Function SDW_check

src/jrd/sdw.cpp:269–328

void SDW_check(thread_db* tdbb)
{
/**************************************
 *
 *	S D W _ c h e c k
 *
 **************************************
 *
 * Functional description
 *	Check a shadow to see if it needs to
 *	be deleted or shut down.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* dbb = tdbb->getDatabase();

	SyncLockGuard guard(&dbb->dbb_shadow_sync, SYNC_EXCLUSIVE, "SDW_check");

	// first get rid of any shadows that need to be
	// deleted or shutdown; deleted shadows must also be shutdown

	// Check to see if there is a valid shadow in the shadow set,
	// if not then it is time to start an conditional shadow (if one has been defined).

	Shadow* next_shadow;
	for (Shadow* shadow = dbb->dbb_shadow; shadow; shadow = next_shadow)
	{
		next_shadow = shadow->sdw_next;

		if (shadow->sdw_flags & SDW_delete)
		{
			MET_delete_shadow(tdbb, shadow->sdw_number);
			gds__log("shadow %s deleted from database %s due to unavailability on write",
					 shadow->sdw_file->fil_string, dbb->dbb_filename.c_str());
		}

		// note that shutting down a shadow is destructive to the shadow block

		if (shadow->sdw_flags & SDW_shutdown)
			shutdown_shadow(shadow);
	}

	if (SDW_check_conditional(tdbb))
	{
		if (SDW_lck_update(tdbb, 0))
		{
			Lock temp_lock(tdbb, sizeof(SLONG), LCK_update_shadow);
			Lock* lock = &temp_lock;
			lock->setKey(-1);

			LCK_lock(tdbb, lock, LCK_EX, LCK_NO_WAIT);
			if (lock->lck_physical == LCK_EX)
			{
				SDW_notify(tdbb);
				SDW_dump_pages(tdbb);
				LCK_release(tdbb, lock);
			}
		}