Function CatalogCacheCreateEntry

src/backend/utils/cache/catcache.c:1871–1972

* CatalogCacheCreateEntry * Create a new CatCTup entry, copying the given HeapTuple and other * supplied data into it. The new entry initially has refcount 0. */

 *		supplied data into it.  The new entry initially has refcount 0.
 */
static CatCTup *
CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp, Datum *arguments,
						uint32 hashValue, Index hashIndex,
						bool negative)
{
	CatCTup    *ct;
	HeapTuple	dtp;
	MemoryContext oldcxt;

	/* negative entries have no tuple associated */
	if (ntp)
	{
		int			i;

		Assert(!negative);

		/*
		 * If there are any out-of-line toasted fields in the tuple, expand
		 * them in-line.  This saves cycles during later use of the catcache
		 * entry, and also protects us against the possibility of the toast
		 * tuples being freed before we attempt to fetch them, in case of
		 * something using a slightly stale catcache entry.
		 */
		if (HeapTupleHasExternal(ntp))
			dtp = toast_flatten_tuple(ntp, cache->cc_tupdesc);
		else
			dtp = ntp;

		/* Allocate memory for CatCTup and the cached tuple in one go */
		oldcxt = MemoryContextSwitchTo(CacheMemoryContext);

		ct = (CatCTup *) palloc(sizeof(CatCTup) +
								MAXIMUM_ALIGNOF + dtp->t_len);
		ct->tuple.t_len = dtp->t_len;
		ct->tuple.t_self = dtp->t_self;
		ct->tuple.t_tableOid = dtp->t_tableOid;
		ct->tuple.t_data = (HeapTupleHeader)
			MAXALIGN(((char *) ct) + sizeof(CatCTup));
		/* copy tuple contents */
		memcpy((char *) ct->tuple.t_data,
			   (const char *) dtp->t_data,
			   dtp->t_len);
		MemoryContextSwitchTo(oldcxt);

		if (dtp != ntp)
			heap_freetuple(dtp);

		/* extract keys - they'll point into the tuple if not by-value */
		for (i = 0; i < cache->cc_nkeys; i++)
		{
			Datum		atp;
			bool		isnull;

			atp = heap_getattr(&ct->tuple,
							   cache->cc_keyno[i],
							   cache->cc_tupdesc,
							   &isnull);
			Assert(!isnull);