src/base/threading/thread_checker_impl.h

// Copyright (c) 2011 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 BASE_THREADING_THREAD_CHECKER_IMPL_H_
#define BASE_THREADING_THREAD_CHECKER_IMPL_H_

#include "base/base_export.h"
#include "base/synchronization/lock.h"
#include "base/threading/platform_thread.h"

namespace base {

// 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 BASE_EXPORT 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:
  void EnsureThreadIdAssigned() const;

#if defined(COBALT) || defined(OS_STARBOARD)
  // Don't use a mutex since the number of mutexes is limited on some platforms.
  mutable base::subtle::Atomic32 valid_thread_id_;
#else
  mutable base::Lock lock_;
  // This is mutable so that CalledOnValidThread can set it.
  // It's guarded by |lock_|.
  mutable PlatformThreadId valid_thread_id_;
#endif
};

}  // namespace base

#endif  // BASE_THREADING_THREAD_CHECKER_IMPL_H_