130 lines · cpp
1//===----------------------------------------------------------------------===//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-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: no-threads10// UNSUPPORTED: c++03, c++1111 12// <shared_mutex>13 14// template <class Mutex> class shared_lock;15 16// bool try_lock();17 18#include <atomic>19#include <cassert>20#include <mutex> // std::defer_lock21#include <shared_mutex>22#include <system_error>23#include <thread>24#include <vector>25 26#include "make_test_thread.h"27#include "test_macros.h"28 29struct Monitor {30 bool try_lock_shared_called = false;31 bool unlock_shared_called = false;32};33 34struct TrackedMutex {35 Monitor* monitor = nullptr;36 37 bool try_lock_shared() {38 if (monitor != nullptr)39 monitor->try_lock_shared_called = true;40 return true;41 }42 void unlock_shared() {43 if (monitor != nullptr)44 monitor->unlock_shared_called = true;45 }46};47 48template <class Mutex>49void test() {50 // Basic sanity test51 {52 Mutex mutex;53 std::vector<std::thread> threads;54 std::atomic<bool> ready(false);55 for (int i = 0; i != 5; ++i) {56 threads.push_back(support::make_test_thread([&] {57 while (!ready) {58 // spin59 }60 61 std::shared_lock<Mutex> lock(mutex, std::defer_lock);62 bool result = lock.try_lock();63 assert(result);64 assert(lock.owns_lock());65 }));66 }67 68 ready = true;69 for (auto& t : threads)70 t.join();71 }72 73 // Make sure that we throw an exception if we try to re-lock a mutex that is74 // already locked by the current thread.75 {76 Mutex mutex;77 78 std::shared_lock<Mutex> lock(mutex, std::defer_lock);79 assert(lock.try_lock());80 assert(lock.owns_lock());81#ifndef TEST_HAS_NO_EXCEPTIONS82 try {83 TEST_IGNORE_NODISCARD lock.try_lock();84 assert(false);85 } catch (std::system_error const& e) {86 assert(e.code() == std::errc::resource_deadlock_would_occur);87 }88#endif89 }90 91 // Make sure that we throw an exception if we try to lock a shared_lock92 // that is not associated to any mutex.93 {94 std::shared_lock<Mutex> lock; // not associated to a mutex95#ifndef TEST_HAS_NO_EXCEPTIONS96 try {97 TEST_IGNORE_NODISCARD lock.try_lock();98 assert(false);99 } catch (std::system_error const& e) {100 assert(e.code() == std::errc::operation_not_permitted);101 }102#endif103 }104}105 106int main(int, char**) {107#if TEST_STD_VER >= 17108 test<std::shared_mutex>();109#endif110 test<std::shared_timed_mutex>();111 test<TrackedMutex>();112 113 // Use shared_lock with a dummy mutex class that tracks whether each114 // operation has been called or not.115 {116 Monitor monitor;117 TrackedMutex mutex{&monitor};118 119 std::shared_lock<TrackedMutex> lock(mutex, std::defer_lock);120 bool result = lock.try_lock();121 assert(result);122 assert(monitor.try_lock_shared_called);123 assert(lock.owns_lock());124 125 lock.unlock();126 assert(monitor.unlock_shared_called);127 }128 return 0;129}130