friendica-github/src/Core/Lock/SemaphoreLock.php
2020-02-09 15:45:36 +01:00

144 lines
3.1 KiB
PHP

<?php
/**
* @copyright Copyright (C) 2020, Friendica
*
* @license GNU AGPL version 3 or any later version
*
* 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 <https://www.gnu.org/licenses/>.
*
*/
namespace Friendica\Core\Lock;
use Friendica\Core\BaseLock;
use Friendica\Core\Cache\Duration;
class SemaphoreLock extends BaseLock
{
private static $semaphore = [];
public function __construct()
{
if (!function_exists('sem_get')) {
throw new \Exception('Semaphore lock not supported');
}
}
/**
* (@inheritdoc)
*/
private static function semaphoreKey($key)
{
$success = true;
$temp = get_temppath();
$file = $temp . '/' . $key . '.sem';
if (!file_exists($file)) {
$success = !empty(file_put_contents($file, $key));
}
return $success ? ftok($file, 'f') : false;
}
/**
* (@inheritdoc)
*/
public function acquire($key, $timeout = 120, $ttl = Duration::FIVE_MINUTES)
{
self::$semaphore[$key] = sem_get(self::semaphoreKey($key));
if (!empty(self::$semaphore[$key])) {
if ((bool)sem_acquire(self::$semaphore[$key], ($timeout === 0))) {
$this->markAcquire($key);
return true;
}
}
return false;
}
/**
* (@inheritdoc)
*
* @param bool $override not necessary parameter for semaphore locks since the lock lives as long as the execution
* of the using function
*/
public function release($key, $override = false)
{
$success = false;
if (!empty(self::$semaphore[$key])) {
try {
$success = @sem_release(self::$semaphore[$key]);
unset(self::$semaphore[$key]);
$this->markRelease($key);
} catch (\Exception $exception) {
$success = false;
}
}
return $success;
}
/**
* (@inheritdoc)
*/
public function isLocked($key)
{
return isset(self::$semaphore[$key]);
}
/**
* {@inheritDoc}
*/
public function getName()
{
return Type::SEMAPHORE;
}
/**
* {@inheritDoc}
*/
public function getLocks(string $prefix = '')
{
// We can just return our own semaphore keys, since we don't know
// the state of other semaphores, even if the .sem files exists
$keys = array_keys(self::$semaphore);
if (empty($prefix)) {
return $keys;
} else {
$result = [];
foreach ($keys as $key) {
if (strpos($key, $prefix) === 0) {
array_push($result, $key);
}
}
return $result;
}
}
/**
* {@inheritDoc}
*/
public function releaseAll($override = false)
{
// Semaphores are just alive during a run, so there is no need to release
// You can just release your own locks
return parent::releaseAll($override);
}
}