libstdc++-v3/testsuite/23_containers/vector/debug/multithreaded_swap.cc

   1 // { dg-do run }
   2 // { dg-options "-pthread"  }
   3 // { dg-require-effective-target c++11 }
   4 // { dg-require-effective-target pthread }
   5 // { dg-require-gthreads "" }
   6 // { dg-require-debug-mode "" }
   7 // Copyright (C) 2010-2025 Free Software Foundation, Inc.
   8 //
   9 // This file is part of the GNU ISO C++ Library.  This library is free
  10 // software; you can redistribute it and/or modify it under the
  11 // terms of the GNU General Public License as published by the
  12 // Free Software Foundation; either version 3, or (at your option)
  13 // any later version.
  14 //
  15 // This library is distributed in the hope that it will be useful,
  16 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 // GNU General Public License for more details.
  19 //
  20 // You should have received a copy of the GNU General Public License along
  21 // with this library; see the file COPYING3.  If not see
  22 // <http://www.gnu.org/licenses/>.
  23 //
  24
  25 // This test check for potential deadlock when swaping sequences in debug
  26 // mode as it requires acquiring 2 locks at the same time.
  27
  28 #include <vector>
  29 #include <memory>
  30 #include <thread>
  31 #include <functional>
  32 #include <testsuite_hooks.h>
  33
  34 // The following function mimic the one in src/debug.cc to associate a mutex
  35 // to a given safe sequence instance.
  36 size_t
  37 get_index(std::vector<int>& v)
  38 {
  39   const size_t mask = 0xf;
  40   // We have to check the address of the internal safe sequence that starts
  41   // after the normal vector memory footprint that is to say a 3 pointers
  42   // offset:
  43   void* __address = reinterpret_cast<char*>(&v) + 3 * sizeof(void*);
  44   return std::_Hash_impl::hash(__address) & mask;
  45 }
  46
  47 void test01()
  48 {
  49   using namespace std;
  50   vector<int> v1, v2;
  51   vector<shared_ptr<vector<int> > > vs;
  52   vector<int> *pv3 = 0, *pv4 = 0;
  53   const int nb_attempts = 100;
  54   for (int i = 0; i != nb_attempts; ++i)
  55     {
  56       vs.push_back(shared_ptr<vector<int> >(new vector<int>()));
  57       if (!pv3)
  58         {
  59           if (get_index(*vs.back()) == get_index(v1))
  60             pv3 = vs.back().get();
  61         }
  62       else if (!pv4)
  63         {
  64           if (get_index(*vs.back()) == get_index(v2))
  65             {
  66               pv4 = vs.back().get();
  67               break;
  68             }
  69         }
  70     }
  71
  72   if (!pv3 || !pv4)
  73     // Maybe an other time...
  74     return;
  75
  76   vector<int> &v3 = *pv3, &v4 = *pv4;
  77
  78   // v1 and v3 shares the same mutex instance, like v2 and v4
  79   // thread t1 lock v1 and v2
  80   thread t1([&v1, &v2]()
  81     {
  82       for (int i = 0; i != 1000; ++i)
  83         v1.swap(v2);
  84     });
  85   // thread t2 lock v4 and v3
  86   thread t2([&v3, &v4]()
  87     {
  88       for (int i = 0; i != 1000; ++i)
  89         v4.swap(v3);
  90     });
  91   t2.join();
  92   t1.join();
  93 }
  94
  95 int main()
  96 {
  97   test01();
  98   return 0;
  99 }