1/*
2 *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
3 *
4 *  Use of this source code is governed by a BSD-style license
5 *  that can be found in the LICENSE file in the root of the source
6 *  tree. An additional intellectual property rights grant can be found
7 *  in the file PATENTS.  All contributing project authors may
8 *  be found in the AUTHORS file in the root of the source tree.
9 */
10
11#ifndef WEBRTC_SYSTEM_WRAPPERS_INCLUDE_RW_LOCK_WRAPPER_H_
12#define WEBRTC_SYSTEM_WRAPPERS_INCLUDE_RW_LOCK_WRAPPER_H_
13
14#include "webrtc/base/thread_annotations.h"
15
16// Note, Windows pre-Vista version of RW locks are not supported natively. For
17// these OSs regular critical sections have been used to approximate RW lock
18// functionality and will therefore have worse performance.
19
20namespace webrtc {
21
22class LOCKABLE RWLockWrapper {
23 public:
24  static RWLockWrapper* CreateRWLock();
25  virtual ~RWLockWrapper() {}
26
27  virtual void AcquireLockExclusive() EXCLUSIVE_LOCK_FUNCTION() = 0;
28  virtual void ReleaseLockExclusive() UNLOCK_FUNCTION() = 0;
29
30  virtual void AcquireLockShared() SHARED_LOCK_FUNCTION() = 0;
31  virtual void ReleaseLockShared() UNLOCK_FUNCTION() = 0;
32};
33
34// RAII extensions of the RW lock. Prevents Acquire/Release missmatches and
35// provides more compact locking syntax.
36class SCOPED_LOCKABLE ReadLockScoped {
37 public:
38  ReadLockScoped(RWLockWrapper& rw_lock) SHARED_LOCK_FUNCTION(rw_lock)
39      : rw_lock_(rw_lock) {
40    rw_lock_.AcquireLockShared();
41  }
42
43  ~ReadLockScoped() UNLOCK_FUNCTION() {
44    rw_lock_.ReleaseLockShared();
45  }
46
47 private:
48  RWLockWrapper& rw_lock_;
49};
50
51class SCOPED_LOCKABLE WriteLockScoped {
52 public:
53  WriteLockScoped(RWLockWrapper& rw_lock) EXCLUSIVE_LOCK_FUNCTION(rw_lock)
54      : rw_lock_(rw_lock) {
55    rw_lock_.AcquireLockExclusive();
56  }
57
58  ~WriteLockScoped() UNLOCK_FUNCTION() {
59    rw_lock_.ReleaseLockExclusive();
60  }
61
62 private:
63  RWLockWrapper& rw_lock_;
64};
65
66}  // namespace webrtc
67
68#endif  // WEBRTC_SYSTEM_WRAPPERS_INCLUDE_RW_LOCK_WRAPPER_H_
69