/*
 * Copyright 2011 Samy Al Bahra.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <ck_bytelock.h>
#include <ck_spinlock.h>
#include <inttypes.h>
#include <stdio.h>

#include "../../common.h"

#ifndef STEPS 
#define STEPS 1000000
#endif

/*
 * This is a naive reader/writer spinlock.
 */
struct rwlock {
        unsigned int readers;
        ck_spinlock_fas_t writer;
};
typedef struct rwlock rwlock_t;

static CK_CC_INLINE void
rwlock_init(rwlock_t *rw)
{

        ck_pr_store_uint(&rw->readers, 0);
        ck_spinlock_fas_init(&rw->writer);
        return;
}

static CK_CC_INLINE void
rwlock_write_lock(rwlock_t *rw)
{

        ck_spinlock_fas_lock(&rw->writer);
        while (ck_pr_load_uint(&rw->readers) != 0)
                ck_pr_stall();

        return;
}

static CK_CC_INLINE void
rwlock_write_unlock(rwlock_t *rw)
{

        ck_spinlock_fas_unlock(&rw->writer);
        return;
}

static CK_CC_INLINE void
rwlock_read_lock(rwlock_t *rw)
{

        for (;;) {
                while (ck_pr_load_uint(&rw->writer.value) != 0)
                        ck_pr_stall();

                ck_pr_inc_uint(&rw->readers);
                if (ck_pr_load_uint(&rw->writer.value) == 0)
                        break;
                ck_pr_dec_uint(&rw->readers);
        }

        return;
}

static CK_CC_INLINE void
rwlock_read_unlock(rwlock_t *rw)
{

        ck_pr_dec_uint(&rw->readers);
        return;
}

int
main(void)
{
        uint64_t s_b, e_b, i;
        ck_bytelock_t bytelock = CK_BYTELOCK_INITIALIZER;
        rwlock_t naive;

        for (i = 0; i < STEPS; i++) {
                ck_bytelock_write_lock(&bytelock, 1);
                ck_bytelock_write_unlock(&bytelock);
        }

        s_b = rdtsc();
        for (i = 0; i < STEPS; i++) {
                ck_bytelock_write_lock(&bytelock, 1);
                ck_bytelock_write_unlock(&bytelock);
        }
        e_b = rdtsc();
        printf("WRITE: bytelock %15" PRIu64 "\n", (e_b - s_b) / STEPS);

        rwlock_init(&naive);
        for (i = 0; i < STEPS; i++) {
                rwlock_write_lock(&naive);
                rwlock_write_unlock(&naive);
        }

        s_b = rdtsc();
        for (i = 0; i < STEPS; i++) {
                rwlock_write_lock(&naive);
                rwlock_write_unlock(&naive);
        }
        e_b = rdtsc();
        printf("WRITE: naive    %15" PRIu64 "\n", (e_b - s_b) / STEPS);

        for (i = 0; i < STEPS; i++) {
                ck_bytelock_read_lock(&bytelock, 1);
                ck_bytelock_read_unlock(&bytelock, 1);
        }
        s_b = rdtsc();
        for (i = 0; i < STEPS; i++) {
                ck_bytelock_read_lock(&bytelock, 1);
                ck_bytelock_read_unlock(&bytelock, 1);
        }
        e_b = rdtsc();
        printf("READ:  bytelock %15" PRIu64 "\n", (e_b - s_b) / STEPS);

        for (i = 0; i < STEPS; i++) {
                rwlock_read_lock(&naive);
                rwlock_read_unlock(&naive);
        }

        s_b = rdtsc();
        for (i = 0; i < STEPS; i++) {
                rwlock_read_lock(&naive);
                rwlock_read_unlock(&naive);
        }
        e_b = rdtsc();
        printf("READ:  naive    %15" PRIu64 "\n", (e_b - s_b) / STEPS);

        return (0);
}