libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.member/detach.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
  11 // <thread>
  12
  13 // class thread
  14
  15 // void detach();
  16
  17 #include <thread>
  18 #include <atomic>
  19 #include <system_error>
  20 #include <cassert>
  21
  22 #include "make_test_thread.h"
  23 #include "test_macros.h"
  24
  25 std::atomic_bool done(false);
  26
  27 class G
  28 {
  29     int alive_;
  30     bool done_;
  31 public:
  32     static int n_alive;
  33     static bool op_run;
  34
  35     G() : alive_(1), done_(false)
  36     {
  37         ++n_alive;
  38     }
  39
  40     G(const G& g) : alive_(g.alive_), done_(false)
  41     {
  42         ++n_alive;
  43     }
  44     ~G()
  45     {
  46         alive_ = 0;
  47         --n_alive;
  48         if (done_) done = true;
  49     }
  50
  51     void operator()()
  52     {
  53         assert(alive_ == 1);
  54         assert(n_alive >= 1);
  55         op_run = true;
  56         done_ = true;
  57     }
  58 };
  59
  60 int G::n_alive = 0;
  61 bool G::op_run = false;
  62
  63 void foo() { done = true; }
  64
  65 int main(int, char**)
  66 {
  67     {
  68         G g;
  69         std::thread t0 = support::make_test_thread(g);
  70         assert(t0.joinable());
  71         t0.detach();
  72         assert(!t0.joinable());
  73         while (!done) {}
  74         assert(G::op_run);
  75         assert(G::n_alive == 1);
  76     }
  77     assert(G::n_alive == 0);
  78     done = false;
  79 #ifndef TEST_HAS_NO_EXCEPTIONS
  80     {
  81         std::thread t0 = support::make_test_thread(foo);
  82         assert(t0.joinable());
  83         t0.detach();
  84         assert(!t0.joinable());
  85         try {
  86             t0.detach();
  87         } catch (std::system_error const&) {
  88         }
  89         // Wait to make sure that the detached thread has started up.
  90         // Without this, we could exit main and start destructing global
  91         // resources that are needed when the thread starts up, while the
  92         // detached thread would start up only later.
  93         while (!done) {}
  94     }
  95 #endif
  96
  97   return 0;
  98 }