Function blocking_ast_bdb

src/jrd/cch.cpp:2592–2647

static int blocking_ast_bdb(void* ast_object)
{
/**************************************
 *
 *	b l o c k i n g _ a s t _ b d b
 *
 **************************************
 *
 * Functional description
 *	Blocking AST for buffer control blocks.  This is called at
 *	AST (signal) level to indicate that a lock is blocking another
 *	process.  If the BufferDesc* is in use, set a flag indicating that the
 *	lock is blocking and return.  When the BufferDesc is released at normal
 *	level the lock will be down graded.  If the BufferDesc* is not in use,
 *	write the page if dirty then downgrade lock.  Things would be
 *	much hairier if UNIX supported asynchronous IO, but it doesn't.
 *	WHEW!
 *
 **************************************/
	// CVC: I assume we need the function call but not the variable.
	/*ThreadSync* const thread = */ThreadSync::getThread("blocking_ast_bdb");

	BufferDesc* const bdb = static_cast<BufferDesc*>(ast_object);

	try
	{
		BufferControl* const bcb = bdb->bdb_bcb;
		fb_assert(!(bcb->bcb_flags & BCB_exclusive));

		Database* const dbb = bcb->bcb_database;
		fb_assert(dbb);

		AsyncContextHolder tdbb(dbb, FB_FUNCTION);

		// Do some fancy footwork to make sure that pages are
		// not removed from the btc tree at AST level. Then
		// restore the flag to whatever it was before.

		const bool keep_pages = (bcb->bcb_flags & BCB_keep_pages) != 0;
		bcb->bcb_flags |= BCB_keep_pages;

		down_grade(tdbb, bdb);

		if (!keep_pages)
			bcb->bcb_flags &= ~BCB_keep_pages;

		if (tdbb->tdbb_status_vector->getState() & IStatus::STATE_ERRORS)
			iscDbLogStatus(dbb->dbb_filename.c_str(), tdbb->tdbb_status_vector);
	}
	catch (const Firebird::Exception&)
	{
		return -1;
	} // no-op

    return 0;
}