| /* |
| * 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. |
| */ |
| |
| #include <cstdlib> |
| #include <iostream> |
| #include <mutex> |
| #include <thread> |
| #include <vector> |
| |
| //------------------------------------------------------------------------ |
| // Create n threads, run them in parallel and wait for them in the master |
| // thread. |
| // Each child thread increments a shared variable m times |
| //------------------------------------------------------------------------ |
| |
| #define MAX_N_WORKER_THREADS 10 |
| |
| int main() |
| { |
| int n_worker_threads = 0; |
| |
| // allocate all threads |
| std::vector< std::thread > threads; |
| |
| // mutex to protect the shared variable |
| std::mutex my_mutex; |
| |
| // variable shared among all threads |
| int shared_var = 0; |
| |
| // number of steps each thread increments the shared_var |
| int nsteps = 1000; |
| |
| for ( int tid = 0; tid < MAX_N_WORKER_THREADS; ++tid ) { |
| try { |
| threads.push_back( std::thread( [&] { |
| std::lock_guard<std::mutex> guard(my_mutex); |
| for ( int i = 0; i < nsteps; ++i ) |
| shared_var++; |
| } ) ); |
| } catch ( const std::system_error& err ) { |
| break; |
| } |
| n_worker_threads++; |
| } |
| |
| // sync up all threads |
| for (int i = 0; i < n_worker_threads; ++i) { |
| threads[i].join(); |
| } |
| |
| // verify |
| if ( shared_var != n_worker_threads * nsteps || n_worker_threads < 1) { |
| return EXIT_FAILURE; |
| } |
| |
| return EXIT_SUCCESS; |
| } |