Clean up some longstanding problems in shared-cache invalidation.

SI messages now include the relevant database OID, so that operations
in one database do not cause useless cache flushes in backends attached
to other databases.  Declare SI messages properly using a union, to
eliminate the former assumption that Oid is the same size as int or Index.
Rewrite the nearly-unreadable code in inval.c, and document it better.
Arrange for catcache flushes at end of command/transaction to happen before
relcache flushes do --- this avoids loading a new tuple into the catcache
while setting up new relcache entry, only to have it be flushed again
immediately.

src/backend/storage/ipc/sinval.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.33 2001/06/16 22:58:13 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.34 2001/06/19 19:42:15 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -55,56 +55,31 @@ InitBackendSharedInvalidationState(void)
 }
 
 /*
- * RegisterSharedInvalid
+ * SendSharedInvalidMessage
  *	Add a shared-cache-invalidation message to the global SI message queue.
- *
- * Note:
- *	Assumes hash index is valid.
- *	Assumes item pointer is valid.
  */
 void
-RegisterSharedInvalid(int cacheId,		/* XXX */
-					  Index hashIndex,
-					  ItemPointer pointer)
+SendSharedInvalidMessage(SharedInvalidationMessage *msg)
 {
-	SharedInvalidData newInvalid;
 	bool		insertOK;
 
-	/*
-	 * This code has been hacked to accept two types of messages.  This
-	 * might be treated more generally in the future.
-	 *
-	 * (1) cacheId= system cache id hashIndex= system cache hash index for a
-	 * (possibly) cached tuple pointer= pointer of (possibly) cached tuple
-	 *
-	 * (2) cacheId= special non-syscache id hashIndex= object id contained in
-	 * (possibly) cached relation descriptor pointer= null
-	 */
-
-	newInvalid.cacheId = cacheId;
-	newInvalid.hashIndex = hashIndex;
-
-	if (ItemPointerIsValid(pointer))
-		ItemPointerCopy(pointer, &newInvalid.pointerData);
-	else
-		ItemPointerSetInvalid(&newInvalid.pointerData);
-
 	SpinAcquire(SInvalLock);
-	insertOK = SIInsertDataEntry(shmInvalBuffer, &newInvalid);
+	insertOK = SIInsertDataEntry(shmInvalBuffer, msg);
 	SpinRelease(SInvalLock);
 	if (!insertOK)
-		elog(DEBUG, "RegisterSharedInvalid: SI buffer overflow");
+		elog(DEBUG, "SendSharedInvalidMessage: SI buffer overflow");
 }
 
 /*
- * InvalidateSharedInvalid
+ * ReceiveSharedInvalidMessages
  *		Process shared-cache-invalidation messages waiting for this backend
  */
 void
-			InvalidateSharedInvalid(void (*invalFunction) (),
-									void (*resetFunction) ())
+ReceiveSharedInvalidMessages(
+	void (*invalFunction) (SharedInvalidationMessage *msg),
+	void (*resetFunction) (void))
 {
-	SharedInvalidData data;
+	SharedInvalidationMessage data;
 	int			getResult;
 	bool		gotMessage = false;
 
@@ -118,15 +93,13 @@ void
 		if (getResult < 0)
 		{
 			/* got a reset message */
-			elog(DEBUG, "InvalidateSharedInvalid: cache state reset");
+			elog(DEBUG, "ReceiveSharedInvalidMessages: cache state reset");
 			resetFunction();
 		}
 		else
 		{
 			/* got a normal data message */
-			invalFunction(data.cacheId,
-						  data.hashIndex,
-						  &data.pointerData);
+			invalFunction(&data);
 		}
 		gotMessage = true;
 	}

src/backend/storage/ipc/sinvaladt.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.39 2001/06/16 22:58:15 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.40 2001/06/19 19:42:15 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -20,7 +20,6 @@
 #include "miscadmin.h"
 #include "storage/backendid.h"
 #include "storage/proc.h"
-#include "storage/sinval.h"
 #include "storage/sinvaladt.h"
 
 SISeg	   *shmInvalBuffer;
@@ -35,7 +34,6 @@ static void SISetProcStateInvalid(SISeg *segP);
 int
 SInvalShmemSize(int maxBackends)
 {
-
 	/*
 	 * Figure space needed. Note sizeof(SISeg) includes the first
 	 * ProcState entry.
@@ -183,14 +181,13 @@ CleanupInvalidationState(int status, Datum arg)
  * Returns true for normal successful insertion, false if had to reset.
  */
 bool
-SIInsertDataEntry(SISeg *segP, SharedInvalidData *data)
+SIInsertDataEntry(SISeg *segP, SharedInvalidationMessage *data)
 {
 	int			numMsgs = segP->maxMsgNum - segP->minMsgNum;
 
 	/* Is the buffer full? */
 	if (numMsgs >= MAXNUMMESSAGES)
 	{
-
 		/*
 		 * Don't panic just yet: slowest backend might have consumed some
 		 * messages but not yet have done SIDelExpiredDataEntries() to
@@ -273,13 +270,12 @@ SISetProcStateInvalid(SISeg *segP)
  */
 int
 SIGetDataEntry(SISeg *segP, int backendId,
-			   SharedInvalidData *data)
+			   SharedInvalidationMessage *data)
 {
 	ProcState  *stateP = &segP->procState[backendId - 1];
 
 	if (stateP->resetState)
 	{
-
 		/*
 		 * Force reset.  We can say we have dealt with any messages added
 		 * since the reset, as well...

src/backend/storage/lmgr/lmgr.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lmgr.c,v 1.46 2001/06/12 05:55:49 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lmgr.c,v 1.47 2001/06/19 19:42:16 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -144,7 +144,7 @@ LockRelation(Relation relation, LOCKMODE lockmode)
 	 * rebuild it and not just delete it.
 	 */
 	RelationIncrementReferenceCount(relation);
-	DiscardInvalid();
+	AcceptInvalidationMessages();
 	RelationDecrementReferenceCount(relation);
 }