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* Copyright 2009 The WebRTC Project Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
#include <string>
#include "webrtc/base/constructormagic.h"
#include "webrtc/base/scoped_ptr.h"
namespace rtc {
class FileStream;
// Implements a very simple cross process lock based on a file.
// When Lock(...) is called we try to open/create the file in read/write
// mode without any sharing. (Or locking it with flock(...) on Unix)
// If the process crash the OS will make sure that the file descriptor
// is released and another process can accuire the lock.
// This doesn't work on ancient OSX/Linux versions if used on NFS.
// (Nfs-client before: ~2.6 and Linux Kernel < 2.6.)
class FileLock {
virtual ~FileLock();
// Attempts to lock the file. The caller owns the returned
// lock object. Returns NULL if the file already was locked.
static FileLock* TryLock(const std::string& path);
void Unlock();
FileLock(const std::string& path, FileStream* file);
void MaybeUnlock();
std::string path_;
scoped_ptr<FileStream> file_;
} // namespace rtc