| //===----------------------------------------------------------------------===// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // UNSUPPORTED: no-threads |
| // UNSUPPORTED: c++03, c++11 |
| |
| // XFAIL: availability-shared_mutex-missing |
| |
| // <shared_mutex> |
| |
| // class timed_mutex; |
| |
| // template <class Rep, class Period> |
| // shared_lock(mutex_type& m, const chrono::duration<Rep, Period>& rel_time); |
| |
| #include <thread> |
| |
| #include <atomic> |
| #include <cassert> |
| #include <cstdlib> |
| #include <shared_mutex> |
| #include <vector> |
| |
| #include "make_test_thread.h" |
| #include "test_macros.h" |
| |
| std::shared_timed_mutex m; |
| |
| typedef std::chrono::steady_clock Clock; |
| typedef Clock::time_point time_point; |
| typedef Clock::duration duration; |
| typedef std::chrono::milliseconds ms; |
| typedef std::chrono::nanoseconds ns; |
| |
| ms LongTime = ms(5000); |
| ms ShortTime = ms(50); |
| |
| static const unsigned Threads = 5; |
| |
| std::atomic<unsigned> CountDown(Threads); |
| |
| void f1() |
| { |
| // Preemptive scheduling means that one cannot make assumptions about when |
| // code executes and therefore we cannot assume anthing about when the mutex |
| // starts waiting relative to code in the main thread. We can however prove |
| // that a timeout occured and that implies that this code is waiting. |
| // See f2() below. |
| // |
| // Nevertheless, we should at least try to ensure that the mutex waits and |
| // therefore we use an atomic variable to signal to the main thread that this |
| // code is just a few instructions away from waiting. |
| --CountDown; |
| std::shared_lock<std::shared_timed_mutex> lk(m, LongTime); |
| assert(lk.owns_lock() == true); |
| } |
| |
| void f2() |
| { |
| time_point t0 = Clock::now(); |
| std::shared_lock<std::shared_timed_mutex> lk(m, ShortTime); |
| time_point t1 = Clock::now(); |
| assert(lk.owns_lock() == false); |
| assert(t1 - t0 >= ShortTime); |
| } |
| |
| int main(int, char**) |
| { |
| { |
| m.lock(); |
| std::vector<std::thread> v; |
| for (unsigned i = 0; i < Threads; ++i) |
| v.push_back(support::make_test_thread(f1)); |
| while (CountDown > 0) |
| std::this_thread::yield(); |
| // Give one more chance for threads to block and wait for the mutex. |
| std::this_thread::yield(); |
| std::this_thread::sleep_for(ShortTime); |
| m.unlock(); |
| for (auto& t : v) |
| t.join(); |
| } |
| { |
| m.lock(); |
| std::vector<std::thread> v; |
| for (unsigned i = 0; i < Threads; ++i) |
| v.push_back(support::make_test_thread(f2)); |
| for (auto& t : v) |
| t.join(); |
| m.unlock(); |
| } |
| |
| return 0; |
| } |