Step_2_Appendix.md

Step 2 Appendix

Intial Prompt

2. Implement c++11 threading example

   2-3 threads running

Parsing prompt:

Uncertain what "threading example" means. Perhaps refering to an included document? Perhaps means to create my own toy example to test class from Step 1. If so, then Step 3 is meat of what this is getting at, so going to parse through that first and come back to this.

Upon reading through Step 3, it does not appear to be related to this Testbench, so I infer that I simply need to make my Testbench threadable with up to 3 threads.

Coding

Added a define statement to the Testbench to dictate number of threads.

// constructing lock_guard with adopt_lock
// NOTE: needs to be compiled with flag -pthread.
// SOURCE: http://www.cplusplus.com/reference/mutex/lock_guard/

#include <iostream>       // std::cout
#include <thread>         // std::thread
#include <mutex>          // std::mutex, std::adopt_lock
#include "LockGuard.h"    // chal::LockGuard

#define THREAD_NUM 3

std::mutex mtx;           // mutex for critical section

void print_thread_id (int id) {
    mtx.lock();
    //std::lock_guard<std::mutex> lck (mtx, std::adopt_lock);
    chal::LockGuard<std::mutex> lck (mtx, std::adopt_lock);

    std::cout << "thread #" << id << '\n';
}

int main ()
{
    std::thread threads[THREAD_NUM]; //creates an array of THREAD_NUM number of thread objects
    // spawn THREAD_NUM threads:
    for (int i=0; i<THREAD_NUM; ++i)
        threads[i] = std::thread(print_thread_id,i+1);

    for (auto& th : threads) th.join();

    return 0;
}