common/isc/ev_waits.c

/*
 * 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]
 */

#if !defined(LINT) && !defined(CODECENTER)
static const char rcsid[] = "$Id: ev_waits.c,v 1.4 2005/04/27 04:56:36 sra Exp $";
#endif

#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 */