diff options
Diffstat (limited to 'lib/public/files/lock.php')
-rw-r--r-- | lib/public/files/lock.php | 259 |
1 files changed, 6 insertions, 253 deletions
diff --git a/lib/public/files/lock.php b/lib/public/files/lock.php index 196134724d3..34d307e8939 100644 --- a/lib/public/files/lock.php +++ b/lib/public/files/lock.php @@ -18,169 +18,20 @@ namespace OCP\Files; -use OCP\Config; -use OC\Files\Filesystem; - /** * Class Lock * @package OC\Files */ -class Lock { +interface Lock { const READ = 1; const WRITE = 2; - /** @var int $retries Number of lock retries to attempt */ - public static $retries = 40; - - /** @var int $retryInterval Milliseconds between retries */ - public static $retryInterval = 50; - - /** @var string $path Filename of the file as represented in storage */ - protected $path; - - /** @var array $stack A stack of lock data */ - protected $stack = array(); - - /** @var resource $handle A file handle used to maintain a lock */ - protected $handle; - - /** @var string $lockFile Filename of the lock file */ - protected $lockFile; - - /** @var resource $lockFileHandle The file handle used to maintain a lock on the lock file */ - protected $lockFileHandle; - /** * Constructor for the lock instance * @param string $path Absolute pathname for a local file on which to obtain a lock */ - public function __construct($path) { - $this->path = Filesystem::normalizePath($path); - } - - protected function obtainReadLock($existingHandle = null) { - \OC_Log::write('lock', sprintf('INFO: Read lock requested for %s', $this->path), \OC_Log::DEBUG); - $timeout = Lock::$retries; - - // Re-use an existing handle or get a new one - if(empty($existingHandle)) { - $handle = fopen($this->path, 'r'); - } - else { - $handle = $existingHandle; - } - - do { - if($this->isLockFileLocked($this->getLockFile($this->path))) { - \OC_Log::write('lock', sprintf('INFO: Read lock has locked lock file %s for %s', $this->getLockFile($this->path), $this->path), \OC_Log::DEBUG); - do { - usleep(Lock::$retryInterval); - $timeout--; - } while($this->isLockFileLocked($this->getLockFile($this->path)) && $timeout > 0); - \OC_Log::write('lock', sprintf('INFO: Lock file %s has become unlocked for %s', $this->getLockFile($this->path), $this->path), \OC_Log::DEBUG); - } - } while ((!$lockReturn = flock($handle, LOCK_SH | LOCK_NB, $wouldBlock)) && $timeout > 0); - if ($wouldBlock == true || $lockReturn == false || $timeout <= 0) { - \OC_Log::write('lock', sprintf('FAIL: Failed to acquire read lock for %s', $this->path), \OC_Log::DEBUG); - return false; - } - $this->handle = $handle; - \OC_Log::write('lock', sprintf('PASS: Acquired read lock for %s', $this->path), \OC_Log::DEBUG); - return true; - } - - protected function obtainWriteLock($existingHandle = null) { - \OC_Log::write('lock', sprintf('INFO: Write lock requested for %s', $this->path), \OC_Log::DEBUG); - - // Re-use an existing handle or get a new one - if (empty($existingHandle)) { - $handle = fopen($this->path, 'c'); - } - else { - $handle = $existingHandle; - } - - // If the file doesn't exist, but we can create a lock for it - if (!file_exists($this->path) && $this->lockLockFile($this->path)) { - $lockReturn = flock($handle, LOCK_EX | LOCK_NB, $wouldBlock); - if ($lockReturn == false || $wouldBlock == true) { - \OC_Log::write('lock', sprintf('FAIL: Write lock failed, unable to exclusively lock new file %s', $this->path), \OC_Log::DEBUG); - return false; - } - $this->handle = $handle; - return true; - } - - - // Since this file does exist, wait for locks to release to get an exclusive lock - $timeout = Lock::$retries; - $haveBlock = false; - while ((!$lockReturn = flock($handle, LOCK_EX | LOCK_NB, $wouldBlock)) && $timeout > 0) { - // We don't have a lock on the original file, try to get a lock on its lock file - if ($haveBlock || $haveBlock = $this->lockLockFile($this->lockFile)) { - usleep(Lock::$retryInterval); - } - else { - \OC_Log::write('lock', sprintf('FAIL: Write lock failed, unable to lock original %s or lock file', $this->path), \OC_Log::DEBUG); - return false; - } - $timeout--; - } - if ($wouldBlock == true || $lockReturn == false) { - \OC_Log::write('lock', sprintf('FAIL: Write lock failed due to timeout on %s', $this->path), \OC_Log::DEBUG); - return false; - } - \OC_Log::write('lock', sprintf('PASS: Write lock succeeded on %s', $this->path), \OC_Log::DEBUG); - - return true; - } - - /** - * Create a lock file and lock it - * Sets $this->lockFile to the specified lock file, indicating that the lock file is IN USE for this lock instance - * Also sets $this->lockFileHandle to a file handle of the lock file - * @param string $filename The name of the file to lock - * @return bool False if lock can't be acquired, true if it can. - */ - protected function lockLockFile ( $filename ) { - $lockFile = $this->getLockFile($filename); - \OC_Log::write('lock', sprintf('INFO: Locking lock file %s for %s', $lockFile, $filename), \OC_Log::DEBUG); - - // If we already manage the lockfile, success - if(!empty($this->lockFile)) { - \OC_Log::write('lock', sprintf('PASS: Lock file %s was locked by this request for %s', $lockFile, $filename), \OC_Log::DEBUG); - return true; - } - - // Check if the lockfile exists, and if not, try to create it - \OC_Log::write('lock', sprintf('INFO: Does lock file %s already exist? %s', $lockFile, file_exists($lockFile) ? 'yes' : 'no'), \OC_Log::DEBUG); - $handle = fopen($lockFile, 'c'); - if(!$handle) { - \OC_Log::write('lock', sprintf('FAIL: Could not create lock file %s', $lockFile), \OC_Log::DEBUG); - return false; - } - - // Attempt to acquire lock on lock file - $wouldBlock = false; - $timeout = self::$retries; - // Wait for lock over timeout - while((!$lockReturn = flock($handle, LOCK_EX | LOCK_NB, $wouldBlock)) && $timeout > 0) { - \OC_Log::write('lock', sprintf('FAIL: Could not acquire lock on lock file %s, %s timeout increments remain.', $lockFile, $timeout), \OC_Log::DEBUG); - usleep(self::$retryInterval); - $timeout--; - } - if ($wouldBlock == true || $lockReturn == false) { - \OC_Log::write('lock', sprintf('FAIL: Could not acquire lock on lock file %s', $lockFile), \OC_Log::DEBUG); - return false; - } - fwrite($handle, $filename); - \OC_Log::write('lock', sprintf('PASS: Wrote filename to lock lock file %s', $lockFile), \OC_Log::DEBUG); - - $this->lockFile = $lockFile; - $this->lockFileHandle = $handle; + public function __construct($path); - return true; - } /** * Add a lock of a specific type to the stack @@ -188,50 +39,12 @@ class Lock { * @param null|resource $existingHandle An existing file handle from an fopen() * @throws LockNotAcquiredException */ - public function addLock($lockType, $existingHandle = null) { - if(!isset($this->stack[$lockType])) { - switch($lockType) { - case Lock::READ: - $result = $this->obtainReadLock($existingHandle); - break; - case Lock::WRITE: - $result = $this->obtainWriteLock($existingHandle); - break; - default: - $result = false; - break; - } - if($result) { - $this->stack[$lockType] = 0; - } - else { - throw new LockNotAcquiredException($this->path, $lockType); - } - } - - \OC_Log::write('lock', sprintf('INFO: Incrementing lock type %d count for %s', $lockType, $this->path), \OC_Log::DEBUG); - $this->stack[$lockType]++; - - } + public function addLock($lockType, $existingHandle = null); /** * Release locks on handles and files */ - public function release($lockType) { - if(isset($this->stack[$lockType])) { - $this->stack[$lockType]--; - if($this->stack[$lockType] <= 0) { - unset($this->stack[$lockType]); - } - } - - if(count($this->stack) == 0) { - // No more locks needed on this file, release the handle and/or lockfile - $this->releaseAll(); - } - - return true; - } + public function release($lockType); /** @@ -239,72 +52,12 @@ class Lock { * @param string $filename The filename of the file to create a lock file for * @return string The filename of the lock file */ - public static function getLockFile($filename) { - static $locksDir = false; - if(!$locksDir) { - $dataDir = Config::getSystemValue('datadirectory'); - $locksDir = $dataDir . '/.locks'; - if(!file_exists($locksDir)) { - mkdir($locksDir); - } - } - $filename = Filesystem::normalizePath($filename); - return $locksDir . '/' . sha1($filename) . '.lock'; - } - - /** - * Determine if a file has an associated and flocked lock file - * @param string $lockFile The filename of the lock file to check - * @return bool True if the lock file is flocked - */ - protected function isLockFileLocked($lockFile) { - if(file_exists($lockFile)) { - if($handle = fopen($lockFile, 'c')) { - if($lock = flock($handle, LOCK_EX | LOCK_NB)) { - // Got lock, not blocking, release and unlink - unlink($lockFile); - fclose($handle); - flock($lock, LOCK_UN); - return false; - } - else { - return true; - } - } - else { - return true; - } - } - return false; - } + public static function getLockFile($filename); /** * Release all queued locks on the file * @return bool */ - public function releaseAll() { - $this->stack = array(); - \OC_Log::write('lock', sprintf('INFO: Releasing locks on %s', $this->path), \OC_Log::DEBUG); - if (!empty($this->handle) && is_resource($this->handle)) { - flock($this->handle, LOCK_UN); - \OC_Log::write('lock', sprintf('INFO: Released lock handle %s on %s', $this->handle, $this->path), \OC_Log::DEBUG); - $this->handle = null; - } - if (!empty($this->lockFile) && file_exists($this->lockFile)) { - unlink($this->lockFile); - \OC_Log::write('lock', sprintf('INFO: Released lock file %s on %s', $this->lockFile, $this->path), \OC_Log::DEBUG); - $this->lockFile = null; - } - \OC_Log::write('lock', sprintf('FREE: Released locks on %s', $this->path), \OC_Log::DEBUG); - return true; - } - - public function __destruct() { - // Only releaseAll if we have locks to release - if(!empty($this->handle) || !empty($this->lockFile)) { - \OC_Log::write('lock', sprintf('INFO: Destroying locks on %s', $this->path), \OC_Log::DEBUG); - $this->releaseAll(); - } - } + public function releaseAll(); }
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