1/*
2  * Copyright (c) 2018, Cornell University
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35  * Authors: Moyang Wang
36  */
37
38#include <condition_variable>
39#include <iostream>
40#include <mutex>
41#include <thread>
42#include <vector>
43
44//------------------------------------------------------------------------
45// Test std::condition_variable
46//------------------------------------------------------------------------
47// The master thread creates N threads, each of which waits on a
48// condition variable of a signal to start. The master thread then set
49// the signal and notifies all other threads to begin.
50
51#define MAX_N_WORKER_THREADS 10
52
53std::mutex mtx;
54std::condition_variable cv;
55bool ready = false;
56
57void print_id( size_t id )
58{
59    std::unique_lock<std::mutex> lck(mtx);
60    while (!ready)
61        cv.wait(lck);
62    // ...
63    std::cout << "thread " << id << '\n';
64}
65
66void go()
67{
68    std::unique_lock<std::mutex> lck(mtx);
69    ready = true;
70    cv.notify_all();
71}
72
73int main( int argc, char* argv[] )
74{
75    size_t n_worker_threads = 0;
76
77    std::vector< std::thread > threads;
78
79    for ( size_t i = 0; i < MAX_N_WORKER_THREADS; i++ ) {
80        try {
81            threads.push_back( std::thread( print_id, i ) );
82        } catch ( const std::system_error& err ) {
83            break;
84        }
85        n_worker_threads++;
86    }
87
88    std::cout << n_worker_threads << " threads ready to race...\n";
89    go();                       // go!
90
91    for (int i = 0; i < n_worker_threads; ++i) {
92        threads[i].join();
93    }
94
95    // if there is no timeout (i.e., threads are all waken up properly, this
96    // test always succeeds)
97    return EXIT_SUCCESS;
98}
99