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Final Class Yiisoft\Mutex\File\FileMutex

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Inheritance	Yiisoft\Mutex\File\FileMutex » Yiisoft\Mutex\Mutex

FileMutex implements mutex "lock" mechanism via local file system files.

This component relies on PHP {@see \Yiisoft\Mutex\File\flock()} function.

Note: this component can maintain the locks only for the single web server, it probably will not suffice in case you are using cloud server solution.

Warning: due to {@see \Yiisoft\Mutex\File\flock()} function nature this component is unreliable when using a multithreaded server API like ISAPI.

Public Methods

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Method	Description	Defined By
__construct()		Yiisoft\Mutex\File\FileMutex

Protected Methods

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Method	Description	Defined By
acquireLock()		Yiisoft\Mutex\File\FileMutex
releaseLock()		Yiisoft\Mutex\File\FileMutex

Method Details

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__construct() public method

public mixed __construct ( string $name, string $mutexPath, integer $directoryMode = 0775, integer\|null $fileMode = null )
$name	string	Mutex name.
$mutexPath	string	The directory to store mutex files.
$directoryMode	integer	The permission to be set for newly created directories. This value will be used by PHP {@see \Yiisoft\Mutex\File\chmod()} function. No umask will be applied. Defaults to 0775, meaning the directory is read-writable by owner and group, but read-only for other users.
$fileMode	integer\|null	The permission to be set for newly created mutex files. This value will be used by PHP {@see \Yiisoft\Mutex\File\chmod()} function. No umask will be applied.

Source code

                public function __construct(string $name, string $mutexPath, int $directoryMode = 0775, ?int $fileMode = null)
{
    FileHelper::ensureDirectory($mutexPath, $directoryMode);
    $this->lockFilePath = $mutexPath . DIRECTORY_SEPARATOR . md5($name) . '.lock';
    $this->fileMode = $fileMode;
    parent::__construct(self::class, $name);
}

acquireLock() protected method

protected boolean acquireLock ( integer $timeout = 0 )
$timeout	integer

Source code

                protected function acquireLock(int $timeout = 0): bool
{
    $resource = fopen($this->lockFilePath, 'wb+');
    if ($resource === false) {
        return false;
    }
    if ($this->fileMode !== null) {
        @chmod($this->lockFilePath, $this->fileMode);
    }
    if (!flock($resource, LOCK_EX | LOCK_NB)) {
        fclose($resource);
        return false;
    }
    /**
     * Under unix, we delete the lock file before releasing the related handle. Thus, it's possible that we've
     * acquired a lock on a non-existing file here (race condition). We must compare the inode of the lock file
     * handle with the inode of the actual lock file.
     * If they do not match we simply continue the loop since we can assume the inodes will be equal on the
     * next try.
     * Example of race condition without inode-comparison:
     * Script A: locks file
     * Script B: opens file
     * Script A: unlinks and unlocks file
     * Script B: locks handle of *unlinked* file
     * Script C: opens and locks *new* file
     * In this case we would have acquired two locks for the same file path.
     *
     * @psalm-suppress PossiblyInvalidArrayAccess We assume that `$resource` is a correct file system pointer
     * resource, so `fstat()` always returns array.
     */
    if (DIRECTORY_SEPARATOR !== '\\' && fstat($resource)['ino'] !== @fileinode($this->lockFilePath)) {
        clearstatcache(true, $this->lockFilePath);
        flock($resource, LOCK_UN);
        fclose($resource);
        return false;
    }
    $this->lockResource = $resource;
    return true;
}

releaseLock() protected method

protected boolean releaseLock ( )

Source code

                protected function releaseLock(): bool
{
    if (!is_resource($this->lockResource)) {
        return false;
    }
    if (DIRECTORY_SEPARATOR === '\\') {
        // Under windows, it's not possible to delete a file opened via fopen (either by own or other process).
        // That's why we must first unlock and close the handle and then *try* to delete the lock file.
        flock($this->lockResource, LOCK_UN);
        fclose($this->lockResource);
        @unlink($this->lockFilePath);
    } else {
        // Under unix, it's possible to delete a file opened via fopen (either by own or other process).
        // That's why we must unlink (the currently locked) lock file first and then unlock and close the handle.
        @unlink($this->lockFilePath);
        flock($this->lockResource, LOCK_UN);
        fclose($this->lockResource);
    }
    $this->lockResource = null;
    return true;
}