libstdc++-v3/testsuite/30_threads/call_once/39909.cc

   1 // { dg-do run { target c++11 } }
   2 // { dg-additional-options "-pthread" { target pthread } }
   3 // { dg-require-gthreads "" }
   4
   5 // Copyright (C) 2009-2024 Free Software Foundation, Inc.
   6 //
   7 // This file is part of the GNU ISO C++ Library.  This library is free
   8 // software; you can redistribute it and/or modify it under the
   9 // terms of the GNU General Public License as published by the
  10 // Free Software Foundation; either version 3, or (at your option)
  11 // any later version.
  12
  13 // This library is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License along
  19 // with this library; see the file COPYING3.  If not see
  20 // <http://www.gnu.org/licenses/>.
  21
  22
  23 #include <mutex>
  24 #include <thread>
  25 #include <testsuite_hooks.h>
  26
  27 std::once_flag flag;
  28 int value = 0;
  29
  30 struct Inc { void operator()() const { ++value; } };
  31
  32 struct Func
  33 {
  34    void operator()() const
  35    {
  36        Inc inc;
  37        for (int i = 0; i < 10000;  ++i)
  38            std::call_once(flag, inc);
  39    }
  40 };
  41
  42 int main()
  43 {
  44    Func f;
  45    std::thread t1(f);
  46    std::thread t2(f);
  47    std::thread t3(f);
  48    t1.join();
  49    t2.join();
  50    t3.join();
  51    VERIFY( value == 1 );
  52    return 0;
  53 }