Add idle_in_transaction_session_timeout.

Vik Fearing, reviewed by Stéphane Schildknecht and me, and revised
slightly by me.

src/backend/utils/errcodes.txt

@@ -229,6 +229,7 @@ Section: Class 25 - Invalid Transaction State
 25007    E    ERRCODE_SCHEMA_AND_DATA_STATEMENT_MIXING_NOT_SUPPORTED         schema_and_data_statement_mixing_not_supported
 25P01    E    ERRCODE_NO_ACTIVE_SQL_TRANSACTION                              no_active_sql_transaction
 25P02    E    ERRCODE_IN_FAILED_SQL_TRANSACTION                              in_failed_sql_transaction
+25P03    E    ERRCODE_IDLE_IN_TRANSACTION_SESSION_TIMEOUT                    idle_in_transaction_session_timeout
 
 Section: Class 26 - Invalid SQL Statement Name
 

src/backend/utils/init/globals.c

@@ -30,6 +30,7 @@ volatile bool InterruptPending = false;
 volatile bool QueryCancelPending = false;
 volatile bool ProcDiePending = false;
 volatile bool ClientConnectionLost = false;
+volatile bool IdleInTransactionSessionTimeoutPending = false;
 volatile uint32 InterruptHoldoffCount = 0;
 volatile uint32 QueryCancelHoldoffCount = 0;
 volatile uint32 CritSectionCount = 0;

src/backend/utils/init/postinit.c

@@ -70,6 +70,7 @@ static void InitCommunication(void);
 static void ShutdownPostgres(int code, Datum arg);
 static void StatementTimeoutHandler(void);
 static void LockTimeoutHandler(void);
+static void IdleInTransactionSessionTimeoutHandler(void);
 static bool ThereIsAtLeastOneRole(void);
 static void process_startup_options(Port *port, bool am_superuser);
 static void process_settings(Oid databaseid, Oid roleid);
@@ -597,6 +598,8 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		RegisterTimeout(DEADLOCK_TIMEOUT, CheckDeadLockAlert);
 		RegisterTimeout(STATEMENT_TIMEOUT, StatementTimeoutHandler);
 		RegisterTimeout(LOCK_TIMEOUT, LockTimeoutHandler);
+		RegisterTimeout(IDLE_IN_TRANSACTION_SESSION_TIMEOUT,
+						IdleInTransactionSessionTimeoutHandler);
 	}
 
 	/*
@@ -1178,6 +1181,13 @@ LockTimeoutHandler(void)
 	kill(MyProcPid, SIGINT);
 }
 
+static void
+IdleInTransactionSessionTimeoutHandler(void)
+{
+	IdleInTransactionSessionTimeoutPending = true;
+	InterruptPending = true;
+	SetLatch(MyLatch);
+}
 
 /*
  * Returns true if at least one role is defined in this database cluster.

src/backend/utils/misc/guc.c

@@ -2065,6 +2065,17 @@ static struct config_int ConfigureNamesInt[] =
 		NULL, NULL, NULL
 	},
 
+	{
+		{"idle_in_transaction_session_timeout", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the maximum allowed duration of any idling transaction."),
+			gettext_noop("A value of 0 turns off the timeout."),
+			GUC_UNIT_MS
+		},
+		&IdleInTransactionSessionTimeout,
+		0, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
 	{
 		{"vacuum_freeze_min_age", PGC_USERSET, CLIENT_CONN_STATEMENT,
 			gettext_noop("Minimum age at which VACUUM should freeze a table row."),

src/backend/utils/misc/postgresql.conf.sample

@@ -529,6 +529,7 @@
 #session_replication_role = 'origin'
 #statement_timeout = 0			# in milliseconds, 0 is disabled
 #lock_timeout = 0			# in milliseconds, 0 is disabled
+#idle_in_transaction_session_timeout = 0		# in milliseconds, 0 is disabled
 #vacuum_freeze_min_age = 50000000
 #vacuum_freeze_table_age = 150000000
 #vacuum_multixact_freeze_min_age = 5000000