libcxx/test/std/thread/thread.jthread/assign.move.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 // ADDITIONAL_COMPILE_FLAGS(gcc-style-warnings): -Wno-self-move
  13
  14 // jthread& operator=(jthread&&) noexcept;
  15
  16 #include <atomic>
  17 #include <cassert>
  18 #include <concepts>
  19 #include <stop_token>
  20 #include <thread>
  21 #include <type_traits>
  22 #include <utility>
  23 #include <vector>
  24
  25 #include "make_test_thread.h"
  26 #include "test_macros.h"
  27
  28 static_assert(std::is_nothrow_move_assignable_v<std::jthread>);
  29
  30 int main(int, char**) {
  31   // If &x == this is true, there are no effects.
  32   {
  33     std::jthread j = support::make_test_jthread([] {});
  34     auto id        = j.get_id();
  35     auto ssource   = j.get_stop_source();
  36     j              = std::move(j);
  37     assert(j.get_id() == id);
  38     assert(j.get_stop_source() == ssource);
  39   }
  40
  41   // if joinable() is true, calls request_stop() and then join()
  42   // request_stop is called
  43   {
  44     std::jthread j1 = support::make_test_jthread([] {});
  45     bool called     = false;
  46     std::stop_callback cb(j1.get_stop_token(), [&called] { called = true; });
  47
  48     std::jthread j2 = support::make_test_jthread([] {});
  49     j1              = std::move(j2);
  50     assert(called);
  51   }
  52
  53   // if joinable() is true, calls request_stop() and then join()
  54   // join is called
  55   {
  56     std::atomic_int calledTimes = 0;
  57     std::vector<std::jthread> jts;
  58     constexpr auto numberOfThreads = 10u;
  59     jts.reserve(numberOfThreads);
  60     for (auto i = 0u; i < numberOfThreads; ++i) {
  61       jts.emplace_back(support::make_test_jthread([&] {
  62         std::this_thread::sleep_for(std::chrono::milliseconds(2));
  63         calledTimes.fetch_add(1, std::memory_order_relaxed);
  64       }));
  65     }
  66
  67     for (auto i = 0u; i < numberOfThreads; ++i) {
  68       jts[i] = std::jthread{};
  69     }
  70
  71     // If join was called as expected, calledTimes must equal to numberOfThreads
  72     // If join was not called, there is a chance that the check below happened
  73     // before test threads incrementing the counter, thus calledTimed would
  74     // be less than numberOfThreads.
  75     // This is not going to catch issues 100%. Creating more threads to increase
  76     // the probability of catching the issue
  77     assert(calledTimes.load(std::memory_order_relaxed) == numberOfThreads);
  78   }
  79
  80   // then assigns the state of x to *this
  81   {
  82     std::jthread j1 = support::make_test_jthread([] {});
  83     std::jthread j2 = support::make_test_jthread([] {});
  84     auto id2        = j2.get_id();
  85     auto ssource2   = j2.get_stop_source();
  86
  87     j1 = std::move(j2);
  88
  89     assert(j1.get_id() == id2);
  90     assert(j1.get_stop_source() == ssource2);
  91   }
  92
  93   // sets x to a default constructed state
  94   {
  95     std::jthread j1 = support::make_test_jthread([] {});
  96     std::jthread j2 = support::make_test_jthread([] {});
  97     j1              = std::move(j2);
  98
  99     assert(j2.get_id() == std::jthread::id());
 100     assert(!j2.get_stop_source().stop_possible());
 101   }
 102
 103   // joinable is false
 104   {
 105     std::jthread j1;
 106     std::jthread j2 = support::make_test_jthread([] {});
 107
 108     auto j2Id = j2.get_id();
 109
 110     j1 = std::move(j2);
 111
 112     assert(j1.get_id() == j2Id);
 113   }
 114
 115   return 0;
 116 }