libstdc++-v3/testsuite/30_threads/try_lock/4.cc

   1 // { dg-do run }
   2 // { dg-additional-options "-pthread" { target pthread } }
   3 // { dg-require-effective-target c++11 }
   4 // { dg-require-gthreads "" }
   5
   6 // Copyright (C) 2010-2021 Free Software Foundation, Inc.
   7 //
   8 // This file is part of the GNU ISO C++ Library.  This library is free
   9 // software; you can redistribute it and/or modify it under the
  10 // terms of the GNU General Public License as published by the
  11 // Free Software Foundation; either version 3, or (at your option)
  12 // any later version.
  13
  14 // This library is distributed in the hope that it will be useful,
  15 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 // GNU General Public License for more details.
  18
  19 // You should have received a copy of the GNU General Public License along
  20 // with this library; see the file COPYING3.  If not see
  21 // <http://www.gnu.org/licenses/>.
  22
  23
  24 #include <mutex>
  25 #include <testsuite_hooks.h>
  26
  27 struct unreliable_lock
  28 {
  29   std::mutex m;
  30   std::unique_lock<std::mutex> l;
  31
  32   static int count;
  33   static int throw_on;
  34   static int lock_on;
  35
  36   unreliable_lock() : l(m, std::defer_lock) { }
  37
  38   ~unreliable_lock()
  39   {
  40     VERIFY( !l.owns_lock() );
  41   }
  42
  43   void lock()
  44   {
  45     if (count == throw_on)
  46       throw throw_on;
  47     ++count;
  48     l.lock();
  49   }
  50   bool try_lock()
  51   {
  52     if (count == throw_on)
  53       throw throw_on;
  54     std::unique_lock<std::mutex> l2(m, std::defer_lock);
  55     if (count == lock_on)
  56       l2.lock();
  57     ++count;
  58     return l.try_lock();
  59   }
  60
  61   void unlock()
  62   {
  63     VERIFY( l.owns_lock() );
  64     l.unlock();
  65   }
  66
  67 };
  68
  69 int unreliable_lock::count = 0;
  70 int unreliable_lock::throw_on = -1;
  71 int unreliable_lock::lock_on = -1;
  72
  73 void test01()
  74 {
  75   unreliable_lock l1, l2, l3;
  76
  77   try
  78     {
  79       unreliable_lock::count = 0;
  80       int result = std::try_lock(l1, l2, l3);
  81       VERIFY( result == -1 );
  82       VERIFY( unreliable_lock::count == 3 );
  83       l1.unlock();
  84       l2.unlock();
  85       l3.unlock();
  86     }
  87   catch (...)
  88     {
  89       VERIFY( false );
  90     }
  91 }
  92
  93 void test02()
  94 {
  95   unreliable_lock l1, l2, l3;
  96
  97   try
  98     {
  99       // test behaviour when a lock is already held
 100       unreliable_lock::lock_on = 0;
 101       while (unreliable_lock::lock_on < 3)
 102       {
 103         unreliable_lock::count = 0;
 104         int failed = std::try_lock(l1, l2, l3);
 105         VERIFY( failed == unreliable_lock::lock_on );
 106         ++unreliable_lock::lock_on;
 107       }
 108     }
 109   catch (...)
 110     {
 111       VERIFY( false );
 112     }
 113 }
 114
 115 void test03()
 116 {
 117   unreliable_lock l1, l2, l3;
 118
 119   try
 120     {
 121       // test behaviour when an exception is thrown
 122       unreliable_lock::throw_on = 0;
 123       while (unreliable_lock::throw_on < 3)
 124       {
 125         unreliable_lock::count = 0;
 126         try
 127           {
 128             std::try_lock(l1, l2, l3);
 129             VERIFY( false );
 130           }
 131         catch (int e)
 132           {
 133             VERIFY( e == unreliable_lock::throw_on );
 134           }
 135         ++unreliable_lock::throw_on;
 136       }
 137     }
 138   catch (...)
 139     {
 140       VERIFY( false );
 141     }
 142 }
 143
 144 int main()
 145 {
 146   test01();
 147   test02();
 148   test03();
 149   return 0;
 150 }