Friendica Communications Platform (please note that this is a clone of the repository at github, issues are handled there) https://friendi.ca
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<?php
namespace Friendica\Core\Lock;
use Friendica\Core\Cache\Cache;
use Friendica\Database\Database;
use Friendica\Util\DateTimeFormat;
/**
* Locking driver that stores the locks in the database
*/
class DatabaseLock extends Lock
{
/**
* The current ID of the process
*
* @var int
*/
private $pid;
/**
* @var Database The database connection of Friendica
*/
private $dba;
/**
* @param null|int $pid The Id of the current process (null means determine automatically)
*/
public function __construct(Database $dba, $pid = null)
{
$this->dba = $dba;
$this->pid = isset($pid) ? $pid : getmypid();
}
/**
* (@inheritdoc)
*/
public function acquireLock($key, $timeout = 120, $ttl = Cache::FIVE_MINUTES)
{
$got_lock = false;
$start = time();
do {
$this->dba->lock('locks');
$lock = $this->dba->selectFirst('locks', ['locked', 'pid'], ['`name` = ? AND `expires` >= ?', $key, DateTimeFormat::utcNow()]);
if ($this->dba->isResult($lock)) {
if ($lock['locked']) {
// We want to lock something that was already locked by us? So we got the lock.
if ($lock['pid'] == $this->pid) {
$got_lock = true;
}
}
if (!$lock['locked']) {
$this->dba->update('locks', ['locked' => true, 'pid' => $this->pid, 'expires' => DateTimeFormat::utc('now + ' . $ttl . 'seconds')], ['name' => $key]);
$got_lock = true;
}
} else {
$this->dba->insert('locks', ['name' => $key, 'locked' => true, 'pid' => $this->pid, 'expires' => DateTimeFormat::utc('now + ' . $ttl . 'seconds')]);
$got_lock = true;
$this->markAcquire($key);
}
$this->dba->unlock();
if (!$got_lock && ($timeout > 0)) {
usleep(rand(100000, 2000000));
}
} while (!$got_lock && ((time() - $start) < $timeout));
return $got_lock;
}
/**
* (@inheritdoc)
*/
public function releaseLock($key, $override = false)
{
if ($override) {
$where = ['name' => $key];
} else {
$where = ['name' => $key, 'pid' => $this->pid];
}
if ($this->dba->exists('locks', $where)) {
$return = $this->dba->delete('locks', $where);
} else {
$return = false;
}
$this->markRelease($key);
return $return;
}
/**
* (@inheritdoc)
*/
public function releaseAll($override = false)
{
$success = parent::releaseAll($override);
if ($override) {
$where = ['1 = 1'];
} else {
$where = ['pid' => $this->pid];
}
$return = $this->dba->delete('locks', $where);
$this->acquiredLocks = [];
return $return && $success;
}
/**
* (@inheritdoc)
*/
public function isLocked($key)
{
$lock = $this->dba->selectFirst('locks', ['locked'], ['`name` = ? AND `expires` >= ?', $key, DateTimeFormat::utcNow()]);
if ($this->dba->isResult($lock)) {
return $lock['locked'] !== false;
} else {
return false;
}
}
/**
* {@inheritDoc}
*/
public function getName()
{
return self::TYPE_DATABASE;
}
/**
* {@inheritDoc}
*/
public function getLocks(string $prefix = '')
{
if (empty($prefix)) {
$where = ['`expires` >= ?', DateTimeFormat::utcNow()];
} else {
$where = ['`expires` >= ? AND `name` LIKE CONCAT(?, \'%\')', DateTimeFormat::utcNow(), $prefix];
}
$stmt = $this->dba->select('locks', ['name'], $where);
$keys = [];
while ($key = $this->dba->fetch($stmt)) {
array_push($keys, $key['name']);
}
$this->dba->close($stmt);
return $keys;
}
}