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src/include/port/atomics/generic.h
430 строк
12 KB
Nathan Bossart
Remove pg_spin_delay().
30 июн 2026, 18:57
30 июн 2026, 18:57
ae27a41
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/*------------------------------------------------------------------------- * * generic.h * Implement higher level operations based on some lower level atomic * operations. * * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/port/atomics/generic.h * *------------------------------------------------------------------------- */ /* intentionally no include guards, should only be included by atomics.h */ #ifndef INSIDE_ATOMICS_H # error "should be included via atomics.h" #endif /* * If read or write barriers are undefined, we upgrade them to full memory * barriers. */ #if !defined(pg_read_barrier_impl) # define pg_read_barrier_impl pg_memory_barrier_impl #endif #if !defined(pg_write_barrier_impl) # define pg_write_barrier_impl pg_memory_barrier_impl #endif /* provide fallback */ #if !defined(PG_HAVE_ATOMIC_FLAG_SUPPORT) && defined(PG_HAVE_ATOMIC_U32_SUPPORT) #define PG_HAVE_ATOMIC_FLAG_SUPPORT typedef pg_atomic_uint32 pg_atomic_flag; #endif #ifndef PG_HAVE_ATOMIC_READ_U32 #define PG_HAVE_ATOMIC_READ_U32 static inline uint32 pg_atomic_read_u32_impl(volatile pg_atomic_uint32 *ptr) { return ptr->value; } #endif #ifndef PG_HAVE_ATOMIC_WRITE_U32 #define PG_HAVE_ATOMIC_WRITE_U32 static inline void pg_atomic_write_u32_impl(volatile pg_atomic_uint32 *ptr, uint32 val) { ptr->value = val; } #endif #ifndef PG_HAVE_ATOMIC_UNLOCKED_WRITE_U32 #define PG_HAVE_ATOMIC_UNLOCKED_WRITE_U32 static inline void pg_atomic_unlocked_write_u32_impl(volatile pg_atomic_uint32 *ptr, uint32 val) { ptr->value = val; } #endif /* * provide fallback for test_and_set using atomic_exchange if available */ #if !defined(PG_HAVE_ATOMIC_TEST_SET_FLAG) && defined(PG_HAVE_ATOMIC_EXCHANGE_U32) #define PG_HAVE_ATOMIC_INIT_FLAG static inline void pg_atomic_init_flag_impl(volatile pg_atomic_flag *ptr) { pg_atomic_write_u32_impl(ptr, 0); } #define PG_HAVE_ATOMIC_TEST_SET_FLAG static inline bool pg_atomic_test_set_flag_impl(volatile pg_atomic_flag *ptr) { return pg_atomic_exchange_u32_impl(ptr, 1) == 0; } #define PG_HAVE_ATOMIC_UNLOCKED_TEST_FLAG static inline bool pg_atomic_unlocked_test_flag_impl(volatile pg_atomic_flag *ptr) { return pg_atomic_read_u32_impl(ptr) == 0; } #define PG_HAVE_ATOMIC_CLEAR_FLAG static inline void pg_atomic_clear_flag_impl(volatile pg_atomic_flag *ptr) { /* XXX: release semantics suffice? */ pg_memory_barrier_impl(); pg_atomic_write_u32_impl(ptr, 0); } /* * provide fallback for test_and_set using atomic_compare_exchange if * available. */ #elif !defined(PG_HAVE_ATOMIC_TEST_SET_FLAG) && defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U32) #define PG_HAVE_ATOMIC_INIT_FLAG static inline void pg_atomic_init_flag_impl(volatile pg_atomic_flag *ptr) { pg_atomic_write_u32_impl(ptr, 0); } #define PG_HAVE_ATOMIC_TEST_SET_FLAG static inline bool pg_atomic_test_set_flag_impl(volatile pg_atomic_flag *ptr) { uint32 value = 0; return pg_atomic_compare_exchange_u32_impl(ptr, &value, 1); } #define PG_HAVE_ATOMIC_UNLOCKED_TEST_FLAG static inline bool pg_atomic_unlocked_test_flag_impl(volatile pg_atomic_flag *ptr) { return pg_atomic_read_u32_impl(ptr) == 0; } #define PG_HAVE_ATOMIC_CLEAR_FLAG static inline void pg_atomic_clear_flag_impl(volatile pg_atomic_flag *ptr) { /* XXX: release semantics suffice? */ pg_memory_barrier_impl(); pg_atomic_write_u32_impl(ptr, 0); } #elif !defined(PG_HAVE_ATOMIC_TEST_SET_FLAG) # error "No pg_atomic_test_and_set provided" #endif /* !defined(PG_HAVE_ATOMIC_TEST_SET_FLAG) */ #ifndef PG_HAVE_ATOMIC_INIT_U32 #define PG_HAVE_ATOMIC_INIT_U32 static inline void pg_atomic_init_u32_impl(volatile pg_atomic_uint32 *ptr, uint32 val_) { ptr->value = val_; } #endif #if !defined(PG_HAVE_ATOMIC_EXCHANGE_U32) && defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U32) #define PG_HAVE_ATOMIC_EXCHANGE_U32 static inline uint32 pg_atomic_exchange_u32_impl(volatile pg_atomic_uint32 *ptr, uint32 xchg_) { uint32 old; old = ptr->value; /* ok if read is not atomic */ while (!pg_atomic_compare_exchange_u32_impl(ptr, &old, xchg_)) /* skip */; return old; } #endif #if !defined(PG_HAVE_ATOMIC_FETCH_ADD_U32) && defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U32) #define PG_HAVE_ATOMIC_FETCH_ADD_U32 static inline uint32 pg_atomic_fetch_add_u32_impl(volatile pg_atomic_uint32 *ptr, int32 add_) { uint32 old; old = ptr->value; /* ok if read is not atomic */ while (!pg_atomic_compare_exchange_u32_impl(ptr, &old, old + add_)) /* skip */; return old; } #endif #if !defined(PG_HAVE_ATOMIC_FETCH_SUB_U32) && defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U32) #define PG_HAVE_ATOMIC_FETCH_SUB_U32 static inline uint32 pg_atomic_fetch_sub_u32_impl(volatile pg_atomic_uint32 *ptr, int32 sub_) { return pg_atomic_fetch_add_u32_impl(ptr, -sub_); } #endif #if !defined(PG_HAVE_ATOMIC_FETCH_AND_U32) && defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U32) #define PG_HAVE_ATOMIC_FETCH_AND_U32 static inline uint32 pg_atomic_fetch_and_u32_impl(volatile pg_atomic_uint32 *ptr, uint32 and_) { uint32 old; old = ptr->value; /* ok if read is not atomic */ while (!pg_atomic_compare_exchange_u32_impl(ptr, &old, old & and_)) /* skip */; return old; } #endif #if !defined(PG_HAVE_ATOMIC_FETCH_OR_U32) && defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U32) #define PG_HAVE_ATOMIC_FETCH_OR_U32 static inline uint32 pg_atomic_fetch_or_u32_impl(volatile pg_atomic_uint32 *ptr, uint32 or_) { uint32 old; old = ptr->value; /* ok if read is not atomic */ while (!pg_atomic_compare_exchange_u32_impl(ptr, &old, old | or_)) /* skip */; return old; } #endif #if !defined(PG_HAVE_ATOMIC_ADD_FETCH_U32) && defined(PG_HAVE_ATOMIC_FETCH_ADD_U32) #define PG_HAVE_ATOMIC_ADD_FETCH_U32 static inline uint32 pg_atomic_add_fetch_u32_impl(volatile pg_atomic_uint32 *ptr, int32 add_) { return pg_atomic_fetch_add_u32_impl(ptr, add_) + add_; } #endif #if !defined(PG_HAVE_ATOMIC_SUB_FETCH_U32) && defined(PG_HAVE_ATOMIC_FETCH_SUB_U32) #define PG_HAVE_ATOMIC_SUB_FETCH_U32 static inline uint32 pg_atomic_sub_fetch_u32_impl(volatile pg_atomic_uint32 *ptr, int32 sub_) { return pg_atomic_fetch_sub_u32_impl(ptr, sub_) - sub_; } #endif #if !defined(PG_HAVE_ATOMIC_READ_MEMBARRIER_U32) && defined(PG_HAVE_ATOMIC_FETCH_ADD_U32) #define PG_HAVE_ATOMIC_READ_MEMBARRIER_U32 static inline uint32 pg_atomic_read_membarrier_u32_impl(volatile pg_atomic_uint32 *ptr) { return pg_atomic_fetch_add_u32_impl(ptr, 0); } #endif #if !defined(PG_HAVE_ATOMIC_WRITE_MEMBARRIER_U32) && defined(PG_HAVE_ATOMIC_EXCHANGE_U32) #define PG_HAVE_ATOMIC_WRITE_MEMBARRIER_U32 static inline void pg_atomic_write_membarrier_u32_impl(volatile pg_atomic_uint32 *ptr, uint32 val) { (void) pg_atomic_exchange_u32_impl(ptr, val); } #endif #if !defined(PG_HAVE_ATOMIC_EXCHANGE_U64) && defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U64) #define PG_HAVE_ATOMIC_EXCHANGE_U64 static inline uint64 pg_atomic_exchange_u64_impl(volatile pg_atomic_uint64 *ptr, uint64 xchg_) { uint64 old; old = ptr->value; /* ok if read is not atomic */ while (!pg_atomic_compare_exchange_u64_impl(ptr, &old, xchg_)) /* skip */; return old; } #endif #ifndef PG_HAVE_ATOMIC_WRITE_U64 #define PG_HAVE_ATOMIC_WRITE_U64 #if defined(PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY) && \ !defined(PG_HAVE_ATOMIC_U64_SIMULATION) static inline void pg_atomic_write_u64_impl(volatile pg_atomic_uint64 *ptr, uint64 val) { /* * On this platform aligned 64bit writes are guaranteed to be atomic, * except if using the fallback implementation, where can't guarantee the * required alignment. */ AssertPointerAlignment(ptr, 8); ptr->value = val; } #else static inline void pg_atomic_write_u64_impl(volatile pg_atomic_uint64 *ptr, uint64 val) { /* * 64 bit writes aren't safe on all platforms. In the generic * implementation implement them as an atomic exchange. */ pg_atomic_exchange_u64_impl(ptr, val); } #endif /* PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY && !PG_HAVE_ATOMIC_U64_SIMULATION */ #endif /* PG_HAVE_ATOMIC_WRITE_U64 */ #ifndef PG_HAVE_ATOMIC_UNLOCKED_WRITE_U64 #define PG_HAVE_ATOMIC_UNLOCKED_WRITE_U64 static inline void pg_atomic_unlocked_write_u64_impl(volatile pg_atomic_uint64 *ptr, uint64 val) { ptr->value = val; } #endif #ifndef PG_HAVE_ATOMIC_READ_U64 #define PG_HAVE_ATOMIC_READ_U64 #if defined(PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY) && \ !defined(PG_HAVE_ATOMIC_U64_SIMULATION) static inline uint64 pg_atomic_read_u64_impl(volatile pg_atomic_uint64 *ptr) { /* * On this platform aligned 64-bit reads are guaranteed to be atomic. */ AssertPointerAlignment(ptr, 8); return ptr->value; } #else static inline uint64 pg_atomic_read_u64_impl(volatile pg_atomic_uint64 *ptr) { uint64 old = 0; /* * 64-bit reads aren't atomic on all platforms. In the generic * implementation implement them as a compare/exchange with 0. That'll * fail or succeed, but always return the old value. Possibly might store * a 0, but only if the previous value also was a 0 - i.e. harmless. */ pg_atomic_compare_exchange_u64_impl(ptr, &old, 0); return old; } #endif /* PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY && !PG_HAVE_ATOMIC_U64_SIMULATION */ #endif /* PG_HAVE_ATOMIC_READ_U64 */ #ifndef PG_HAVE_ATOMIC_INIT_U64 #define PG_HAVE_ATOMIC_INIT_U64 static inline void pg_atomic_init_u64_impl(volatile pg_atomic_uint64 *ptr, uint64 val_) { ptr->value = val_; } #endif #if !defined(PG_HAVE_ATOMIC_FETCH_ADD_U64) && defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U64) #define PG_HAVE_ATOMIC_FETCH_ADD_U64 static inline uint64 pg_atomic_fetch_add_u64_impl(volatile pg_atomic_uint64 *ptr, int64 add_) { uint64 old; old = ptr->value; /* ok if read is not atomic */ while (!pg_atomic_compare_exchange_u64_impl(ptr, &old, old + add_)) /* skip */; return old; } #endif #if !defined(PG_HAVE_ATOMIC_FETCH_SUB_U64) && defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U64) #define PG_HAVE_ATOMIC_FETCH_SUB_U64 static inline uint64 pg_atomic_fetch_sub_u64_impl(volatile pg_atomic_uint64 *ptr, int64 sub_) { return pg_atomic_fetch_add_u64_impl(ptr, -sub_); } #endif #if !defined(PG_HAVE_ATOMIC_FETCH_AND_U64) && defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U64) #define PG_HAVE_ATOMIC_FETCH_AND_U64 static inline uint64 pg_atomic_fetch_and_u64_impl(volatile pg_atomic_uint64 *ptr, uint64 and_) { uint64 old; old = ptr->value; /* ok if read is not atomic */ while (!pg_atomic_compare_exchange_u64_impl(ptr, &old, old & and_)) /* skip */; return old; } #endif #if !defined(PG_HAVE_ATOMIC_FETCH_OR_U64) && defined(PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U64) #define PG_HAVE_ATOMIC_FETCH_OR_U64 static inline uint64 pg_atomic_fetch_or_u64_impl(volatile pg_atomic_uint64 *ptr, uint64 or_) { uint64 old; old = ptr->value; /* ok if read is not atomic */ while (!pg_atomic_compare_exchange_u64_impl(ptr, &old, old | or_)) /* skip */; return old; } #endif #if !defined(PG_HAVE_ATOMIC_ADD_FETCH_U64) && defined(PG_HAVE_ATOMIC_FETCH_ADD_U64) #define PG_HAVE_ATOMIC_ADD_FETCH_U64 static inline uint64 pg_atomic_add_fetch_u64_impl(volatile pg_atomic_uint64 *ptr, int64 add_) { return pg_atomic_fetch_add_u64_impl(ptr, add_) + add_; } #endif #if !defined(PG_HAVE_ATOMIC_SUB_FETCH_U64) && defined(PG_HAVE_ATOMIC_FETCH_SUB_U64) #define PG_HAVE_ATOMIC_SUB_FETCH_U64 static inline uint64 pg_atomic_sub_fetch_u64_impl(volatile pg_atomic_uint64 *ptr, int64 sub_) { return pg_atomic_fetch_sub_u64_impl(ptr, sub_) - sub_; } #endif #if !defined(PG_HAVE_ATOMIC_READ_MEMBARRIER_U64) && defined(PG_HAVE_ATOMIC_FETCH_ADD_U64) #define PG_HAVE_ATOMIC_READ_MEMBARRIER_U64 static inline uint64 pg_atomic_read_membarrier_u64_impl(volatile pg_atomic_uint64 *ptr) { return pg_atomic_fetch_add_u64_impl(ptr, 0); } #endif #if !defined(PG_HAVE_ATOMIC_WRITE_MEMBARRIER_U64) && defined(PG_HAVE_ATOMIC_EXCHANGE_U64) #define PG_HAVE_ATOMIC_WRITE_MEMBARRIER_U64 static inline void pg_atomic_write_membarrier_u64_impl(volatile pg_atomic_uint64 *ptr, uint64 val) { (void) pg_atomic_exchange_u64_impl(ptr, val); } #endif