/*
 * Copyright (c) 2008 Bret S. Lambert <blambert@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>

#define THREAD_COUNT 64

#define TEXT    "barnacles"
#define TEXT_N  "barnacles\n"

void    run_threads(void (*)(void *), void *);

static pthread_rwlock_t start;
static void     (*real_func)(void *);

static void *
thread(void *arg)
{
        int     r;

        if ((r = pthread_rwlock_rdlock(&start)))
                errc(1, r, "could not obtain lock in thread");
        real_func(arg);
        if ((r = pthread_rwlock_unlock(&start)))
                errc(1, r, "could not release lock in thread");
        return NULL;
}

void
run_threads(void (*func)(void *), void *arg)
{
        pthread_t       self, pthread[THREAD_COUNT];
        int     i, r;

        self = pthread_self();
        real_func = func;
        if ((r = pthread_rwlock_init(&start, NULL)))
                errc(1, r, "could not initialize lock");

        if ((r = pthread_rwlock_wrlock(&start)))                /* block */
                errc(1, r, "could not lock lock");

        for (i = 0; i < THREAD_COUNT; i++)
                if ((r = pthread_create(&pthread[i], NULL, thread, arg))) {
                        warnc(r, "could not create thread");
                        pthread[i] = self;
                }


        if ((r = pthread_rwlock_unlock(&start)))                /* unleash */
                errc(1, r, "could not release lock");

        sleep(1);

        if ((r = pthread_rwlock_wrlock(&start)))                /* sync */
                errx(1, "parent could not sync with children: %s",
                    strerror(r));

        for (i = 0; i < THREAD_COUNT; i++)
                if (! pthread_equal(pthread[i], self) &&
                    (r = pthread_join(pthread[i], NULL)))
                        warnc(r, "could not join thread");
}