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/*
* Copyright (c) 2018, Cornell University
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* Neither the name of Cornell University nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Tuan Ta
*/
#include <pthread.h>
#include <atomic>
#include <cstdlib>
#include <iostream>
//------------------------------------------------------------------------
// Create n threads, run them in parallel and wait for them in the master
// thread.
// Each child thread increments a shared variable m times atomically
//------------------------------------------------------------------------
#define MAX_N_WORKER_THREADS 10
typedef struct
{
int nsteps;
std::atomic<int>* shared_var;
} ThreadArg;
void* func( void* args )
{
ThreadArg* my_args = ( ThreadArg* ) args;
int nsteps = my_args->nsteps;
std::atomic<int>* shared_var = my_args->shared_var;
for ( int i = 0; i < nsteps; ++i ) {
std::atomic_fetch_add(shared_var, 1);
}
return nullptr;
}
int main( int argc, const char* argv[] )
{
int n_worker_threads = 0;
// allocate all threads
pthread_t* threads = new pthread_t[MAX_N_WORKER_THREADS];
// variable shared among all threads
std::atomic<int> shared_var(0);
// number of steps each thread increments the shared_var
int nsteps = 1000;
// set up threads' arguments
ThreadArg* t_args = new ThreadArg[MAX_N_WORKER_THREADS];
int ret = 0;
for ( size_t tid = 0; tid < MAX_N_WORKER_THREADS; tid++ ){
t_args[tid].nsteps = nsteps;
t_args[tid].shared_var = &shared_var;
// spawn thread
ret = pthread_create( threads + tid, nullptr, func, &t_args[tid] );
if (ret != 0) {
break;
}
n_worker_threads++;
}
// sync up all threads
for ( int tid = 0; tid < n_worker_threads; ++tid ) {
pthread_join( threads[tid], nullptr );
}
// clean up
delete[] threads;
delete[] t_args;
// verify
if ( shared_var != n_worker_threads * nsteps || n_worker_threads < 1)
return EXIT_FAILURE;
return EXIT_SUCCESS;
}
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