1 | //===- llvm/Support/Mutex.h - Mutex Operating System Concept -----*- C++ -*-===// |
2 | // |
3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
4 | // See https://llvm.org/LICENSE.txt for license information. |
5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
6 | // |
7 | //===----------------------------------------------------------------------===// |
8 | // |
9 | // This file declares the llvm::sys::Mutex class. |
10 | // |
11 | //===----------------------------------------------------------------------===// |
12 | |
13 | #ifndef LLVM_SUPPORT_MUTEX_H |
14 | #define LLVM_SUPPORT_MUTEX_H |
15 | |
16 | #include "llvm/Support/Threading.h" |
17 | #include <cassert> |
18 | #include <mutex> |
19 | |
20 | namespace llvm |
21 | { |
22 | namespace sys |
23 | { |
24 | /// SmartMutex - A mutex with a compile time constant parameter that |
25 | /// indicates whether this mutex should become a no-op when we're not |
26 | /// running in multithreaded mode. |
27 | template<bool mt_only> |
28 | class SmartMutex { |
29 | std::recursive_mutex impl; |
30 | unsigned acquired = 0; |
31 | |
32 | public: |
33 | bool lock() { |
34 | if (!mt_only || llvm_is_multithreaded()) { |
35 | impl.lock(); |
36 | return true; |
37 | } |
38 | // Single-threaded debugging code. This would be racy in |
39 | // multithreaded mode, but provides not basic checks in single |
40 | // threaded mode. |
41 | ++acquired; |
42 | return true; |
43 | } |
44 | |
45 | bool unlock() { |
46 | if (!mt_only || llvm_is_multithreaded()) { |
47 | impl.unlock(); |
48 | return true; |
49 | } |
50 | // Single-threaded debugging code. This would be racy in |
51 | // multithreaded mode, but provides not basic checks in single |
52 | // threaded mode. |
53 | assert(acquired && "Lock not acquired before release!" ); |
54 | --acquired; |
55 | return true; |
56 | } |
57 | |
58 | bool try_lock() { |
59 | if (!mt_only || llvm_is_multithreaded()) |
60 | return impl.try_lock(); |
61 | return true; |
62 | } |
63 | }; |
64 | |
65 | /// Mutex - A standard, always enforced mutex. |
66 | typedef SmartMutex<false> Mutex; |
67 | |
68 | template <bool mt_only> |
69 | using SmartScopedLock = std::lock_guard<SmartMutex<mt_only>>; |
70 | |
71 | typedef SmartScopedLock<false> ScopedLock; |
72 | } |
73 | } |
74 | |
75 | #endif |
76 | |