4f4ce13944
The challenge with measuring time in tests is that slow and/or busy machines can cause tests to fail in unexpected ways. After this change, three tests should be much more robust. The only remaining and tiny race that I can think of is preemption after `--countDown`. That being said, the race isn't fixable because the standard library doesn't provide a way to count threads that are waiting to acquire a lock. Reviewers: ldionne, EricWF, howard.hinnant, mclow.lists, #libc Reviewed By: ldionne, #libc Subscribers: dexonsmith, jfb, broadwaylamb, libcxx-commits Tags: #libc Differential Revision: https://reviews.llvm.org/D79406
67 lines
1.5 KiB
C++
67 lines
1.5 KiB
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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// UNSUPPORTED: libcpp-has-no-threads
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// UNSUPPORTED: c++98, c++03, c++11
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// shared_timed_mutex was introduced in macosx10.12
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// UNSUPPORTED: with_system_cxx_lib=macosx10.11
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// UNSUPPORTED: with_system_cxx_lib=macosx10.10
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// UNSUPPORTED: with_system_cxx_lib=macosx10.9
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// <shared_mutex>
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// class shared_timed_mutex;
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// void lock();
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#include <shared_mutex>
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#include <thread>
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#include <cstdlib>
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#include <cassert>
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#include "test_macros.h"
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std::shared_timed_mutex m;
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typedef std::chrono::system_clock Clock;
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typedef Clock::time_point time_point;
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typedef Clock::duration duration;
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typedef std::chrono::milliseconds ms;
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typedef std::chrono::nanoseconds ns;
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std::atomic<bool> ready(false);
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time_point start;
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ms WaitTime = ms(250);
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void f()
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{
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ready.store(true);
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m.lock();
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time_point t0 = start;
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time_point t1 = Clock::now();
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m.unlock();
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assert(t0.time_since_epoch() > ms(0));
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assert(t1 - t0 >= WaitTime);
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}
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int main(int, char**)
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{
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m.lock();
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std::thread t(f);
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while (!ready)
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std::this_thread::yield();
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start = Clock::now();
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std::this_thread::sleep_for(WaitTime);
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m.unlock();
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t.join();
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return 0;
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}
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