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: c++03, c++11, c++14, c++17
  11 // XFAIL: availability-synchronization_library-missing
  12
  13 // ~jthread();
  14
  15 #include <atomic>
  16 #include <cassert>
  17 #include <optional>
  18 #include <stop_token>
  19 #include <thread>
  20 #include <type_traits>
  21 #include <vector>
  22
  23 #include "make_test_thread.h"
  24 #include "test_macros.h"
  25
  26 int main(int, char**) {
  27   // !joinable()
  28   {
  29     std::jthread jt;
  30     assert(!jt.joinable());
  31   }
  32
  33   // If joinable() is true, calls request_stop() and then join().
  34   // request_stop is called
  35   {
  36     std::optional<std::jthread> jt = support::make_test_jthread([] {});
  37     bool called                    = false;
  38     std::stop_callback cb(jt->get_stop_token(), [&called] { called = true; });
  39     jt.reset();
  40     assert(called);
  41   }
  42
  43   // If joinable() is true, calls request_stop() and then join().
  44   // join is called
  45   {
  46     std::atomic_int calledTimes = 0;
  47     std::vector<std::jthread> jts;
  48
  49     constexpr auto numberOfThreads = 10u;
  50     jts.reserve(numberOfThreads);
  51     for (auto i = 0u; i < numberOfThreads; ++i) {
  52       jts.emplace_back(support::make_test_jthread([&calledTimes] {
  53         std::this_thread::sleep_for(std::chrono::milliseconds{2});
  54         calledTimes.fetch_add(1, std::memory_order_relaxed);
  55       }));
  56     }
  57     jts.clear();
  58
  59     // If join was called as expected, calledTimes must equal to numberOfThreads
  60     // If join was not called, there is a chance that the check below happened
  61     // before test threads incrementing the counter, thus calledTimed would
  62     // be less than numberOfThreads.
  63     // This is not going to catch issues 100%. Creating more threads would increase
  64     // the probability of catching the issue
  65     assert(calledTimes.load(std::memory_order_relaxed) == numberOfThreads);
  66   }
  67
  68   return 0;
  69 }