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<?php
/**
* StatusNet, the distributed open-source microblogging tool
*
* Simple-minded queue manager for storing items in the database
*
* PHP version 5
*
* LICENCE: 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/>.
*
* @category QueueManager
* @package StatusNet
* @author Evan Prodromou <evan@controlyourself.ca>
* @copyright 2009 StatusNet, Inc.
* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
* @link http://status.net/
*/
class DBQueueManager extends QueueManager
{
var $qis = array();
function enqueue($object, $queue)
{
$notice = $object;
$qi = new Queue_item();
$qi->notice_id = $notice->id;
$qi->transport = $queue;
$qi->created = $notice->created;
$result = $qi->insert();
if (!$result) {
common_log_db_error($qi, 'INSERT', __FILE__);
throw new ServerException('DB error inserting queue item');
}
return true;
}
function service($queue, $handler)
{
while (true) {
$this->_log(LOG_DEBUG, 'Checking for notices...');
$timeout = $handler->timeout();
$notice = $this->_nextItem($queue, $timeout);
if (empty($notice)) {
$this->_log(LOG_DEBUG, 'No notices waiting; idling.');
// Nothing in the queue. Do you
// have other tasks, like servicing your
// XMPP connection, to do?
$handler->idle(QUEUE_HANDLER_MISS_IDLE);
} else {
$this->_log(LOG_INFO, 'Got notice '. $notice->id);
// Yay! Got one!
if ($handler->handle_notice($notice)) {
$this->_log(LOG_INFO, 'Successfully handled notice '. $notice->id);
$this->_done($notice, $queue);
} else {
$this->_log(LOG_INFO, 'Failed to handle notice '. $notice->id);
$this->_fail($notice, $queue);
}
// Chance to e.g. service your XMPP connection
$this->_log(LOG_DEBUG, 'Idling after success.');
$handler->idle(QUEUE_HANDLER_HIT_IDLE);
}
// XXX: when do we give up?
}
}
function _nextItem($queue, $timeout=null)
{
$start = time();
$result = null;
$sleeptime = 1;
do {
$qi = Queue_item::top($queue);
if (empty($qi)) {
$this->_log(LOG_DEBUG, "No new queue items, sleeping $sleeptime seconds.");
sleep($sleeptime);
$sleeptime *= 2;
} else {
$notice = Notice::staticGet('id', $qi->notice_id);
if (!empty($notice)) {
$result = $notice;
} else {
$this->_log(LOG_INFO, 'dequeued non-existent notice ' . $notice->id);
$qi->delete();
$qi->free();
$qi = null;
}
$sleeptime = 1;
}
} while (empty($result) && (is_null($timeout) || (time() - $start) < $timeout));
return $result;
}
function _done($object, $queue)
{
// XXX: right now, we only handle notices
$notice = $object;
$qi = Queue_item::pkeyGet(array('notice_id' => $notice->id,
'transport' => $queue));
if (empty($qi)) {
$this->_log(LOG_INFO, 'Cannot find queue item for notice '.$notice->id.', queue '.$queue);
} else {
if (empty($qi->claimed)) {
$this->_log(LOG_WARNING, 'Reluctantly releasing unclaimed queue item '.
'for '.$notice->id.', queue '.$queue);
}
$qi->delete();
$qi->free();
$qi = null;
}
$this->_log(LOG_INFO, 'done with notice ID = ' . $notice->id);
$notice->free();
$notice = null;
}
function _fail($object, $queue)
{
// XXX: right now, we only handle notices
$notice = $object;
$qi = Queue_item::pkeyGet(array('notice_id' => $notice->id,
'transport' => $queue));
if (empty($qi)) {
$this->_log(LOG_INFO, 'Cannot find queue item for notice '.$notice->id.', queue '.$queue);
} else {
if (empty($qi->claimed)) {
$this->_log(LOG_WARNING, 'Ignoring failure for unclaimed queue item '.
'for '.$notice->id.', queue '.$queue);
} else {
$orig = clone($qi);
$qi->claimed = null;
$qi->update($orig);
$qi = null;
}
}
$this->_log(LOG_INFO, 'done with notice ID = ' . $notice->id);
$notice->free();
$notice = null;
}
function _log($level, $msg)
{
common_log($level, 'DBQueueManager: '.$msg);
}
}
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