tests/test-progs/pthread/src/test_atomic.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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  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.
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  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
  36   */
  37
  38 #include <pthread.h>
  39
  40 #include <atomic>
  41 #include <cstdlib>
  42 #include <iostream>
  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 atomically
  48 //------------------------------------------------------------------------
  49
  50 #define MAX_N_WORKER_THREADS 10
  51
  52 typedef struct
  53 {
  54     int nsteps;
  55     std::atomic<int>* shared_var;
  56 } ThreadArg;
  57
  58 void* func( void* args )
  59 {
  60     ThreadArg* my_args = ( ThreadArg* ) args;
  61
  62     int nsteps = my_args->nsteps;
  63     std::atomic<int>* shared_var = my_args->shared_var;
  64
  65     for ( int i = 0; i < nsteps; ++i ) {
  66         std::atomic_fetch_add(shared_var, 1);
  67     }
  68
  69     return nullptr;
  70 }
  71
  72 int main( int argc, const char* argv[] )
  73 {
  74     int n_worker_threads = 0;
  75
  76     // allocate all threads
  77     pthread_t* threads = new pthread_t[MAX_N_WORKER_THREADS];
  78
  79     // variable shared among all threads
  80     std::atomic<int> shared_var(0);
  81
  82     // number of steps each thread increments the shared_var
  83     int nsteps = 1000;
  84
  85     // set up threads' arguments
  86     ThreadArg* t_args = new ThreadArg[MAX_N_WORKER_THREADS];
  87
  88     int ret = 0;
  89     for ( size_t tid = 0; tid < MAX_N_WORKER_THREADS; tid++ ){
  90         t_args[tid].nsteps = nsteps;
  91         t_args[tid].shared_var = &shared_var;
  92
  93         // spawn thread
  94         ret = pthread_create( threads + tid, nullptr, func, &t_args[tid] );
  95
  96         if (ret != 0) {
  97             break;
  98         }
  99
 100         n_worker_threads++;
 101     }
 102
 103     // sync up all threads
 104     for ( int tid = 0; tid < n_worker_threads; ++tid ) {
 105         pthread_join( threads[tid], nullptr );
 106     }
 107
 108     // clean up
 109     delete[] threads;
 110     delete[] t_args;
 111
 112     // verify
 113     if ( shared_var != n_worker_threads * nsteps || n_worker_threads < 1)
 114         return EXIT_FAILURE;
 115
 116     return EXIT_SUCCESS;
 117 }