[CP] [dblink][4.x] add defensive measure for unexpected ref of tx desc

src/sql/ob_sql_trans_control.cpp

@@ -208,6 +208,14 @@ int ObSqlTransControl::implicit_end_trans(ObExecContext &exec_ctx,
 #endif
   ObSQLSessionInfo *session = GET_MY_SESSION(exec_ctx);
   CK (OB_NOT_NULL(session));
+  if (OB_SUCCESS != ret) {
+    // do nothing
+  } else if (session->associated_xa()) {
+    // NOTE that not support dblink trans in this interface
+    // PLEASE handle implicit cases for dblink trans instead of this interface
+    ret = OB_ERR_UNEXPECTED;
+    LOG_ERROR("executing do end trans in xa", K(ret), K(session->get_xid()));
+  }
   int64_t tx_id = 0;
   OX (tx_id = session->get_tx_id().get_id());
   CHECK_TX_FREE_ROUTE(exec_ctx, session);

src/storage/tx/ob_tx_api.cpp

@@ -133,7 +133,7 @@ int ObTransService::finalize_tx_(ObTxDesc &tx)
  * - for tx which is a shadow copy of original tx (started on another server)
  *   release just free its memory used
  */
-int ObTransService::release_tx(ObTxDesc &tx)
+int ObTransService::release_tx(ObTxDesc &tx, const bool is_from_xa)
 {
   /*
    * for compatible with cross tenant session usage
@@ -148,6 +148,9 @@ int ObTransService::release_tx(ObTxDesc &tx)
     MTL_SWITCH(tx.tenant_id_) {
       return MTL(ObTransService*)->release_tx(tx);
     }
+  } else if (NULL != tx.get_xa_ctx() && !is_from_xa) {
+    ret = OB_ERR_UNEXPECTED;
+    TRANS_LOG(ERROR, "unexpected case", K(ret), K(is_from_xa), K(tx));
   } else {
     ObTransTraceLog &tlog = tx.get_tlog();
     REC_TRANS_TRACE_EXT(&tlog, release, OB_Y(ret),

src/storage/tx/ob_tx_api.h

@@ -100,10 +100,11 @@ int submit_commit_tx(ObTxDesc &tx,
  * this is the end of lifecycle of a transaction
  *
  * @tx:         the target transaction's descriptor
+ * @is_from_xa: whether xa ctx calls this interface
  *
  * Return: OB_SUCCESS - OK
  */
-int release_tx(ObTxDesc &tx);
+int release_tx(ObTxDesc &tx, const bool is_from_xa = false);
 
 /**
  * reuse_tx - reuse transaction descriptor

src/storage/tx/ob_xa_ctx.cpp

@@ -158,7 +158,7 @@ int ObXACtx::init(const ObXATransID &xid,
 int ObXACtx::handle_timeout(const int64_t delay)
 {
   int ret = OB_SUCCESS;
-  TRANS_LOG(INFO, "start to handle timeout for xa trans", K(*this), "lbt", lbt());
+  TRANS_LOG(INFO, "start to handle timeout for xa trans", K(*this));
 
   if (OB_SUCC(lock_.wrlock(common::ObLatchIds::XA_CTX_LOCK, 5000000/*5 seconds*/))) {
     if (is_exiting_) {
@@ -490,7 +490,7 @@ int ObXACtx::get_branch_info_(const ObXATransID &xid,
 
 void ObXACtx::set_terminated_()
 {
-  TRANS_LOG(INFO, "set terminated", K_(is_terminated), K(*this), "lbt", lbt());
+  TRANS_LOG(INFO, "set terminated", K_(is_terminated), K(*this));
   is_terminated_ = true;
   need_print_trace_log_ = true;
   REC_TRACE_EXT(tlog_, terminate, OB_ID(ctx_ref), get_uref());
@@ -503,9 +503,18 @@ int ObXACtx::xa_rollback_terminate_(const int cause)
   int ret = OB_SUCCESS;
 
   (void)unregister_timeout_task_();
-  if (OB_FAIL(MTL(ObTransService*)->abort_tx(*tx_desc_, cause))) {
+  if (OB_ISNULL(tx_desc_)) {
+    ret = OB_ERR_UNEXPECTED;
+    TRANS_LOG(ERROR, "trans desc is null", K(ret), K(*this));
+  } else {
+    ObTransID tx_id = tx_desc_->get_tx_id();
+    const int tx_ref_count = tx_desc_->get_ref();
+    if (tx_id != trans_id_ || MIN_TX_REF_COUNT > tx_ref_count) {
+      TRANS_LOG(ERROR, "unexpected trans desc", K(tx_ref_count), K(tx_id), K(*this));
+    } else if (OB_FAIL(MTL(ObTransService*)->abort_tx(*tx_desc_, cause))) {
       TRANS_LOG(WARN, "abort tx for session terminate failed", K(ret), K(*this));
     }
+  }
   set_terminated_();
 
   return ret;
@@ -804,7 +813,8 @@ int ObXACtx::process_xa_start_response(const obrpc::ObXAStartRPCResponse &resp)
   } else if (OB_FAIL(MTL(ObTransService *)->recover_tx(tx_info, tx_desc_))) {
     TRANS_LOG(WARN, "recover tx failed", K(ret), K(*this), K(tx_info));
   } else {
-    // do nothing
+    // increment reference of tx_desc
+    tx_desc_->inc_ref(1);
   }
 
   TRANS_LOG(INFO, "xa start response", K(ret), K(*this));
@@ -1632,7 +1642,10 @@ int ObXACtx::xa_start_remote_second_(const ObXATransID &xid,
 int ObXACtx::save_tx_desc_(ObTxDesc *tx_desc)
 {
   int ret = OB_SUCCESS;
+  // NOTE that the tx_desc should be valid
   tx_desc_ = tx_desc;
+  // increment tx_desc ref
+  tx_desc_->inc_ref(1);
   return ret;
 }
 
@@ -2284,6 +2297,7 @@ void ObXACtx::try_exit_()
 int ObXACtx::set_exiting_()
 {
   int ret = OB_SUCCESS;
+  int tx_ref_count = -1;
 
   if (is_exiting_) {
     // do nothing
@@ -2296,15 +2310,24 @@ int ObXACtx::set_exiting_()
   } else {
     is_exiting_ = true;
     if (NULL != tx_desc_) {
-      tx_desc_->reset_for_xa();
+      ObTransID tx_id = tx_desc_->get_tx_id();
-      MTL(ObTransService *)->release_tx(*tx_desc_);
+      tx_ref_count = tx_desc_->get_ref();
+      if (tx_id != trans_id_ || MIN_TX_REF_COUNT > tx_ref_count) {
+        ret = OB_ERR_UNEXPECTED;
+        TRANS_LOG(ERROR, "unexpected trans desc", K(ret), K(tx_ref_count), K(tx_id), K(*this));
+      } else {
+        const bool is_from_xa = true;
+        tx_desc_->dec_ref(1);
+        // tx_desc_->reset_for_xa();
+        MTL(ObTransService *)->release_tx(*tx_desc_, is_from_xa);
+      }
       tx_desc_ = NULL;
     }
     if (OB_FAIL(xa_ctx_mgr_->erase_xa_ctx(trans_id_))) {
       TRANS_LOG(WARN, "erase xa ctx failed", K(ret), K_(xid), K(*this));
     }
   }
-  TRANS_LOG(INFO, "xa ctx set exiting", K(ret), K_(xid), K(*this));
+  TRANS_LOG(INFO, "xa ctx set exiting", K(ret), K(tx_ref_count), K_(xid), K(*this));
 
   return ret;
 }
@@ -2911,13 +2934,7 @@ int ObXACtx::wait_xa_prepare(const ObXATransID &xid, const int64_t timeout_us)
   }
 
   if (OB_LIKELY(!is_exiting_)) {
-    is_exiting_ = true;
+    set_exiting_();
-    if (OB_NOT_NULL(xa_ctx_mgr_)) {
-      xa_ctx_mgr_->erase_xa_ctx(trans_id_);
-    }
-    // release tx desc
-    MTL(ObTransService*)->release_tx(*tx_desc_);
-    tx_desc_ = NULL;
   }
 
   TRANS_LOG(INFO, "wait xa prepare", K(ret), K(*this));
@@ -2958,7 +2975,7 @@ int ObXACtx::two_phase_end_trans(const ObXATransID &xid,
       ret = OB_INVALID_ARGUMENT;
       TRANS_LOG(WARN, "invalid trans descriptor", K(ret), K(xid));
     } else {
-      tx_desc_ = tx;
+      save_tx_desc_(tx);
       request_id_ = request_id;
       if (is_rollback) {
         xa_trans_state_ = ObXATransState::ROLLBACKING;

src/storage/tx/ob_xa_ctx.h

@@ -257,6 +257,8 @@ private:
   int get_dblink_client_(const common::sqlclient::DblinkDriverProto dblink_type,
                          common::sqlclient::ObISQLConnection *dblink_conn,
                          ObDBLinkClient *&dblink_client);
+private:
+  static const int MIN_TX_REF_COUNT = 3;
 private:
   bool is_inited_;
   ObXACtxMgr *xa_ctx_mgr_;