inval.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 736 行 · 第 1/2 页

 *					  private support functions
 * ----------------------------------------------------------------
 */

/*
 * RegisterCatcacheInvalidation
 *
 * Register an invalidation event for a catcache tuple entry.
 */
static void
RegisterCatcacheInvalidation(int cacheId,
							 uint32 hashValue,
							 ItemPointer tuplePtr,
							 Oid dbId)
{
	AddCatcacheInvalidationMessage(&CurrentCmdInvalidMsgs,
								   cacheId, hashValue, tuplePtr, dbId);
}

/*
 * RegisterRelcacheInvalidation
 *
 * As above, but register a relcache invalidation event.
 */
static void
RegisterRelcacheInvalidation(Oid dbId, Oid relId)
{
	AddRelcacheInvalidationMessage(&CurrentCmdInvalidMsgs,
								   dbId, relId);

	/*
	 * If the relation being invalidated is one of those cached in the
	 * relcache init file, mark that we need to zap that file at commit.
	 */
	if (RelationIdIsInInitFile(relId))
		RelcacheInitFileInval = true;
}

/*
 * LocalExecuteInvalidationMessage
 *
 * Process a single invalidation message (which could be either type).
 * Only the local caches are flushed; this does not transmit the message
 * to other backends.
 */
static void
LocalExecuteInvalidationMessage(SharedInvalidationMessage *msg)
{
	int			i;

	if (msg->id >= 0)
	{
		if (msg->cc.dbId == MyDatabaseId || msg->cc.dbId == 0)
		{
			CatalogCacheIdInvalidate(msg->cc.id,
									 msg->cc.hashValue,
									 &msg->cc.tuplePtr);

			for (i = 0; i < cache_callback_count; i++)
			{
				struct CACHECALLBACK *ccitem = cache_callback_list + i;

				if (ccitem->id == msg->cc.id)
					(*ccitem->function) (ccitem->arg, InvalidOid);
			}
		}
	}
	else if (msg->id == SHAREDINVALRELCACHE_ID)
	{
		if (msg->rc.dbId == MyDatabaseId || msg->rc.dbId == 0)
		{
			RelationIdInvalidateRelationCacheByRelationId(msg->rc.relId);

			for (i = 0; i < cache_callback_count; i++)
			{
				struct CACHECALLBACK *ccitem = cache_callback_list + i;

				if (ccitem->id == SHAREDINVALRELCACHE_ID)
					(*ccitem->function) (ccitem->arg, msg->rc.relId);
			}
		}
	}
	else
		elog(FATAL, "unrecognized SI message id: %d", msg->id);
}

/*
 *		InvalidateSystemCaches
 *
 *		This blows away all tuples in the system catalog caches and
 *		all the cached relation descriptors (and closes their files too).
 *		Relation descriptors that have positive refcounts are then rebuilt.
 *
 *		We call this when we see a shared-inval-queue overflow signal,
 *		since that tells us we've lost some shared-inval messages and hence
 *		don't know what needs to be invalidated.
 */
static void
InvalidateSystemCaches(void)
{
	int			i;

	ResetCatalogCaches();
	RelationCacheInvalidate();

	for (i = 0; i < cache_callback_count; i++)
	{
		struct CACHECALLBACK *ccitem = cache_callback_list + i;

		(*ccitem->function) (ccitem->arg, InvalidOid);
	}
}

/*
 * PrepareForTupleInvalidation
 *		Detect whether invalidation of this tuple implies invalidation
 *		of catalog/relation cache entries; if so, register inval events.
 */
static void
PrepareForTupleInvalidation(Relation relation, HeapTuple tuple,
							void (*CacheIdRegisterFunc) (int, uint32,
													   ItemPointer, Oid),
							void (*RelationIdRegisterFunc) (Oid, Oid))
{
	Oid			tupleRelId;
	Oid			relationId;

	if (IsBootstrapProcessingMode())
		return;

	/*
	 * We only need to worry about invalidation for tuples that are in
	 * system relations; user-relation tuples are never in catcaches and
	 * can't affect the relcache either.
	 */
	if (!IsSystemRelation(relation))
		return;

	/*
	 * TOAST tuples can likewise be ignored here. Note that TOAST tables
	 * are considered system relations so they are not filtered by the
	 * above test.
	 */
	if (IsToastRelation(relation))
		return;

	/*
	 * First let the catcache do its thing
	 */
	PrepareToInvalidateCacheTuple(relation, tuple,
								  CacheIdRegisterFunc);

	/*
	 * Now, is this tuple one of the primary definers of a relcache entry?
	 */
	tupleRelId = RelationGetRelid(relation);

	if (tupleRelId == RelOid_pg_class)
		relationId = HeapTupleGetOid(tuple);
	else if (tupleRelId == RelOid_pg_attribute)
		relationId = ((Form_pg_attribute) GETSTRUCT(tuple))->attrelid;
	else
		return;

	/*
	 * Yes.  We need to register a relcache invalidation event for the
	 * relation identified by relationId.
	 *
	 * KLUGE ALERT: we always send the relcache event with MyDatabaseId, even
	 * if the rel in question is shared.  This essentially means that only
	 * backends in this same database will react to the relcache flush
	 * request.  This is in fact appropriate, since only those backends
	 * could see our pg_class or pg_attribute change anyway.  It looks a
	 * bit ugly though.
	 */
	(*RelationIdRegisterFunc) (MyDatabaseId, relationId);
}


/* ----------------------------------------------------------------
 *					  public functions
 * ----------------------------------------------------------------
 */

/*
 * AcceptInvalidationMessages
 *		Read and process invalidation messages from the shared invalidation
 *		message queue.
 *
 * Note:
 *		This should be called as the first step in processing a transaction.
 */
void
AcceptInvalidationMessages(void)
{
	ReceiveSharedInvalidMessages(LocalExecuteInvalidationMessage,
								 InvalidateSystemCaches);
}

/*
 * AtEOXactInvalidationMessages
 *		Process queued-up invalidation messages at end of transaction.
 *
 * If isCommit, we must send out the messages in our PriorCmdInvalidMsgs list
 * to the shared invalidation message queue.  Note that these will be read
 * not only by other backends, but also by our own backend at the next
 * transaction start (via AcceptInvalidationMessages).	This means that
 * we can skip immediate local processing of anything that's still in
 * CurrentCmdInvalidMsgs, and just send that list out too.
 *
 * If not isCommit, we are aborting, and must locally process the messages
 * in PriorCmdInvalidMsgs.	No messages need be sent to other backends,
 * since they'll not have seen our changed tuples anyway.  We can forget
 * about CurrentCmdInvalidMsgs too, since those changes haven't touched
 * the caches yet.
 *
 * In any case, reset the various lists to empty.  We need not physically
 * free memory here, since TopTransactionContext is about to be emptied
 * anyway.
 *
 * Note:
 *		This should be called as the last step in processing a transaction.
 */
void
AtEOXactInvalidationMessages(bool isCommit)
{
	if (isCommit)
	{
		/*
		 * Relcache init file invalidation requires processing both before
		 * and after we send the SI messages.  However, we need not do
		 * anything unless we committed.
		 */
		if (RelcacheInitFileInval)
			RelationCacheInitFileInvalidate(true);

		AppendInvalidationMessages(&PriorCmdInvalidMsgs,
								   &CurrentCmdInvalidMsgs);

		ProcessInvalidationMessages(&PriorCmdInvalidMsgs,
									SendSharedInvalidMessage);

		if (RelcacheInitFileInval)
			RelationCacheInitFileInvalidate(false);
	}
	else
	{
		ProcessInvalidationMessages(&PriorCmdInvalidMsgs,
									LocalExecuteInvalidationMessage);
	}

	RelcacheInitFileInval = false;

	DiscardInvalidationMessages(&PriorCmdInvalidMsgs, false);
	DiscardInvalidationMessages(&CurrentCmdInvalidMsgs, false);
}

/*
 * CommandEndInvalidationMessages
 *		Process queued-up invalidation messages at end of one command
 *		in a transaction.
 *
 * Here, we send no messages to the shared queue, since we don't know yet if
 * we will commit.	We do need to locally process the CurrentCmdInvalidMsgs
 * list, so as to flush our caches of any entries we have outdated in the
 * current command.  We then move the current-cmd list over to become part
 * of the prior-cmds list.
 *
 * The isCommit = false case is not currently used, but may someday be
 * needed to support rollback to a savepoint within a transaction.
 *
 * Note:
 *		This should be called during CommandCounterIncrement(),
 *		after we have advanced the command ID.
 */
void
CommandEndInvalidationMessages(bool isCommit)
{
	if (isCommit)
	{
		ProcessInvalidationMessages(&CurrentCmdInvalidMsgs,
									LocalExecuteInvalidationMessage);
		AppendInvalidationMessages(&PriorCmdInvalidMsgs,
								   &CurrentCmdInvalidMsgs);
	}
	else
	{
		/* XXX what needs to be done here? */
	}
}

/*
 * CacheInvalidateHeapTuple
 *		Register the given tuple for invalidation at end of command
 *		(ie, current command is outdating this tuple).
 */
void
CacheInvalidateHeapTuple(Relation relation, HeapTuple tuple)
{
	PrepareForTupleInvalidation(relation, tuple,
								RegisterCatcacheInvalidation,
								RegisterRelcacheInvalidation);
}

/*
 * CacheInvalidateRelcache
 *		Register invalidation of the specified relation's relcache entry
 *		at end of command.
 *
 * This is used in places that need to force relcache rebuild but aren't
 * changing any of the tuples recognized as contributors to the relcache
 * entry by PrepareForTupleInvalidation.  (An example is dropping an index.)
 */
void
CacheInvalidateRelcache(Oid relationId)
{
	/* See KLUGE ALERT in PrepareForTupleInvalidation */
	RegisterRelcacheInvalidation(MyDatabaseId, relationId);
}

/*
 * CacheRegisterSyscacheCallback
 *		Register the specified function to be called for all future
 *		invalidation events in the specified cache.
 *
 * NOTE: currently, the OID argument to the callback routine is not
 * provided for syscache callbacks; the routine doesn't really get any
 * useful info as to exactly what changed.	It should treat every call
 * as a "cache flush" request.
 */
void
CacheRegisterSyscacheCallback(int cacheid,
							  CacheCallbackFunction func,
							  Datum arg)
{
	if (cache_callback_count >= MAX_CACHE_CALLBACKS)
		elog(FATAL, "out of cache_callback_list slots");

	cache_callback_list[cache_callback_count].id = cacheid;
	cache_callback_list[cache_callback_count].function = func;
	cache_callback_list[cache_callback_count].arg = arg;

	++cache_callback_count;
}

/*
 * CacheRegisterRelcacheCallback
 *		Register the specified function to be called for all future
 *		relcache invalidation events.  The OID of the relation being
 *		invalidated will be passed to the function.
 *
 * NOTE: InvalidOid will be passed if a cache reset request is received.
 * In this case the called routines should flush all cached state.
 */
void
CacheRegisterRelcacheCallback(CacheCallbackFunction func,
							  Datum arg)
{
	if (cache_callback_count >= MAX_CACHE_CALLBACKS)
		elog(FATAL, "out of cache_callback_list slots");

	cache_callback_list[cache_callback_count].id = SHAREDINVALRELCACHE_ID;
	cache_callback_list[cache_callback_count].function = func;
	cache_callback_list[cache_callback_count].arg = arg;

	++cache_callback_count;
}