port SavepointContexts

Author: kelvich

src/backend/access/transam/xact.c

@@ -179,6 +179,7 @@ typedef struct TransactionStateData
 	SubTransactionId subTransactionId;	/* my subxact ID */
 	char	   *name;			/* savepoint name, if any */
 	int			savepointLevel; /* savepoint level */
+	void*		savepointContext;	/* savepoint XTM context */
 	TransState	state;			/* low-level state */
 	TBlockState blockState;		/* high-level state */
 	int			nestingLevel;	/* transaction nesting depth */
@@ -210,6 +211,7 @@ static TransactionStateData TopTransactionStateData = {
 	0,							/* subtransaction id */
 	NULL,						/* savepoint name */
 	0,							/* savepoint level */
+	NULL,						/* savepoint context */
 	TRANS_DEFAULT,				/* transaction state */
 	TBLOCK_DEFAULT,				/* transaction block state from the client
 								 * perspective */
@@ -4264,6 +4266,7 @@ ReleaseSavepoint(List *options)
 	{
 		Assert(xact->blockState == TBLOCK_SUBINPROGRESS);
 		xact->blockState = TBLOCK_SUBRELEASE;
+		TM->ReleaseSavepointContext(xact->savepointContext);
 		if (xact == target)
 			break;
 		xact = xact->parent;
@@ -4383,9 +4386,11 @@ RollbackToSavepoint(List *options)
 		else
 			elog(FATAL, "RollbackToSavepoint: unexpected state %s",
 				 BlockStateAsString(xact->blockState));
+		TM->ReleaseSavepointContext(xact->savepointContext);
 		xact = xact->parent;
 		Assert(PointerIsValid(xact));
 	}
+	TM->RestoreSavepointContext(xact->savepointContext);
 
 	/* And mark the target as "restart pending" */
 	if (xact->blockState == TBLOCK_SUBINPROGRESS)
@@ -4563,6 +4568,8 @@ RollbackAndReleaseCurrentSubTransaction(void)
 	CleanupSubTransaction();
 
 	s = CurrentTransactionState;	/* changed by pop */
+	TM->RestoreSavepointContext(s->savepointContext);
+
 	AssertState(s->blockState == TBLOCK_SUBINPROGRESS ||
 				s->blockState == TBLOCK_INPROGRESS ||
 				s->blockState == TBLOCK_STARTED);
@@ -5141,6 +5148,7 @@ PushTransaction(void)
 	GetUserIdAndSecContext(&s->prevUser, &s->prevSecContext);
 	s->prevXactReadOnly = XactReadOnly;
 	s->parallelModeLevel = 0;
+	s->savepointContext = TM->CreateSavepointContext();
 
 	CurrentTransactionState = s;
 
@@ -5171,6 +5179,7 @@ PopTransaction(void)
 	if (s->parent == NULL)
 		elog(FATAL, "PopTransaction with no parent");
 
+	TM->ReleaseSavepointContext(s->savepointContext);
 	CurrentTransactionState = s->parent;
 
 	/* Let's just make sure CurTransactionContext is good */

src/backend/access/transam/xtm.c

@@ -58,6 +58,19 @@ void PgInitializeSequence(int64* init, int64* step)
 	*step = 1;
 }
 
+void* PgCreateSavepointContext(void)
+{
+	return NULL;
+}
+
+void PgRestoreSavepointContext(void* ctx)
+{
+}
+
+void PgReleaseSavepointContext(void* ctx)
+{
+}
+
 
 TransactionManager PgTM = {
 	PgTransactionIdGetStatus,
@@ -73,7 +86,10 @@ TransactionManager PgTM = {
 	PgGetTransactionStateSize,
 	PgSerializeTransactionState,
 	PgDeserializeTransactionState,
-	PgInitializeSequence
+	PgInitializeSequence,
+	PgCreateSavepointContext,
+	PgRestoreSavepointContext,
+	PgReleaseSavepointContext
 };
 
 TransactionManager *TM = &PgTM;

src/include/access/xtm.h

@@ -94,6 +94,22 @@ typedef struct
 	 */
 	void        (*InitializeSequence)(int64* start, int64* step);
 
+	/*
+	 * Create custom savepoint context.
+	 * This function can be used to accociate any data with savepoint which will be used by RestoreSavepointContext function to restore context
+	 */
+	void*       (*CreateSavepointContext)(void);
+
+	/*
+	 * Restore context saved by CreateSavepointContext
+	 */
+	void        (*RestoreSavepointContext)(void* ctx);
+
+	/*
+	 * Release context saved by CreateSavepointContext
+	 */
+	void        (*ReleaseSavepointContext)(void* ctx);
+
 }	TransactionManager;
 
 /* Get pointer to transaction manager: actually returns content of TM variable */
@@ -128,6 +144,9 @@ extern size_t PgGetTransactionStateSize(void);
 extern void PgSerializeTransactionState(void* ctx);
 extern void PgDeserializeTransactionState(void* ctx);
 extern void PgInitializeSequence(int64* start, int64* step);
+extern void* PgCreateSavepointContext(void);
+extern void PgRestoreSavepointContext(void*);
+extern void PgReleaseSavepointContext(void*);
 
 
 #endif