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);

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

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

class QueueHandler extends Daemon {

    var $_id = 'generic';

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

    function name() {
        return strtolower($this->class_name().'.'.$this->get_id());
    }
    
    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 run() {
        if (!$this->start()) {
            return false;
        }
        $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);
                    $notice->free();
                    unset($notice);
                    $notice = null;
                } else {
                    $this->log(LOG_WARNING, 'queue item for notice that does not exist');
                }
                $qi->delete();
                $qi->free();
                unset($qi);
                $this->idle(0);
            } else {
                $this->clear_old_claims();
                $this->idle(5);
            }    
        } while (true);
        if (!$this->finish()) {
            return false;
        }
        return 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);
        $qi->free();
        unset($qi);
    }
    
    function log($level, $msg) {
        common_log($level, $this->class_name() . ' ('. $this->get_id() .'): '.$msg);
    }
}