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