lock_impl.h - mozsearch

Enable keyboard shortcuts

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

// 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_LOCK_IMPL_H_

#define BASE_LOCK_IMPL_H_

#include "base/basictypes.h"

#if defined(XP_WIN)

#  include <windows.h>

#else

#  include <pthread.h>

#endif

namespace base {

namespace internal {

// This class implements the underlying platform-specific spin-lock mechanism

// used for the Lock class.  Most users should not use LockImpl directly, but

// should instead use Lock.

class LockImpl {

 public:

#if defined(XP_WIN)

  using NativeHandle = SRWLOCK;

#else

  using NativeHandle = pthread_mutex_t;

#endif

  LockImpl();

  ~LockImpl();

  // If the lock is not held, take it and return true.  If the lock is already

  // held by something else, immediately return false.

  bool Try();

  // Take the lock, blocking until it is available if necessary.

  void Lock();

  // Release the lock.  This must only be called by the lock's holder: after

  // a successful call to Try, or a call to Lock.

  void Unlock();

  // Return the native underlying lock.

  // TODO(awalker): refactor lock and condition variables so that this is

  // unnecessary.

  NativeHandle* native_handle() { return &native_handle_; }

#if defined(XP_UNIX)

  // Whether this lock will attempt to use priority inheritance.

  static bool PriorityInheritanceAvailable();

#endif

 private:

  NativeHandle native_handle_;

  DISALLOW_COPY_AND_ASSIGN(LockImpl);

};

}  // namespace internal

}  // namespace base

#endif  // BASE_LOCK_IMPL_H_