webrtc/base/thread_checker_impl.h

/*
 *  Copyright (c) 2014 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.
 */

// Borrowed from Chromium's src/base/threading/thread_checker_impl.h.

#ifndef WEBRTC_BASE_THREAD_CHECKER_IMPL_H_
#define WEBRTC_BASE_THREAD_CHECKER_IMPL_H_

#if defined(WEBRTC_POSIX)
#include <pthread.h>
#include <unistd.h>
#endif

#include "webrtc/base/criticalsection.h"

namespace rtc {

// Used for identifying the current thread. Always an integer value.
#if defined(WEBRTC_WIN)
typedef DWORD PlatformThreadId;
typedef DWORD PlatformThreadRef;
#elif defined(WEBRTC_POSIX)
typedef pid_t PlatformThreadId;
typedef pthread_t PlatformThreadRef;
#endif

// TODO(tommi): This+PlatformThreadId belongs in a common thread related header.
PlatformThreadId CurrentThreadId();
PlatformThreadRef CurrentThreadRef();

// Compares two thread identifiers for equality.
bool IsThreadRefEqual(const PlatformThreadRef& a, const PlatformThreadRef& b);

// Real implementation of ThreadChecker, for use in debug mode, or
// for temporary use in release mode (e.g. to CHECK on a threading issue
// seen only in the wild).
//
// Note: You should almost always use the ThreadChecker class to get the
// right version for your build configuration.
class ThreadCheckerImpl {
 public:
  ThreadCheckerImpl();
  ~ThreadCheckerImpl();

  bool CalledOnValidThread() const;

  // Changes the thread that is checked for in CalledOnValidThread.  This may
  // be useful when an object may be created on one thread and then used
  // exclusively on another thread.
  void DetachFromThread();

 private:
  mutable CriticalSection lock_;
  // This is mutable so that CalledOnValidThread can set it.
  // It's guarded by |lock_|.
  mutable PlatformThreadRef valid_thread_;
};

}  // namespace rtc

#endif  // WEBRTC_BASE_THREAD_CHECKER_IMPL_H_