78 lines
2.1 KiB
C
78 lines
2.1 KiB
C
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//===- llvm/Support/Mutex.h - Mutex Operating System Concept -----*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file declares the llvm::sys::Mutex class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_MUTEX_H
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#define LLVM_SUPPORT_MUTEX_H
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#include "llvm/Support/Threading.h"
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#include <cassert>
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#include <mutex>
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namespace llvm
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{
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namespace sys
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{
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/// SmartMutex - A mutex with a compile time constant parameter that
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/// indicates whether this mutex should become a no-op when we're not
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/// running in multithreaded mode.
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template<bool mt_only>
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class SmartMutex {
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std::recursive_mutex impl;
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unsigned acquired = 0;
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public:
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bool lock() {
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if (!mt_only || llvm_is_multithreaded()) {
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impl.lock();
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return true;
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} else {
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// Single-threaded debugging code. This would be racy in
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// multithreaded mode, but provides not sanity checks in single
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// threaded mode.
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++acquired;
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return true;
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}
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}
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bool unlock() {
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if (!mt_only || llvm_is_multithreaded()) {
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impl.unlock();
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return true;
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} else {
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// Single-threaded debugging code. This would be racy in
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// multithreaded mode, but provides not sanity checks in single
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// threaded mode.
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assert(acquired && "Lock not acquired before release!");
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--acquired;
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return true;
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}
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}
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bool try_lock() {
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if (!mt_only || llvm_is_multithreaded())
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return impl.try_lock();
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else return true;
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}
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};
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/// Mutex - A standard, always enforced mutex.
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typedef SmartMutex<false> Mutex;
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template <bool mt_only>
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using SmartScopedLock = std::lock_guard<SmartMutex<mt_only>>;
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typedef SmartScopedLock<false> ScopedLock;
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}
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}
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#endif
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