LockHandler.php

<?php declare(strict_types=1);

namespace MyApp\Adapter\Repository\Couchbase;

use MyApp\Exception\DocumentIsLockedException;

class LockHandler
{
  
    // ...
  
    /**
     * Wait for a lock to be released, acquire a lock, and return lock data.
     *
     * @throws \MyApp\Exception\DocumentIsLockedException if we waited too
     * long and the lock has still not been released
     *
     * @param callable $attemptToAcquireLock This is passed in as a callable so
     * the LockHandler can remain generic and not have to know how to try to
     * obtain a lock. You just pass in a method that returns lock data or
     * falsey and this handles the waiting, tracking, exceptions, and logging.
     *
     * @return array whatever the $attemptToAcquireLock callable returns
     */
    public function waitAndAcquire(
        string $docKey,
        callable $attemptToAcquireLock
    ): array {
        $currentAttempt = 1;
        // loop until we reach max number of attemps
        $maxLockCheckAttempts = $this->config['max_lock_check_attempts'];
        while ($currentAttempt != $maxLockCheckAttempts) {
            if ($currentAttempt == 10) {
                Log::warning("Unusually long lock of doc keys: {$docKey}");
            }
            $lock = $attemptToAcquireLock(
                $docKey,
                $this->config['max_lock_time_in_seconds']
            );
            if ($lock) {
                $this->lockTracker->track($docKey, $lock);
                return $lock;
            }
            // keep retrying to access lock key if doc is locked
            $currentAttempt++;
            
            \usleep($this->config['sleep_time_in_microseconds']);
        }
        $message = "Document {$docKey} is locked for too long!";
        throw new DocumentIsLockedException($message);
    }
}