Introduce transaction_timeout

This commit adds timeout that is expected to be used as a prevention
of long-running queries. Any session within the transaction will be
terminated after spanning longer than this timeout.

However, this timeout is not applied to prepared transactions.
Only transactions with user connections are affected.

Discussion: https://postgr.es/m/CAAhFRxiQsRs2Eq5kCo9nXE3HTugsAAJdSQSmxncivebAxdmBjQ%40mail.gmail.com
Author: Andrey Borodin <amborodin@acm.org>
Author: Japin Li <japinli@hotmail.com>
Author: Junwang Zhao <zhjwpku@gmail.com>
Reviewed-by: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Fujii Masao <masao.fujii@oss.nttdata.com>
Reviewed-by: bt23nguyent <bt23nguyent@oss.nttdata.com>
Reviewed-by: Yuhang Qiu <iamqyh@gmail.com>

1 files changed, 43 insertions, 3 deletions

diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 01b5530f0b1..de9f5d1a6c4 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -3418,6 +3418,17 @@ ProcessInterrupts(void)
 			IdleInTransactionSessionTimeoutPending = false;
 	}
 
+	if (TransactionTimeoutPending)
+	{
+		/* As above, ignore the signal if the GUC has been reset to zero. */
+		if (TransactionTimeout > 0)
+			ereport(FATAL,
+					(errcode(ERRCODE_TRANSACTION_TIMEOUT),
+					 errmsg("terminating connection due to transaction timeout")));
+		else
+			TransactionTimeoutPending = false;
+	}
+
 	if (IdleSessionTimeoutPending)
 	{
 		/* As above, ignore the signal if the GUC has been reset to zero. */
@@ -3632,6 +3643,15 @@ check_log_stats(bool *newval, void **extra, GucSource source)
 	return true;
 }
 
+/* GUC assign hook for transaction_timeout */
+void
+assign_transaction_timeout(int newval, void *extra)
+{
+	if (TransactionTimeout <= 0 &&
+		get_timeout_active(TRANSACTION_TIMEOUT))
+		disable_timeout(TRANSACTION_TIMEOUT, false);
+}
+
 
 /*
  * set_debug_options --- apply "-d N" command line option
@@ -4483,12 +4503,18 @@ PostgresMain(const char *dbname, const char *username)
 				pgstat_report_activity(STATE_IDLEINTRANSACTION_ABORTED, NULL);
 
 				/* Start the idle-in-transaction timer */
-				if (IdleInTransactionSessionTimeout > 0)
+				if (IdleInTransactionSessionTimeout > 0
+					&& (IdleInTransactionSessionTimeout < TransactionTimeout || TransactionTimeout == 0))
 				{
 					idle_in_transaction_timeout_enabled = true;
 					enable_timeout_after(IDLE_IN_TRANSACTION_SESSION_TIMEOUT,
 										 IdleInTransactionSessionTimeout);
 				}
+
+				/* Schedule or reschedule transaction timeout */
+				if (TransactionTimeout > 0 && !get_timeout_active(TRANSACTION_TIMEOUT))
+					enable_timeout_after(TRANSACTION_TIMEOUT,
+										 TransactionTimeout);
 			}
 			else if (IsTransactionOrTransactionBlock())
 			{
@@ -4496,12 +4522,18 @@ PostgresMain(const char *dbname, const char *username)
 				pgstat_report_activity(STATE_IDLEINTRANSACTION, NULL);
 
 				/* Start the idle-in-transaction timer */
-				if (IdleInTransactionSessionTimeout > 0)
+				if (IdleInTransactionSessionTimeout > 0
+					&& (IdleInTransactionSessionTimeout < TransactionTimeout || TransactionTimeout == 0))
 				{
 					idle_in_transaction_timeout_enabled = true;
 					enable_timeout_after(IDLE_IN_TRANSACTION_SESSION_TIMEOUT,
 										 IdleInTransactionSessionTimeout);
 				}
+
+				/* Schedule or reschedule transaction timeout */
+				if (TransactionTimeout > 0 && !get_timeout_active(TRANSACTION_TIMEOUT))
+					enable_timeout_after(TRANSACTION_TIMEOUT,
+										 TransactionTimeout);
 			}
 			else
 			{
@@ -4554,6 +4586,13 @@ PostgresMain(const char *dbname, const char *username)
 					enable_timeout_after(IDLE_SESSION_TIMEOUT,
 										 IdleSessionTimeout);
 				}
+
+				/*
+				 * If GUC is changed then it's handled in
+				 * assign_transaction_timeout().
+				 */
+				if (TransactionTimeout > 0 && get_timeout_active(TRANSACTION_TIMEOUT))
+					disable_timeout(TRANSACTION_TIMEOUT, false);
 			}
 
 			/* Report any recently-changed GUC options */
@@ -5112,7 +5151,8 @@ enable_statement_timeout(void)
 	/* must be within an xact */
 	Assert(xact_started);
 
-	if (StatementTimeout > 0)
+	if (StatementTimeout > 0
+		&& (StatementTimeout < TransactionTimeout || TransactionTimeout == 0))
 	{
 		if (!get_timeout_active(STATEMENT_TIMEOUT))
 			enable_timeout_after(STATEMENT_TIMEOUT, StatementTimeout);