/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2010 David Xu <davidxu@freebsd.org>
 * 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 unmodified, 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 ``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 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 <stdlib.h>
#include "thr_private.h"

#define HASHSHIFT       9
#define HASHSIZE        (1 << HASHSHIFT)
#define SC_HASH(wchan) ((unsigned)                              \
        ((((uintptr_t)(wchan) >> 3)                             \
        ^ ((uintptr_t)(wchan) >> (HASHSHIFT + 3)))              \
        & (HASHSIZE - 1)))
#define SC_LOOKUP(wc)   &sc_table[SC_HASH(wc)]

struct sleepqueue_chain {
        struct umutex           sc_lock;
        int                     sc_enqcnt;
        LIST_HEAD(, sleepqueue) sc_queues;
        int                     sc_type;
};

static struct sleepqueue_chain  sc_table[HASHSIZE];

void
_sleepq_init(void)
{
        int     i;

        for (i = 0; i < HASHSIZE; ++i) {
                LIST_INIT(&sc_table[i].sc_queues);
                _thr_umutex_init(&sc_table[i].sc_lock);
        }
}

struct sleepqueue *
_sleepq_alloc(void)
{
        struct sleepqueue *sq;

        sq = __thr_calloc(1, sizeof(struct sleepqueue));
        TAILQ_INIT(&sq->sq_blocked);
        SLIST_INIT(&sq->sq_freeq);
        return (sq);
}

void
_sleepq_free(struct sleepqueue *sq)
{
        __thr_free(sq);
}

void
_sleepq_lock(void *wchan)
{
        struct pthread *curthread = _get_curthread();
        struct sleepqueue_chain *sc;

        sc = SC_LOOKUP(wchan);
        THR_LOCK_ACQUIRE_SPIN(curthread, &sc->sc_lock);
}

void
_sleepq_unlock(void *wchan)
{
        struct sleepqueue_chain *sc;
        struct pthread *curthread = _get_curthread();
                    
        sc = SC_LOOKUP(wchan);
        THR_LOCK_RELEASE(curthread, &sc->sc_lock);
}

static inline struct sleepqueue *
lookup(struct sleepqueue_chain *sc, void *wchan)
{
        struct sleepqueue *sq;

        LIST_FOREACH(sq, &sc->sc_queues, sq_hash)
                if (sq->sq_wchan == wchan)
                        return (sq);
        return (NULL);
}

struct sleepqueue *
_sleepq_lookup(void *wchan)
{
        return (lookup(SC_LOOKUP(wchan), wchan));
}

void
_sleepq_add(void *wchan, struct pthread *td)
{
        struct sleepqueue_chain *sc;
        struct sleepqueue *sq;

        sc = SC_LOOKUP(wchan);
        sq = lookup(sc, wchan);
        if (sq != NULL) {
                SLIST_INSERT_HEAD(&sq->sq_freeq, td->sleepqueue, sq_flink);
        } else {
                sq = td->sleepqueue;
                LIST_INSERT_HEAD(&sc->sc_queues, sq, sq_hash);
                sq->sq_wchan = wchan;
                /* sq->sq_type = type; */
        }
        td->sleepqueue = NULL;
        td->wchan = wchan;
        if (((++sc->sc_enqcnt << _thr_queuefifo) & 0xff) != 0)
                TAILQ_INSERT_HEAD(&sq->sq_blocked, td, wle);
        else
                TAILQ_INSERT_TAIL(&sq->sq_blocked, td, wle);
}

int
_sleepq_remove(struct sleepqueue *sq, struct pthread *td)
{
        int rc;

        TAILQ_REMOVE(&sq->sq_blocked, td, wle);
        if (TAILQ_EMPTY(&sq->sq_blocked)) {
                LIST_REMOVE(sq, sq_hash);
                td->sleepqueue = sq;
                rc = 0;
        } else {
                td->sleepqueue = SLIST_FIRST(&sq->sq_freeq);
                SLIST_REMOVE_HEAD(&sq->sq_freeq, sq_flink);
                rc = 1;
        }
        td->wchan = NULL;
        return (rc);
}

void
_sleepq_drop(struct sleepqueue *sq,
        void (*cb)(struct pthread *, void *arg), void *arg)
{
        struct pthread *td;
        struct sleepqueue *sq2;

        td = TAILQ_FIRST(&sq->sq_blocked);
        if (td == NULL)
                return;
        LIST_REMOVE(sq, sq_hash);
        TAILQ_REMOVE(&sq->sq_blocked, td, wle);
        if (cb != NULL)
                cb(td, arg);
        td->sleepqueue = sq;
        td->wchan = NULL;
        sq2 = SLIST_FIRST(&sq->sq_freeq);
        TAILQ_FOREACH(td, &sq->sq_blocked, wle) {
                if (cb != NULL)
                        cb(td, arg);
                td->sleepqueue = sq2;
                td->wchan = NULL;
                sq2 = SLIST_NEXT(sq2, sq_flink);
        }
        TAILQ_INIT(&sq->sq_blocked);
        SLIST_INIT(&sq->sq_freeq);
}