1*bb722a7dSDimitry Andric //===--- A self contained equivalent of std::mutex --------------*- C++ -*-===// 2*bb722a7dSDimitry Andric // 3*bb722a7dSDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4*bb722a7dSDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 5*bb722a7dSDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6*bb722a7dSDimitry Andric // 7*bb722a7dSDimitry Andric //===----------------------------------------------------------------------===// 8*bb722a7dSDimitry Andric 9*bb722a7dSDimitry Andric #ifndef LLVM_LIBC_SRC___SUPPORT_CPP_MUTEX_H 10*bb722a7dSDimitry Andric #define LLVM_LIBC_SRC___SUPPORT_CPP_MUTEX_H 11*bb722a7dSDimitry Andric 12*bb722a7dSDimitry Andric #include "src/__support/macros/config.h" 13*bb722a7dSDimitry Andric 14*bb722a7dSDimitry Andric namespace LIBC_NAMESPACE_DECL { 15*bb722a7dSDimitry Andric namespace cpp { 16*bb722a7dSDimitry Andric 17*bb722a7dSDimitry Andric // Assume the calling thread has already obtained mutex ownership. 18*bb722a7dSDimitry Andric struct adopt_lock_t { 19*bb722a7dSDimitry Andric explicit adopt_lock_t() = default; 20*bb722a7dSDimitry Andric }; 21*bb722a7dSDimitry Andric 22*bb722a7dSDimitry Andric // Tag used to make a scoped lock take ownership of a locked mutex. 23*bb722a7dSDimitry Andric constexpr adopt_lock_t adopt_lock{}; 24*bb722a7dSDimitry Andric 25*bb722a7dSDimitry Andric // An RAII class for easy locking and unlocking of mutexes. 26*bb722a7dSDimitry Andric template <typename MutexType> class lock_guard { 27*bb722a7dSDimitry Andric MutexType &mutex; 28*bb722a7dSDimitry Andric 29*bb722a7dSDimitry Andric public: 30*bb722a7dSDimitry Andric // Calls `m.lock()` upon resource acquisition. lock_guard(MutexType & m)31*bb722a7dSDimitry Andric explicit lock_guard(MutexType &m) : mutex(m) { mutex.lock(); } 32*bb722a7dSDimitry Andric 33*bb722a7dSDimitry Andric // Acquires ownership of the mutex object `m` without attempting to lock 34*bb722a7dSDimitry Andric // it. The behavior is undefined if the current thread does not hold the 35*bb722a7dSDimitry Andric // lock on `m`. Does not call `m.lock()` upon resource acquisition. lock_guard(MutexType & m,adopt_lock_t)36*bb722a7dSDimitry Andric lock_guard(MutexType &m, adopt_lock_t /* t */) : mutex(m) {} 37*bb722a7dSDimitry Andric ~lock_guard()38*bb722a7dSDimitry Andric ~lock_guard() { mutex.unlock(); } 39*bb722a7dSDimitry Andric 40*bb722a7dSDimitry Andric // non-copyable 41*bb722a7dSDimitry Andric lock_guard &operator=(const lock_guard &) = delete; 42*bb722a7dSDimitry Andric lock_guard(const lock_guard &) = delete; 43*bb722a7dSDimitry Andric }; 44*bb722a7dSDimitry Andric 45*bb722a7dSDimitry Andric // Deduction guide for lock_guard to suppress CTAD warnings. 46*bb722a7dSDimitry Andric template <typename T> lock_guard(T &) -> lock_guard<T>; 47*bb722a7dSDimitry Andric 48*bb722a7dSDimitry Andric } // namespace cpp 49*bb722a7dSDimitry Andric } // namespace LIBC_NAMESPACE_DECL 50*bb722a7dSDimitry Andric 51*bb722a7dSDimitry Andric #endif // LLVM_LIBC_SRC___SUPPORT_CPP_MUTEX_H 52