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<?php |
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namespace TH\Lock; |
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use Psr\Log\LoggerInterface; |
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use Psr\Log\NullLogger; |
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class FileLock implements Lock |
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{ |
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const EXCLUSIVE = true; |
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const SHARED = false; |
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const BLOCKING = true; |
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const NON_BLOCKING = false; |
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private $lock_file; |
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private $exclusive; |
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private $blocking; |
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private $fh; |
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private $remove_on_release; |
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private $logger; |
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/** |
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* @param string $lock_file path to file |
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* @param boolean $exclusive true for an exclusive lock, false for shared one |
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* @param boolean $blocking true to wait for lock to be available, |
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* false to throw exception instead of waiting |
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* @param boolean $remove_on_release remove file on release if no other lock remains |
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* @param LoggerInterface $logger |
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*/ |
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public function __construct( |
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$lock_file, |
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$exclusive = FileLock::EXCLUSIVE, |
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$blocking = FileLock::NON_BLOCKING, |
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$remove_on_release = false, |
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LoggerInterface $logger = null |
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) { |
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$this->lock_file = $lock_file; |
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$this->exclusive = $exclusive; |
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$this->blocking = $blocking; |
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$this->remove_on_release = $remove_on_release; |
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$this->logger = $logger ?: new NullLogger; |
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} |
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/** |
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* @inherit |
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*/ |
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public function acquire() |
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{ |
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if ($this->exclusive === FileLock::EXCLUSIVE) { |
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$lock_type = "exclusive"; |
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$operation = LOCK_EX; |
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} else { |
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$lock_type = "shared"; |
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$operation = LOCK_SH; |
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} |
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if ($this->blocking === FileLock::NON_BLOCKING) { |
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$operation |= LOCK_NB; |
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} |
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$this->tryAcquire($operation, $lock_type); |
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} |
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/** |
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* try to acquire lock on file, throw in case of faillure |
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* @param int $operation |
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* @param string $lock_type lock type description |
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* @return void |
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* @see https://php.net/flock |
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*/ |
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private function tryAcquire($operation, $lock_type) |
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{ |
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$log_data = [ |
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"lock_file" => $this->lock_file, |
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"lock_type" => $lock_type |
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]; |
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if (!$this->flock($operation)) { |
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$this->logger->debug("could not acquire {lock_type} lock on {lock_file}", $log_data); |
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throw new RuntimeException( |
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"Could not acquire $lock_type lock on {$this->lock_file}" |
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); |
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} |
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$this->logger->debug("{lock_type} lock acquired on {lock_file}", $log_data); |
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} |
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public function release() |
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{ |
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if ($this->fh === null) { |
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return; |
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} |
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if ($this->remove_on_release && $this->flock(LOCK_EX | LOCK_NB)) { |
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if (is_file($this->lock_file)) { |
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unlink($this->lock_file); |
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} |
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} |
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$this->flock(LOCK_UN); |
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fclose($this->fh); |
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$this->fh = null; |
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$this->logger->debug("{lock_type} lock released on {lock_file}", ["lock_file" => $this->lock_file]); |
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} |
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public function __destruct() |
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{ |
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$this->release(); |
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} |
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/** |
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* @return boolean |
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*/ |
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private function flock($operation) |
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{ |
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if ($this->fh === null) { |
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$this->fh = fopen($this->lock_file, "c"); |
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} |
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if (!is_resource($this->fh)) { |
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throw new RuntimeException("Could not open lock file {$this->lock_file}"); |
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} |
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return flock($this->fh, $operation); |
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} |
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} |
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