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von raredesign | Dez 3, 2019 | Allgemein | 0 Kommentare
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| Current Path : /var/www/web28/html/wp-content/plugins/matomo/app/core/Concurrency/ |
| Current File : //var/www/web28/html/wp-content/plugins/matomo/app/core/Concurrency/Lock.php |
<?php
/**
* Matomo - free/libre analytics platform
*
* @link https://matomo.org
* @license https://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
*/
namespace Piwik\Concurrency;
use Piwik\Common;
use Piwik\Date;
class Lock
{
public const MAX_KEY_LEN = 70;
public const DEFAULT_TTL = 60;
/**
* @var LockBackend
*/
private $backend;
private $namespace;
private $lockKey = null;
private $lockValue = null;
private $defaultTtl = null;
private $lastAcquireTime = null;
/**
* @param LockBackend $backend
* @param string $namespace
* @param int|null $defaultTtl defaults to {@link self::DEFAULT_TTL}
*/
public function __construct(\Piwik\Concurrency\LockBackend $backend, $namespace, $defaultTtl = null)
{
if (mb_strlen($namespace) > self::MAX_KEY_LEN - 32) {
// A longer namespace could be cut off for too long ids, so we don't support it
throw new \InvalidArgumentException('Lock namespace must be shorter than ' . (self::MAX_KEY_LEN - 32) . ' chars');
}
$this->backend = $backend;
$this->namespace = $namespace;
$this->lockKey = $this->namespace;
$this->defaultTtl = $defaultTtl ?: self::DEFAULT_TTL;
}
/**
* For BC only
*
* @todo remove in Matomo 6.0
* @deprecated use {@link reacquireLock()} instead.
* @return bool
*/
public function reexpireLock() : bool
{
return $this->reacquireLock();
}
/**
* Reacquires the current lock. The TTL will be extended if 1/4 of the TTL already passed by.
*
* @return bool
*/
public function reacquireLock() : bool
{
$timeBetweenReexpires = $this->defaultTtl - $this->defaultTtl / 4;
$now = Date::getNowTimestamp();
if (!empty($this->lastAcquireTime) && $now <= $this->lastAcquireTime + $timeBetweenReexpires) {
return false;
}
return $this->expireLock($this->defaultTtl);
}
public function getNumberOfAcquiredLocks() : int
{
return count($this->getAllAcquiredLockKeys());
}
/**
* Returns all acquired lock keys for the iniatially set namespace.
*
* @return string[]
*/
public function getAllAcquiredLockKeys() : array
{
return $this->backend->getKeysMatchingPattern($this->namespace . '*');
}
/**
* Executes and returns the result of the provided callback if a lock with given id can be acquired
* The method will automatically retry to acquire the lock up to 5 minutes.
*
* @param string $id
* @param callable $callback
* @return mixed
* @throws \Exception if lock couldn't be acquired within 5 minutes
*/
public function execute($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();
}
}
/**
* Acquires a lock with the given id using the provided TTL
*
* @param string $id
* @param int $ttlInSeconds
* @return bool
*/
public function acquireLock($id, $ttlInSeconds = 60)
{
$this->lockKey = $this->namespace . $id;
if (mb_strlen($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 and to ensure the namespaceis still containe
$md5Len = 32;
$this->lockKey = mb_substr($this->lockKey, 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;
$this->lastAcquireTime = Date::getNowTimestamp();
}
return !!$locked;
}
/**
* Return if the acquired lock is currently locked
*
* @return bool
*/
public function isLocked() : bool
{
if (!$this->lockValue) {
return false;
}
return $this->lockValue === $this->backend->get($this->lockKey);
}
/**
* Releases the acquired lock
*
* @return void
*/
public function unlock() : void
{
if ($this->lockValue) {
$this->backend->deleteIfKeyHasValue($this->lockKey, $this->lockValue);
$this->lockValue = null;
}
}
/**
* For BC only
*
* @deprecated use {@link extendLock()} instead.
* @todo remove in Matomo 6.0
* @return bool
*/
public function expireLock($ttlInSeconds) : bool
{
return $this->extendLock($ttlInSeconds);
}
public function extendLock($ttlInSeconds) : bool
{
if ($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->lastAcquireTime = 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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