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

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