oceanbase

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/**
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 * Copyright (c) 2021 OceanBase
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 * OceanBase CE is licensed under Mulan PubL v2.
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 * You can use this software according to the terms and conditions of the Mulan PubL v2.
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 * You may obtain a copy of Mulan PubL v2 at:
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 *          http://license.coscl.org.cn/MulanPubL-2.0
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 * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
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 * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
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 * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
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 * See the Mulan PubL v2 for more details.
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 */
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#define USING_LOG_PREFIX SERVER
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#include "obmp_disconnect.h"
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#include "lib/stat/ob_session_stat.h"
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#include "rpc/ob_request.h"
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#include "observer/ob_server_struct.h"
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#include "sql/session/ob_sql_session_mgr.h"
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#include "sql/ob_sql_trans_control.h"
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using namespace oceanbase::observer;
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using namespace oceanbase::common;
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ObMPDisconnect::ObMPDisconnect(const sql::ObFreeSessionCtx &ctx)
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    : ctx_(ctx)
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{
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}
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ObMPDisconnect::~ObMPDisconnect()
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{
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}
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int ObMPDisconnect::kill_unfinished_session(uint32_t sessid)
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{
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  int ret = OB_SUCCESS;
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  sql::ObSQLSessionInfo *session = NULL;
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  sql::ObSessionGetterGuard guard(*GCTX.session_mgr_, sessid);
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  if (OB_FAIL(guard.get_session(session))) {
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    LOG_WARN("get session fail", K(ret));
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  } else if (OB_ISNULL(session)) {
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    ret = OB_ERR_UNEXPECTED;
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    LOG_ERROR("fail to get session info", K(session), K(sessid), K(ret));
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  } else {
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    /* NOTE:
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     * 在Disconnect的上下文中，两种可能：
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     * (1) 长SQL先执行，并且正在执行，那么它已经能够检测到IS_KILLED标记
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     *     此时disconnect_session会等待长SQL执行退出后才结束session中的事务
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     * (2) disconnect_session先执行，它会结束事务并返回，然后执行后面的free_session
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     *     (free_session 并不是释放 session 内存，只是一个逻辑删除的动作）。
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     *     当长SQL拿到query_lock锁，它会立即检测IS_KILLED状态，检测到后立即退出处理流程。
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     *     最终引用计数减为0，session被物理回收。
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     */
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    if (OB_FAIL(GCTX.session_mgr_->disconnect_session(*session))) {
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      LOG_WARN("fail to disconnect session", K(session), K(sessid), K(ret));
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    }
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  }
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  return ret;
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}
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int ObMPDisconnect::run()
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{
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  int ret = OB_SUCCESS;
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  bool is_need_clear = false;
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  if (ctx_.sessid_ != 0) {
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    if (OB_ISNULL(GCTX.session_mgr_)) {
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      ret = OB_INVALID_ARGUMENT;
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      LOG_WARN("invalid session mgr", K(GCTX.session_mgr_), K(ret));
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    } else {
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      ObSMConnection conn;
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      conn.sessid_ = ctx_.sessid_;
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      conn.is_need_clear_sessid_ = true;
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      // bugfix:
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      (void) kill_unfinished_session(ctx_.sessid_); // ignore ret
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      if (OB_FAIL(GCTX.session_mgr_->free_session(ctx_))) {
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        LOG_WARN("free session fail", K(ctx_));
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      } else {
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        common::ObTenantStatEstGuard guard(ctx_.tenant_id_);
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        EVENT_INC(SQL_USER_LOGOUTS_CUMULATIVE);
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        LOG_INFO("free session successfully", "sessid", ctx_.sessid_);
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        if (OB_UNLIKELY(OB_FAIL(sql::ObSQLSessionMgr::is_need_clear_sessid(&conn, is_need_clear)))) {
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          LOG_ERROR("fail to judge need clear", K(ret), "sessid", conn.sessid_, "server_id", GCTX.server_id_);
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        } else if (is_need_clear) {
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          if (OB_FAIL(GCTX.session_mgr_->mark_sessid_unused(conn.sessid_))) {
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            LOG_WARN("mark session id unused failed", K(ret), "sessid", conn.sessid_);
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          } else {
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            LOG_INFO("mark session id unused", "sessid", conn.sessid_);
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          }
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        }
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      }
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    }
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  }
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  return ret;
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}
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