Function get_related

src/jrd/cch.cpp:4020–4068

static int get_related(BufferDesc* bdb, PagesArray &lowPages, int limit, const ULONG mark)
{
/**************************************
 *
 *	g e t _ r e l a t e d
 *
 **************************************
 *
 * Functional description
 *  Recursively walk low part of precedence graph of given buffer and put
 *  low pages numbers into array.
 *
 **************************************/
	BufferControl* bcb = bdb->bdb_bcb;
	fb_assert(bcb->bcb_syncPrecedence.ourExclusiveLock());

	const struct que* base = &bdb->bdb_lower;
	for (const struct que* que_inst = base->que_forward; que_inst != base;
		 que_inst = que_inst->que_forward)
	{
		const Precedence* precedence = BLOCK(que_inst, Precedence, pre_lower);
		if (precedence->pre_flags & PRE_cleared)
			continue;

		BufferDesc* low = precedence->pre_low;
		if (low->bdb_prec_walk_mark == mark)
			continue;

		if (!--limit)
			return 0;

		const SLONG lowPage = low->bdb_page.getPageNum();
		FB_SIZE_T pos;
		if (!lowPages.find(lowPage, pos))
			lowPages.insert(pos, lowPage);

		if (QUE_NOT_EMPTY(low->bdb_lower))
		{
			limit = get_related(low, lowPages, limit, mark);
			if (!limit)
				return 0;
		}
		else
			low->bdb_prec_walk_mark = mark;
	}

	bdb->bdb_prec_walk_mark = mark;
	return limit;
}


static LockState lock_buffer(thread_db* tdbb, BufferDesc* bdb, const SSHORT wait,