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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@status.net>
* @author Brion Vibber <brion@status.net>
* @copyright 2009-2010 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
{
/**
* Saves a notice object reference into the queue item table.
* @return boolean true on success
* @throws ServerException on failure
*/
public 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');
}
$this->stats('enqueued', $queue);
return true;
}
/**
* Poll every minute for new events during idle periods.
* We'll look in more often when there's data available.
*
* @return int seconds
*/
public function pollInterval()
{
return 60;
}
/**
* Run a polling cycle during idle processing in the input loop.
* @return boolean true if we had a hit
*/
public function poll()
{
$this->_log(LOG_DEBUG, 'Checking for notices...');
$item = $this->_nextItem();
if ($item === false) {
$this->_log(LOG_DEBUG, 'No notices waiting; idling.');
return false;
}
if ($item === true) {
// We dequeued an entry for a deleted or invalid notice.
// Consider it a hit for poll rate purposes.
return true;
}
list($queue, $notice) = $item;
$this->_log(LOG_INFO, 'Got notice '. $notice->id . ' for transport ' . $queue);
// Yay! Got one!
$handler = $this->getHandler($queue);
if ($handler) {
if ($handler->handle_notice($notice)) {
$this->_log(LOG_INFO, "[$queue:notice $notice->id] Successfully handled notice");
$this->_done($notice, $queue);
} else {
$this->_log(LOG_INFO, "[$queue:notice $notice->id] Failed to handle notice");
$this->_fail($notice, $queue);
}
} else {
$this->_log(LOG_INFO, "[$queue:notice $notice->id] No handler for queue $queue; discarding.");
$this->_done($notice, $queue);
}
return true;
}
/**
* Pop the oldest unclaimed item off the queue set and claim it.
*
* @return mixed false if no items; true if bogus hit; otherwise array(string, Notice)
* giving the queue transport name.
*/
protected function _nextItem()
{
$start = time();
$result = null;
$qi = Queue_item::top();
if (empty($qi)) {
return false;
}
$queue = $qi->transport;
$notice = Notice::staticGet('id', $qi->notice_id);
if (empty($notice)) {
$this->_log(LOG_INFO, "[$queue:notice $notice->id] dequeued non-existent notice");
$qi->delete();
return true;
}
$result = $notice;
return array($queue, $notice);
}
/**
* Delete our claimed item from the queue after successful processing.
*
* @param Notice $object
* @param string $queue
*/
protected function _done($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)) {
$this->_log(LOG_INFO, "[$queue:notice $notice->id] Cannot find queue item");
} else {
if (empty($qi->claimed)) {
$this->_log(LOG_WARNING, "[$queue:notice $notice->id] Reluctantly releasing unclaimed queue item");
}
$qi->delete();
$qi->free();
}
$this->_log(LOG_INFO, "[$queue:notice $notice->id] done with item");
$this->stats('handled', $queue);
$notice->free();
}
/**
* Free our claimed queue item for later reprocessing in case of
* temporary failure.
*
* @param Notice $object
* @param string $queue
*/
protected function _fail($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)) {
$this->_log(LOG_INFO, "[$queue:notice $notice->id] Cannot find queue item");
} else {
if (empty($qi->claimed)) {
$this->_log(LOG_WARNING, "[$queue:notice $notice->id] Ignoring failure for unclaimed queue item");
} else {
$orig = clone($qi);
$qi->claimed = null;
$qi->update($orig);
$qi = null;
}
}
$this->_log(LOG_INFO, "[$queue:notice $notice->id] done with queue item");
$this->stats('error', $queue);
$notice->free();
}
protected function _log($level, $msg)
{
common_log($level, 'DBQueueManager: '.$msg);
}
}
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