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/* Test of thread-local storage in multithreaded situations.
Copyright (C) 2005, 2008-2023 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 <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2005. */
#include <config.h>
#include <threads.h>
#ifdef thread_local
/* Whether to help the scheduler through explicit thrd_yield().
Uncomment this to see if the operating system has a fair scheduler. */
#define EXPLICIT_YIELD 1
/* Whether to print debugging messages. */
#define ENABLE_DEBUGGING 0
/* Number of simultaneous threads. */
#define THREAD_COUNT 16
/* Number of operations performed in each thread. */
#define REPEAT_COUNT 50000
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#if HAVE_DECL_ALARM
# include <signal.h>
# include <unistd.h>
#endif
#include "macros.h"
#if ENABLE_DEBUGGING
# define dbgprintf printf
#else
# define dbgprintf if (0) printf
#endif
#if EXPLICIT_YIELD
# define yield() thrd_yield ()
#else
# define yield()
#endif
/* Returns a reference to the current thread as a pointer, for debugging. */
#if defined __MVS__
/* On IBM z/OS, pthread_t is a struct with an 8-byte '__' field.
The first three bytes of this field appear to uniquely identify a
pthread_t, though not necessarily representing a pointer. */
# define thrd_current_pointer() (*((void **) thrd_current ().__))
#elif defined __sun
/* On Solaris, thrd_t is merely an 'unsigned int'. */
# define thrd_current_pointer() ((void *) (uintptr_t) thrd_current ())
#else
# define thrd_current_pointer() ((void *) thrd_current ())
#endif
static void
perhaps_yield (void)
{
/* Call yield () only with a certain probability, otherwise the
sequence of thread activations may be too predictable. */
if ((((unsigned int) rand () >> 3) % 4) == 0)
yield ();
}
/* ----------------------- Test thread-local storage ----------------------- */
#define KEYS_COUNT 4
static unsigned int thread_local value0;
static unsigned int thread_local value1;
static unsigned int thread_local value2;
static unsigned int thread_local value3;
static int
worker_thread (void *arg)
{
unsigned int id = (unsigned int) (uintptr_t) arg;
int i, j, repeat;
unsigned int *values[KEYS_COUNT] = { &value0, &value1, &value2, &value3 };
dbgprintf ("Worker %p started\n", thrd_current_pointer ());
/* Initialize the per-thread storage. */
dbgprintf ("Worker %p before first assignment\n", thrd_current_pointer ());
for (i = 0; i < KEYS_COUNT; i++)
{
*values[i] = (((unsigned int) rand () >> 3) % 1000000) * THREAD_COUNT + id;
/* Hopefully no arithmetic overflow. */
if ((*values[i] % THREAD_COUNT) != id)
abort ();
}
dbgprintf ("Worker %p after first assignment\n", thrd_current_pointer ());
perhaps_yield ();
/* Shuffle around the pointers. */
for (repeat = REPEAT_COUNT; repeat > 0; repeat--)
{
dbgprintf ("Worker %p doing value swapping\n", thrd_current_pointer ());
i = ((unsigned int) rand () >> 3) % KEYS_COUNT;
j = ((unsigned int) rand () >> 3) % KEYS_COUNT;
if (i != j)
{
unsigned int vi = *values[i];
unsigned int vj = *values[j];
*values[i] = vj;
*values[j] = vi;
}
perhaps_yield ();
}
/* Verify that all the values are from this thread. */
dbgprintf ("Worker %p before final verify\n", thrd_current_pointer ());
for (i = 0; i < KEYS_COUNT; i++)
if ((*values[i] % THREAD_COUNT) != id)
abort ();
dbgprintf ("Worker %p after final verify\n", thrd_current_pointer ());
perhaps_yield ();
dbgprintf ("Worker %p dying.\n", thrd_current_pointer ());
return 0;
}
static void
test_thread_local (void)
{
int pass, i;
for (pass = 0; pass < 2; pass++)
{
thrd_t threads[THREAD_COUNT];
/* Spawn the threads. */
for (i = 0; i < THREAD_COUNT; i++)
ASSERT (thrd_create (&threads[i], worker_thread, (void *) (uintptr_t) i)
== thrd_success);
/* Wait for the threads to terminate. */
for (i = 0; i < THREAD_COUNT; i++)
ASSERT (thrd_join (threads[i], NULL) == thrd_success);
}
}
/* -------------------------------------------------------------------------- */
int
main ()
{
#if HAVE_DECL_ALARM
/* Declare failure if test takes too long, by using default abort
caused by SIGALRM. */
int alarm_value = 600;
signal (SIGALRM, SIG_DFL);
alarm (alarm_value);
#endif
printf ("Starting test_thread_local ..."); fflush (stdout);
test_thread_local ();
printf (" OK\n"); fflush (stdout);
return 0;
}
#else
/* No thread-local storage support available in the compiler and linker. */
#include <stdio.h>
int
main ()
{
fputs ("Skipping test: thread_local not supported\n", stderr);
return 77;
}
#endif
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