1// Copyright (c) 2011 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef BASE_SYNCHRONIZATION_LOCK_IMPL_H_
6#define BASE_SYNCHRONIZATION_LOCK_IMPL_H_
7
8#include "build/build_config.h"
9
10#if defined(OS_WIN)
11#include <windows.h>
12#elif defined(OS_POSIX)
13#include <pthread.h>
14#endif
15
16#include "base/base_export.h"
17#include "base/basictypes.h"
18
19namespace base {
20namespace internal {
21
22// This class implements the underlying platform-specific spin-lock mechanism
23// used for the Lock class.  Most users should not use LockImpl directly, but
24// should instead use Lock.
25class BASE_EXPORT LockImpl {
26 public:
27#if defined(OS_WIN)
28  typedef CRITICAL_SECTION NativeHandle;
29#elif defined(OS_POSIX)
30  typedef pthread_mutex_t NativeHandle;
31#endif
32
33  LockImpl();
34  ~LockImpl();
35
36  // If the lock is not held, take it and return true.  If the lock is already
37  // held by something else, immediately return false.
38  bool Try();
39
40  // Take the lock, blocking until it is available if necessary.
41  void Lock();
42
43  // Release the lock.  This must only be called by the lock's holder: after
44  // a successful call to Try, or a call to Lock.
45  void Unlock();
46
47  // Return the native underlying lock.
48  // TODO(awalker): refactor lock and condition variables so that this is
49  // unnecessary.
50  NativeHandle* native_handle() { return &native_handle_; }
51
52 private:
53  NativeHandle native_handle_;
54
55  DISALLOW_COPY_AND_ASSIGN(LockImpl);
56};
57
58}  // namespace internal
59}  // namespace base
60
61#endif  // BASE_SYNCHRONIZATION_LOCK_IMPL_H_
62