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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 an object into the queue item table.
* @return boolean true on success
* @throws ServerException on failure
*/
public function enqueue($object, $queue)
{
$qi = new Queue_item();
$qi->frame = serialize($object);
$qi->transport = $queue;
$qi->created = common_sql_now();
$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 queued objects...');
$qi = $this->_nextItem();
if ($qi === false) {
$this->_log(LOG_DEBUG, 'No queue items waiting; idling.');
return false;
}
if ($qi === true) {
// We dequeued an entry for a deleted or invalid object.
// Consider it a hit for poll rate purposes.
return true;
}
$queue = $qi->transport;
$object = unserialize($qi->frame);
$this->_log(LOG_INFO, 'Got item id=' . $qi->id . ' for transport ' . $queue);
// Yay! Got one!
$handler = $this->getHandler($queue);
if ($handler) {
if ($handler->handle($object)) {
$this->_log(LOG_INFO, "[$queue] Successfully handled object");
$this->_done($qi);
} else {
$this->_log(LOG_INFO, "[$queue] Failed to handle object");
$this->_fail($qi);
}
} else {
$this->_log(LOG_INFO, "[$queue] No handler for queue $queue; discarding.");
$this->_done($qi);
}
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 Queue_item
*/
protected function _nextItem()
{
$start = time();
$result = null;
$qi = Queue_item::top();
if (empty($qi)) {
return false;
}
return $qi;
}
/**
* Delete our claimed item from the queue after successful processing.
*
* @param QueueItem $qi
*/
protected function _done($qi)
{
if (empty($qi)) {
$this->_log(LOG_INFO, "_done passed an empty queue item");
} else {
if (empty($qi->claimed)) {
$this->_log(LOG_WARNING, "Reluctantly releasing unclaimed queue item");
}
$qi->delete();
$qi->free();
}
$this->_log(LOG_INFO, "done with item");
}
/**
* Free our claimed queue item for later reprocessing in case of
* temporary failure.
*
* @param QueueItem $qi
*/
protected function _fail($qi)
{
if (empty($qi)) {
$this->_log(LOG_INFO, "_fail passed an empty queue item");
} else {
if (empty($qi->claimed)) {
$this->_log(LOG_WARNING, "Ignoring failure for unclaimed queue item");
} else {
$orig = clone($qi);
$qi->claimed = null;
$qi->update($orig);
$qi = null;
}
}
$this->_log(LOG_INFO, "done with queue item");
}
protected function _log($level, $msg)
{
common_log($level, 'DBQueueManager: '.$msg);
}
}
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