Function SearchCatCacheList

src/backend/utils/cache/catcache.c:1572–1841

* SearchCatCacheList * * Generate a list of all tuples matching a partial key (that is, * a key specifying just the first K of the cache's N key columns). * * It doesn't make any sense to specify all of the cache's key columns * here: since the key is unique, there could be at most one match, so * you ought to use SearchCatCache() instead. Hence this function takes * one fewer Datum

 *		and must call ReleaseCatCacheList() when done with the list.
 */
CatCList *
SearchCatCacheList(CatCache *cache,
				   int nkeys,
				   Datum v1,
				   Datum v2,
				   Datum v3)
{
	Datum		v4 = 0;			/* dummy last-column value */
	Datum		arguments[CATCACHE_MAXKEYS];
	uint32		lHashValue;
	dlist_iter	iter;
	CatCList   *cl;
	CatCTup    *ct;
	List	   *volatile ctlist;
	ListCell   *ctlist_item;
	int			nmembers;
	bool		ordered;
	HeapTuple	ntp;
	MemoryContext oldcxt;
	int			i;

	/*
	 * one-time startup overhead for each cache
	 */
	if (cache->cc_tupdesc == NULL)
		CatalogCacheInitializeCache(cache);

	Assert(nkeys > 0 && nkeys < cache->cc_nkeys);

#ifdef CATCACHE_STATS
	cache->cc_lsearches++;
#endif

	/* Initialize local parameter array */
	arguments[0] = v1;
	arguments[1] = v2;
	arguments[2] = v3;
	arguments[3] = v4;

	/*
	 * compute a hash value of the given keys for faster search.  We don't
	 * presently divide the CatCList items into buckets, but this still lets
	 * us skip non-matching items quickly most of the time.
	 */
	lHashValue = CatalogCacheComputeHashValue(cache, nkeys, v1, v2, v3, v4);

	/*
	 * scan the items until we find a match or exhaust our list
	 *
	 * Note: it's okay to use dlist_foreach here, even though we modify the
	 * dlist within the loop, because we don't continue the loop afterwards.
	 */
	dlist_foreach(iter, &cache->cc_lists)
	{
		cl = dlist_container(CatCList, cache_elem, iter.cur);

		if (cl->dead)
			continue;			/* ignore dead entries */