<?php
declare(strict_types=1);
namespace malkusch\lock\mutex;
use InvalidArgumentException;
use malkusch\lock\exception\LockAcquireException;
use malkusch\lock\exception\LockReleaseException;
/**
* System V IPC based mutex implementation.
*
* @author Markus Malkusch <markus@malkusch.de>
* @link bitcoin:1P5FAZ4QhXCuwYPnLZdk3PJsqePbu1UDDA Donations
* @license WTFPL
*/
class SemaphoreMutex extends LockMutex
{
/**
* @var \SysvSemaphore|resource The semaphore id.
*/
private $semaphore;
/**
* Sets the semaphore id.
*
* Use {@link sem_get()} to create the semaphore id.
*
* Example:
* <code>
* $semaphore = sem_get(ftok(__FILE__, "a"));
* $mutex = new SemaphoreMutex($semaphore);
* </code>
*
* @param \SysvSemaphore|resource $semaphore The semaphore id.
* @throws \InvalidArgumentException The semaphore id is not a valid resource.
*/
public function __construct($semaphore)
{
if (!$semaphore instanceof \SysvSemaphore && !is_resource($semaphore)) {
throw new InvalidArgumentException('The semaphore id is not a valid resource.');
}
$this->semaphore = $semaphore;
}
/**
* @internal
*/
protected function lock(): void
{
if (!sem_acquire($this->semaphore)) {
throw new LockAcquireException('Failed to acquire the Semaphore.');
}
}
/**
* @internal
*/
protected function unlock(): void
{
if (!sem_release($this->semaphore)) {
throw new LockReleaseException('Failed to release the Semaphore.');
}
}
}