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/* -*- 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_
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