libcxx/test/std/thread/thread.mutex/thread.once/thread.once.callonce/race.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 // <mutex>
  12
  13 // struct once_flag;
  14
  15 // template<class Callable, class ...Args>
  16 //   void call_once(once_flag& flag, Callable&& func, Args&&... args);
  17
  18 // This test is supposed to be run with ThreadSanitizer and verifies that
  19 // call_once properly synchronizes user state, a data race that was fixed
  20 // in r280621.
  21
  22 #include <mutex>
  23 #include <thread>
  24 #include <cassert>
  25
  26 #include "make_test_thread.h"
  27 #include "test_macros.h"
  28
  29 std::once_flag flg0;
  30 long global = 0;
  31
  32 void init0()
  33 {
  34     ++global;
  35 }
  36
  37 void f0()
  38 {
  39     std::call_once(flg0, init0);
  40     assert(global == 1);
  41 }
  42
  43 int main(int, char**)
  44 {
  45     std::thread t0 = support::make_test_thread(f0);
  46     std::thread t1 = support::make_test_thread(f0);
  47     t0.join();
  48     t1.join();
  49     assert(global == 1);
  50
  51   return 0;
  52 }