libcxx/test/std/thread/thread.condition/thread.condition.condvarany/notify_all.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 // <condition_variable>
  12
  13 // class condition_variable_any;
  14
  15 // void notify_all();
  16
  17 #include <condition_variable>
  18 #include <mutex>
  19 #include <thread>
  20 #include <vector>
  21 #include <atomic>
  22 #include <cassert>
  23
  24 #include "make_test_thread.h"
  25 #include "test_macros.h"
  26
  27 std::condition_variable_any cv;
  28
  29 typedef std::timed_mutex L0;
  30 typedef std::unique_lock<L0> L1;
  31
  32 L0 m0;
  33
  34 const unsigned threadCount = 2;
  35 bool pleaseExit = false;
  36 std::atomic<unsigned> notReady;
  37
  38 void helper() {
  39   L1 lk(m0);
  40   --notReady;
  41   while (pleaseExit == false)
  42     cv.wait(lk);
  43 }
  44
  45 int main(int, char**)
  46 {
  47   notReady = threadCount;
  48   std::vector<std::thread> threads(threadCount);
  49   for (unsigned i = 0; i < threadCount; i++)
  50     threads[i] = support::make_test_thread(helper);
  51   {
  52     while (notReady > 0)
  53       std::this_thread::yield();
  54     // At this point, both threads have had a chance to acquire the lock and are
  55     // either waiting on the condition variable or about to wait.
  56     L1 lk(m0);
  57     pleaseExit = true;
  58     // POSIX does not guarantee reliable scheduling if notify_all is called
  59     // without the lock being held.
  60     cv.notify_all();
  61   }
  62   // The test will hang if not all of the threads were woken.
  63   for (unsigned i = 0; i < threadCount; i++)
  64     threads[i].join();
  65
  66   return 0;
  67 }