Function buf_extend

src/backend/access/bitmap/bitmapinsert.c:1980–2010

* buf_extend() -- Enlarge the memory allocated to a buffer. * Return how many bytes are added to the buffer. */

 * Return how many bytes are added to the buffer.
 */
static uint16
buf_extend(BMTIDBuffer *buf)
{
	uint16 bytes;
	uint16 size;
	
	if (buf->num_cwords > 0 && buf->curword < buf->num_cwords - 1)
		return 0; /* already large enough */

	if(buf->num_cwords == 0)
	{
		size = BUF_INIT_WORDS;
		buf->cwords = (BM_HRL_WORD *)
			palloc0(BUF_INIT_WORDS * sizeof(BM_HRL_WORD));
		buf->last_tids = (uint64 *)palloc0(BUF_INIT_WORDS * sizeof(uint64));
		bytes = BUF_INIT_WORDS * sizeof(BM_HRL_WORD) +
			BUF_INIT_WORDS * sizeof(uint64);
	}
	else
	{
		size = buf->num_cwords;
		buf->cwords = repalloc(buf->cwords, 2 * size * sizeof(BM_HRL_WORD));
		MemSet(buf->cwords + size, 0, size * sizeof(BM_HRL_WORD));
		buf->last_tids = repalloc(buf->last_tids, 2 * size * sizeof(uint64));
		MemSet(buf->last_tids + size, 0, size * sizeof(uint64));
		bytes = 2 * size * sizeof(BM_HRL_WORD) +
			2 * size * sizeof(uint64);
	}
	buf->num_cwords += size;
	return bytes;
}

/*
 * Spill some HRL compressed tids to disk