gnu-social/lib/queuehandler.php

<?php
/*
 * StatusNet - the distributed open-source microblogging tool
 * Copyright (C) 2008, 2009, StatusNet, 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/>.
 */

if (!defined('STATUSNET') && !defined('LACONICA')) { exit(1); }

require_once(INSTALLDIR.'/lib/daemon.php');
require_once(INSTALLDIR.'/classes/Queue_item.php');
require_once(INSTALLDIR.'/classes/Notice.php');

define('CLAIM_TIMEOUT', 1200);
define('QUEUE_HANDLER_MISS_IDLE', 10);
define('QUEUE_HANDLER_HIT_IDLE', 0);

/**
 * Base class for queue handlers.
 *
 * As extensions of the Daemon class, each queue handler has the ability
 * to launch itself in the background, at which point it'll pass control
 * to the configured QueueManager class to poll for updates.
 *
 * Subclasses must override at least the following methods:
 * - transport
 * - start
 * - finish
 * - handle_notice
 *
 * Some subclasses will also want to override the idle handler:
 * - idle
 */
class QueueHandler extends Daemon
{

    function __construct($id=null, $daemonize=true)
    {
        parent::__construct($daemonize);

        if ($id) {
            $this->set_id($id);
        }
    }

    /**
     * How many seconds a polling-based queue manager should wait between
     * checks for new items to handle.
     *
     * Defaults to 60 seconds; override to speed up or slow down.
     *
     * @return int timeout in seconds
     */
    function timeout()
    {
        return 60;
    }

    function class_name()
    {
        return ucfirst($this->transport()) . 'Handler';
    }

    function name()
    {
        return strtolower($this->class_name().'.'.$this->get_id());
    }

    /**
     * Return transport keyword which identifies items this queue handler
     * services; must be defined for all subclasses.
     *
     * Must be 8 characters or less to fit in the queue_item database.
     * ex "email", "jabber", "sms", "irc", ...
     *
     * @return string
     */
    function transport()
    {
        return null;
    }

    /**
     * Initialization, run when the queue handler starts.
     * If this function indicates failure, the handler run will be aborted.
     *
     * @fixme run() will abort if this does not return true,
     *        but some subclasses do not bother.
     * @return boolean true on success, false on failure
     */
    function start()
    {
    }

    /**
     * Cleanup, run when the queue handler ends.
     * If this function indicates failure, a warning will be logged.
     *
     * @fixme run() will throw warnings if this does not return true,
     *        but many subclasses do not bother.
     * @return boolean true on success, false on failure
     */
    function finish()
    {
    }

    /**
     * Here's the meat of your queue handler -- you're handed a Notice
     * object, which you may do as you will with.
     *
     * If this function indicates failure, a warning will be logged
     * and the item is placed back in the queue to be re-run.
     *
     * @param Notice $notice
     * @return boolean true on success, false on failure
     */
    function handle_notice($notice)
    {
        return true;
    }

    /**
     * Setup and start of run loop for this queue handler as a daemon.
     * Most of the heavy lifting is passed on to the QueueManager's service()
     * method, which passes control back to our handle_notice() method for
     * each notice that comes in on the queue.
     *
     * Most of the time this will not need to be overridden in a subclass.
     *
     * @return boolean true on success, false on failure
     */
    function run()
    {
        if (!$this->start()) {
            $this->log(LOG_WARNING, 'failed to start');
            return false;
        }

        $this->log(LOG_INFO, 'checking for queued notices');

        $queue   = $this->transport();
        $timeout = $this->timeout();

        $qm = QueueManager::get();

        $qm->service($queue, $this);

        $this->log(LOG_INFO, 'finished servicing the queue');

        if (!$this->finish()) {
            $this->log(LOG_WARNING, 'failed to clean up');
            return false;
        }

        $this->log(LOG_INFO, 'terminating normally');

        return true;
    }

    /**
     * Called by QueueHandler after each handled item or empty polling cycle.
     * This is a good time to e.g. service your XMPP connection.
     *
     * Does not need to be overridden if there's no maintenance to do.
     *
     * @param int $timeout seconds to sleep if there's nothing to do
     */
    function idle($timeout=0)
    {
        if ($timeout > 0) {
            sleep($timeout);
        }
    }

    function log($level, $msg)
    {
        common_log($level, $this->class_name() . ' ('. $this->get_id() .'): '.$msg);
    }

    function getSockets()
    {
        return array();
    }
}