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/* This testcase is part of GDB, the GNU debugger.
Copyright 2018-2020 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
/* This defines the number of threads to spawn. */
#define THREADCOUNT 4
/* Global barrier type to control synchronization between threads. */
static pthread_barrier_t print_barrier;
/* Define global thread identifiers. */
static pthread_t threads[THREADCOUNT];
/* Hold values for each thread at the index supplied to the thread
on creation. */
static int thread_ids[THREADCOUNT];
/* Find the value associated with the calling thread. */
static int
get_value ()
{
for (int tid = 0; tid < THREADCOUNT; ++tid)
{
if (pthread_equal (threads[tid], pthread_self ()))
return thread_ids[tid];
}
/* Value for the main thread. */
return 1;
}
/* Return the nth Fibonacci number. */
static unsigned long
fast_fib (unsigned int n)
{
int a = 0;
int b = 1;
int t;
for (unsigned int i = 0; i < n; ++i)
{
t = b;
b = a + b;
a = t;
}
return a;
}
/* Encapsulate the synchronization of the threads. Perform a barrier before
and after the computation. */
static void *
thread_function (void *args)
{
int tid = *((int *) args);
int status = pthread_barrier_wait (&print_barrier);
if (status == PTHREAD_BARRIER_SERIAL_THREAD)
printf ("All threads entering compute region\n");
unsigned long result = fast_fib (100); /* testmarker01 */
status = pthread_barrier_wait (&print_barrier);
if (status == PTHREAD_BARRIER_SERIAL_THREAD)
printf ("All threads outputting results\n");
pthread_barrier_wait (&print_barrier);
printf ("Thread %d Result: %lu\n", tid, result);
}
int
main (void)
{
int err = pthread_barrier_init (&print_barrier, NULL, THREADCOUNT);
if (err != 0)
{
fprintf (stderr, "Barrier creation failed\n");
return EXIT_FAILURE;
}
/* Create the worker threads (main). */
printf ("Spawning worker threads\n");
for (int tid = 0; tid < THREADCOUNT; ++tid)
{
/* Add 2 so the value maps to the debugger's thread identifiers. */
thread_ids[tid] = tid + 2; /* prethreadcreationmarker */
err = pthread_create (&threads[tid], NULL, thread_function,
(void *) &thread_ids[tid]);
if (err != 0)
{
fprintf (stderr, "Thread creation failed\n");
return EXIT_FAILURE;
}
}
/* Wait for the threads to complete then exit. */
for (int tid = 0; tid < THREADCOUNT; ++tid)
pthread_join (threads[tid], NULL);
return EXIT_SUCCESS;
}
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