FSLockManager.php

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<?php

class FSLockManager extends LockManager {
        protected $lockTypeMap = array(
                self::LOCK_SH => self::LOCK_SH,
                self::LOCK_UW => self::LOCK_SH,
                self::LOCK_EX => self::LOCK_EX
        );

        protected $lockDir; // global dir for all servers

        protected $handles = array();

        function __construct( array $config ) {
                parent::__construct( $config );
                $this->lockDir = $config['lockDirectory'];
        }

        protected function doLock( array $paths, $type ) {
                $status = Status::newGood();

                $lockedPaths = array(); // files locked in this attempt
                foreach ( $paths as $path ) {
                        $status->merge( $this->doSingleLock( $path, $type ) );
                        if ( $status->isOK() ) {
                                $lockedPaths[] = $path;
                        } else {
                                // Abort and unlock everything
                                $status->merge( $this->doUnlock( $lockedPaths, $type ) );
                                return $status;
                        }
                }

                return $status;
        }

        protected function doUnlock( array $paths, $type ) {
                $status = Status::newGood();

                foreach ( $paths as $path ) {
                        $status->merge( $this->doSingleUnlock( $path, $type ) );
                }

                return $status;
        }

        protected function doSingleLock( $path, $type ) {
                $status = Status::newGood();

                if ( isset( $this->locksHeld[$path][$type] ) ) {
                        ++$this->locksHeld[$path][$type];
                } elseif ( isset( $this->locksHeld[$path][self::LOCK_EX] ) ) {
                        $this->locksHeld[$path][$type] = 1;
                } else {
                        wfSuppressWarnings();
                        $handle = fopen( $this->getLockPath( $path ), 'a+' );
                        wfRestoreWarnings();
                        if ( !$handle ) { // lock dir missing?
                                wfMkdirParents( $this->lockDir );
                                $handle = fopen( $this->getLockPath( $path ), 'a+' ); // try again
                        }
                        if ( $handle ) {
                                // Either a shared or exclusive lock
                                $lock = ( $type == self::LOCK_SH ) ? LOCK_SH : LOCK_EX;
                                if ( flock( $handle, $lock | LOCK_NB ) ) {
                                        // Record this lock as active
                                        $this->locksHeld[$path][$type] = 1;
                                        $this->handles[$path][$type] = $handle;
                                } else {
                                        fclose( $handle );
                                        $status->fatal( 'lockmanager-fail-acquirelock', $path );
                                }
                        } else {
                                $status->fatal( 'lockmanager-fail-openlock', $path );
                        }
                }

                return $status;
        }

        protected function doSingleUnlock( $path, $type ) {
                $status = Status::newGood();

                if ( !isset( $this->locksHeld[$path] ) ) {
                        $status->warning( 'lockmanager-notlocked', $path );
                } elseif ( !isset( $this->locksHeld[$path][$type] ) ) {
                        $status->warning( 'lockmanager-notlocked', $path );
                } else {
                        $handlesToClose = array();
                        --$this->locksHeld[$path][$type];
                        if ( $this->locksHeld[$path][$type] <= 0 ) {
                                unset( $this->locksHeld[$path][$type] );
                                // If a LOCK_SH comes in while we have a LOCK_EX, we don't
                                // actually add a handler, so check for handler existence.
                                if ( isset( $this->handles[$path][$type] ) ) {
                                        // Mark this handle to be unlocked and closed
                                        $handlesToClose[] = $this->handles[$path][$type];
                                        unset( $this->handles[$path][$type] );
                                }
                        }
                        // Unlock handles to release locks and delete
                        // any lock files that end up with no locks on them...
                        if ( wfIsWindows() ) {
                                // Windows: for any process, including this one,
                                // calling unlink() on a locked file will fail
                                $status->merge( $this->closeLockHandles( $path, $handlesToClose ) );
                                $status->merge( $this->pruneKeyLockFiles( $path ) );
                        } else {
                                // Unix: unlink() can be used on files currently open by this 
                                // process and we must do so in order to avoid race conditions
                                $status->merge( $this->pruneKeyLockFiles( $path ) );
                                $status->merge( $this->closeLockHandles( $path, $handlesToClose ) );
                        }
                }

                return $status;
        }

        private function closeLockHandles( $path, array $handlesToClose ) {
                $status = Status::newGood();
                foreach ( $handlesToClose as $handle ) {
                        wfSuppressWarnings();
                        if ( !flock( $handle, LOCK_UN ) ) {
                                $status->fatal( 'lockmanager-fail-releaselock', $path );
                        }
                        if ( !fclose( $handle ) ) {
                                $status->warning( 'lockmanager-fail-closelock', $path );
                        }
                        wfRestoreWarnings();
                }
                return $status;
        }

        private function pruneKeyLockFiles( $path ) {
                $status = Status::newGood();
                if ( !count( $this->locksHeld[$path] ) ) {
                        wfSuppressWarnings();
                        # No locks are held for the lock file anymore
                        if ( !unlink( $this->getLockPath( $path ) ) ) {
                                $status->warning( 'lockmanager-fail-deletelock', $path );
                        }
                        wfRestoreWarnings();
                        unset( $this->locksHeld[$path] );
                        unset( $this->handles[$path] );
                }
                return $status;
        }

        protected function getLockPath( $path ) {
                $hash = self::sha1Base36( $path );
                return "{$this->lockDir}/{$hash}.lock";
        }

        function __destruct() {
                // Make sure remaining locks get cleared for sanity
                foreach ( $this->locksHeld as $path => $locks ) {
                        $this->doSingleUnlock( $path, self::LOCK_EX );
                        $this->doSingleUnlock( $path, self::LOCK_SH );
                }
        }
}