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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef RLZ_LIB_RECURSIVE_CROSS_PROCESS_LOCK_POSIX_H_
#define RLZ_LIB_RECURSIVE_CROSS_PROCESS_LOCK_POSIX_H_
#include <pthread.h>
class FilePath;
namespace rlz_lib {
// Creating a recursive cross-process mutex on Windows is one line. On POSIX,
// there's no primitive for that, so this lock is emulated by an in-process
// mutex to get the recursive part, followed by a cross-process lock for the
// cross-process part.
// This is a struct so that it doesn't need a static initializer.
struct RecursiveCrossProcessLock {
// Tries to acquire a recursive cross-process lock. Note that this _always_
// acquires the in-process lock (if it wasn't already acquired). The parent
// directory of |lock_file| must exist.
bool TryGetCrossProcessLock(const FilePath& lock_filename);
// Releases the lock. Should always be called, even if
// TryGetCrossProcessLock() returned |false|.
void ReleaseLock();
pthread_mutex_t recursive_lock_;
pthread_t locking_thread_;
int file_lock_;
};
// On Mac, PTHREAD_RECURSIVE_MUTEX_INITIALIZER doesn't exist before 10.7 and
// is buggy on 10.7 (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51906#c34),
// so emulate recursive locking with a normal non-recursive mutex.
#define RECURSIVE_CROSS_PROCESS_LOCK_INITIALIZER \
{ PTHREAD_MUTEX_INITIALIZER, 0, -1 }
} // namespace rlz_lib
#endif // RLZ_LIB_RECURSIVE_CROSS_PROCESS_LOCK_POSIX_H_