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<?php
/**
* Matomo - free/libre analytics platform
*
* @link https://matomo.org
* @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
*
*/
namespace Piwik\Concurrency;
use Piwik\ArchiveProcessor\ArchivingStatus;
use Piwik\Common;
use Piwik\Date;
class Lock
{
const MAX_KEY_LEN = 70;
const DEFAULT_TTL = 60;
/**
* @var LockBackend
*/
private $backend;
private $lockKeyStart;
private $lockKey = null;
private $lockValue = null;
private $defaultTtl = null;
private $lastExpireTime = null;
public function __construct(LockBackend $backend, $lockKeyStart, $defaultTtl = null)
{
$this->backend = $backend;
$this->lockKeyStart = $lockKeyStart;
$this->lockKey = $this->lockKeyStart;
$this->defaultTtl = $defaultTtl ?: self::DEFAULT_TTL;
}
public function reexpireLock()
{
$timeBetweenReexpires = $this->defaultTtl - ($this->defaultTtl / 4);
$now = Date::getNowTimestamp();
if (!empty($this->lastExpireTime) &&
$now <= $this->lastExpireTime + $timeBetweenReexpires
) {
return false;
}
return $this->expireLock($this->defaultTtl);
}
public function getNumberOfAcquiredLocks()
{
return count($this->getAllAcquiredLockKeys());
}
public function getAllAcquiredLockKeys()
{
return $this->backend->getKeysMatchingPattern($this->lockKeyStart . '*');
}
public function execute($id, $callback)
{
$i = 0;
while (!$this->acquireLock($id)) {
$i++;
usleep( 100 * 1000 ); // 100ms
if ($i > 50) { // give up after 5seconds (50 * 100ms)
throw new \Exception('Could not get the lock for ID: ' . $id);
}
};
try {
return $callback();
} finally {
$this->unlock();
}
}
public function acquireLock($id, $ttlInSeconds = 60)
{
$this->lockKey = $this->lockKeyStart . $id;
if (Common::mb_strlen($this->lockKey) > self::MAX_KEY_LEN) {
// Lock key might be too long for DB column, so we hash it but leave the start of the original as well
// to make it more readable
$md5Len = 32;
$this->lockKey = Common::mb_substr($id, 0, self::MAX_KEY_LEN - $md5Len - 1) . md5($id);
}
$lockValue = substr(Common::generateUniqId(), 0, 12);
$locked = $this->backend->setIfNotExists($this->lockKey, $lockValue, $ttlInSeconds);
if ($locked) {
$this->lockValue = $lockValue;
$this->ttlUsed = $ttlInSeconds;
$this->lastExpireTime = Date::getNowTimestamp();
}
return $locked;
}
public function isLocked()
{
if (!$this->lockValue) {
return false;
}
return $this->lockValue === $this->backend->get($this->lockKey);
}
public function unlock()
{
if ($this->lockValue) {
$this->backend->deleteIfKeyHasValue($this->lockKey, $this->lockValue);
$this->lockValue = null;
}
}
public function expireLock($ttlInSeconds)
{
if ($ttlInSeconds > 0) {
if ($this->lockValue) {
$success = $this->backend->expireIfKeyHasValue($this->lockKey, $this->lockValue, $ttlInSeconds);
if (!$success) {
$value = $this->backend->get($this->lockKey);
$message = sprintf('Failed to expire key %s (%s / %s).', $this->lockKey, $this->lockValue, (string)$value);
if ($value === false) {
Common::printDebug($message . ' It seems like the key already expired as it no longer exists.');
} elseif (!empty($value) && $value == $this->lockValue) {
Common::printDebug($message . ' We still have the lock but for some reason it did not expire.');
} elseif (!empty($value)) {
Common::printDebug($message . ' This lock has been acquired by another process/server.');
} else {
Common::printDebug($message . ' Failed to expire key.');
}
return false;
}
$this->lastExpireTime = Date::getNowTimestamp();
return true;
} else {
Common::printDebug('Lock is not acquired, cannot update expiration.');
}
} else {
Common::printDebug('Provided TTL ' . $ttlInSeconds . ' is in valid in Lock::expireLock().');
}
return false;
}
}
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