Function InitCatCache

src/backend/utils/cache/catcache.c:763–855

#endif

CatCache *
InitCatCache(int id,
			 Oid reloid,
			 Oid indexoid,
			 int nkeys,
			 const int *key,
			 int nbuckets)
{
	CatCache   *cp;
	MemoryContext oldcxt;
	size_t		sz;
	int			i;

	/*
	 * nbuckets is the initial number of hash buckets to use in this catcache.
	 * It will be enlarged later if it becomes too full.
	 *
	 * nbuckets must be a power of two.  We check this via Assert rather than
	 * a full runtime check because the values will be coming from constant
	 * tables.
	 *
	 * If you're confused by the power-of-two check, see comments in
	 * bitmapset.c for an explanation.
	 */
	Assert(nbuckets > 0 && (nbuckets & -nbuckets) == nbuckets);

	/*
	 * first switch to the cache context so our allocations do not vanish at
	 * the end of a transaction
	 */
	if (!CacheMemoryContext)
		CreateCacheMemoryContext();

	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);

	/*
	 * if first time through, initialize the cache group header
	 */
	if (CacheHdr == NULL)
	{
		CacheHdr = (CatCacheHeader *) palloc(sizeof(CatCacheHeader));
		slist_init(&CacheHdr->ch_caches);
		CacheHdr->ch_ntup = 0;
#ifdef CATCACHE_STATS
		/* set up to dump stats at backend exit */
		on_proc_exit(CatCachePrintStats, 0);
#endif
	}

	/*
	 * Allocate a new cache structure, aligning to a cacheline boundary
	 *
	 * Note: we rely on zeroing to initialize all the dlist headers correctly
	 */
	sz = sizeof(CatCache) + PG_CACHE_LINE_SIZE;
	cp = (CatCache *) CACHELINEALIGN(palloc0(sz));
	cp->cc_bucket = palloc0(nbuckets * sizeof(dlist_head));