Merge pull request #818 from citusdata/fix_xact_callbacks

Directly register transaction callbacks in PG_init

cr: @anarazel

src/backend/distributed/executor/multi_router_executor.c

@@ -80,7 +80,6 @@ bool AllModificationsCommutative = false;
  */
 static HTAB *xactParticipantHash = NULL;
 static List *xactShardConnSetList = NIL;
-static shmem_startup_hook_type prev_shmem_startup_hook = NULL;
 static bool subXactAbortAttempted = false;
 
 /* functions needed during start phase */
@@ -113,7 +112,6 @@ static void RecordShardIdParticipant(uint64 affectedShardId,
 									 NodeConnectionEntry *participantEntry);
 
 /* functions needed by callbacks and hooks */
-static void RegisterRouterExecutorXactCallbacks(void);
 static void RouterTransactionCallback(XactEvent event, void *arg);
 static void RouterSubtransactionCallback(SubXactEvent event, SubTransactionId subId,
 										 SubTransactionId parentSubid, void *arg);
@@ -1202,32 +1200,13 @@ RouterExecutorEnd(QueryDesc *queryDesc)
 
 
 /*
- * InstallRouterExecutorShmemHook simply installs a hook (intended to be called
+ * RegisterRouterExecutorXactCallbacks registers this executor's callbacks.
- * once during backend startup), which will itself register all the transaction
- * callbacks needed by this executor.
  */
 void
-InstallRouterExecutorShmemHook(void)
-{
-	prev_shmem_startup_hook = shmem_startup_hook;
-	shmem_startup_hook = RegisterRouterExecutorXactCallbacks;
-}
-
-
-/*
- * RegisterRouterExecutorXactCallbacks registers (sub-)transaction callbacks
- * needed by this executor before calling any previous shmem startup hooks.
- */
-static void
 RegisterRouterExecutorXactCallbacks(void)
 {
 	RegisterXactCallback(RouterTransactionCallback, NULL);
 	RegisterSubXactCallback(RouterSubtransactionCallback, NULL);
-
-	if (prev_shmem_startup_hook != NULL)
-	{
-		prev_shmem_startup_hook();
-	}
 }
 
 

src/backend/distributed/shared_library_init.c

@@ -154,8 +154,8 @@ _PG_init(void)
 	WorkerNodeRegister();
 
 	/* initialize transaction callbacks */
-	InstallRouterExecutorShmemHook();
+	RegisterRouterExecutorXactCallbacks();
-	InstallMultiShardXactShmemHook();
+	RegisterShardPlacementXactCallbacks();
 }
 
 

src/backend/distributed/transaction/multi_shard_transaction.c

@@ -27,11 +27,9 @@
 
 /* Global variables used in commit handler */
 static HTAB *shardConnectionHash = NULL;
-static shmem_startup_hook_type prev_shmem_startup_hook = NULL;
 static bool subXactAbortAttempted = false;
 
 /* functions needed by callbacks and hooks */
-static void RegisterShardPlacementXactCallbacks(void);
 static void CompleteShardPlacementTransactions(XactEvent event, void *arg);
 static void MultiShardSubXactCallback(SubXactEvent event, SubTransactionId subId,
 									  SubTransactionId parentSubid, void *arg);
@@ -229,32 +227,14 @@ ConnectionList(HTAB *connectionHash)
 
 
 /*
- * InstallMultiShardXactShmemHook simply installs a hook (intended to be called
+ * RegisterShardPlacementXactCallbacks registers transaction callbacks needed
- * once during backend startup), which will itself register all the transaction
+ * for multi-shard transactions.
- * callbacks needed by multi-shard transaction logic.
  */
 void
-InstallMultiShardXactShmemHook(void)
-{
-	prev_shmem_startup_hook = shmem_startup_hook;
-	shmem_startup_hook = RegisterShardPlacementXactCallbacks;
-}
-
-
-/*
- * RegisterShardPlacementXactCallbacks registers transaction callbacks needed
- * for multi-shard transactions before calling previous shmem startup hooks.
- */
-static void
 RegisterShardPlacementXactCallbacks(void)
 {
 	RegisterXactCallback(CompleteShardPlacementTransactions, NULL);
 	RegisterSubXactCallback(MultiShardSubXactCallback, NULL);
-
-	if (prev_shmem_startup_hook != NULL)
-	{
-		prev_shmem_startup_hook();
-	}
 }
 
 

src/include/distributed/multi_router_executor.h

@@ -37,6 +37,6 @@ extern void RouterExecutorStart(QueryDesc *queryDesc, int eflags, Task *task);
 extern void RouterExecutorRun(QueryDesc *queryDesc, ScanDirection direction, long count);
 extern void RouterExecutorFinish(QueryDesc *queryDesc);
 extern void RouterExecutorEnd(QueryDesc *queryDesc);
-extern void InstallRouterExecutorShmemHook(void);
+extern void RegisterRouterExecutorXactCallbacks(void);
 
 #endif /* MULTI_ROUTER_EXECUTOR_H_ */

src/include/distributed/multi_shard_transaction.h

@@ -33,7 +33,7 @@ extern ShardConnections * GetShardHashConnections(HTAB *connectionHash, int64 sh
 												  bool *connectionsFound);
 extern List * ConnectionList(HTAB *connectionHash);
 extern void CloseConnections(List *connectionList);
-extern void InstallMultiShardXactShmemHook(void);
+extern void RegisterShardPlacementXactCallbacks(void);
 
 
 #endif /* MULTI_SHARD_TRANSACTION_H */