gnu-social/lib/queuehandler.php

<?php
/*
 * Laconica - a distributed open-source microblogging tool
 * Copyright (C) 2008, Controlez-Vous, Inc.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

define('CLAIM_TIMEOUT', 1200);

class QueueHandler {

	var $_id = 'generic';

	function QueueHandler($id=NULL) {
		if ($id) {
			$this->set_id($id);
		}
	}
	
	function class_name() {
		return ucfirst($this->transport()) . 'Handler';
	}
	
	function get_id() {
		return $this->_id;
	}

	function set_id($id) {
		$this->_id = $id;
	}
	
	function transport() {
		return NULL;
	}
	
	function start() {
	}
	
	function finish() {
	}

	function handle_notice($notice) {
		return true;
	}
	
	function handle_queue() {
		$this->log(LOG_INFO, 'checking for queued notices');
		$transport = $this->transport();
		do {
			$qi = Queue_item::top($transport);
			if ($qi) {
				$this->log(LOG_INFO, 'Got item enqueued '.common_exact_date($qi->created));
				$notice = Notice::staticGet($qi->notice_id);
				if ($notice) {
					$this->log(LOG_INFO, 'broadcasting notice ID = ' . $notice->id);
					# XXX: what to do if broadcast fails?
					$result = $this->handle_notice($notice);
					if (!$result) {
						$this->log(LOG_WARNING, 'Failed broadcast for notice ID = ' . $notice->id);
						$orig = $qi;
						$qi->claimed = NULL;
						$qi->update($orig);
						$this->log(LOG_WARNING, 'Abandoned claim for notice ID = ' . $notice->id);
						continue;
					}
					$this->log(LOG_INFO, 'finished broadcasting notice ID = ' . $notice->id);
					$notice = NULL;
				} else {
					$this->log(LOG_WARNING, 'queue item for notice that does not exist');
				}
				$qi->delete();
				$this->idle(0);
			} else {
				$this->clear_old_claims();
				$this->idle(5);
			}	
		} while (true);
	}

	function idle($timeout=0) {
		if ($timeout>0) {
			sleep($timeout);
		}
	}
	
	function clear_old_claims() {
		$qi = new Queue_item();
		$qi->transport = $this->transport();
		$qi->whereAdd('now() - claimed > '.CLAIM_TIMEOUT);
		$qi->update(DB_DATAOBJECT_WHEREADD_ONLY);
	}
	
	function log($level, $msg) {
		common_log($level, $this->class_name() . ' ('. $this->get_id() .'): '.$msg);
	}
}