ResourceMutex.php

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<?php
 
/*
 * This file is part of the TYPO3 CMS project.
 *
 * It is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, either version 2
 * of the License, or any later version.
 *
 * For the full copyright and license information, please read the
 * LICENSE.txt file that was distributed with this source code.
 *
 * The TYPO3 project - inspiring people to share!
 */
 
namespace ‪TYPO3\CMS\Core\Locking;
 
use ‪TYPO3\CMS\Core\Locking\Exception\LockAcquireException;
use ‪TYPO3\CMS\Core\Locking\Exception\LockAcquireWouldBlockException;
use ‪TYPO3\CMS\Core\Locking\Exception\LockCreateException;
 
class ‪ResourceMutex
{
    private ‪$lockFactory;
 
    private ‪$accessLocks = [];
 
    private ‪$workerLocks = [];
 
    public function ‪__construct(‪LockFactory ‪$lockFactory)
    {
        $this->lockFactory = ‪$lockFactory;
    }
 
    public function ‪acquireLock(string $scope, string $key): void
    {
        $this->accessLocks[$scope] = $this->lockFactory->createLocker($scope);
 
        $this->workerLocks[$scope] = $this->lockFactory->createLocker(
            $key,
            ‪LockingStrategyInterface::LOCK_CAPABILITY_EXCLUSIVE | ‪LockingStrategyInterface::LOCK_CAPABILITY_NOBLOCK
        );
 
        do {
            if (!$this->accessLocks[$scope]->acquire()) {
                throw new \RuntimeException('Could not acquire access lock for "' . $scope . '"".', 1601923209);
            }
 
            try {
                $locked = $this->workerLocks[$scope]->acquire(
                    ‪LockingStrategyInterface::LOCK_CAPABILITY_EXCLUSIVE | ‪LockingStrategyInterface::LOCK_CAPABILITY_NOBLOCK
                );
            } catch (‪LockAcquireWouldBlockException $e) {
                // somebody else has the lock, we keep waiting
 
                // first release the access lock
                $this->accessLocks[$scope]->release();
                // now lets make a short break (100ms) until we try again, since
                // the page generation by the lock owner will take a while anyways
                usleep(100000);
                continue;
            }
            $this->accessLocks[$scope]->release();
            if ($locked) {
                break;
            }
            throw new \RuntimeException('Could not acquire image process lock for ' . $key . '.', 1601923215);
        } while (true);
    }
 
    public function ‪releaseLock(string $scope): void
    {
        if ($this->accessLocks[$scope] ?? null) {
            if (!$this->accessLocks[$scope]->acquire()) {
                throw new \RuntimeException('Could not acquire access lock for "' . $scope . '"".', 1601923319);
            }
 
            $this->workerLocks[$scope]->release();
            $this->workerLocks[$scope]->destroy();
            $this->workerLocks[$scope] = null;
 
            $this->accessLocks[$scope]->release();
            $this->accessLocks[$scope] = null;
        }
    }
}