3
* Copyright 2011, Google Inc.
5
* Redistribution and use in source and binary forms, with or without
6
* modification, are permitted provided that the following conditions are met:
8
* 1. Redistributions of source code must retain the above copyright notice,
9
* this list of conditions and the following disclaimer.
10
* 2. Redistributions in binary form must reproduce the above copyright notice,
11
* this list of conditions and the following disclaimer in the documentation
12
* and/or other materials provided with the distribution.
13
* 3. The name of the author may not be used to endorse or promote products
14
* derived from this software without specific prior written permission.
16
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
19
* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
#ifndef TALK_BASE_SHAREDEXCLUSIVELOCK_H_
29
#define TALK_BASE_SHAREDEXCLUSIVELOCK_H_
31
#include "talk/base/constructormagic.h"
32
#include "talk/base/criticalsection.h"
33
#include "talk/base/event.h"
37
// This class provides shared-exclusive lock. It can be used in cases like
38
// multiple-readers/single-writer model.
39
class SharedExclusiveLock {
41
SharedExclusiveLock();
43
// Locking/unlocking methods. It is encouraged to use SharedScope or
44
// ExclusiveScope for protection.
46
void UnlockExclusive();
51
talk_base::CriticalSection cs_exclusive_;
52
talk_base::CriticalSection cs_shared_;
53
talk_base::Event shared_count_is_zero_;
56
DISALLOW_COPY_AND_ASSIGN(SharedExclusiveLock);
61
explicit SharedScope(SharedExclusiveLock* lock) : lock_(lock) {
66
lock_->UnlockShared();
70
SharedExclusiveLock* lock_;
72
DISALLOW_COPY_AND_ASSIGN(SharedScope);
75
class ExclusiveScope {
77
explicit ExclusiveScope(SharedExclusiveLock* lock) : lock_(lock) {
78
lock_->LockExclusive();
82
lock_->UnlockExclusive();
86
SharedExclusiveLock* lock_;
88
DISALLOW_COPY_AND_ASSIGN(ExclusiveScope);
91
} // namespace talk_base
93
#endif // TALK_BASE_SHAREDEXCLUSIVELOCK_H_