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