libcxx/test/std/thread/thread.stoptoken/stoptoken/stop_possible.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 // [[nodiscard]] bool stop_possible() const noexcept;
  15 // Returns: false if:
  16 //    - *this does not have ownership of a stop state, or
  17 //    - a stop request was not made and there are no associated stop_source objects;
  18 // otherwise, true.
  19
  20 #include <cassert>
  21 #include <concepts>
  22 #include <optional>
  23 #include <stop_token>
  24 #include <type_traits>
  25
  26 #include "make_test_thread.h"
  27 #include "test_macros.h"
  28
  29 template <class T>
  30 concept IsStopPossibleNoexcept = requires(const T& t) {
  31   { t.stop_possible() } noexcept;
  32 };
  33
  34 static_assert(IsStopPossibleNoexcept<std::stop_token>);
  35
  36 int main(int, char**) {
  37   // no state
  38   {
  39     const std::stop_token st;
  40     assert(!st.stop_possible());
  41   }
  42
  43   // a stop request was not made and there are no associated stop_source objects
  44   {
  45     std::optional<std::stop_source> ss{std::in_place};
  46     const auto st = ss->get_token();
  47     ss.reset();
  48
  49     assert(!st.stop_possible());
  50   }
  51
  52   // a stop request was not made, but there is an associated stop_source objects
  53   {
  54     std::stop_source ss;
  55     const auto st = ss.get_token();
  56     assert(st.stop_possible());
  57   }
  58
  59   // a stop request was made and there are no associated stop_source objects
  60   {
  61     std::optional<std::stop_source> ss{std::in_place};
  62     const auto st = ss->get_token();
  63     ss->request_stop();
  64     ss.reset();
  65
  66     assert(st.stop_possible());
  67   }
  68
  69   // a stop request was made and there is an associated stop_source objects
  70   {
  71     std::stop_source ss;
  72     const auto st = ss.get_token();
  73     ss.request_stop();
  74     assert(st.stop_possible());
  75   }
  76
  77   // a stop request was made on a different thread and
  78   // there are no associated stop_source objects
  79   {
  80     std::optional<std::stop_source> ss{std::in_place};
  81     const auto st = ss->get_token();
  82
  83     std::thread t = support::make_test_thread([&]() {
  84       ss->request_stop();
  85       ss.reset();
  86     });
  87
  88     assert(st.stop_possible());
  89     t.join();
  90     assert(st.stop_possible());
  91
  92   }
  93
  94   return 0;
  95 }