Function CCH_fetch_lock

src/jrd/cch.cpp:830–897

LockState CCH_fetch_lock(thread_db* tdbb, WIN* window, int lock_type, int wait, SCHAR page_type)
{
/**************************************
 *
 *	C C H _ f e t c h _ l o c k
 *
 **************************************
 *
 * Functional description
 *	Fetch a latch and lock for a specific page.
 *
 * input
 *
 *	wait:
 *	LCK_WAIT (1)	=> Wait as long a necessary to get the lock.
 *		This can cause deadlocks of course.
 *
 *	LCK_NO_WAIT (0)	=>
 *		If the latch can't be acquired immediately, give up and return -2.
 *		If the lock can't be acquired immediately, give up and return -1.
 *
 *	<negative number>	=> Lock (latch) timeout interval in seconds.
 *
 * return
 *	0:	fetch & lock were successful, page doesn't need to be read.
 *	1:	fetch & lock were successful, page needs to be read from disk.
 *	-1:	lock timed out, fetch failed.
 *	-2:	latch timed out, fetch failed, lock not attempted.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* const dbb = tdbb->getDatabase();
	BufferControl* const bcb = dbb->dbb_bcb;

	// if there has been a shadow added recently, go out and
	// find it before we grant any more write locks

	if (dbb->dbb_ast_flags & DBB_get_shadows)
		SDW_get_shadows(tdbb);

	// Look for the page in the cache.

	BufferDesc* bdb = get_buffer(tdbb, window->win_page,
		((lock_type >= LCK_write) ? SYNC_EXCLUSIVE : SYNC_SHARED), wait);

	if (wait != 1 && bdb == 0)
		return lsLatchTimeout; // latch timeout

	fb_assert(bdb->bdb_page == window->win_page);
	if (!(bdb->bdb_flags & BDB_read_pending))
		fb_assert(bdb->bdb_buffer->pag_pageno == window->win_page.getPageNum());
	else
		fb_assert(bdb->ourExclusiveLock() || bdb->bdb_lock && bdb->bdb_lock->lck_logical == LCK_none);

	if (lock_type >= LCK_write)
		bdb->bdb_flags |= BDB_writer;

	window->win_bdb = bdb;