Function PrepareToInvalidateCacheTuple

src/backend/utils/cache/catcache.c:2073–2131

* PrepareToInvalidateCacheTuple() * * This is part of a rather subtle chain of events, so pay attention: * * When a tuple is inserted or deleted, it cannot be flushed from the * catcaches immediately, for reasons explained at the top of cache/inval.c. * Instead we have to add entry(s) for the tuple to a list of pending tuple * invalidations that will be done at the end of the command or tra

 *	system relation.
 */
void
PrepareToInvalidateCacheTuple(Relation relation,
							  HeapTuple tuple,
							  HeapTuple newtuple,
							  void (*function) (int, uint32, Oid))
{
	slist_iter	iter;
	Oid			reloid;

	CACHE_elog(DEBUG2, "PrepareToInvalidateCacheTuple: called");

	/*
	 * sanity checks
	 */
	Assert(RelationIsValid(relation));
	Assert(HeapTupleIsValid(tuple));
	Assert(function != NULL);
	Assert(PointerIsValid(function));
	Assert(CacheHdr != NULL);

	reloid = RelationGetRelid(relation);

	/* ----------------
	 *	for each cache
	 *	   if the cache contains tuples from the specified relation
	 *		   compute the tuple's hash value(s) in this cache,
	 *		   and call the passed function to register the information.
	 * ----------------
	 */

	slist_foreach(iter, &CacheHdr->ch_caches)
	{
		CatCache   *ccp = slist_container(CatCache, cc_next, iter.cur);
		uint32		hashvalue;
		Oid			dbid;

		if (ccp->cc_reloid != reloid)
			continue;

		/* Just in case cache hasn't finished initialization yet... */
		if (ccp->cc_tupdesc == NULL)
			CatalogCacheInitializeCache(ccp);

		hashvalue = CatalogCacheComputeTupleHashValue(ccp, ccp->cc_nkeys, tuple);
		dbid = ccp->cc_relisshared ? (Oid) 0 : MyDatabaseId;

		(*function) (ccp->id, hashvalue, dbid);

		if (newtuple)
		{
			uint32		newhashvalue;

			newhashvalue = CatalogCacheComputeTupleHashValue(ccp, ccp->cc_nkeys, newtuple);

			if (newhashvalue != hashvalue)
				(*function) (ccp->id, newhashvalue, dbid);
		}
	}