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 and run them one after another
45// Each child thread writes its thread id to an output array
46//------------------------------------------------------------------------
47
48#define MAX_N_WORKER_THREADS 10
49
50typedef struct
51{
52    int tid;
53    int* output;
54} ThreadArg;
55
56void* func( void* args )
57{
58    ThreadArg* my_args = ( ThreadArg* ) args;
59
60    // write tid to this thread's output
61    (*my_args->output) = my_args->tid;
62
63    return nullptr;
64}
65
66int main( int argc, const char* argv[] )
67{
68    int n_worker_threads = 0;
69
70    // allocate all threads
71    pthread_t* threads = new pthread_t[MAX_N_WORKER_THREADS];
72    ThreadArg* t_args = new ThreadArg[MAX_N_WORKER_THREADS];
73
74    // create an output array for all threads
75    int* outputs = new int[MAX_N_WORKER_THREADS];
76    int ret;
77
78    // try to spawn as many worker threads as possible
79    for ( int tid = 0; tid < MAX_N_WORKER_THREADS; ++tid ) {
80
81        // set up thread args
82        t_args[tid].tid = tid;
83        t_args[tid].output = outputs + tid;
84
85        // spawn thread
86        ret = pthread_create( threads + tid, nullptr, func, &t_args[tid] );
87        if (ret != 0 ) {
88            break;
89        }
90
91        n_worker_threads++;
92
93        // wait for the thread to join before moving on
94        pthread_join( threads[tid], nullptr );
95    }
96
97    // verify
98    bool passed = true;
99    for ( int i = 0; i < n_worker_threads; ++i ) {
100        if ( outputs[i] != i ) {
101            passed = false;
102            break;
103        }
104    }
105
106    // clean up
107    delete[] threads;
108    delete[] t_args;
109    delete[] outputs;
110
111    // failed if outputs are not correct or no worker thread was spawned
112    if (!passed || n_worker_threads < 1)
113        return EXIT_FAILURE;
114
115    return EXIT_SUCCESS;
116}
117