/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1996-1999 by Internet Software Consortium
 *
 * 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 ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC 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.
 */

/* ev_waits.c - implement deferred function calls for the eventlib
 * vix 05dec95 [initial]
 */

#include "port_before.h"
#include "fd_setsize.h"

#include <errno.h>

#include <isc/eventlib.h>
#include <isc/assertions.h>
#include "eventlib_p.h"

#include "port_after.h"

/* Forward. */

static void             print_waits(evContext_p *ctx);
static evWaitList *     evNewWaitList(evContext_p *);
static void             evFreeWaitList(evContext_p *, evWaitList *);
static evWaitList *     evGetWaitList(evContext_p *, const void *, int);


/* Public. */

/*%
 * Enter a new wait function on the queue.
 */
int
evWaitFor(evContext opaqueCtx, const void *tag,
          evWaitFunc func, void *uap, evWaitID *id)
{
        evContext_p *ctx = opaqueCtx.opaque;
        evWait *new;
        evWaitList *wl = evGetWaitList(ctx, tag, 1);

        OKNEW(new);
        new->func = func;
        new->uap = uap;
        new->tag = tag;
        new->next = NULL;
        if (wl->last != NULL)
                wl->last->next = new;
        else
                wl->first = new;
        wl->last = new;
        if (id != NULL)
                id->opaque = new;
        if (ctx->debug >= 9)
                print_waits(ctx);
        return (0);
}

/*%
 * Mark runnable all waiting functions having a certain tag.
 */
int
evDo(evContext opaqueCtx, const void *tag) {
        evContext_p *ctx = opaqueCtx.opaque;
        evWaitList *wl = evGetWaitList(ctx, tag, 0);
        evWait *first;

        if (!wl) {
                errno = ENOENT;
                return (-1);
        }

        first = wl->first;
        INSIST(first != NULL);

        if (ctx->waitDone.last != NULL)
                ctx->waitDone.last->next = first;
        else
                ctx->waitDone.first = first;
        ctx->waitDone.last = wl->last;
        evFreeWaitList(ctx, wl);

        return (0);
}

/*%
 * Remove a waiting (or ready to run) function from the queue.
 */
int
evUnwait(evContext opaqueCtx, evWaitID id) {
        evContext_p *ctx = opaqueCtx.opaque;
        evWait *this, *prev;
        evWaitList *wl;
        int found = 0;

        this = id.opaque;
        INSIST(this != NULL);
        wl = evGetWaitList(ctx, this->tag, 0);
        if (wl != NULL) {
                for (prev = NULL, this = wl->first;
                     this != NULL;
                     prev = this, this = this->next)
                        if (this == (evWait *)id.opaque) {
                                found = 1;
                                if (prev != NULL)
                                        prev->next = this->next;
                                else
                                        wl->first = this->next;
                                if (wl->last == this)
                                        wl->last = prev;
                                if (wl->first == NULL)
                                        evFreeWaitList(ctx, wl);
                                break;
                        }
        }

        if (!found) {
                /* Maybe it's done */
                for (prev = NULL, this = ctx->waitDone.first;
                     this != NULL;
                     prev = this, this = this->next)
                        if (this == (evWait *)id.opaque) {
                                found = 1;
                                if (prev != NULL)
                                        prev->next = this->next;
                                else
                                        ctx->waitDone.first = this->next;
                                if (ctx->waitDone.last == this)
                                        ctx->waitDone.last = prev;
                                break;
                        }
        }

        if (!found) {
                errno = ENOENT;
                return (-1);
        }

        FREE(this);

        if (ctx->debug >= 9)
                print_waits(ctx);

        return (0);
}

int
evDefer(evContext opaqueCtx, evWaitFunc func, void *uap) {
        evContext_p *ctx = opaqueCtx.opaque;
        evWait *new;

        OKNEW(new);
        new->func = func;
        new->uap = uap;
        new->tag = NULL;
        new->next = NULL;
        if (ctx->waitDone.last != NULL)
                ctx->waitDone.last->next = new;
        else
                ctx->waitDone.first = new;
        ctx->waitDone.last = new;
        if (ctx->debug >= 9)
                print_waits(ctx);
        return (0);
}

/* Private. */

static void
print_waits(evContext_p *ctx) {
        evWaitList *wl;
        evWait *this;

        evPrintf(ctx, 9, "wait waiting:\n");
        for (wl = ctx->waitLists; wl != NULL; wl = wl->next) {
                INSIST(wl->first != NULL);
                evPrintf(ctx, 9, "  tag %p:", wl->first->tag);
                for (this = wl->first; this != NULL; this = this->next)
                        evPrintf(ctx, 9, " %p", this);
                evPrintf(ctx, 9, "\n");
        }
        evPrintf(ctx, 9, "wait done:");
        for (this = ctx->waitDone.first; this != NULL; this = this->next)
                evPrintf(ctx, 9, " %p", this);
        evPrintf(ctx, 9, "\n");
}

static evWaitList *
evNewWaitList(evContext_p *ctx) {
        evWaitList *new;

        NEW(new);
        if (new == NULL)
                return (NULL);
        new->first = new->last = NULL;
        new->prev = NULL;
        new->next = ctx->waitLists;
        if (new->next != NULL)
                new->next->prev = new;
        ctx->waitLists = new;
        return (new);
}

static void
evFreeWaitList(evContext_p *ctx, evWaitList *this) {

        INSIST(this != NULL);

        if (this->prev != NULL)
                this->prev->next = this->next;
        else
                ctx->waitLists = this->next;
        if (this->next != NULL)
                this->next->prev = this->prev;
        FREE(this);
}

static evWaitList *
evGetWaitList(evContext_p *ctx, const void *tag, int should_create) {
        evWaitList *this;

        for (this = ctx->waitLists; this != NULL; this = this->next) {
                if (this->first != NULL && this->first->tag == tag)
                        break;
        }
        if (this == NULL && should_create)
                this = evNewWaitList(ctx);
        return (this);
}

/*! \file */