libcxx/test/std/thread/thread.jthread/dtor.pass.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-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // UNSUPPORTED: no-threads
  10 // UNSUPPORTED: libcpp-has-no-experimental-stop_token
  11 // UNSUPPORTED: c++03, c++11, c++14, c++17
  12 // XFAIL: availability-synchronization_library-missing
  13
  14 // ~jthread();
  15
  16 #include <atomic>
  17 #include <cassert>
  18 #include <optional>
  19 #include <stop_token>
  20 #include <thread>
  21 #include <type_traits>
  22 #include <vector>
  23
  24 #include "make_test_thread.h"
  25 #include "test_macros.h"
  26
  27 int main(int, char**) {
  28   // !joinable()
  29   {
  30     std::jthread jt;
  31     assert(!jt.joinable());
  32   }
  33
  34   // If joinable() is true, calls request_stop() and then join().
  35   // request_stop is called
  36   {
  37     std::optional<std::jthread> jt = support::make_test_jthread([] {});
  38     bool called                    = false;
  39     std::stop_callback cb(jt->get_stop_token(), [&called] { called = true; });
  40     jt.reset();
  41     assert(called);
  42   }
  43
  44   // If joinable() is true, calls request_stop() and then join().
  45   // join is called
  46   {
  47     std::atomic_int calledTimes = 0;
  48     std::vector<std::jthread> jts;
  49
  50     constexpr auto numberOfThreads = 10u;
  51     jts.reserve(numberOfThreads);
  52     for (auto i = 0u; i < numberOfThreads; ++i) {
  53       jts.emplace_back(support::make_test_jthread([&calledTimes] {
  54         std::this_thread::sleep_for(std::chrono::milliseconds{2});
  55         calledTimes.fetch_add(1, std::memory_order_relaxed);
  56       }));
  57     }
  58     jts.clear();
  59
  60     // If join was called as expected, calledTimes must equal to numberOfThreads
  61     // If join was not called, there is a chance that the check below happened
  62     // before test threads incrementing the counter, thus calledTimed would
  63     // be less than numberOfThreads.
  64     // This is not going to catch issues 100%. Creating more threads would increase
  65     // the probability of catching the issue
  66     assert(calledTimes.load(std::memory_order_relaxed) == numberOfThreads);
  67   }
  68
  69   return 0;
  70 }