tests/test-progs/pthread/src/test_std_mutex.cpp

   1 /*
   2   * Copyright (c) 2018, Cornell University
   3   * All rights reserved.
   4   *
   5   * Redistribution and use in source and binary forms, with or
   6   * without modification, are permitted provided that the following
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   9   * Redistributions of source code must retain the above copyright
  10   * notice, this list of conditions and the following disclaimer.
  11   *
  12   * Redistributions in binary form must reproduce the above
  13   * copyright notice, this list of conditions and the following
  14   * disclaimer in the documentation and/or other materials provided
  15   * with the distribution.
  16   *
  17   * Neither the name of Cornell University nor the names of its
  18   * contributors may be used to endorse or promote products derived
  19   * from this software without specific prior written permission.
  20   *
  21   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  22   * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  23   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  24   * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  25   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
  26   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  27   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  28   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  29   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  30   * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  32   * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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  34   *
  35   * Authors: Tuan Ta, Moyang Wang
  36   */
  37
  38 #include <cstdlib>
  39 #include <iostream>
  40 #include <mutex>
  41 #include <thread>
  42 #include <vector>
  43
  44 //------------------------------------------------------------------------
  45 // Create n threads, run them in parallel and wait for them in the master
  46 // thread.
  47 // Each child thread increments a shared variable m times
  48 //------------------------------------------------------------------------
  49
  50 #define MAX_N_WORKER_THREADS 10
  51
  52 int main( int argc, const char* argv[] )
  53 {
  54     int n_worker_threads = 0;
  55
  56     // allocate all threads
  57     std::vector< std::thread > threads;
  58
  59     // mutex to protect the shared variable
  60     std::mutex my_mutex;
  61
  62     // variable shared among all threads
  63     int shared_var = 0;
  64
  65     // number of steps each thread increments the shared_var
  66     int nsteps = 1000;
  67
  68     for ( int tid = 0; tid < MAX_N_WORKER_THREADS; ++tid ) {
  69         try {
  70             threads.push_back( std::thread( [&] {
  71                         std::lock_guard<std::mutex> guard(my_mutex);
  72                         for ( int i = 0; i < nsteps; ++i )
  73                             shared_var++;
  74                     } ) );
  75         } catch ( const std::system_error& err ) {
  76             break;
  77         }
  78         n_worker_threads++;
  79     }
  80
  81     // sync up all threads
  82     for (int i = 0; i < n_worker_threads; ++i) {
  83         threads[i].join();
  84     }
  85
  86     // verify
  87     if ( shared_var != n_worker_threads * nsteps || n_worker_threads < 1) {
  88         return EXIT_FAILURE;
  89     }
  90
  91     return EXIT_SUCCESS;
  92 }