PG_FINALLY

This gives an alternative way of catching exceptions, for the common
case where the cleanup code is the same in the error and non-error
cases.  So instead of

    PG_TRY();
    {
        ... code that might throw ereport(ERROR) ...
    }
    PG_CATCH();
    {
        cleanup();
	PG_RE_THROW();
    }
    PG_END_TRY();
    cleanup();

one can write

    PG_TRY();
    {
        ... code that might throw ereport(ERROR) ...
    }
    PG_FINALLY();
    {
        cleanup();
    }
    PG_END_TRY();

Discussion: https://www.postgresql.org/message-id/flat/95a822c3-728b-af0e-d7e5-71890507ae0c%402ndquadrant.com

src/backend/commands/async.c

@@ -2028,22 +2028,15 @@ asyncQueueReadAllNotifications(void)
 													   snapshot);
 		} while (!reachedStop);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		/* Update shared state */
 		LWLockAcquire(AsyncQueueLock, LW_SHARED);
 		QUEUE_BACKEND_POS(MyBackendId) = pos;
 		LWLockRelease(AsyncQueueLock);
-
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
-	/* Update shared state */
-	LWLockAcquire(AsyncQueueLock, LW_SHARED);
-	QUEUE_BACKEND_POS(MyBackendId) = pos;
-	LWLockRelease(AsyncQueueLock);
-
 	/* Done with snapshot */
 	UnregisterSnapshot(snapshot);
 }

src/backend/commands/copy.c

@@ -1916,13 +1916,11 @@ BeginCopyTo(ParseState *pstate,
 			{
 				cstate->copy_file = AllocateFile(cstate->filename, PG_BINARY_W);
 			}
-			PG_CATCH();
+			PG_FINALLY();
 			{
 				umask(oumask);
-				PG_RE_THROW();
 			}
 			PG_END_TRY();
-			umask(oumask);
 			if (cstate->copy_file == NULL)
 			{
 				/* copy errno because ereport subfunctions might change it */

src/backend/commands/event_trigger.c

@@ -934,13 +934,11 @@ EventTriggerSQLDrop(Node *parsetree)
 	{
 		EventTriggerInvoke(runlist, &trigdata);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		currentEventTriggerState->in_sql_drop = false;
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
-	currentEventTriggerState->in_sql_drop = false;
 
 	/* Cleanup. */
 	list_free(runlist);
@@ -1007,17 +1005,13 @@ EventTriggerTableRewrite(Node *parsetree, Oid tableOid, int reason)
 	{
 		EventTriggerInvoke(runlist, &trigdata);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		currentEventTriggerState->table_rewrite_oid = InvalidOid;
 		currentEventTriggerState->table_rewrite_reason = 0;
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
-	currentEventTriggerState->table_rewrite_oid = InvalidOid;
-	currentEventTriggerState->table_rewrite_reason = 0;
-
 	/* Cleanup. */
 	list_free(runlist);
 

src/backend/commands/extension.c

@@ -942,17 +942,13 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 
 		execute_sql_string(c_sql);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		creating_extension = false;
 		CurrentExtensionObject = InvalidOid;
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
-	creating_extension = false;
-	CurrentExtensionObject = InvalidOid;
-
 	/*
 	 * Restore the GUC variables we set above.
 	 */

src/backend/commands/subscriptioncmds.c

@@ -493,16 +493,11 @@ CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
 								slotname)));
 			}
 		}
-		PG_CATCH();
+		PG_FINALLY();
 		{
-			/* Close the connection in case of failure. */
 			walrcv_disconnect(wrconn);
-			PG_RE_THROW();
 		}
 		PG_END_TRY();
-
-		/* And we are done with the remote side. */
-		walrcv_disconnect(wrconn);
 	}
 	else
 		ereport(WARNING,
@@ -1023,16 +1018,12 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 
 		walrcv_clear_result(res);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
-		/* Close the connection in case of failure */
 		walrcv_disconnect(wrconn);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
-	walrcv_disconnect(wrconn);
-
 	pfree(cmd.data);
 
 	table_close(rel, NoLock);

src/backend/commands/trigger.c

@@ -2431,13 +2431,11 @@ ExecCallTriggerFunc(TriggerData *trigdata,
 	{
 		result = FunctionCallInvoke(fcinfo);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		MyTriggerDepth--;
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
-	MyTriggerDepth--;
 
 	pgstat_end_function_usage(&fcusage, true);
 

src/backend/commands/vacuum.c

@@ -430,17 +430,13 @@ vacuum(List *relations, VacuumParams *params,
 			}
 		}
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		in_vacuum = false;
 		VacuumCostActive = false;
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
-	in_vacuum = false;
-	VacuumCostActive = false;
-
 	/*
 	 * Finish up processing.
 	 */