Clean up the API for DestReceiver objects by eliminating the assumption

that a Portal is a useful and sufficient additional argument for
CreateDestReceiver --- it just isn't, in most cases.  Instead formalize
the approach of passing any needed parameters to the receiver separately.

One unexpected benefit of this change is that we can declare typedef Portal
in a less surprising location.

This patch is just code rearrangement and doesn't change any functionality.
I'll tackle the HOLD-cursor-vs-toast problem in a follow-on patch.

14 files changed, 94 insertions, 69 deletions

diff --git a/src/backend/access/common/printtup.c b/src/backend/access/common/printtup.c
index 71d4ee1cbe..aabaf1d346 100644
--- a/src/backend/access/common/printtup.c
+++ b/src/backend/access/common/printtup.c
@@ -67,31 +67,16 @@ typedef struct
  * ----------------
  */
 DestReceiver *
-printtup_create_DR(CommandDest dest, Portal portal)
+printtup_create_DR(CommandDest dest)
 {
-	DR_printtup *self = (DR_printtup *) palloc(sizeof(DR_printtup));
+	DR_printtup *self = (DR_printtup *) palloc0(sizeof(DR_printtup));
 
-	if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
-		self->pub.receiveSlot = printtup;
-	else
-	{
-		/*
-		 * In protocol 2.0 the Bind message does not exist, so there is no way
-		 * for the columns to have different print formats; it's sufficient to
-		 * look at the first one.
-		 */
-		if (portal->formats && portal->formats[0] != 0)
-			self->pub.receiveSlot = printtup_internal_20;
-		else
-			self->pub.receiveSlot = printtup_20;
-	}
+	self->pub.receiveSlot = printtup;			/* might get changed later */
 	self->pub.rStartup = printtup_startup;
 	self->pub.rShutdown = printtup_shutdown;
 	self->pub.rDestroy = printtup_destroy;
 	self->pub.mydest = dest;
 
-	self->portal = portal;
-
 	/*
 	 * Send T message automatically if DestRemote, but not if
 	 * DestRemoteExecute
@@ -105,6 +90,33 @@ printtup_create_DR(CommandDest dest, Portal portal)
 	return (DestReceiver *) self;
 }
 
+/*
+ * Set parameters for a DestRemote (or DestRemoteExecute) receiver
+ */
+void
+SetRemoteDestReceiverParams(DestReceiver *self, Portal portal)
+{
+	DR_printtup *myState = (DR_printtup *) self;
+
+	Assert(myState->pub.mydest == DestRemote ||
+		   myState->pub.mydest == DestRemoteExecute);
+
+	myState->portal = portal;
+
+	if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
+	{
+		/*
+		 * In protocol 2.0 the Bind message does not exist, so there is no way
+		 * for the columns to have different print formats; it's sufficient to
+		 * look at the first one.
+		 */
+		if (portal->formats && portal->formats[0] != 0)
+			myState->pub.receiveSlot = printtup_internal_20;
+		else
+			myState->pub.receiveSlot = printtup_20;
+	}
+}
+
 static void
 printtup_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
 {
diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 1208579f15..bfda0e111a 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -1050,7 +1050,7 @@ DoCopy(const CopyStmt *stmt, const char *queryString)
 		PushUpdatedSnapshot(GetActiveSnapshot());
 
 		/* Create dest receiver for COPY OUT */
-		dest = CreateDestReceiver(DestCopyOut, NULL);
+		dest = CreateDestReceiver(DestCopyOut);
 		((DR_copy *) dest)->cstate = cstate;
 
 		/* Create a QueryDesc requesting no output */
diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c
index 9047cbcdec..7d64fe0eed 100644
--- a/src/backend/commands/portalcmds.c
+++ b/src/backend/commands/portalcmds.c
@@ -26,6 +26,7 @@
 #include "access/xact.h"
 #include "commands/portalcmds.h"
 #include "executor/executor.h"
+#include "executor/tstoreReceiver.h"
 #include "tcop/pquery.h"
 #include "utils/memutils.h"
 #include "utils/snapmgr.h"
@@ -351,7 +352,10 @@ PersistHoldablePortal(Portal portal)
 		ExecutorRewind(queryDesc);
 
 		/* Change the destination to output to the tuplestore */
-		queryDesc->dest = CreateDestReceiver(DestTuplestore, portal);
+		queryDesc->dest = CreateDestReceiver(DestTuplestore);
+		SetTuplestoreDestReceiverParams(queryDesc->dest,
+										portal->holdStore,
+										portal->holdContext);
 
 		/* Fetch the result set into the tuplestore */
 		ExecutorRun(queryDesc, ForwardScanDirection, 0L);
diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 290649f06a..45966b5f58 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -2833,7 +2833,7 @@ OpenIntoRel(QueryDesc *queryDesc)
 	/*
 	 * Now replace the query's DestReceiver with one for SELECT INTO
 	 */
-	queryDesc->dest = CreateDestReceiver(DestIntoRel, NULL);
+	queryDesc->dest = CreateDestReceiver(DestIntoRel);
 	myState = (DR_intorel *) queryDesc->dest;
 	Assert(myState->pub.mydest == DestIntoRel);
 	myState->estate = estate;
@@ -2877,10 +2877,6 @@ CloseIntoRel(QueryDesc *queryDesc)
 
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
- *
- * Since CreateDestReceiver doesn't accept the parameters we'd need,
- * we just leave the private fields zeroed here.  OpenIntoRel will
- * fill them in.
  */
 DestReceiver *
 CreateIntoRelDestReceiver(void)
@@ -2893,6 +2889,8 @@ CreateIntoRelDestReceiver(void)
 	self->pub.rDestroy = intorel_destroy;
 	self->pub.mydest = DestIntoRel;
 
+	/* private fields will be set by OpenIntoRel */
+
 	return (DestReceiver *) self;
 }
 
diff --git a/src/backend/executor/functions.c b/src/backend/executor/functions.c
index 29fae145cb..c467e970e8 100644
--- a/src/backend/executor/functions.c
+++ b/src/backend/executor/functions.c
@@ -398,7 +398,7 @@ postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
 	{
 		DR_sqlfunction *myState;
 
-		dest = CreateDestReceiver(DestSQLFunction, NULL);
+		dest = CreateDestReceiver(DestSQLFunction);
 		/* pass down the needed info to the dest receiver routines */
 		myState = (DR_sqlfunction *) dest;
 		Assert(myState->pub.mydest == DestSQLFunction);
@@ -1269,10 +1269,6 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
 
 /*
  * CreateSQLFunctionDestReceiver -- create a suitable DestReceiver object
- *
- * Since CreateDestReceiver doesn't accept the parameters we'd need,
- * we just leave the private fields zeroed here.  postquel_start will
- * fill them in.
  */
 DestReceiver *
 CreateSQLFunctionDestReceiver(void)
@@ -1285,6 +1281,8 @@ CreateSQLFunctionDestReceiver(void)
 	self->pub.rDestroy = sqlfunction_destroy;
 	self->pub.mydest = DestSQLFunction;
 
+	/* private fields will be set by postquel_start */
+
 	return (DestReceiver *) self;
 }
 
diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index e1578338d7..57288c122e 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -1227,7 +1227,7 @@ SPI_cursor_fetch(Portal portal, bool forward, long count)
 {
 	_SPI_cursor_operation(portal,
 						  forward ? FETCH_FORWARD : FETCH_BACKWARD, count,
-						  CreateDestReceiver(DestSPI, NULL));
+						  CreateDestReceiver(DestSPI));
 	/* we know that the DestSPI receiver doesn't need a destroy call */
 }
 
@@ -1256,7 +1256,7 @@ SPI_scroll_cursor_fetch(Portal portal, FetchDirection direction, long count)
 {
 	_SPI_cursor_operation(portal,
 						  direction, count,
-						  CreateDestReceiver(DestSPI, NULL));
+						  CreateDestReceiver(DestSPI));
 	/* we know that the DestSPI receiver doesn't need a destroy call */
 }
 
@@ -1744,8 +1744,7 @@ _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
 			if (!read_only)
 				CommandCounterIncrement();
 
-			dest = CreateDestReceiver(canSetTag ? DestSPI : DestNone,
-									  NULL);
+			dest = CreateDestReceiver(canSetTag ? DestSPI : DestNone);
 
 			if (snapshot == InvalidSnapshot)
 			{
diff --git a/src/backend/executor/tstoreReceiver.c b/src/backend/executor/tstoreReceiver.c
index 512d856ec6..c0405a47b4 100644
--- a/src/backend/executor/tstoreReceiver.c
+++ b/src/backend/executor/tstoreReceiver.c
@@ -72,10 +72,9 @@ tstoreDestroyReceiver(DestReceiver *self)
  * Initially create a DestReceiver object.
  */
 DestReceiver *
-CreateTuplestoreDestReceiver(Tuplestorestate *tStore,
-							 MemoryContext tContext)
+CreateTuplestoreDestReceiver(void)
 {
-	TStoreState *self = (TStoreState *) palloc(sizeof(TStoreState));
+	TStoreState *self = (TStoreState *) palloc0(sizeof(TStoreState));
 
 	self->pub.receiveSlot = tstoreReceiveSlot;
 	self->pub.rStartup = tstoreStartupReceiver;
@@ -83,8 +82,22 @@ CreateTuplestoreDestReceiver(Tuplestorestate *tStore,
 	self->pub.rDestroy = tstoreDestroyReceiver;
 	self->pub.mydest = DestTuplestore;
 
-	self->tstore = tStore;
-	self->cxt = tContext;
+	/* private fields will be set by SetTuplestoreDestReceiverParams */
 
 	return (DestReceiver *) self;
 }
+
+/*
+ * Set parameters for a TuplestoreDestReceiver
+ */
+void
+SetTuplestoreDestReceiverParams(DestReceiver *self,
+								Tuplestorestate *tStore,
+								MemoryContext tContext)
+{
+	TStoreState *myState = (TStoreState *) self;
+
+	Assert(myState->pub.mydest == DestTuplestore);
+	myState->tstore = tStore;
+	myState->cxt = tContext;
+}
diff --git a/src/backend/tcop/dest.c b/src/backend/tcop/dest.c
index 74ec8629d6..520affa987 100644
--- a/src/backend/tcop/dest.c
+++ b/src/backend/tcop/dest.c
@@ -94,21 +94,16 @@ BeginCommand(const char *commandTag, CommandDest dest)
 
 /* ----------------
  *		CreateDestReceiver - return appropriate receiver function set for dest
- *
- * Note: a Portal must be specified for destinations DestRemote,
- * DestRemoteExecute, and DestTuplestore.  It can be NULL for the others.
  * ----------------
  */
 DestReceiver *
-CreateDestReceiver(CommandDest dest, Portal portal)
+CreateDestReceiver(CommandDest dest)
 {
 	switch (dest)
 	{
 		case DestRemote:
 		case DestRemoteExecute:
-			if (portal == NULL)
-				elog(ERROR, "no portal specified for DestRemote receiver");
-			return printtup_create_DR(dest, portal);
+			return printtup_create_DR(dest);
 
 		case DestNone:
 			return &donothingDR;
@@ -120,13 +115,7 @@ CreateDestReceiver(CommandDest dest, Portal portal)
 			return &spi_printtupDR;
 
 		case DestTuplestore:
-			if (portal == NULL)
-				elog(ERROR, "no portal specified for DestTuplestore receiver");
-			if (portal->holdStore == NULL ||
-				portal->holdContext == NULL)
-				elog(ERROR, "portal has no holdStore");
-			return CreateTuplestoreDestReceiver(portal->holdStore,
-												portal->holdContext);
+			return CreateTuplestoreDestReceiver();
 
 		case DestIntoRel:
 			return CreateIntoRelDestReceiver();
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 09892780ba..90c4c8400e 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -979,7 +979,9 @@ exec_simple_query(const char *query_string)
 		/*
 		 * Now we can create the destination receiver object.
 		 */
-		receiver = CreateDestReceiver(dest, portal);
+		receiver = CreateDestReceiver(dest);
+		if (dest == DestRemote)
+			SetRemoteDestReceiverParams(receiver, portal);
 
 		/*
 		 * Switch back to transaction context for execution.
@@ -1835,7 +1837,9 @@ exec_execute_message(const char *portal_name, long max_rows)
 	 * Create dest receiver in MessageContext (we don't want it in transaction
 	 * context, because that may get deleted if portal contains VACUUM).
 	 */
-	receiver = CreateDestReceiver(dest, portal);
+	receiver = CreateDestReceiver(dest);
+	if (dest == DestRemoteExecute)
+		SetRemoteDestReceiverParams(receiver, portal);
 
 	/*
 	 * Ensure we are in a transaction command (this should normally be the
diff --git a/src/backend/tcop/pquery.c b/src/backend/tcop/pquery.c
index 143a39e382..77271bab9c 100644
--- a/src/backend/tcop/pquery.c
+++ b/src/backend/tcop/pquery.c
@@ -18,6 +18,7 @@
 #include "access/xact.h"
 #include "commands/prepare.h"
 #include "commands/trigger.h"
+#include "executor/tstoreReceiver.h"
 #include "miscadmin.h"
 #include "pg_trace.h"
 #include "tcop/pquery.h"
@@ -1032,7 +1033,10 @@ FillPortalStore(Portal portal, bool isTopLevel)
 	char		completionTag[COMPLETION_TAG_BUFSIZE];
 
 	PortalCreateHoldStore(portal);
-	treceiver = CreateDestReceiver(DestTuplestore, portal);
+	treceiver = CreateDestReceiver(DestTuplestore);
+	SetTuplestoreDestReceiverParams(treceiver,
+									portal->holdStore,
+									portal->holdContext);
 
 	completionTag[0] = '\0';
 
diff --git a/src/include/access/printtup.h b/src/include/access/printtup.h
index 7313153cb8..661116de57 100644
--- a/src/include/access/printtup.h
+++ b/src/include/access/printtup.h
@@ -14,9 +14,11 @@
 #ifndef PRINTTUP_H
 #define PRINTTUP_H
 
-#include "tcop/dest.h"
+#include "utils/portal.h"
 
-extern DestReceiver *printtup_create_DR(CommandDest dest, Portal portal);
+extern DestReceiver *printtup_create_DR(CommandDest dest);
+
+extern void SetRemoteDestReceiverParams(DestReceiver *self, Portal portal);
 
 extern void SendRowDescriptionMessage(TupleDesc typeinfo, List *targetlist,
 						  int16 *formats);
diff --git a/src/include/executor/tstoreReceiver.h b/src/include/executor/tstoreReceiver.h
index 09096bfd39..9bf3136832 100644
--- a/src/include/executor/tstoreReceiver.h
+++ b/src/include/executor/tstoreReceiver.h
@@ -19,7 +19,10 @@
 #include "utils/tuplestore.h"
 
 
-extern DestReceiver *CreateTuplestoreDestReceiver(Tuplestorestate *tStore,
-							 MemoryContext tContext);
+extern DestReceiver *CreateTuplestoreDestReceiver(void);
+
+extern void SetTuplestoreDestReceiverParams(DestReceiver *self,
+											Tuplestorestate *tStore,
+											MemoryContext tContext);
 
 #endif   /* TSTORE_RECEIVER_H */
diff --git a/src/include/tcop/dest.h b/src/include/tcop/dest.h
index b12c4e2b75..dc26d498f0 100644
--- a/src/include/tcop/dest.h
+++ b/src/include/tcop/dest.h
@@ -35,6 +35,12 @@
  * The same receiver object may be re-used multiple times; eventually it is
  * destroyed by calling its rDestroy method.
  *
+ * In some cases, receiver objects require additional parameters that must
+ * be passed to them after calling CreateDestReceiver.  Since the set of
+ * parameters varies for different receiver types, this is not handled by
+ * this module, but by direct calls from the calling code to receiver type
+ * specific functions.
+ *
  * The DestReceiver object returned by CreateDestReceiver may be a statically
  * allocated object (for destination types that require no local state),
  * in which case rDestroy is a no-op.  Alternatively it can be a palloc'd
@@ -120,14 +126,10 @@ struct _DestReceiver
 
 extern DestReceiver *None_Receiver;		/* permanent receiver for DestNone */
 
-/* This is a forward reference to utils/portal.h */
-
-typedef struct PortalData *Portal;
-
 /* The primary destination management functions */
 
 extern void BeginCommand(const char *commandTag, CommandDest dest);
-extern DestReceiver *CreateDestReceiver(CommandDest dest, Portal portal);
+extern DestReceiver *CreateDestReceiver(CommandDest dest);
 extern void EndCommand(const char *commandTag, CommandDest dest);
 
 /* Additional functions that go with destination management, more or less. */
diff --git a/src/include/utils/portal.h b/src/include/utils/portal.h
index 7e3dd7d903..7a56687e9a 100644
--- a/src/include/utils/portal.h
+++ b/src/include/utils/portal.h
@@ -102,10 +102,7 @@ typedef enum PortalStatus
 	PORTAL_FAILED				/* portal got error (can't re-run it) */
 } PortalStatus;
 
-/*
- * Note: typedef Portal is declared in tcop/dest.h as
- *		typedef struct PortalData *Portal;
- */
+typedef struct PortalData *Portal;
 
 typedef struct PortalData
 {