1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef RLZ_LIB_RECURSIVE_CROSS_PROCESS_LOCK_POSIX_H_ 6 #define RLZ_LIB_RECURSIVE_CROSS_PROCESS_LOCK_POSIX_H_ 7 8 #include <pthread.h> 9 10 namespace base { 11 class FilePath; 12 } 13 14 namespace rlz_lib { 15 16 // Creating a recursive cross-process mutex on Windows is one line. On POSIX, 17 // there's no primitive for that, so this lock is emulated by an in-process 18 // mutex to get the recursive part, followed by a cross-process lock for the 19 // cross-process part. 20 // This is a struct so that it doesn't need a static initializer. 21 struct RecursiveCrossProcessLock { 22 // Tries to acquire a recursive cross-process lock. Note that this _always_ 23 // acquires the in-process lock (if it wasn't already acquired). The parent 24 // directory of |lock_file| must exist. 25 bool TryGetCrossProcessLock(const base::FilePath& lock_filename); 26 27 // Releases the lock. Should always be called, even if 28 // TryGetCrossProcessLock() returned |false|. 29 void ReleaseLock(); 30 31 pthread_mutex_t recursive_lock_; 32 pthread_t locking_thread_; 33 34 int file_lock_; 35 }; 36 37 // On Mac, PTHREAD_RECURSIVE_MUTEX_INITIALIZER doesn't exist before 10.7 and 38 // is buggy on 10.7 (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51906#c34), 39 // so emulate recursive locking with a normal non-recursive mutex. 40 #define RECURSIVE_CROSS_PROCESS_LOCK_INITIALIZER \ 41 { PTHREAD_MUTEX_INITIALIZER, 0, -1 } 42 43 } // namespace rlz_lib 44 45 #endif // RLZ_LIB_RECURSIVE_CROSS_PROCESS_LOCK_POSIX_H_ 46
