libstdc++-v3/testsuite/18_support/pthread_guard.cc

   1 //
   2 // Copyright (C) 2007-2014 Free Software Foundation, Inc.
   3 //
   4 // This file is part of the GNU ISO C++ Library.  This library is free
   5 // software; you can redistribute it and/or modify it under the
   6 // terms of the GNU General Public License as published by the
   7 // Free Software Foundation; either version 3, or (at your option)
   8 // any later version.
   9 //
  10 // This library is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU General Public License along
  16 // with this library; see the file COPYING3.  If not see
  17 // <http://www.gnu.org/licenses/>.
  18
  19 // { dg-do run { target *-*-freebsd* *-*-dragonfly* *-*-netbsd* *-*-linux* *-*-gnu* *-*-solaris* *-*-cygwin *-*-darwin* } }
  20 // { dg-options "-pthread" { target *-*-freebsd* *-*-dragonfly* *-*-netbsd* *-*-linux* *-*-gnu* *-*-solaris* *-*-darwin* } }
  21
  22 #include <cstdlib>
  23 #include <pthread.h>
  24
  25 // This used to deadlock with the old libstdc++ because there is only one
  26 // global mutex guarding initialization of statics and it is held during by
  27 // the initializer thread of a static until the variable is completely
  28 // initialized. If the initializer thread creates and waits for another thread
  29 // which also initializes a static variable, there will be a deadlock because
  30 // the first thread is holding the mutex and waiting for the second thread,
  31 // which is blocked when it is acquiring the mutex.
  32
  33 int
  34 get_bar (void)
  35 {
  36   return 1;
  37 }
  38
  39 void*
  40 do_something (void *arg)
  41 {
  42   static int bar __attribute__((unused)) = get_bar ();
  43   return 0;
  44 }
  45
  46 int
  47 get_foo (void)
  48 {
  49   pthread_t new_thread;
  50
  51   if (pthread_create (&new_thread, 0, do_something, 0) != 0)
  52     std::abort ();
  53
  54   if (pthread_join (new_thread, 0) != 0)
  55     std::abort ();
  56
  57   return 1;
  58 }
  59
  60 int
  61 main (int argc, char **argv)
  62 {
  63   static int foo __attribute__((unused)) = get_foo ();
  64   return 0;
  65 }