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
7  * conditions are met:
8  *
9  * Redistributions of source code must retain the above copyright
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.
16  *
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
33  * POSSIBILITY OF SUCH DAMAGE.
34  *
35  * Authors: Tuan Ta
36  */
37
38#include <pthread.h>
39
40#include <cstdlib>
41#include <iostream>
42
43//------------------------------------------------------------------------
44// Create n threads, run them in parallel and wait for them in the master
45// thread.
46// Each child thread writes its thread id to an output array
47//------------------------------------------------------------------------
48
49#define MAX_N_WORKER_THREADS 10
50
51typedef struct
52{
53    int tid;
54    int* output;
55} ThreadArg;
56
57void* func( void* args )
58{
59    ThreadArg* my_args = ( ThreadArg* ) args;
60
61    // write tid to this thread's output
62    (*my_args->output) = my_args->tid;
63
64    return nullptr;
65}
66
67int main( int argc, const char* argv[] )
68{
69    int n_worker_threads = 0;
70
71    // allocate all threads
72    pthread_t* threads = new pthread_t[MAX_N_WORKER_THREADS];
73    ThreadArg* t_args = new ThreadArg[MAX_N_WORKER_THREADS];
74
75    // create an output array for all threads
76    int* outputs = new int[MAX_N_WORKER_THREADS];
77    int ret;
78
79    // try to spawn as many worker threads as possible
80    for ( int tid = 0; tid < MAX_N_WORKER_THREADS; ++tid ) {
81
82        // set up thread args
83        t_args[tid].tid = tid;
84        t_args[tid].output = outputs + tid;
85
86        // spawn thread
87        ret = pthread_create( threads + tid, nullptr, func, &t_args[tid] );
88        if (ret != 0) {
89            break;
90        }
91
92        n_worker_threads++;
93    }
94
95    // sync up all threads
96    for ( int tid = 0; tid < n_worker_threads; ++tid ) {
97        pthread_join( threads[tid], nullptr );
98    }
99
100    // verify
101    bool passed = true;
102    for ( int i = 0; i < n_worker_threads; ++i ) {
103        if ( outputs[i] != i ) {
104            passed = false;
105        }
106    }
107
108    // clean up
109    delete[] threads;
110    delete[] t_args;
111    delete[] outputs;
112
113    // failed if outputs are not correct or no worker thread was spawned
114    if (!passed || n_worker_threads < 1)
115        return EXIT_FAILURE;
116
117    return EXIT_SUCCESS;
118}
119