friendica/src/Util/Lock/DatabaseLockDriver.php

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<?php
2018-06-26 23:28:07 +02:00
namespace Friendica\Util\Lock;
use dba;
use Friendica\Database\DBM;
/**
* Locking driver that stores the locks in the database
*/
class DatabaseLockDriver implements ILockDriver
{
/**
* @brief Sets a lock for a given name
*
* @param string $key The Name of the lock
* @param integer $timeout Seconds until we give up
*
* @return boolean Was the lock successful?
*/
public function acquireLock($key, $timeout = 120)
{
$got_lock = false;
$start = time();
do {
dba::lock('locks');
$lock = dba::selectFirst('locks', ['locked', 'pid'], ['name' => $key]);
if (DBM::is_result($lock)) {
if ($lock['locked']) {
// When the process id isn't used anymore, we can safely claim the lock for us.
if (!posix_kill($lock['pid'], 0)) {
$lock['locked'] = false;
}
// We want to lock something that was already locked by us? So we got the lock.
if ($lock['pid'] == getmypid()) {
$got_lock = true;
}
}
if (!$lock['locked']) {
dba::update('locks', ['locked' => true, 'pid' => getmypid()], ['name' => $key]);
$got_lock = true;
}
} elseif (!DBM::is_result($lock)) {
dba::insert('locks', ['name' => $key, 'locked' => true, 'pid' => getmypid()]);
$got_lock = true;
}
dba::unlock();
if (!$got_lock && ($timeout > 0)) {
usleep(rand(100000, 2000000));
}
} while (!$got_lock && ((time() - $start) < $timeout));
return $got_lock;
}
/**
* @brief Removes a lock if it was set by us
*
* @param string $key Name of the lock
*
* @return mixed
*/
public function releaseLock($key)
{
dba::update('locks', ['locked' => false, 'pid' => 0], ['name' => $key, 'pid' => getmypid()]);
return;
}
/**
* @brief Removes all lock that were set by us
*
* @return void
*/
public function releaseAll()
{
dba::update('locks', ['locked' => false, 'pid' => 0], ['pid' => getmypid()]);
}
}