shouldn't happen. TBLOCK_DEFAULT means the previous * StartTransactionCommand didn't set the STARTED state * appropriately, while TBLOCK_PARALLEL_INPROGRESS should be ended * by EndParallelWorkerTransaction(), not this function. */ case TBLOCK_DEFAULT: case TBLOCK_PARALLEL_INPROGRESS: elog(FATAL, "CommitTransactionCommand: unexpected state %s", BlockStateAsString(s->blockState)); break; /* * If we aren't in a transaction block, just do our usual * transaction commit, and return to the idle state. */ case TBLOCK_STARTED: CommitTransaction(); s->blockState = TBLOCK_DEFAULT; break; /* * We are completing a "BEGIN TRANSACTION" command, so we change * to the "transaction block in progress" state and return. (We * assume the BEGIN did nothing to the database, so we need no * CommandCounterIncrement.) */ case TBLOCK_BEGIN: s->blockState = TBLOCK_INPROGRESS; break; /* * This is the case when we have finished executing a command * someplace within a transaction block. We increment the command * counter and return. */ case TBLOCK_INPROGRESS: case TBLOCK_IMPLICIT_INPROGRESS: case TBLOCK_SUBINPROGRESS: CommandCounterIncrement(); break; /* * We are completing a "COMMIT" command. Do it and return to the * idle state. */ case TBLOCK_END: CommitTransaction(); s->blockState = TBLOCK_DEFAULT; if (s->chain) { StartTransaction(); s->blockState = TBLOCK_INPROGRESS; s->chain = false; RestoreTransactionCharacteristics(&savetc); } break; /* * Here we are in the middle of a transaction block but one of the * commands caused an abort so we do nothing but remain in the * abort state. Eventually we will get a ROLLBACK command. */ case TBLOCK_ABORT: case TBLOCK_SUBABORT: break; /* * Here we were in an aborted transaction block and we just got * the ROLLBACK command from the user, so clean up the * already-aborted transaction and return to the idle state. */ case TBLOCK_ABORT_END: CleanupTransaction(); s->blockState = TBLOCK_DEFAULT; if (s->chain) { StartTransaction(); s->blockState = TBLOCK_INPROGRESS; s->chain = false; RestoreTransactionCharacteristics(&savetc); } break; /* * Here we were in a perfectly good transaction block but the user * told us to ROLLBACK anyway. We have to abort the transaction * and then clean up. */ case TBLOCK_ABORT_PENDING: AbortTransaction(); CleanupTransaction(); s->blockState = TBLOCK_DEFAULT; if (s->chain) { StartTransaction(); s->blockState = TBLOCK_INPROGRESS; s->chain = false; RestoreTransactionCharacteristics(&savetc); } break; /* * We are completing a "PREPARE TRANSACTION" command. Do it and * return to the idle state. */ case TBLOCK_PREPARE: PrepareTransaction(); s->blockState = TBLOCK_DEFAULT; break; /* * The user issued a SAVEPOINT inside a transaction block. Start a * subtransaction. (DefineSavepoint already did PushTransaction, * so as to have someplace to put the SUBBEGIN state.) */ case TBLOCK_SUBBEGIN: StartSubTransaction(); s->blockState = TBLOCK_SUBINPROGRESS; break; /* * The user issued a RELEASE command, so we end the current * subtransaction and return to the parent transaction. The parent * might be ended too, so repeat till we find an INPROGRESS * transaction or subtransaction. */ case TBLOCK_SUBRELEASE: do { CommitSubTransaction(); s = CurrentTransactionState; /* changed by pop */ } while (s->blockState == TBLOCK_SUBRELEASE); Assert(s->blockState == TBLOCK_INPROGRESS || s->blockState == TBLOCK_SUBINPROGRESS); break; /* * The user issued a COMMIT, so we end the current subtransaction * hierarchy and perform final commit. We do this by rolling up * any subtransactions into their parent, which leads to O(N^2) * operations with respect to resource owners - this isn't that * bad until we approach a thousands of savepoints but is * necessary for correctness should after triggers create new * resource owners. */ case TBLOCK_SUBCOMMIT: do { CommitSubTransaction(); s = CurrentTransactionState; /* changed by pop */ } while (s->blockState == TBLOCK_SUBCOMMIT); /* If we had a COMMIT command, finish off the main xact too */ if (s->blockState == TBLOCK_END) { Assert(s->parent == NULL); CommitTransaction(); s->blockState = TBLOCK_DEFAULT; if (s->chain) { StartTransaction(); s->blockState = TBLOCK_INPROGRESS; s->chain = false; RestoreTransactionCharacteristics(&savetc); } } else if (s->blockState == TBLOCK_PREPARE) { Assert(s->parent == NULL); PrepareTransaction(); s->blockState = TBLOCK_DEFAULT; } else elog(ERROR, "CommitTransactionCommand: unexpected state %s", BlockStateAsString(s->blockState)); break; /* * The current already-failed subtransaction is ending due to a * ROLLBACK or ROLLBACK TO command, so pop it and recursively * examine the parent (which could be in any of several states). * As we need to examine the parent, return false to request the * caller to do the next iteration. */ case TBLOCK_SUBABORT_END: CleanupSubTransaction(); return false; /* * As above, but it's not dead yet, so abort first. */ case TBLOCK_SUBABORT_PENDING: AbortSubTransaction(); CleanupSubTransaction(); return false; /* * The current subtransaction is the target of a ROLLBACK TO * command. Abort and pop it, then start a new subtransaction * with the same name. */ case TBLOCK_SUBRESTART: { char *name; int savepointLevel; /* save name and keep Cleanup from freeing it */ name = s->name; s->name = NULL; savepointLevel = s->savepointLevel; AbortSubTransaction(); CleanupSubTransaction(); DefineSavepoint(NULL); s = CurrentTransactionState; /* changed by push */ s->name = name; s->savepointLevel = savepointLevel; /* This is the same as TBLOCK_SUBBEGIN case */ Assert(s->blockState == TBLOCK_SUBBEGIN); StartSubTransaction(); s->blockState = TBLOCK_SUBINPROGRESS; } break; /* * Same as above, but the subtransaction had already failed, so we * don't need AbortSubTransaction. */ case TBLOCK_SUBABORT_RESTART: { char *name; int savepointLevel; /* save name and keep Cleanup from freeing it */ name = s->name; s->name = NULL; savepointLevel = s->savepointLevel; CleanupSubTransaction(); DefineSavepoint(NULL); s = CurrentTransactionState; /* changed by push */ s->name = name; s->savepointLevel = savepointLevel; /* This is the same as TBLOCK_SUBBEGIN case */ Assert(s->blockState == TBLOCK_SUBBEGIN); StartSubTransaction(); s->blockState = TBLOCK_SUBINPROGRESS; } break; } /* Done, no more iterations required */ return true; } /* * AbortCurrentTransaction -- a wrapper function handling the * loop over subtransactions to avoid potentially dangerous recursion in * AbortCurrentTransactionInternal(). */ void AbortCurrentTransaction(void) { /* * Repeatedly call AbortCurrentTransactionInternal() until all the work is * done. */ while (!AbortCurrentTransactionInternal()) { } } /* * AbortCurrentTransactionInternal - a function doing an iteration of work * regarding handling the current transaction abort. In the case of * subtransactions more than one iterations could be required. Returns * true when no more iterations required, false otherwise. */ static bool AbortCurrentTransactionInternal(void) { TransactionState s = CurrentTransactionState; switch (s->blockState) { case TBLOCK_DEFAULT: if (s->state == TRANS_DEFAULT) { /* we are idle, so nothing to do */ } else { /* * We can get here after an error during transaction start * (state will be TRANS_START). Need to clean up the * incompletely started transaction. First, adjust the * low-level state to suppress warning message from * AbortTransaction. */ if (s->state == TRANS_START) s->state = TRANS_INPROGRESS; AbortTransaction(); CleanupTransaction(); } break; /* * If we aren't in a transaction block, we just do the basic abort * & cleanup transaction. For this purpose, we treat an implicit * transaction block as if it were a simple statement. */ case TBLOCK_STARTED: case TBLOCK_IMPLICIT_INPROGRESS: AbortTransaction(); CleanupTransaction(); s->blockState = TBLOCK_DEFAULT; break; /* * If we are in TBLOCK_BEGIN it means something screwed up right * after reading "BEGIN TRANSACTION". We assume that the user * will interpret the error as meaning the BEGIN failed to get him * into a transaction block, so we should abort and return to idle * state. */ case TBLOCK_BEGIN: AbortTransaction(); CleanupTransaction(); s->blockState = TBLOCK_DEFAULT; break; /* * We are somewhere in a transaction block and we've gotten a * failure, so we abort the transaction and set up the persistent * ABORT state. We will stay in ABORT until we get a ROLLBACK. */ case TBLOCK_INPROGRESS: case TBLOCK_PARALLEL_INPROGRESS: AbortTransaction(); s->blockState = TBLOCK_ABORT; /* CleanupTransaction happens when we exit TBLOCK_ABORT_END */ break; /* * Here, we failed while trying to COMMIT. Clean up the * transaction and return to idle state (we do not want to stay in * the transaction). */ case TBLOCK_END: AbortTransaction(); CleanupTransaction(); s->blockState = TBLOCK_DEFAULT; break; /* * Here, we are already in an aborted transaction state and are * waiting for a ROLLBACK, but for some reason we failed again! So * we just remain in the abort state. */ case TBLOCK_ABORT: case TBLOCK_SUBABORT: break; /* * We are in a failed transaction and we got the ROLLBACK command. * We have already aborted, we just need to cleanup and go to idle * state. */ case TBLOCK_ABORT_END: CleanupTransaction(); s->blockState = TBLOCK_DEFAULT; break; /* * We are in a live transaction and we got a ROLLBACK command. * Abort, cleanup, go to idle state. */ case TBLOCK_ABORT_PENDING: AbortTransaction(); CleanupTransaction(); s->blockState = TBLOCK_DEFAULT; break; /* * Here, we failed while trying to PREPARE. Clean up the * transaction and return to idle state (we do not want to stay in * the transaction). */ case TBLOCK_PREPARE: AbortTransaction(); CleanupTransaction(); s->blockState = TBLOCK_DEFAULT; break; /* * We got an error inside a subtransaction. Abort just the * subtransaction, and go to the persistent SUBABORT state until * we get ROLLBACK. */ case TBLOCK_SUBINPROGRESS: AbortSubTransaction(); s->blockState = TBLOCK_SUBABORT; break; /* * If we failed while trying to create a subtransaction, clean up * the broken subtransaction and abort the parent. The same * applies if we get a failure while ending a subtransaction. As * we need to abort the parent, return false to request the caller * to do the next iteration. */ case TBLOCK_SUBBEGIN: case TBLOCK_SUBRELEASE: case TBLOCK_SUBCOMMIT: case TBLOCK_SUBABORT_PENDING: case TBLOCK_SUBRESTART: AbortSubTransaction(); CleanupSubTransaction(); return false; /* * Same as above, except the Abort() was already done. */ case TBLOCK_SUBABORT_END: case TBLOCK_SUBABORT_RESTART: CleanupSubTransaction(); return false; } /* Done, no more iterations required */ return true; } /* * PreventInTransactionBlock * * This routine is to be called by statements that must not run inside * a transaction block, typically because they have non-rollback-able * side effects or do internal commits. * * If this routine completes successfully, then the calling statement is * guaranteed that if it completes without error, its results will be * committed immediately. * * If we have already started a transaction block, issue an error; also issue * an error if we appear to be running inside a user-defined function (which * could issue more commands and possibly cause a failure after the statement * completes). Subtransactions are verboten too. * * We must also set XACT_FLAGS_NEEDIMMEDIATECOMMIT in MyXactFlags, to ensure * that postgres.c follows through by committing after the statement is done. * * isTopLevel: passed down from ProcessUtility to determine whether we are * inside a function. (We will always fail if this is false, but it's * convenient to centralize the check here instead of making callers do it.) * stmtType: statement type name, for error messages. */ void PreventInTransactionBlock(bool isTopLevel, const char *stmtType) { /* * xact block already started? */ if (IsTransactionBlock()) ereport(ERROR, (errcode(ERRCODE_ACTIVE_SQL_TRANSACTION), /* translator: %s represents an SQL statement name */ errmsg("%s cannot run inside a transaction block", stmtType))); /* * subtransaction? */ if (IsSubTransaction()) ereport(ERROR, (errcode(ERRCODE_ACTIVE_SQL_TRANSACTION), /* translator: %s represents an SQL statement name */ errmsg("%s cannot run inside a subtransaction", stmtType))); /* * inside a function call? */ if (!isTopLevel) ereport(ERROR, (errcode(ERRCODE_ACTIVE_SQL_TRANSACTION), /* translator: %s represents an SQL statement name */ errmsg("%s cannot be executed from a function or procedure", stmtType))); /* If we got past IsTransactionBlock test, should be in default state */ if (CurrentTransactionState->blockState != TBLOCK_DEFAULT && CurrentTransactionState->blockState != TBLOCK_STARTED) elog(FATAL, "cannot prevent transaction chain"); /* All okay. Set the flag to make sure the right thing happens later. */ MyXactFlags |= XACT_FLAGS_NEEDIMMEDIATECOMMIT; } /* * WarnNoTransactionBlock * RequireTransactionBlock * * These two functions allow for warnings or errors if a command is executed * outside of a transaction block. This is useful for commands that have no * effects that persist past transaction end (and so calling them outside a * transaction block is presumably an error). DECLARE CURSOR is an example. * While top-level transaction control commands (BEGIN/COMMIT/ABORT) and SET * that have no effect issue warnings, all other no-effect commands generate * errors. * * If we appear to be running inside a user-defined function, we do not * issue anything, since the function could issue more commands that make * use of the current statement's results. Likewise subtransactions. * Thus these are inverses for PreventInTransactionBlock. * * isTopLevel: passed down from ProcessUtility to determine whether we are * inside a function. * stmtType: statement type name, for warning or error messages. */ void WarnNoTransactionBlock(bool isTopLevel, const char *stmtType) { CheckTransactionBlock(isTopLevel, false, stmtType); } void RequireTransactionBlock(bool isTopLevel, const char *stmtType) { CheckTransactionBlock(isTopLevel, true, stmtType); } /* * This is the implementation of the above two. */ static void CheckTransactionBlock(bool isTopLevel, bool throwError, const char *stmtType) { /* * xact block already started? */ if (IsTransactionBlock()) return; /* * subtransaction? */ if (IsSubTransaction()) return; /* * inside a function call? */ if (!isTopLevel) return; ereport(throwError ? ERROR : WARNING, (errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION), /* translator: %s represents an SQL statement name */ errmsg("%s can only be used in transaction blocks", stmtType))); } /* * IsInTransactionBlock * * This routine is for statements that need to behave differently inside * a transaction block than when running as single commands. ANALYZE is * currently the only example. * * If this routine returns "false", then the calling statement is allowed * to perform internal transaction-commit-and-start cycles; there is not a * risk of messing up any transaction already in progress. (Note that this * is not the identical guarantee provided by PreventInTransactionBlock, * since we will not force a post-statement commit.) * * isTopLevel: passed down from ProcessUtility to determine whether we are * inside a function. */ bool IsInTransactionBlock(bool isTopLevel) { /* * Return true on same conditions that would make * PreventInTransactionBlock error out */ if (IsTransactionBlock()) return true; if (IsSubTransaction()) return true; if (!isTopLevel) return true; if (CurrentTransactionState->blockState != TBLOCK_DEFAULT && CurrentTransactionState->blockState != TBLOCK_STARTED) return true; return false; } /* * Register or deregister callback functions for start- and end-of-xact * operations. * * These functions are intended for use by dynamically loaded modules. * For built-in modules we generally just hardwire the appropriate calls * (mainly because it's easier to control the order that way, where needed). * * At transaction end, the callback occurs post-commit or post-abort, so the * callback functions can only do noncritical cleanup. */ void RegisterXactCallback(XactCallback callback, void *arg) { XactCallbackItem *item; item = (XactCallbackItem *) MemoryContextAlloc(TopMemoryContext, sizeof(XactCallbackItem)); item->callback = callback; item->arg = arg; item->next = Xact_callbacks; Xact_callbacks = item; } void UnregisterXactCallback(XactCallback callback, void *arg) { XactCallbackItem *item; XactCallbackItem *prev; prev = NULL; for (item = Xact_callbacks; item; prev = item, item = item->next) { if (item->callback == callback && item->arg == arg) { if (prev) prev->next = item->next; else Xact_callbacks = item->next; pfree(item); break; } } } static void CallXactCallbacks(XactEvent event) { XactCallbackItem *item; XactCallbackItem *next; for (item = Xact_callbacks; item; item = next) { /* allow callbacks to unregister themselves when called */ next = item->next; item->callback(event, item->arg); } } /* * Register or deregister callback functions for start- and end-of-subxact * operations. * * Pretty much same as above, but for subtransaction events. * * At subtransaction end, the callback occurs post-subcommit or post-subabort, * so the callback functions can only do noncritical cleanup. At * subtransaction start, the callback is called when the subtransaction has * finished initializing. */ void RegisterSubXactCallback(SubXactCallback callback, void *arg) { SubXactCallbackItem *item; item = (SubXactCallbackItem *) MemoryContextAlloc(TopMemoryContext, sizeof(SubXactCallbackItem)); item->callback = callback; item->arg = arg; item->next = SubXact_callbacks; SubXact_callbacks = item; } void UnregisterSubXactCallback(SubXactCallback callback, void *arg) { SubXactCallbackItem *item; SubXactCallbackItem *prev; prev = NULL; for (item = SubXact_callbacks; item; prev = item, item = item->next) { if (item->callback == callback && item->arg == arg) { if (prev) prev->next = item->next; else SubXact_callbacks = item->next; pfree(item); break; } } } static void CallSubXactCallbacks(SubXactEvent event, SubTransactionId mySubid, SubTransactionId parentSubid) { SubXactCallbackItem *item; SubXactCallbackItem *next; for (item = SubXact_callbacks; item; item = next) { /* allow callbacks to unregister themselves when called */ next = item->next; item->callback(event, mySubid, parentSubid, item->arg); } } /* ---------------------------------------------------------------- * transaction block support * ---------------------------------------------------------------- */ /* * BeginTransactionBlock * This executes a BEGIN command. */ void BeginTransactionBlock(void) { TransactionState s = CurrentTransactionState; switch (s->blockState) { /* * We are not inside a transaction block, so allow one to begin. */ case TBLOCK_STARTED: s->blockState = TBLOCK_BEGIN; break; /* * BEGIN converts an implicit transaction block to a regular one. * (Note that we allow this even if we've already done some * commands, which is a bit odd but matches historical practice.) */ case TBLOCK_IMPLICIT_INPROGRESS: s->blockState = TBLOCK_BEGIN; break; /* * Already a transaction block in progress. */ case TBLOCK_INPROGRESS: case TBLOCK_PARALLEL_INPROGRESS: case TBLOCK_SUBINPROGRESS: case TBLOCK_ABORT: case TBLOCK_SUBABORT: ereport(WARNING, (errcode(ERRCODE_ACTIVE_SQL_TRANSACTION), errmsg("there is already a transaction in progress"))); break; /* These cases are invalid. */ case TBLOCK_DEFAULT: case TBLOCK_BEGIN: case TBLOCK_SUBBEGIN: case TBLOCK_END: case TBLOCK_SUBRELEASE: case TBLOCK_SUBCOMMIT: case TBLOCK_ABORT_END: case TBLOCK_SUBABORT_END: case TBLOCK_ABORT_PENDING: case TBLOCK_SUBABORT_PENDING: case TBLOCK_SUBRESTART: case TBLOCK_SUBABORT_RESTART: case TBLOCK_PREPARE: elog(FATAL, "BeginTransactionBlock: unexpected state %s", BlockStateAsString(s->blockState)); break; } } /* * PrepareTransactionBlock * This executes a PREPARE command. * * Since PREPARE may actually do a ROLLBACK, the result indicates what * happened: true for PREPARE, false for ROLLBACK. * * Note that we don't actually do anything here except change blockState. * The real work will be done in the upcoming PrepareTransaction(). * We do it this way because it's not convenient to change memory context, * resource owner, etc while executing inside a Portal. */ bool PrepareTransactionBlock(const char *gid) { TransactionState s; bool result; /* Set up to commit the current transaction */ result = EndTransactionBlock(false); /* If successful, change outer tblock state to PREPARE */ if (result) { s = CurrentTransactionState; while (s->parent != NULL) s = s->parent; if (s->blockState == TBLOCK_END) { /* Save GID where PrepareTransaction can find it again */ prepareGID = MemoryContextStrdup(TopTransactionContext, gid); s->blockState = TBLOCK_PREPARE; } else { /* * ignore case where we are not in a transaction; * EndTransactionBlock already issued a warning. */ Assert(s->blockState == TBLOCK_STARTED || s->blockState == TBLOCK_IMPLICIT_INPROGRESS); /* Don't send back a PREPARE result tag... */ result = false; } } return result; } /* * EndTransactionBlock * This executes a COMMIT command. * * Since COMMIT may actually do a ROLLBACK, the result indicates what * happened: true for COMMIT, false for ROLLBACK. * * Note that we don't actually do anything here except change blockState. * The real work will be done in the upcoming CommitTransactionCommand(). * We do it this way because it's not convenient to change memory context, * resource owner, etc while executing inside a Portal. */ bool EndTransactionBlock(bool chain) { TransactionState s = CurrentTransactionState; bool result = false; switch (s->blockState) { /* * We are in a transaction block, so tell CommitTransactionCommand * to COMMIT. */ case TBLOCK_INPROGRESS: s->blockState = TBLOCK_END; result = true; break; /* * We are in an implicit transaction block. If AND CHAIN was * specified, error. Otherwise commit, but issue a warning * because there was no explicit BEGIN before this. */ case TBLOCK_IMPLICIT_INPROGRESS: if (chain) ereport(ERROR, (errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION), /* translator: %s represents an SQL statement name */ errmsg("%s can only be used in transaction blocks", "COMMIT AND CHAIN"))); else ereport(WARNING, (errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION), errmsg("there is no transaction in progress"))); s->blockState = TBLOCK_END; result = true; break; /* * We are in a failed transaction block. Tell * CommitTransactionCommand it's time to exit the block. */ case TBLOCK_ABORT: s->blockState = TBLOCK_ABORT_END; break; /* * We are in a live subtransaction block. Set up to subcommit all * open subtransactions and then commit the main transaction. */ case TBLOCK_SUBINPROGRESS: while (s->parent != NULL) { if (s->blockState == TBLOCK_SUBINPROGRESS) s->blockState = TBLOCK_SUBCOMMIT; else elog(FATAL, "EndTransactionBlock: unexpected state %s", BlockStateAsString(s->blockState)); s = s->parent; } if (s->blockState == TBLOCK_INPROGRESS) s->blockState = TBLOCK_END; else elog(FATAL, "EndTransactionBlock: unexpected state %s", BlockStateAsString(s->blockState)); result = true; break; /* * Here we are inside an aborted subtransaction. Treat the COMMIT * as ROLLBACK: set up to abort everything and exit the main * transaction. */ case TBLOCK_SUBABORT: while (s->parent != NULL) { if (s->blockState == TBLOCK_SUBINPROGRESS) s->blockState = TBLOCK_SUBABORT_PENDING; else if (s->blockState == TBLOCK_SUBABORT) s->blockState = TBLOCK_SUBABORT_END; else elog(FATAL, "EndTransactionBlock: unexpected state %s", BlockStateAsString(s->blockState)); s = s->parent; } if (s->blockState == TBLOCK_INPROGRESS) s->blockState = TBLOCK_ABORT_PENDING; else if (s->blockState == TBLOCK_ABORT) s->blockState = TBLOCK_ABORT_END; else elog(FATAL, "EndTransactionBlock: unexpected state %s", BlockStateAsString(s->blockState)); break; /* * The user issued COMMIT when not inside a transaction. For * COMMIT without CHAIN, issue a WARNING, staying in * TBLOCK_STARTED state. The upcoming call to * CommitTransactionCommand() will then close the transaction and * put us back into the default state. For COMMIT AND CHAIN, * error. */ case TBLOCK_STARTED: if (chain) ereport(ERROR, (errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION), /* translator: %s represents an SQL statement name */ errmsg("%s can only be used in transaction blocks", "COMMIT AND CHAIN"))); else ereport(WARNING, (errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION), errmsg("there is no transaction in progress"))); result = true; break; /* * The user issued a COMMIT that somehow ran inside a parallel * worker. We can't cope with that. */ case TBLOCK_PARALLEL_INPROGRESS: ereport(FATAL, (errcode(ERRCODE_INVALID_TRANSACTION_STATE), errmsg("cannot commit during a parallel operation"))); break; /* These cases are invalid. */ case TBLOCK_DEFAULT: case TBLOCK_BEGIN: case TBLOCK_SUBBEGIN: case TBLOCK_END: case TBLOCK_SUBRELEASE: case TBLOCK_SUBCOMMIT: case TBLOCK_ABORT_END: case TBLOCK_SUBABORT_END: case TBLOCK_ABORT_PENDING: case TBLOCK_SUBABORT_PENDING: case TBLOCK_SUBRESTART: case TBLOCK_SUBABORT_RESTART: case TBLOCK_PREPARE: elog(FATAL, "EndTransactionBlock: unexpected state %s", BlockStateAsString(s->blockState)); break; } Assert(s->blockState == TBLOCK_STARTED || s->blockState == TBLOCK_END || s->blockState == TBLOCK_ABORT_END || s->blockState == TBLOCK_ABORT_PENDING); s->chain = chain; return result; } /* * UserAbortTransactionBlock * This executes a ROLLBACK command. * * As above, we don't actually do anything here except change blockState. */ void UserAbortTransactionBlock(bool chain) { TransactionState s = CurrentTransactionState; switch (s->blockState) { /* * We are inside a transaction block and we got a ROLLBACK command * from the user, so tell CommitTransactionCommand to abort and * exit the transaction block. */ case TBLOCK_INPROGRESS: s->blockState = TBLOCK_ABORT_PENDING; break; /* * We are inside a failed transaction block and we got a ROLLBACK * command from the user. Abort processing is already done, so * CommitTransactionCommand just has to cleanup and go back to * idle state. */ case TBLOCK_ABORT: s->blockState = TBLOCK_ABORT_END; break; /* * We are inside a subtransaction. Mark everything up to top * level as exitable. */ case TBLOCK_SUBINPROGRESS: case TBLOCK_SUBABORT: while (s->parent != NULL) { if (s->blockState == TBLOCK_SUBINPROGRESS) s->blockState = TBLOCK_SUBABORT_PENDING; else if (s->blockState == TBLOCK_SUBABORT) s->blockState = TBLOCK_SUBABORT_END; else elog(FATAL, "UserAbortTransactionBlock: unexpected state %s", BlockStateAsString(s->blockState)); s = s->parent; } if (s->blockState == TBLOCK_INPROGRESS) s->blockState = TBLOCK_ABORT_PENDING; else if (s->blockState == TBLOCK_ABORT) s->blockState = TBLOCK_ABORT_END; else elog(FATAL, "UserAbortTransactionBlock: unexpected state %s", BlockStateAsString(s->blockState)); break; /* * The user issued ABORT when not inside a transaction. For * ROLLBACK without CHAIN, issue a WARNING and go to abort state. * The upcoming call to CommitTransactionCommand() will then put * us back into the default state. For ROLLBACK AND CHAIN, error. * * We do the same thing with ABORT inside an implicit transaction, * although in this case we might be rolling back actual database * state changes. (It's debatable whether we should issue a * WARNING in this case, but we have done so historically.) */ case TBLOCK_STARTED: case TBLOCK_IMPLICIT_INPROGRESS: if (chain) ereport(ERROR, (errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION), /* translator: %s represents an SQL statement name */ errmsg("%s can only be used in transaction blocks", "ROLLBACK AND CHAIN"))); else ereport(WARNING, (errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION), errmsg("there is no transaction in progress"))); s->blockState = TBLOCK_ABORT_PENDING; break; /* * The user issued an ABORT that somehow ran inside a parallel * worker. We can't cope with that. */ case TBLOCK_PARALLEL_INPROGRESS: ereport(FATAL, (errcode(ERRCODE_INVALID_TRANSACTION_STATE), errmsg("cannot abort during a parallel operation"))); break; /* These cases are invalid. */ case TBLOCK_DEFAULT: case TBLOCK_BEGIN: case TBLOCK_SUBBEGIN: case TBLOCK_END: case TBLOCK_SUBRELEASE: case TBLOCK_SUBCOMMIT: case TBLOCK_ABORT_END: case TBLOCK_SUBABORT_END: case TBLOCK_ABORT_PENDING: case TBLOCK_SUBABORT_PENDING: case TBLOCK_SUBRESTART: case TBLOCK_SUBABORT_RESTART: case TBLOCK_PREPARE: elog(FATAL, "UserAbortTransactionBlock: unexpected state %s", BlockStateAsString(s->blockState)); break; } Assert(s->blockState == TBLOCK_ABORT_END || s->blockState == TBLOCK_ABORT_PENDING); s->chain = chain; } /* * BeginImplicitTransactionBlock * Start an implicit transaction block if we're not already in one. * * Unlike BeginTransactionBlock, this is called directly from the main loop * in postgres.c, not within a Portal. So we can just change blockState * without a lot of ceremony. We do not expect caller to do * CommitTransactionCommand/StartTransactionCommand. */ void BeginImplicitTransactionBlock(void) { TransactionState s = CurrentTransactionState; /* * If we are in STARTED state (that is, no transaction block is open), * switch to IMPLICIT_INPROGRESS state, creating an implicit transaction * block. * * For caller convenience, we consider all other transaction states as * legal here; otherwise the caller would need its own state check, which * seems rather pointless. */ if (s->blockState == TBLOCK_STARTED) s->blockState = TBLOCK_IMPLICIT_INPROGRESS; } /* * EndImplicitTransactionBlock * End an implicit transaction block, if we're in one. * * Like EndTransactionBlock, we just make any needed blockState change here. * The real work will be done in the upcoming CommitTransactionCommand(). */ void EndImplicitTransactionBlock(void) { TransactionState s = CurrentTransactionState; /* * If we are in IMPLICIT_INPROGRESS state, switch back to STARTED state, * allowing CommitTransactionCommand to commit whatever happened during * the implicit transaction block as though it were a single statement. * * For caller convenience, we consider all other transaction states as * legal here; otherwise the caller would need its own state check, which * seems rather pointless. */ if (s->blockState == TBLOCK_IMPLICIT_INPROGRESS) s->blockState = TBLOCK_STARTED; } /* * DefineSavepoint * This executes a SAVEPOINT command. */ void DefineSavepoint(const char *name) { TransactionState s = CurrentTransactionState; /* * Workers synchronize transaction state at the beginning of each parallel * operation, so we can't account for new subtransactions after that * point. (Note that this check will certainly error out if s->blockState * is TBLOCK_PARALLEL_INPROGRESS, so we can treat that as an invalid case * below.) */ if (IsInParallelMode() || IsParallelWorker()) ereport(ERROR, (errcode(ERRCODE_INVALID_TRANSACTION_STATE), errmsg("cannot define savepoints during a parallel operation"))); switch (s->blockState) { case TBLOCK_INPROGRESS: case TBLOCK_SUBINPROGRESS: /* Normal subtransaction start */ PushTransaction(); s = CurrentTransactionState; /* changed by push */ /* * Savepoint names, like the TransactionState block itself, live * in TopTransactionContext. */ if (name) s->name = MemoryContextStrdup(TopTransactionContext, name); break; /* * We disallow savepoint commands in implicit transaction blocks. * There would be no great difficulty in allowing them so far as * this module is concerned, but a savepoint seems inconsistent * with exec_simple_query's behavior of abandoning the whole query * string upon error. Also, the point of an implicit transaction * block (as opposed to a regular one) is to automatically close * after an error, so it's hard to see how a savepoint would fit * into that. * * The error messages for this are phrased as if there were no * active transaction block at all, which is historical but * perhaps could be improved. */ case TBLOCK_IMPLICIT_INPROGRESS: ereport(ERROR, (errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION), /* translator: %s represents an SQL statement name */ errmsg("%s can only be used in transaction blocks", "SAVEPOINT"))); break; /* These cases are invalid. */ case TBLOCK_DEFAULT: case TBLOCK_STARTED: case TBLOCK_BEGIN: case TBLOCK_PARALLEL_INPROGRESS: case TBLOCK_SUBBEGIN: case TBLOCK_END: case TBLOCK_SUBRELEASE: case TBLOCK_SUBCOMMIT: case TBLOCK_ABORT: case TBLOCK_SUBABORT: case TBLOCK_ABORT_END: case TBLOCK_SUBABORT_END: case TBLOCK_ABORT_PENDING: case TBLOCK_SUBABORT_PENDING: case TBLOCK_SUBRESTART: case TBLOCK_SUBABORT_RESTART: case TBLOCK_PREPARE: elog(FATAL, "DefineSavepoint: unexpected state %s", BlockStateAsString(s->blockState)); break; } } /* * ReleaseSavepoint * This executes a RELEASE command. * * As above, we don't actually do anything here except change blockState. */ void ReleaseSavepoint(const char *name) { TransactionState s = CurrentTransactionState; TransactionState target, xact; /* * Workers synchronize transaction state at the beginning of each parallel * operation, so we can't account for transaction state change after that * point. (Note that this check will certainly error out if s->blockState * is TBLOCK_PARALLEL_INPROGRESS, so we can treat that as an invalid case * below.) */ if (IsInParallelMode() || IsParallelWorker()) ereport(ERROR, (errcode(ERRCODE_INVALID_TRANSACTION_STATE), errmsg("cannot release savepoints during a parallel operation"))); switch (s->blockState) { /* * We can't release a savepoint if there is no savepoint defined. */ case TBLOCK_INPROGRESS: ereport(ERROR, (errcode(ERRCODE_S_E_INVALID_SPECIFICATION), errmsg("savepoint \"%s\" does not exist", name))); break; case TBLOCK_IMPLICIT_INPROGRESS: /* See comment about implicit transactions in DefineSavepoint */ ereport(ERROR, (errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION), /* translator: %s represents an SQL statement name */ errmsg("%s can only be used in transaction blocks", "RELEASE SAVEPOINT"))); break; /* * We are in a non-aborted subtransaction. This is the only valid * case. */ case TBLOCK_SUBINPROGRESS: break; /* These cases are invalid. */ case TBLOCK_DEFAULT: case TBLOCK_STARTED: case TBLOCK_BEGIN: case TBLOCK_PARALLEL_INPROGRESS: case TBLOCK_SUBBEGIN: case TBLOCK_END: case TBLOCK_SUBRELEASE: case TBLOCK_SUBCOMMIT: case TBLOCK_ABORT: case TBLOCK_SUBABORT: case TBLOCK_ABORT_END: case TBLOCK_SUBABORT_END: case TBLOCK_ABORT_PENDING: case TBLOCK_SUBABORT_PENDING: case TBLOCK_SUBRESTART: case TBLOCK_SUBABORT_RESTART: case TBLOCK_PREPARE: elog(FATAL, "ReleaseSavepoint: unexpected state %s", BlockStateAsString(s->blockState)); break; } for (target = s; target; target = target->parent) { if (target->name && strcmp(target->name, name) == 0) break; } if (!target) ereport(ERROR, (errcode(ERRCODE_S_E_INVALID_SPECIFICATION), errmsg("savepoint \"%s\" does not exist", name))); /* disallow crossing savepoint level boundaries */ if (target->savepointLevel != s->savepointLevel) ereport(ERROR, (errcode(ERRCODE_S_E_INVALID_SPECIFICATION), errmsg("savepoint \"%s\" does not exist within current savepoint level", name))); /* * Mark "commit pending" all subtransactions up to the target * subtransaction. The actual commits will happen when control gets to * CommitTransactionCommand. */ xact = CurrentTransactionState; for (;;) { Assert(xact->blockState == TBLOCK_SUBINPROGRESS); xact->blockState = TBLOCK_SUBRELEASE; if (xact == target) break; xact = xact->parent; Assert(xact); } } /* * RollbackToSavepoint * This executes a ROLLBACK TO <savepoint> command. * * As above, we don't actually do anything here except change blockState. */ void RollbackToSavepoint(const char *name) { TransactionState s = CurrentTransactionState; TransactionState target, xact; /* * Workers synchronize transaction state at the beginning of each parallel * operation, so we can't account for transaction state change after that * point. (Note that this check will certainly error out if s->blockState * is TBLOCK_PARALLEL_INPROGRESS, so we can treat that as an invalid case * below.) */ if (IsInParallelMode() || IsParallelWorker()) ereport(ERROR, (errcode(ERRCODE_INVALID_TRANSACTION_STATE), errmsg("cannot rollback to savepoints during a parallel operation"))); switch (s->blockState) { /* * We can't rollback to a savepoint if there is no savepoint * defined. */ case TBLOCK_INPROGRESS: case TBLOCK_ABORT: ereport(ERROR, (errcode(ERRCODE_S_E_INVALID_SPECIFICATION), errmsg("savepoint \"%s\" does not exist", name))); break; case TBLOCK_IMPLICIT_INPROGRESS: /* See comment about implicit transactions in DefineSavepoint */ ereport(ERROR, (errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION), /* translator: %s represents an SQL statement name */ errmsg("%s can only be used in transaction blocks", "ROLLBACK TO SAVEPOINT"))); break; /* * There is at least one savepoint, so proceed. */ case TBLOCK_SUBINPROGRESS: case TBLOCK_SUBABORT: break; /* These cases are invalid. */ case TBLOCK_DEFAULT: case TBLOCK_STARTED: case TBLOCK_BEGIN: case TBLOCK_PARALLEL_INPROGRESS: case TBLOCK_SUBBEGIN: case TBLOCK_END: case TBLOCK_SUBRELEASE: case TBLOCK_SUBCOMMIT: case TBLOCK_ABORT_END: case TBLOCK_SUBABORT_END: case TBLOCK_ABORT_PENDING: case TBLOCK_SUBABORT_PENDING: case TBLOCK_SUBRESTART: case TBLOCK_SUBABORT_RESTART: case TBLOCK_PREPARE: elog(FATAL, "RollbackToSavepoint: unexpected state %s", BlockStateAsString(s->blockState)); break; } for (target = s; target; target = target->parent) { if (target->name && strcmp(target->name, name) == 0) break; } if (!target) ereport(ERROR, (errcode(ERRCODE_S_E_INVALID_SPECIFICATION), errmsg("savepoint \"%s\" does not exist", name))); /* disallow crossing savepoint level boundaries */ if (target->savepointLevel != s->savepointLevel) ereport(ERROR, (errcode(ERRCODE_S_E_INVALID_SPECIFICATION), errmsg("savepoint \"%s\" does not exist within current savepoint level", name))); /* * Mark "abort pending" all subtransactions up to the target * subtransaction. The actual aborts will happen when control gets to * CommitTransactionCommand. */ xact = CurrentTransactionState; for (;;) { if (xact == target) break; if (xact->blockState == TBLOCK_SUBINPROGRESS) xact->blockState = TBLOCK_SUBABORT_PENDING; else if (xact->blockState == TBLOCK_SUBABORT) xact->blockState = TBLOCK_SUBABORT_END; else elog(FATAL, "RollbackToSavepoint: unexpected state %s", BlockStateAsString(xact->blockState)); xact = xact->parent; Assert(xact); } /* And mark the target as "restart pending" */ if (xact->blockState == TBLOCK_SUBINPROGRESS) xact->blockState = TBLOCK_SUBRESTART; else if (xact->blockState == TBLOCK_SUBABORT) xact->blockState = TBLOCK_SUBABORT_RESTART; else elog(FATAL, "RollbackToSavepoint: unexpected state %s", BlockStateAsString(xact->blockState)); } /* * BeginInternalSubTransaction * This is the same as DefineSavepoint except it allows TBLOCK_STARTED, * TBLOCK_IMPLICIT_INPROGRESS, TBLOCK_PARALLEL_INPROGRESS, TBLOCK_END, * and TBLOCK_PREPARE states, and therefore it can safely be used in * functions that might be called when not inside a BEGIN block or when * running deferred triggers at COMMIT/PREPARE time. Also, it * automatically does CommitTransactionCommand/StartTransactionCommand * instead of expecting the caller to do it. */ void BeginInternalSubTransaction(const char *name) { TransactionState s = CurrentTransactionState; bool save_ExitOnAnyError = ExitOnAnyError; /* * Errors within this function are improbable, but if one does happen we * force a FATAL exit. Callers generally aren't prepared to handle losing * control, and moreover our transaction state is probably corrupted if we * fail partway through; so an ordinary ERROR longjmp isn't okay. */ ExitOnAnyError = true; /* * We do not check for parallel mode here. It's permissible to start and * end "internal" subtransactions while in parallel mode, so long as no * new XIDs or command IDs are assigned. Enforcement of that occurs in * AssignTransactionId() and CommandCounterIncrement(). */ switch (s->blockState) { case TBLOCK_STARTED: case TBLOCK_INPROGRESS: case TBLOCK_IMPLICIT_INPROGRESS: case TBLOCK_PARALLEL_INPROGRESS: case TBLOCK_END: case TBLOCK_PREPARE: case TBLOCK_SUBINPROGRESS: /* Normal subtransaction start */ PushTransaction(); s = CurrentTransactionState; /* changed by push */ /* * Savepoint names, like the TransactionState block itself, live * in TopTransactionContext. */ if (name) s->name = MemoryContextStrdup(TopTransactionContext, name); break; /* These cases are invalid. */ case TBLOCK_DEFAULT: case TBLOCK_BEGIN: case TBLOCK_SUBBEGIN: case TBLOCK_SUBRELEASE: case TBLOCK_SUBCOMMIT: case TBLOCK_ABORT: case TBLOCK_SUBABORT: case TBLOCK_ABORT_END: case TBLOCK_SUBABORT_END: case TBLOCK_ABORT_PENDING: case TBLOCK_SUBABORT_PENDING: case TBLOCK_SUBRESTART: case TBLOCK_SUBABORT_RESTART: elog(FATAL, "BeginInternalSubTransaction: unexpected state %s", BlockStateAsString(s->blockState)); break; } CommitTransactionCommand(); StartTransactionCommand(); ExitOnAnyError = save_ExitOnAnyError; } /* * ReleaseCurrentSubTransaction * * RELEASE (ie, commit) the innermost subtransaction, regardless of its * savepoint name (if any). * NB: do NOT use CommitTransactionCommand/StartTransactionCommand with this. */ void ReleaseCurrentSubTransaction(void) { TransactionState s = CurrentTransactionState; /* * We do not check for parallel mode here. It's permissible to start and * end "internal" subtransactions while in parallel mode, so long as no * new XIDs or command IDs are assigned. */ if (s->blockState != TBLOCK_SUBINPROGRESS) elog(ERROR, "ReleaseCurrentSubTransaction: unexpected state %s", BlockStateAsString(s->blockState)); Assert(s->state == TRANS_INPROGRESS); MemoryContextSwitchTo(CurTransactionContext); CommitSubTransaction(); s = CurrentTransactionState; /* changed by pop */ Assert(s->state == TRANS_INPROGRESS); } /* * RollbackAndReleaseCurrentSubTransaction * * ROLLBACK and RELEASE (ie, abort) the innermost subtransaction, regardless * of its savepoint name (if any). * NB: do NOT use CommitTransactionCommand/StartTransactionCommand with this. */ void RollbackAndReleaseCurrentSubTransaction(void) { TransactionState s = CurrentTransactionState; /* * We do not check for parallel mode here. It's permissible to start and * end "internal" subtransactions while in parallel mode, so long as no * new XIDs or command IDs are assigned. */ switch (s->blockState) { /* Must be in a subtransaction */ case TBLOCK_SUBINPROGRESS: case TBLOCK_SUBABORT: break; /* These cases are invalid. */ case TBLOCK_DEFAULT: case TBLOCK_STARTED: case TBLOCK_BEGIN: case TBLOCK_IMPLICIT_INPROGRESS: case TBLOCK_PARALLEL_INPROGRESS: case TBLOCK_SUBBEGIN: case TBLOCK_INPROGRESS: case TBLOCK_END: case TBLOCK_SUBRELEASE: case TBLOCK_SUBCOMMIT: case TBLOCK_ABORT: case TBLOCK_ABORT_END: case TBLOCK_SUBABORT_END: case TBLOCK_ABORT_PENDING: case TBLOCK_SUBABORT_PENDING: case TBLOCK_SUBRESTART: case TBLOCK_SUBABORT_RESTART: case TBLOCK_PREPARE: elog(FATAL, "RollbackAndReleaseCurrentSubTransaction: unexpected state %s", BlockStateAsString(s->blockState)); break; } /* * Abort the current subtransaction, if needed. */ if (s->blockState == TBLOCK_SUBINPROGRESS) AbortSubTransaction(); /* And clean it up, too */ CleanupSubTransaction(); s = CurrentTransactionState; /* changed by pop */ Assert(s->blockState == TBLOCK_SUBINPROGRESS || s->blockState == TBLOCK_INPROGRESS || s->blockState == TBLOCK_IMPLICIT_INPROGRESS || s->blockState == TBLOCK_PARALLEL_INPROGRESS || s->blockState == TBLOCK_STARTED); } /* * AbortOutOfAnyTransaction * * This routine is provided for error recovery purposes. It aborts any * active transaction or transaction block, leaving the system in a known * idle state. */ void AbortOutOfAnyTransaction(void) { TransactionState s = CurrentTransactionState; /* Ensure we're not running in a doomed memory context */ AtAbort_Memory(); /* * Get out of any transaction or nested transaction */ do { switch (s->blockState) { case TBLOCK_DEFAULT: if (s->state == TRANS_DEFAULT) { /* Not in a transaction, do nothing */ } else { /* * We can get here after an error during transaction start * (state will be TRANS_START). Need to clean up the * incompletely started transaction. First, adjust the * low-level state to suppress warning message from * AbortTransaction. */ if (s->state == TRANS_START) s->state = TRANS_INPROGRESS; AbortTransaction(); CleanupTransaction(); } break; case TBLOCK_STARTED: case TBLOCK_BEGIN: case TBLOCK_INPROGRESS: case TBLOCK_IMPLICIT_INPROGRESS: case TBLOCK_PARALLEL_INPROGRESS: case TBLOCK_END: case TBLOCK_ABORT_PENDING: case TBLOCK_PREPARE: /* In a transaction, so clean up */ AbortTransaction(); CleanupTransaction(); s->blockState = TBLOCK_DEFAULT; break; case TBLOCK_ABORT: case TBLOCK_ABORT_END: /* * AbortTransaction is already done, still need Cleanup. * However, if we failed partway through running ROLLBACK, * there will be an active portal running that command, which * we need to shut down before doing CleanupTransaction. */ AtAbort_Portals(); CleanupTransaction(); s->blockState = TBLOCK_DEFAULT; break; /* * In a subtransaction, so clean it up and abort parent too */ case TBLOCK_SUBBEGIN: case TBLOCK_SUBINPROGRESS: case TBLOCK_SUBRELEASE: case TBLOCK_SUBCOMMIT: case TBLOCK_SUBABORT_PENDING: case TBLOCK_SUBRESTART: AbortSubTransaction(); CleanupSubTransaction(); s = CurrentTransactionState; /* changed by pop */ break; case TBLOCK_SUBABORT: case TBLOCK_SUBABORT_END: case TBLOCK_SUBABORT_RESTART: /* As above, but AbortSubTransaction already done */ if (s->curTransactionOwner) { /* As in TBLOCK_ABORT, might have a live portal to zap */ AtSubAbort_Portals(s->subTransactionId, s->parent->subTransactionId, s->curTransactionOwner, s->parent->curTransactionOwner); } CleanupSubTransaction(); s = CurrentTransactionState; /* changed by pop */ break; } } while (s->blockState != TBLOCK_DEFAULT); /* Should be out of all subxacts now */ Assert(s->parent == NULL); /* * Revert to TopMemoryContext, to ensure we exit in a well-defined state * whether there were any transactions to close or not. (Callers that * don't intend to exit soon should switch to some other context to avoid * long-term memory leaks.) */ MemoryContextSwitchTo(TopMemoryContext); } /* * IsTransactionBlock --- are we within a transaction block? */ bool IsTransactionBlock(void) { TransactionState s = CurrentTransactionState; if (s->blockState == TBLOCK_DEFAULT || s->blockState == TBLOCK_STARTED) return false; return true; } /* * IsTransactionOrTransactionBlock --- are we within either a transaction * or a transaction block? (The backend is only really "idle" when this * returns false.) * * This should match up with IsTransactionBlock and IsTransactionState. */ bool IsTransactionOrTransactionBlock(void) { TransactionState s = CurrentTransactionState; if (s->blockState == TBLOCK_DEFAULT) return false; return true; } /* * TransactionBlockStatusCode - return status code to send in ReadyForQuery */ char TransactionBlockStatusCode(void) { TransactionState s = CurrentTransactionState; switch (s->blockState) { case TBLOCK_DEFAULT: case TBLOCK_STARTED: return 'I'; /* idle --- not in transaction */ case TBLOCK_BEGIN: case TBLOCK_SUBBEGIN: case TBLOCK_INPROGRESS: case TBLOCK_IMPLICIT_INPROGRESS: case TBLOCK_PARALLEL_INPROGRESS: case TBLOCK_SUBINPROGRESS: case TBLOCK_END: case TBLOCK_SUBRELEASE: case TBLOCK_SUBCOMMIT: case TBLOCK_PREPARE: return 'T'; /* in transaction */ case TBLOCK_ABORT: case TBLOCK_SUBABORT: case TBLOCK_ABORT_END: case TBLOCK_SUBABORT_END: case TBLOCK_ABORT_PENDING: case TBLOCK_SUBABORT_PENDING: case TBLOCK_SUBRESTART: case TBLOCK_SUBABORT_RESTART: return 'E'; /* in failed transaction */ } /* should never get here */ elog(FATAL, "invalid transaction block state: %s", BlockStateAsString(s->blockState)); return 0; /* keep compiler quiet */ } /* * IsSubTransaction */ bool IsSubTransaction(void) { TransactionState s = CurrentTransactionState; if (s->nestingLevel >= 2) return true; return false; } /* * StartSubTransaction * * If you're wondering why this is separate from PushTransaction: it's because * we can't conveniently do this stuff right inside DefineSavepoint. The * SAVEPOINT utility command will be executed inside a Portal, and if we * muck with CurrentMemoryContext or CurrentResourceOwner then exit from * the Portal will undo those settings. So we make DefineSavepoint just * push a dummy transaction block, and when control returns to the main * idle loop, CommitTransactionCommand will be called, and we'll come here * to finish starting the subtransaction. */ static void StartSubTransaction(void) { TransactionState s = CurrentTransactionState; if (s->state != TRANS_DEFAULT) elog(WARNING, "StartSubTransaction while in %s state", TransStateAsString(s->state)); s->state = TRANS_START; /* * Initialize subsystems for new subtransaction * * must initialize resource-management stuff first */ AtSubStart_Memory(); AtSubStart_ResourceOwner(); AfterTriggerBeginSubXact(); s->state = TRANS_INPROGRESS; /* * Call start-of-subxact callbacks */ CallSubXactCallbacks(SUBXACT_EVENT_START_SUB, s->subTransactionId, s->parent->subTransactionId); ShowTransactionState("StartSubTransaction"); } /* * CommitSubTransaction * * The caller has to make sure to always reassign CurrentTransactionState * if it has a local pointer to it after calling this function. */ static void CommitSubTransaction(void) { TransactionState s = CurrentTransactionState; ShowTransactionState("CommitSubTransaction"); if (s->state != TRANS_INPROGRESS) elog(WARNING, "CommitSubTransaction while in %s state", TransStateAsString(s->state)); /* Pre-commit processing goes here */ CallSubXactCallbacks(SUBXACT_EVENT_PRE_COMMIT_SUB, s->subTransactionId, s->parent->subTransactionId); /* * If this subxact has started any unfinished parallel operation, clean up * its workers and exit parallel mode. Warn about leaked resources. */ AtEOSubXact_Parallel(true, s->subTransactionId); if (s->parallelModeLevel != 0) { elog(WARNING, "parallelModeLevel is %d not 0 at end of subtransaction", s->parallelModeLevel); s->parallelModeLevel = 0; } /* Do the actual "commit", such as it is */ s->state = TRANS_COMMIT; /* Must CCI to ensure commands of subtransaction are seen as done */ CommandCounterIncrement(); /* * Prior to 8.4 we marked subcommit in clog at this point. We now only * perform that step, if required, as part of the atomic update of the * whole transaction tree at top level commit or abort. */ /* Post-commit cleanup */ if (FullTransactionIdIsValid(s->fullTransactionId)) AtSubCommit_childXids(); AfterTriggerEndSubXact(true); AtSubCommit_Portals(s->subTransactionId, s->parent->subTransactionId, s->parent->nestingLevel, s->parent->curTransactionOwner); AtEOSubXact_LargeObject(true, s->subTransactionId, s->parent->subTransactionId); AtSubCommit_Notify(); CallSubXactCallbacks(SUBXACT_EVENT_COMMIT_SUB, s->subTransactionId, s->parent->subTransactionId); ResourceOwnerRelease(s->curTransactionOwner, RESOURCE_RELEASE_BEFORE_LOCKS, true, false); AtEOSubXact_RelationCache(true, s->subTransactionId, s->parent->subTransactionId); AtEOSubXact_TypeCache(); AtEOSubXact_Inval(true); AtSubCommit_smgr(); /* * The only lock we actually release here is the subtransaction XID lock. */ CurrentResourceOwner = s->curTransactionOwner; if (FullTransactionIdIsValid(s->fullTransactionId)) XactLockTableDelete(XidFromFullTransactionId(s->fullTransactionId)); /* * Other locks should get transferred to their parent resource owner. */ ResourceOwnerRelease(s->curTransactionOwner, RESOURCE_RELEASE_LOCKS, true, false); ResourceOwnerRelease(s->curTransactionOwner, RESOURCE_RELEASE_AFTER_LOCKS, true, false); AtEOXact_GUC(true, s->gucNestLevel); AtEOSubXact_SPI(true, s->subTransactionId); AtEOSubXact_on_commit_actions(true, s->subTransactionId, s->parent->subTransactionId); AtEOSubXact_Namespace(true, s->subTransactionId, s->parent->subTransactionId); AtEOSubXact_Files(true, s->subTransactionId, s->parent->subTransactionId); AtEOSubXact_HashTables(true, s->nestingLevel); AtEOSubXact_PgStat(true, s->nestingLevel); AtSubCommit_Snapshot(s->nestingLevel); /* * We need to restore the upper transaction's read-only state, in case the * upper is read-write while the child is read-only; GUC will incorrectly * think it should leave the child state in place. */ XactReadOnly = s->prevXactReadOnly; CurrentResourceOwner = s->parent->curTransactionOwner; CurTransactionResourceOwner = s->parent->curTransactionOwner; ResourceOwnerDelete(s->curTransactionOwner); s->curTransactionOwner = NULL; AtSubCommit_Memory(); s->state = TRANS_DEFAULT; PopTransaction(); } /* * AbortSubTransaction */ static void AbortSubTransaction(void) { TransactionState s = CurrentTransactionState; /* Prevent cancel/die interrupt while cleaning up */ HOLD_INTERRUPTS(); /* Make sure we have a valid memory context and resource owner */ AtSubAbort_Memory(); AtSubAbort_ResourceOwner(); /* * Release any LW locks we might be holding as quickly as possible. * (Regular locks, however, must be held till we finish aborting.) * Releasing LW locks is critical since we might try to grab them again * while cleaning up! * * FIXME This may be incorrect --- Are there some locks we should keep? * Buffer locks, for example? I don't think so but I'm not sure. */ LWLockReleaseAll(); /* * Cleanup waiting for LSN if any. */ WaitLSNCleanup(); pgstat_report_wait_end(); pgstat_progress_end_command(); pgaio_error_cleanup(); UnlockBuffers(); /* Reset WAL record construction state */ XLogResetInsertion(); /* Cancel condition variable sleep */ ConditionVariableCancelSleep(); /* * Also clean up any open wait for lock, since the lock manager will choke * if we try to wait for another lock before doing this. */ LockErrorCleanup(); /* * If any timeout events are still active, make sure the timeout interrupt * is scheduled. This covers possible loss of a timeout interrupt due to * longjmp'ing out of the SIGINT handler (see notes in handle_sig_alarm). * We delay this till after LockErrorCleanup so that we don't uselessly * reschedule lock or deadlock check timeouts. */ reschedule_timeouts(); /* * Re-enable signals, in case we got here by longjmp'ing out of a signal * handler. We do this fairly early in the sequence so that the timeout * infrastructure will be functional if needed while aborting. */ sigprocmask(SIG_SETMASK, &UnBlockSig, NULL); /* * check the current transaction state */ ShowTransactionState("AbortSubTransaction"); if (s->state != TRANS_INPROGRESS) elog(WARNING, "AbortSubTransaction while in %s state", TransStateAsString(s->state)); s->state = TRANS_ABORT; /* * Reset user ID which might have been changed transiently. (See notes in * AbortTransaction.) */ SetUserIdAndSecContext(s->prevUser, s->prevSecContext); /* Forget about any active REINDEX. */ ResetReindexState(s->nestingLevel); /* Reset logical streaming state. */ ResetLogicalStreamingState(); /* * No need for SnapBuildResetExportedSnapshotState() here, snapshot * exports are not supported in subtransactions. */ /* * If this subxact has started any unfinished parallel operation, clean up * its workers and exit parallel mode. Don't warn about leaked resources. */ AtEOSubXact_Parallel(false, s->subTransactionId); s->parallelModeLevel = 0; /* * We can skip all this stuff if the subxact failed before creating a * ResourceOwner... */ if (s->curTransactionOwner) { AfterTriggerEndSubXact(false); AtSubAbort_Portals(s->subTransactionId, s->parent->subTransactionId, s->curTransactionOwner, s->parent->curTransactionOwner); AtEOSubXact_LargeObject(false, s->subTransactionId, s->parent->subTransactionId); AtSubAbort_Notify(); /* Advertise the fact that we aborted in pg_xact. */ (void) RecordTransactionAbort(true); /* Post-abort cleanup */ if (FullTransactionIdIsValid(s->fullTransactionId)) AtSubAbort_childXids(); CallSubXactCallbacks(SUBXACT_EVENT_ABORT_SUB, s->subTransactionId, s->parent->subTransactionId); ResourceOwnerRelease(s->curTransactionOwner, RESOURCE_RELEASE_BEFORE_LOCKS, false, false); AtEOXact_Aio(false); AtEOSubXact_RelationCache(false, s->subTransactionId, s->parent->subTransactionId); AtEOSubXact_TypeCache(); AtEOSubXact_Inval(false); ResourceOwnerRelease(s->curTransactionOwner, RESOURCE_RELEASE_LOCKS, false, false); ResourceOwnerRelease(s->curTransactionOwner, RESOURCE_RELEASE_AFTER_LOCKS, false, false); AtSubAbort_smgr(); AtEOXact_GUC(false, s->gucNestLevel); AtEOSubXact_SPI(false, s->subTransactionId); AtEOSubXact_on_commit_actions(false, s->subTransactionId, s->parent->subTransactionId); AtEOSubXact_Namespace(false, s->subTransactionId, s->parent->subTransactionId); AtEOSubXact_Files(false, s->subTransactionId, s->parent->subTransactionId); AtEOSubXact_HashTables(false, s->nestingLevel); AtEOSubXact_PgStat(false, s->nestingLevel); AtSubAbort_Snapshot(s->nestingLevel); } /* * Restore the upper transaction's read-only state, too. This should be * redundant with GUC's cleanup but we may as well do it for consistency * with the commit case. */ XactReadOnly = s->prevXactReadOnly; RESUME_INTERRUPTS(); } /* * CleanupSubTransaction * * The caller has to make sure to always reassign CurrentTransactionState * if it has a local pointer to it after calling this function. */ static void CleanupSubTransaction(void) { TransactionState s = CurrentTransactionState; ShowTransactionState("CleanupSubTransaction"); if (s->state != TRANS_ABORT) elog(WARNING, "CleanupSubTransaction while in %s state", TransStateAsString(s->state)); AtSubCleanup_Portals(s->subTransactionId); CurrentResourceOwner = s->parent->curTransactionOwner; CurTransactionResourceOwner = s->parent->curTransactionOwner; if (s->curTransactionOwner) ResourceOwnerDelete(s->curTransactionOwner); s->curTransactionOwner = NULL; AtSubCleanup_Memory(); s->state = TRANS_DEFAULT; PopTransaction(); } /* * PushTransaction * Create transaction state stack entry for a subtransaction * * The caller has to make sure to always reassign CurrentTransactionState * if it has a local pointer to it after calling this function. */ static void PushTransaction(void) { TransactionState p = CurrentTransactionState; TransactionState s; /* * We keep subtransaction state nodes in TopTransactionContext. */ s = (TransactionState) MemoryContextAllocZero(TopTransactionContext, sizeof(TransactionStateData)); /* * Assign a subtransaction ID, watching out for counter wraparound. */ currentSubTransactionId += 1; if (currentSubTransactionId == InvalidSubTransactionId) { currentSubTransactionId -= 1; pfree(s); ereport(ERROR, (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), errmsg("cannot have more than 2^32-1 subtransactions in a transaction"))); } /* * We can now stack a minimally valid subtransaction without fear of * failure. */ s->fullTransactionId = InvalidFullTransactionId; /* until assigned */ s->subTransactionId = currentSubTransactionId; s->parent = p; s->nestingLevel = p->nestingLevel + 1; s->gucNestLevel = NewGUCNestLevel(); s->savepointLevel = p->savepointLevel; s->state = TRANS_DEFAULT; s->blockState = TBLOCK_SUBBEGIN; GetUserIdAndSecContext(&s->prevUser, &s->prevSecContext); s->prevXactReadOnly = XactReadOnly; s->startedInRecovery = p->startedInRecovery; s->parallelModeLevel = 0; s->parallelChildXact = (p->parallelModeLevel != 0 || p->parallelChildXact); s->topXidLogged = false; CurrentTransactionState = s; /* * AbortSubTransaction and CleanupSubTransaction have to be able to cope * with the subtransaction from here on out; in particular they should not * assume that it necessarily has a transaction context, resource owner, * or XID. */ } /* * PopTransaction * Pop back to parent transaction state * * The caller has to make sure to always reassign CurrentTransactionState * if it has a local pointer to it after calling this function. */ static void PopTransaction(void) { TransactionState s = CurrentTransactionState; if (s->state != TRANS_DEFAULT) elog(WARNING, "PopTransaction while in %s state", TransStateAsString(s->state)); if (s->parent == NULL) elog(FATAL, "PopTransaction with no parent"); CurrentTransactionState = s->parent; /* Let's just make sure CurTransactionContext is good */ CurTransactionContext = s->parent->curTransactionContext; MemoryContextSwitchTo(CurTransactionContext); /* Ditto for ResourceOwner links */ CurTransactionResourceOwner = s->parent->curTransactionOwner; CurrentResourceOwner = s->parent->curTransactionOwner; /* Free the old child structure */ if (s->name) pfree(s->name); pfree(s); } /* * EstimateTransactionStateSpace * Estimate the amount of space that will be needed by * SerializeTransactionState. It would be OK to overestimate slightly, * but it's simple for us to work out the precise value, so we do. */ Size EstimateTransactionStateSpace(void) { TransactionState s; Size nxids = 0; Size size = SerializedTransactionStateHeaderSize; for (s = CurrentTransactionState; s != NULL; s = s->parent) { if (FullTransactionIdIsValid(s->fullTransactionId)) nxids = add_size(nxids, 1); nxids = add_size(nxids, s->nChildXids); } return add_size(size, mul_size(sizeof(TransactionId), nxids)); } /* * SerializeTransactionState * Write out relevant details of our transaction state that will be * needed by a parallel worker. * * We need to save and restore XactDeferrable, XactIsoLevel, and the XIDs * associated with this transaction. These are serialized into a * caller-supplied buffer big enough to hold the number of bytes reported by * EstimateTransactionStateSpace(). We emit the XIDs in sorted order for the * convenience of the receiving process. */ void SerializeTransactionState(Size maxsize, char *start_address) { TransactionState s; Size nxids = 0; Size i = 0; TransactionId *workspace; SerializedTransactionState *result; result = (SerializedTransactionState *) start_address; result->xactIsoLevel = XactIsoLevel; result->xactDeferrable = XactDeferrable; result->topFullTransactionId = XactTopFullTransactionId; result->currentFullTransactionId = CurrentTransactionState->fullTransactionId; result->currentCommandId = currentCommandId; /* * If we're running in a parallel worker and launching a parallel worker * of our own, we can just pass along the information that was passed to * us. */ if (nParallelCurrentXids > 0) { result->nParallelCurrentXids = nParallelCurrentXids; memcpy(&result->parallelCurrentXids[0], ParallelCurrentXids, nParallelCurrentXids * sizeof(TransactionId)); return; } /* * OK, we need to generate a sorted list of XIDs that our workers should * view as current. First, figure out how many there are. */ for (s = CurrentTransactionState; s != NULL; s = s->parent) { if (FullTransactionIdIsValid(s->fullTransactionId)) nxids = add_size(nxids, 1); nxids = add_size(nxids, s->nChildXids); } Assert(SerializedTransactionStateHeaderSize + nxids * sizeof(TransactionId) <= maxsize); /* Copy them to our scratch space. */ workspace = palloc(nxids * sizeof(TransactionId)); for (s = CurrentTransactionState; s != NULL; s = s->parent) { if (FullTransactionIdIsValid(s->fullTransactionId)) workspace[i++] = XidFromFullTransactionId(s->fullTransactionId); if (s->nChildXids > 0) memcpy(&workspace[i], s->childXids, s->nChildXids * sizeof(TransactionId)); i += s->nChildXids; } Assert(i == nxids); /* Sort them. */ qsort(workspace, nxids, sizeof(TransactionId), xidComparator); /* Copy data into output area. */ result->nParallelCurrentXids = nxids; memcpy(&result->parallelCurrentXids[0], workspace, nxids * sizeof(TransactionId)); } /* * StartParallelWorkerTransaction * Start a parallel worker transaction, restoring the relevant * transaction state serialized by SerializeTransactionState. */ void StartParallelWorkerTransaction(char *tstatespace) { SerializedTransactionState *tstate; Assert(CurrentTransactionState->blockState == TBLOCK_DEFAULT); StartTransaction(); tstate = (SerializedTransactionState *) tstatespace; XactIsoLevel = tstate->xactIsoLevel; XactDeferrable = tstate->xactDeferrable; XactTopFullTransactionId = tstate->topFullTransactionId; CurrentTransactionState->fullTransactionId = tstate->currentFullTransactionId; currentCommandId = tstate->currentCommandId; nParallelCurrentXids = tstate->nParallelCurrentXids; ParallelCurrentXids = &tstate->parallelCurrentXids[0]; CurrentTransactionState->blockState = TBLOCK_PARALLEL_INPROGRESS; } /* * EndParallelWorkerTransaction * End a parallel worker transaction. */ void EndParallelWorkerTransaction(void) { Assert(CurrentTransactionState->blockState == TBLOCK_PARALLEL_INPROGRESS); CommitTransaction(); CurrentTransactionState->blockState = TBLOCK_DEFAULT; } /* * ShowTransactionState * Debug support */ static void ShowTransactionState(const char *str) { /* skip work if message will definitely not be printed */ if (message_level_is_interesting(DEBUG5)) ShowTransactionStateRec(str, CurrentTransactionState); } /* * ShowTransactionStateRec * Recursive subroutine for ShowTransactionState */ static void ShowTransactionStateRec(const char *str, TransactionState s) { StringInfoData buf; if (s->parent) { /* * Since this function recurses, it could be driven to stack overflow. * This is just a debugging aid, so we can leave out some details * instead of erroring out with check_stack_depth(). */ if (stack_is_too_deep()) ereport(DEBUG5, (errmsg_internal("%s(%d): parent omitted to avoid stack overflow", str, s->nestingLevel))); else ShowTransactionStateRec(str, s->parent); } initStringInfo(&buf); if (s->nChildXids > 0) { int i; appendStringInfo(&buf, ", children: %u", s->childXids[0]); for (i = 1; i < s->nChildXids; i++) appendStringInfo(&buf, " %u", s->childXids[i]); } ereport(DEBUG5, (errmsg_internal("%s(%d) name: %s; blockState: %s; state: %s, xid/subid/cid: %u/%u/%u%s%s", str, s->nestingLevel, s->name ? s->name : "unnamed", BlockStateAsString(s->blockState), TransStateAsString(s->state), XidFromFullTransactionId(s->fullTransactionId), s->subTransactionId, currentCommandId, currentCommandIdUsed ? " (used)" : "", buf.data))); pfree(buf.data); } /* * BlockStateAsString * Debug support */ static const char * BlockStateAsString(TBlockState blockState) { switch (blockState) { case TBLOCK_DEFAULT: return "DEFAULT"; case TBLOCK_STARTED: return "STARTED"; case TBLOCK_BEGIN: return "BEGIN"; case TBLOCK_INPROGRESS: return "INPROGRESS"; case TBLOCK_IMPLICIT_INPROGRESS: return "IMPLICIT_INPROGRESS"; case TBLOCK_PARALLEL_INPROGRESS: return "PARALLEL_INPROGRESS"; case TBLOCK_END: return "END"; case TBLOCK_ABORT: return "ABORT"; case TBLOCK_ABORT_END: return "ABORT_END"; case TBLOCK_ABORT_PENDING: return "ABORT_PENDING"; case TBLOCK_PREPARE: return "PREPARE"; case TBLOCK_SUBBEGIN: return "SUBBEGIN"; case TBLOCK_SUBINPROGRESS: return "SUBINPROGRESS"; case TBLOCK_SUBRELEASE: return "SUBRELEASE"; case TBLOCK_SUBCOMMIT: return "SUBCOMMIT"; case TBLOCK_SUBABORT: return "SUBABORT"; case TBLOCK_SUBABORT_END: return "SUBABORT_END"; case TBLOCK_SUBABORT_PENDING: return "SUBABORT_PENDING"; case TBLOCK_SUBRESTART: return "SUBRESTART"; case TBLOCK_SUBABORT_RESTART: return "SUBABORT_RESTART"; } return "UNRECOGNIZED"; } /* * TransStateAsString * Debug support */ static const char * TransStateAsString(TransState state) { switch (state) { case TRANS_DEFAULT: return "DEFAULT"; case TRANS_START: return "START"; case TRANS_INPROGRESS: return "INPROGRESS"; case TRANS_COMMIT: return "COMMIT"; case TRANS_ABORT: return "ABORT"; case TRANS_PREPARE: return "PREPARE"; } return "UNRECOGNIZED"; } /* * xactGetCommittedChildren * * Gets the list of committed children of the current transaction. The return * value is the number of child transactions. *ptr is set to point to an * array of TransactionIds. The array is allocated in TopTransactionContext; * the caller should *not* pfree() it (this is a change from pre-8.4 code!). * If there are no subxacts, *ptr is set to NULL. */ int xactGetCommittedChildren(TransactionId **ptr) { TransactionState s = CurrentTransactionState; if (s->nChildXids == 0) *ptr = NULL; else *ptr = s->childXids; return s->nChildXids; } /* * XLOG support routines */ /* * Log the commit record for a plain or twophase transaction commit. * * A 2pc commit will be emitted when twophase_xid is valid, a plain one * otherwise. */ XLogRecPtr XactLogCommitRecord(TimestampTz commit_time, int nsubxacts, TransactionId *subxacts, int nrels, RelFileLocator *rels, int ndroppedstats, xl_xact_stats_item *droppedstats, int nmsgs, SharedInvalidationMessage *msgs, bool relcacheInval, int xactflags, TransactionId twophase_xid, const char *twophase_gid) { xl_xact_commit xlrec; xl_xact_xinfo xl_xinfo; xl_xact_dbinfo xl_dbinfo; xl_xact_subxacts xl_subxacts; xl_xact_relfilelocators xl_relfilelocators; xl_xact_stats_items xl_dropped_stats; xl_xact_invals xl_invals; xl_xact_twophase xl_twophase; xl_xact_origin xl_origin; uint8 info; Assert(CritSectionCount > 0); xl_xinfo.xinfo = 0; /* decide between a plain and 2pc commit */ if (!TransactionIdIsValid(twophase_xid)) info = XLOG_XACT_COMMIT; else info = XLOG_XACT_COMMIT_PREPARED; /* First figure out and collect all the information needed */ xlrec.xact_time = commit_time; if (relcacheInval) xl_xinfo.xinfo |= XACT_COMPLETION_UPDATE_RELCACHE_FILE; if (forceSyncCommit) xl_xinfo.xinfo |= XACT_COMPLETION_FORCE_SYNC_COMMIT; if ((xactflags & XACT_FLAGS_ACQUIREDACCESSEXCLUSIVELOCK)) xl_xinfo.xinfo |= XACT_XINFO_HAS_AE_LOCKS; /* * Check if the caller would like to ask standbys for immediate feedback * once this commit is applied. */ if (synchronous_commit >= SYNCHRONOUS_COMMIT_REMOTE_APPLY) xl_xinfo.xinfo |= XACT_COMPLETION_APPLY_FEEDBACK; /* * Relcache invalidations requires information about the current database * and so does logical decoding. */ if (nmsgs > 0 || XLogLogicalInfoActive()) { xl_xinfo.xinfo |= XACT_XINFO_HAS_DBINFO; xl_dbinfo.dbId = MyDatabaseId; xl_dbinfo.tsId = MyDatabaseTableSpace; } if (nsubxacts > 0) { xl_xinfo.xinfo |= XACT_XINFO_HAS_SUBXACTS; xl_subxacts.nsubxacts = nsubxacts; } if (nrels > 0) { xl_xinfo.xinfo |= XACT_XINFO_HAS_RELFILELOCATORS; xl_relfilelocators.nrels = nrels; info |= XLR_SPECIAL_REL_UPDATE; } if (ndroppedstats > 0) { xl_xinfo.xinfo |= XACT_XINFO_HAS_DROPPED_STATS; xl_dropped_stats.nitems = ndroppedstats; } if (nmsgs > 0) { xl_xinfo.xinfo |= XACT_XINFO_HAS_INVALS; xl_invals.nmsgs = nmsgs; } if (TransactionIdIsValid(twophase_xid)) { xl_xinfo.xinfo |= XACT_XINFO_HAS_TWOPHASE; xl_twophase.xid = twophase_xid; Assert(twophase_gid != NULL); if (XLogLogicalInfoActive()) xl_xinfo.xinfo |= XACT_XINFO_HAS_GID; } /* dump transaction origin information */ if (replorigin_xact_state.origin != InvalidReplOriginId) { xl_xinfo.xinfo |= XACT_XINFO_HAS_ORIGIN; xl_origin.origin_lsn = replorigin_xact_state.origin_lsn; xl_origin.origin_timestamp = replorigin_xact_state.origin_timestamp; } if (xl_xinfo.xinfo != 0) info |= XLOG_XACT_HAS_INFO; /* Then include all the collected data into the commit record. */ XLogBeginInsert(); XLogRegisterData(&xlrec, sizeof(xl_xact_commit)); if (xl_xinfo.xinfo != 0) XLogRegisterData(&xl_xinfo.xinfo, sizeof(xl_xinfo.xinfo)); if (xl_xinfo.xinfo & XACT_XINFO_HAS_DBINFO) XLogRegisterData(&xl_dbinfo, sizeof(xl_dbinfo)); if (xl_xinfo.xinfo & XACT_XINFO_HAS_SUBXACTS) { XLogRegisterData(&xl_subxacts, MinSizeOfXactSubxacts); XLogRegisterData(subxacts, nsubxacts * sizeof(TransactionId)); } if (xl_xinfo.xinfo & XACT_XINFO_HAS_RELFILELOCATORS) { XLogRegisterData(&xl_relfilelocators, MinSizeOfXactRelfileLocators); XLogRegisterData(rels, nrels * sizeof(RelFileLocator)); } if (xl_xinfo.xinfo & XACT_XINFO_HAS_DROPPED_STATS) { XLogRegisterData(&xl_dropped_stats, MinSizeOfXactStatsItems); XLogRegisterData(droppedstats, ndroppedstats * sizeof(xl_xact_stats_item)); } if (xl_xinfo.xinfo & XACT_XINFO_HAS_INVALS) { XLogRegisterData(&xl_invals, MinSizeOfXactInvals); XLogRegisterData(msgs, nmsgs * sizeof(SharedInvalidationMessage)); } if (xl_xinfo.xinfo & XACT_XINFO_HAS_TWOPHASE) { XLogRegisterData(&xl_twophase, sizeof(xl_xact_twophase)); if (xl_xinfo.xinfo & XACT_XINFO_HAS_GID) XLogRegisterData(twophase_gid, strlen(twophase_gid) + 1); } if (xl_xinfo.xinfo & XACT_XINFO_HAS_ORIGIN) XLogRegisterData(&xl_origin, sizeof(xl_xact_origin)); /* we allow filtering by xacts */ XLogSetRecordFlags(XLOG_INCLUDE_ORIGIN); return XLogInsert(RM_XACT_ID, info); } /* * Log the commit record for a plain or twophase transaction abort. * * A 2pc abort will be emitted when twophase_xid is valid, a plain one * otherwise. */ XLogRecPtr XactLogAbortRecord(TimestampTz abort_time, int nsubxacts, TransactionId *subxacts, int nrels, RelFileLocator *rels, int ndroppedstats, xl_xact_stats_item *droppedstats, int xactflags, TransactionId twophase_xid, const char *twophase_gid) { xl_xact_abort xlrec; xl_xact_xinfo xl_xinfo; xl_xact_subxacts xl_subxacts; xl_xact_relfilelocators xl_relfilelocators; xl_xact_stats_items xl_dropped_stats; xl_xact_twophase xl_twophase; xl_xact_dbinfo xl_dbinfo; xl_xact_origin xl_origin; uint8 info; Assert(CritSectionCount > 0); xl_xinfo.xinfo = 0; /* decide between a plain and 2pc abort */ if (!TransactionIdIsValid(twophase_xid)) info = XLOG_XACT_ABORT; else info = XLOG_XACT_ABORT_PREPARED; /* First figure out and collect all the information needed */ xlrec.xact_time = abort_time; if ((xactflags & XACT_FLAGS_ACQUIREDACCESSEXCLUSIVELOCK)) xl_xinfo.xinfo |= XACT_XINFO_HAS_AE_LOCKS; if (nsubxacts > 0) { xl_xinfo.xinfo |= XACT_XINFO_HAS_SUBXACTS; xl_subxacts.nsubxacts = nsubxacts; } if (nrels > 0) { xl_xinfo.xinfo |= XACT_XINFO_HAS_RELFILELOCATORS; xl_relfilelocators.nrels = nrels; info |= XLR_SPECIAL_REL_UPDATE; } if (ndroppedstats > 0) { xl_xinfo.xinfo |= XACT_XINFO_HAS_DROPPED_STATS; xl_dropped_stats.nitems = ndroppedstats; } if (TransactionIdIsValid(twophase_xid)) { xl_xinfo.xinfo |= XACT_XINFO_HAS_TWOPHASE; xl_twophase.xid = twophase_xid; Assert(twophase_gid != NULL); if (XLogLogicalInfoActive()) xl_xinfo.xinfo |= XACT_XINFO_HAS_GID; } if (TransactionIdIsValid(twophase_xid) && XLogLogicalInfoActive()) { xl_xinfo.xinfo |= XACT_XINFO_HAS_DBINFO; xl_dbinfo.dbId = MyDatabaseId; xl_dbinfo.tsId = MyDatabaseTableSpace; } /* * Dump transaction origin information. We need this during recovery to * update the replication origin progress. */ if (replorigin_xact_state.origin != InvalidReplOriginId) { xl_xinfo.xinfo |= XACT_XINFO_HAS_ORIGIN; xl_origin.origin_lsn = replorigin_xact_state.origin_lsn; xl_origin.origin_timestamp = replorigin_xact_state.origin_timestamp; } if (xl_xinfo.xinfo != 0) info |= XLOG_XACT_HAS_INFO; /* Then include all the collected data into the abort record. */ XLogBeginInsert(); XLogRegisterData(&xlrec, MinSizeOfXactAbort); if (xl_xinfo.xinfo != 0) XLogRegisterData(&xl_xinfo, sizeof(xl_xinfo)); if (xl_xinfo.xinfo & XACT_XINFO_HAS_DBINFO) XLogRegisterData(&xl_dbinfo, sizeof(xl_dbinfo)); if (xl_xinfo.xinfo & XACT_XINFO_HAS_SUBXACTS) { XLogRegisterData(&xl_subxacts, MinSizeOfXactSubxacts); XLogRegisterData(subxacts, nsubxacts * sizeof(TransactionId)); } if (xl_xinfo.xinfo & XACT_XINFO_HAS_RELFILELOCATORS) { XLogRegisterData(&xl_relfilelocators, MinSizeOfXactRelfileLocators); XLogRegisterData(rels, nrels * sizeof(RelFileLocator)); } if (xl_xinfo.xinfo & XACT_XINFO_HAS_DROPPED_STATS) { XLogRegisterData(&xl_dropped_stats, MinSizeOfXactStatsItems); XLogRegisterData(droppedstats, ndroppedstats * sizeof(xl_xact_stats_item)); } if (xl_xinfo.xinfo & XACT_XINFO_HAS_TWOPHASE) { XLogRegisterData(&xl_twophase, sizeof(xl_xact_twophase)); if (xl_xinfo.xinfo & XACT_XINFO_HAS_GID) XLogRegisterData(twophase_gid, strlen(twophase_gid) + 1); } if (xl_xinfo.xinfo & XACT_XINFO_HAS_ORIGIN) XLogRegisterData(&xl_origin, sizeof(xl_xact_origin)); /* Include the replication origin */ XLogSetRecordFlags(XLOG_INCLUDE_ORIGIN); return XLogInsert(RM_XACT_ID, info); } /* * Before 9.0 this was a fairly short function, but now it performs many * actions for which the order of execution is critical. */ static void xact_redo_commit(xl_xact_parsed_commit *parsed, TransactionId xid, XLogRecPtr lsn, ReplOriginId origin_id) { TransactionId max_xid; TimestampTz commit_time; Assert(TransactionIdIsValid(xid)); max_xid = TransactionIdLatest(xid, parsed->nsubxacts, parsed->subxacts); /* Make sure nextXid is beyond any XID mentioned in the record. */ AdvanceNextFullTransactionIdPastXid(max_xid); Assert(((parsed->xinfo & XACT_XINFO_HAS_ORIGIN) == 0) == (origin_id == InvalidReplOriginId)); if (parsed->xinfo & XACT_XINFO_HAS_ORIGIN) commit_time = parsed->origin_timestamp; else commit_time = parsed->xact_time; /* Set the transaction commit timestamp and metadata */ TransactionTreeSetCommitTsData(xid, parsed->nsubxacts, parsed->subxacts, commit_time, origin_id); if (standbyState == STANDBY_DISABLED) { /* * Mark the transaction committed in pg_xact. */ TransactionIdCommitTree(xid, parsed->nsubxacts, parsed->subxacts); } else { /* * If a transaction completion record arrives that has as-yet * unobserved subtransactions then this will not have been fully * handled by the call to RecordKnownAssignedTransactionIds() in the * main recovery loop in PerformWalRecovery(). So we need to do * bookkeeping again to cover that case. This is confusing and it is * easy to think this call is irrelevant, which has happened three * times in development already. Leave it in. */ RecordKnownAssignedTransactionIds(max_xid); /* * Mark the transaction committed in pg_xact. We use async commit * protocol during recovery to provide information on database * consistency for when users try to set hint bits. It is important * that we do not set hint bits until the minRecoveryPoint is past * this commit record. This ensures that if we crash we don't see hint * bits set on changes made by transactions that haven't yet * recovered. It's unlikely but it's good to be safe. */ TransactionIdAsyncCommitTree(xid, parsed->nsubxacts, parsed->subxacts, lsn); /* * We must mark clog before we update the ProcArray. */ ExpireTreeKnownAssignedTransactionIds(xid, parsed->nsubxacts, parsed->subxacts, max_xid); /* * Send any cache invalidations attached to the commit. We must * maintain the same order of invalidation then release locks as * occurs in CommitTransaction(). */ ProcessCommittedInvalidationMessages(parsed->msgs, parsed->nmsgs, XactCompletionRelcacheInitFileInval(parsed->xinfo), parsed->dbId, parsed->tsId); /* * Release locks, if any. We do this for both two phase and normal one * phase transactions. In effect we are ignoring the prepare phase and * just going straight to lock release. */ if (parsed->xinfo & XACT_XINFO_HAS_AE_LOCKS) StandbyReleaseLockTree(xid, parsed->nsubxacts, parsed->subxacts); } if (parsed->xinfo & XACT_XINFO_HAS_ORIGIN) { /* recover apply progress */ replorigin_advance(origin_id, parsed->origin_lsn, lsn, false /* backward */ , false /* WAL */ ); } /* Make sure files supposed to be dropped are dropped */ if (parsed->nrels > 0) { /* * First update minimum recovery point to cover this WAL record. Once * a relation is deleted, there's no going back. The buffer manager * enforces the WAL-first rule for normal updates to relation files, * so that the minimum recovery point is always updated before the * corresponding change in the data file is flushed to disk, but we * have to do the same here since we're bypassing the buffer manager. * * Doing this before deleting the files means that if a deletion fails * for some reason, you cannot start up the system even after restart, * until you fix the underlying situation so that the deletion will * succeed. Alternatively, we could update the minimum recovery point * after deletion, but that would leave a small window where the * WAL-first rule would be violated. */ XLogFlush(lsn); /* Make sure files supposed to be dropped are dropped */ DropRelationFiles(parsed->xlocators, parsed->nrels, true); } if (parsed->nstats > 0) { /* see equivalent call for relations above */ XLogFlush(lsn); pgstat_execute_transactional_drops(parsed->nstats, parsed->stats, true); } /* * We issue an XLogFlush() for the same reason we emit ForceSyncCommit() * in normal operation. For example, in CREATE DATABASE, we copy all files * from the template database, and then commit the transaction. If we * crash after all the files have been copied but before the commit, you * have files in the data directory without an entry in pg_database. To * minimize the window for that, we use ForceSyncCommit() to rush the * commit record to disk as quick as possible. We have the same window * during recovery, and forcing an XLogFlush() (which updates * minRecoveryPoint during recovery) helps to reduce that problem window, * for any user that requested ForceSyncCommit(). */ if (XactCompletionForceSyncCommit(parsed->xinfo)) XLogFlush(lsn); /* * If asked by the primary (because someone is waiting for a synchronous * commit = remote_apply), we will need to ask walreceiver to send a reply * immediately. */ if (XactCompletionApplyFeedback(parsed->xinfo)) XLogRequestWalReceiverReply(); } /* * Be careful with the order of execution, as with xact_redo_commit(). * The two functions are similar but differ in key places. * * Note also that an abort can be for a subtransaction and its children, * not just for a top level abort. That means we have to consider * topxid != xid, whereas in commit we would find topxid == xid always * because subtransaction commit is never WAL logged. */ static void xact_redo_abort(xl_xact_parsed_abort *parsed, TransactionId xid, XLogRecPtr lsn, ReplOriginId origin_id) { TransactionId max_xid; Assert(TransactionIdIsValid(xid)); /* Make sure nextXid is beyond any XID mentioned in the record. */ max_xid = TransactionIdLatest(xid, parsed->nsubxacts, parsed->subxacts); AdvanceNextFullTransactionIdPastXid(max_xid); if (standbyState == STANDBY_DISABLED) { /* Mark the transaction aborted in pg_xact, no need for async stuff */ TransactionIdAbortTree(xid, parsed->nsubxacts, parsed->subxacts); } else { /* * If a transaction completion record arrives that has as-yet * unobserved subtransactions then this will not have been fully * handled by the call to RecordKnownAssignedTransactionIds() in the * main recovery loop in PerformWalRecovery(). So we need to do * bookkeeping again to cover that case. This is confusing and it is * easy to think this call is irrelevant, which has happened three * times in development already. Leave it in. */ RecordKnownAssignedTransactionIds(max_xid); /* Mark the transaction aborted in pg_xact, no need for async stuff */ TransactionIdAbortTree(xid, parsed->nsubxacts, parsed->subxacts); /* * We must update the ProcArray after we have marked clog. */ ExpireTreeKnownAssignedTransactionIds(xid, parsed->nsubxacts, parsed->subxacts, max_xid); /* * There are no invalidation messages to send or undo. */ /* * Release locks, if any. There are no invalidations to send. */ if (parsed->xinfo & XACT_XINFO_HAS_AE_LOCKS) StandbyReleaseLockTree(xid, parsed->nsubxacts, parsed->subxacts); } if (parsed->xinfo & XACT_XINFO_HAS_ORIGIN) { /* recover apply progress */ replorigin_advance(origin_id, parsed->origin_lsn, lsn, false /* backward */ , false /* WAL */ ); } /* Make sure files supposed to be dropped are dropped */ if (parsed->nrels > 0) { /* * See comments about update of minimum recovery point on truncation, * in xact_redo_commit(). */ XLogFlush(lsn); DropRelationFiles(parsed->xlocators, parsed->nrels, true); } if (parsed->nstats > 0) { /* see equivalent call for relations above */ XLogFlush(lsn); pgstat_execute_transactional_drops(parsed->nstats, parsed->stats, true); } } void xact_redo(XLogReaderState *record) { uint8 info = XLogRecGetInfo(record) & XLOG_XACT_OPMASK; /* Backup blocks are not used in xact records */ Assert(!XLogRecHasAnyBlockRefs(record)); if (info == XLOG_XACT_COMMIT) { xl_xact_commit *xlrec = (xl_xact_commit *) XLogRecGetData(record); xl_xact_parsed_commit parsed; ParseCommitRecord(XLogRecGetInfo(record), xlrec, &parsed); xact_redo_commit(&parsed, XLogRecGetXid(record), record->EndRecPtr, XLogRecGetOrigin(record)); } else if (info == XLOG_XACT_COMMIT_PREPARED) { xl_xact_commit *xlrec = (xl_xact_commit *) XLogRecGetData(record); xl_xact_parsed_commit parsed; ParseCommitRecord(XLogRecGetInfo(record), xlrec, &parsed); xact_redo_commit(&parsed, parsed.twophase_xid, record->EndRecPtr, XLogRecGetOrigin(record)); /* Delete TwoPhaseState gxact entry and/or 2PC file. */ LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE); PrepareRedoRemove(parsed.twophase_xid, false); LWLockRelease(TwoPhaseStateLock); } else if (info == XLOG_XACT_ABORT) { xl_xact_abort *xlrec = (xl_xact_abort *) XLogRecGetData(record); xl_xact_parsed_abort parsed; ParseAbortRecord(XLogRecGetInfo(record), xlrec, &parsed); xact_redo_abort(&parsed, XLogRecGetXid(record), record->EndRecPtr, XLogRecGetOrigin(record)); } else if (info == XLOG_XACT_ABORT_PREPARED) { xl_xact_abort *xlrec = (xl_xact_abort *) XLogRecGetData(record); xl_xact_parsed_abort parsed; ParseAbortRecord(XLogRecGetInfo(record), xlrec, &parsed); xact_redo_abort(&parsed, parsed.twophase_xid, record->EndRecPtr, XLogRecGetOrigin(record)); /* Delete TwoPhaseState gxact entry and/or 2PC file. */ LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE); PrepareRedoRemove(parsed.twophase_xid, false); LWLockRelease(TwoPhaseStateLock); } else if (info == XLOG_XACT_PREPARE) { /* * Store xid and start/end pointers of the WAL record in TwoPhaseState * gxact entry. */ LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE); PrepareRedoAdd(InvalidFullTransactionId, XLogRecGetData(record), record->ReadRecPtr, record->EndRecPtr, XLogRecGetOrigin(record)); LWLockRelease(TwoPhaseStateLock); } else if (info == XLOG_XACT_ASSIGNMENT) { xl_xact_assignment *xlrec = (xl_xact_assignment *) XLogRecGetData(record); if (standbyState >= STANDBY_INITIALIZED) ProcArrayApplyXidAssignment(xlrec->xtop, xlrec->nsubxacts, xlrec->xsub); } else if (info == XLOG_XACT_INVALIDATIONS) { /* * XXX we do ignore this for now, what matters are invalidations * written into the commit record. */ } else elog(PANIC, "xact_redo: unknown op code %u", info); }