1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
/*
** Copyright (c) 2021 LunarG, Inc.
**
** Permission is hereby granted, free of charge, to any person obtaining a
** copy of this software and associated documentation files (the "Software"),
** to deal in the Software without restriction, including without limitation
** the rights to use, copy, modify, merge, publish, distribute, sublicense,
** and/or sell copies of the Software, and to permit persons to whom the
** Software is furnished to do so, subject to the following conditions:
**
** The above copyright notice and this permission notice shall be included in
** all copies or substantial portions of the Software.
**
** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
** AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
** LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
** FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
** DEALINGS IN THE SOFTWARE.
*/
#ifndef GFXRECON_UTIL_SHARED_MUTEX_H
#define GFXRECON_UTIL_SHARED_MUTEX_H
#include "util/defines.h"
#include <atomic>
#include <mutex>
GFXRECON_BEGIN_NAMESPACE(gfxrecon)
GFXRECON_BEGIN_NAMESPACE(util)
// A shared (reader/writer) mutex implementation using std::mutex and std::atomic.
class SharedMutex
{
public:
SharedMutex() : reader_count_(0), wait_for_writer_(false) {}
// Exclusive lock which waits for current readers in a spin lock then acquires the mutex. A thread's read lock can
// be promoted to a write lock.
void lock();
void unlock();
void lock_shared();
void unlock_shared();
private:
// Not copyable or movable
SharedMutex(const SharedMutex&) = delete;
SharedMutex& operator=(const SharedMutex&) = delete;
private:
static thread_local std::atomic_bool has_read_lock_;
private:
std::mutex writer_mutex;
std::atomic_size_t reader_count_;
std::atomic_bool wait_for_writer_;
};
GFXRECON_END_NAMESPACE(util)
GFXRECON_END_NAMESPACE(gfxrecon)
#endif // GFXRECON_UTIL_SHARED_MUTEX_H
|
