inval.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

/*
 * Execute the given function for all the messages in an invalidation list.
 * The list is not altered.
 *
 * catcache entries are processed first, for reasons mentioned above.
 */
static void
ProcessInvalidationMessages(InvalidationListHeader *hdr,
							void (*func) (SharedInvalidationMessage *msg))
{
	ProcessMessageList(hdr->cclist, func(msg));
	ProcessMessageList(hdr->rclist, func(msg));
}

/* ----------------------------------------------------------------
 *					  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(&transInvalInfo->CurrentCmdInvalidMsgs,
								   cacheId, hashValue, tuplePtr, dbId);
}

/*
 * RegisterRelcacheInvalidation
 *
 * As above, but register a relcache invalidation event.
 */
static void
RegisterRelcacheInvalidation(Oid dbId, Oid relId)
{
	AddRelcacheInvalidationMessage(&transInvalInfo->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))
		transInvalInfo->RelcacheInitFileInval = true;
}

/*
 * RegisterSmgrInvalidation
 *
 * As above, but register an smgr invalidation event.
 */
static void
RegisterSmgrInvalidation(RelFileNode rnode)
{
	AddSmgrInvalidationMessage(&transInvalInfo->CurrentCmdInvalidMsgs,
							   rnode);
}

/*
 * LocalExecuteInvalidationMessage
 *
 * Process a single invalidation message (which could be of any 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 == InvalidOid)
		{
			RelationCacheInvalidateEntry(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 if (msg->id == SHAREDINVALSMGR_ID)
	{
		/*
		 * We could have smgr entries for relations of other databases, so no
		 * short-circuit test is possible here.
		 */
		smgrclosenode(msg->sm.rnode);
	}
	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 smgr cache entries.
 *		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();	/* gets smgr cache too */

	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)
{
	Oid			tupleRelId;
	Oid			databaseId;
	Oid			relationId;

	/* Do nothing during bootstrap */
	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,
								  RegisterCatcacheInvalidation);

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

	if (tupleRelId == RelationRelationId)
	{
		Form_pg_class classtup = (Form_pg_class) GETSTRUCT(tuple);
		RelFileNode rnode;

		relationId = HeapTupleGetOid(tuple);
		if (classtup->relisshared)
			databaseId = InvalidOid;
		else
			databaseId = MyDatabaseId;

		/*
		 * We need to send out an smgr inval as well as a relcache inval. This
		 * is needed because other backends might possibly possess smgr cache
		 * but not relcache entries for the target relation.
		 *
		 * Note: during a pg_class row update that assigns a new relfilenode
		 * or reltablespace value, we will be called on both the old and new
		 * tuples, and thus will broadcast invalidation messages showing both
		 * the old and new RelFileNode values.	This ensures that other
		 * backends will close smgr references to the old file.
		 *
		 * XXX possible future cleanup: it might be better to trigger smgr
		 * flushes explicitly, rather than indirectly from pg_class updates.
		 */
		if (classtup->reltablespace)
			rnode.spcNode = classtup->reltablespace;
		else
			rnode.spcNode = MyDatabaseTableSpace;
		rnode.dbNode = databaseId;
		rnode.relNode = classtup->relfilenode;
		RegisterSmgrInvalidation(rnode);
	}
	else if (tupleRelId == AttributeRelationId)
	{
		Form_pg_attribute atttup = (Form_pg_attribute) GETSTRUCT(tuple);

		relationId = atttup->attrelid;

		/*
		 * KLUGE ALERT: we always send the relcache event with MyDatabaseId,
		 * even if the rel in question is shared (which we can't easily tell).
		 * 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_attribute
		 * change anyway.  It looks a bit ugly though.
		 */
		databaseId = MyDatabaseId;
	}
	else
		return;

	/*
	 * Yes.  We need to register a relcache invalidation event.
	 */
	RegisterRelcacheInvalidation(databaseId, 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);

	/*
	 * Test code to force cache flushes anytime a flush could happen.
	 *
	 * If used with CLOBBER_FREED_MEMORY, CLOBBER_CACHE_ALWAYS provides a
	 * fairly thorough test that the system contains no cache-flush hazards.
	 * However, it also makes the system unbelievably slow --- the regression
	 * tests take about 100 times longer than normal.
	 *
	 * If you're a glutton for punishment, try CLOBBER_CACHE_RECURSIVELY.
	 * This slows things by at least a factor of 10000, so I wouldn't suggest
	 * trying to run the entire regression tests that way.  It's useful to
	 * try a few simple tests, to make sure that cache reload isn't subject
	 * to internal cache-flush hazards, but after you've done a few thousand
	 * recursive reloads it's unlikely you'll learn more.
	 */
#if defined(CLOBBER_CACHE_ALWAYS)
	{
		static bool in_recursion = false;

		if (!in_recursion)
		{
			in_recursion = true;
			InvalidateSystemCaches();
			in_recursion = false;
		}
	}
#elif defined(CLOBBER_CACHE_RECURSIVELY)
	InvalidateSystemCaches();
#endif
}

/*
 * AtStart_Inval
 *		Initialize inval lists at start of a main transaction.
 */
void
AtStart_Inval(void)
{
	Assert(transInvalInfo == NULL);
	transInvalInfo = (TransInvalidationInfo *)
		MemoryContextAllocZero(TopTransactionContext,
							   sizeof(TransInvalidationInfo));
	transInvalInfo->my_level = GetCurrentTransactionNestLevel();
}

/*
 * AtPrepare_Inval
 *		Save the inval lists state at 2PC transaction prepare.
 *
 * In this phase we just generate 2PC records for all the pending invalidation
 * work.
 */
void
AtPrepare_Inval(void)
{
	/* Must be at top of stack */
	Assert(transInvalInfo != NULL && transInvalInfo->parent == NULL);

	/*
	 * Relcache init file invalidation requires processing both before and
	 * after we send the SI messages.
	 */
	if (transInvalInfo->RelcacheInitFileInval)
		RegisterTwoPhaseRecord(TWOPHASE_RM_INVAL_ID, TWOPHASE_INFO_FILE_BEFORE,
							   NULL, 0);

	AppendInvalidationMessages(&transInvalInfo->PriorCmdInvalidMsgs,
							   &transInvalInfo->CurrentCmdInvalidMsgs);

	ProcessInvalidationMessages(&transInvalInfo->PriorCmdInvalidMsgs,
								PersistInvalidationMessage);

	if (transInvalInfo->RelcacheInitFileInval)
		RegisterTwoPhaseRecord(TWOPHASE_RM_INVAL_ID, TWOPHASE_INFO_FILE_AFTER,
							   NULL, 0);
}

/*
 * PostPrepare_Inval
 *		Clean up after successful PREPARE.
 *
 * Here, we want to act as though the transaction aborted, so that we will
 * undo any syscache changes it made, thereby bringing us into sync with the
 * outside world, which doesn't believe the transaction committed yet.
 *
 * If the prepared transaction is later aborted, there is nothing more to
 * do; if it commits, we will receive the consequent inval messages just
 * like everyone else.
 */
void