schedule.c

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/*
 * Copyright 2008 Vincent Sanders <vince@simtec.co.uk>
 *
 * This file is part of NetSurf, http://www.netsurf-browser.org/
 *
 * NetSurf is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * NetSurf is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <stdlib.h>
#include <time.h>
 
#include "utils/sys_time.h"
#include "utils/log.h"
#include "utils/errors.h"
 
#include "windows/schedule.h"
 
/* linked list of scheduled callbacks */
static struct nscallback *schedule_list = NULL;
 
/**
 * scheduled callback.
 */
struct nscallback
{
        struct nscallback *next;
        struct timeval tv;
        void (*callback)(void *p);
        void *p;
};
 
 
/**
 * Unschedule a callback.
 *
 * \param  callback  callback function
 * \param  p         user parameter, passed to callback function
 *
 * All scheduled callbacks matching both callback and p are removed.
 */
 
static nserror schedule_remove(void (*callback)(void *p), void *p)
{
        struct nscallback *cur_nscb;
        struct nscallback *prev_nscb;
        struct nscallback *unlnk_nscb;
 
        /* check there is something on the list to remove */
        if (schedule_list == NULL) {
                return NSERROR_OK;
        }
 
        NSLOG(schedule, DEBUG, "removing %p, %p", callback, p);
 
        cur_nscb = schedule_list;
        prev_nscb = NULL;
 
        while (cur_nscb != NULL) {
                if ((cur_nscb->callback ==  callback) &&
                    (cur_nscb->p ==  p)) {
                        /* item to remove */
 
                        NSLOG(schedule, DEBUG,
                              "callback entry %p removing  %p(%p)",
                              cur_nscb,
                              cur_nscb->callback,
                              cur_nscb->p);
 
                        /* remove callback */
                        unlnk_nscb = cur_nscb;
                        cur_nscb = unlnk_nscb->next;
 
                        if (prev_nscb == NULL) {
                                schedule_list = cur_nscb;
                        } else {
                                prev_nscb->next = cur_nscb;
                        }
                        free (unlnk_nscb);
                } else {
                        /* move to next element */
                        prev_nscb = cur_nscb;
                        cur_nscb = prev_nscb->next;
                }
        }
        return NSERROR_OK;
}
 
/* exported interface documented in windows/schedule.h */
nserror win32_schedule(int ival, void (*callback)(void *p), void *p)
{
        struct nscallback *nscb;
        struct timeval tv;
        nserror ret;
 
        ret = schedule_remove(callback, p);
        if ((ival < 0) || (ret != NSERROR_OK)) {
                return ret;
        }
 
        tv.tv_sec = ival / 1000; /* miliseconds to seconds */
        tv.tv_usec = (ival % 1000) * 1000; /* remainder to microseconds */
 
        nscb = calloc(1, sizeof(struct nscallback));
        if (nscb == NULL) {
                return NSERROR_NOMEM;
        }
 
        NSLOG(schedule, DEBUG,
              "adding callback %p for %p(%p) at %d cs",
               nscb, callback, p, ival);
 
        gettimeofday(&nscb->tv, NULL);
        timeradd(&nscb->tv, &tv, &nscb->tv);
 
        nscb->callback = callback;
        nscb->p = p;
 
        /* add to list front */
        nscb->next = schedule_list;
        schedule_list = nscb;
 
        return NSERROR_OK;
}
 
/* exported interface documented in schedule.h */
int 
schedule_run(void)
{
        struct timeval tv;
        struct timeval nexttime;
        struct timeval rettime;
        struct nscallback *cur_nscb;
        struct nscallback *prev_nscb;
        struct nscallback *unlnk_nscb;
 
        if (schedule_list == NULL)
                return -1;
 
        /* reset enumeration to the start of the list */
        cur_nscb = schedule_list;
        prev_nscb = NULL;
        nexttime = cur_nscb->tv;
 
        gettimeofday(&tv, NULL);
 
        while (cur_nscb != NULL) {
                if (timercmp(&tv, &cur_nscb->tv, >)) {
                        /* scheduled time */
 
                        /* remove callback */
                        unlnk_nscb = cur_nscb;
 
                        if (prev_nscb == NULL) {
                                schedule_list = unlnk_nscb->next;
                        } else {
                                prev_nscb->next = unlnk_nscb->next;
                        }
 
                        NSLOG(schedule, DEBUG,
                              "callback entry %p running %p(%p)",
                              unlnk_nscb,
                              unlnk_nscb->callback,
                              unlnk_nscb->p);
                        /* call callback */
                        unlnk_nscb->callback(unlnk_nscb->p);
 
                        free(unlnk_nscb);
 
                        /* dispatched events can modify the list,
                         * instead of locking we simply reset list
                         * enumeration to the start.
                         */ 
                        if (schedule_list == NULL)
                                return -1; /* no more callbacks scheduled */
                        
                        cur_nscb = schedule_list;
                        prev_nscb = NULL;
                        nexttime = cur_nscb->tv;
                } else {
                        /* if the time to the event is sooner than the
                         * currently recorded soonest event record it 
                         */
                        if (timercmp(&nexttime, &cur_nscb->tv, >)) {
                                nexttime = cur_nscb->tv;
                        }
                        /* move to next element */
                        prev_nscb = cur_nscb;
                        cur_nscb = prev_nscb->next;
                }
        }
 
        /* make returned time relative to now */
        timersub(&nexttime, &tv, &rettime);
 
        NSLOG(schedule, DEBUG,
              "returning time to next event as %ldms",
              (rettime.tv_sec * 1000) + (rettime.tv_usec / 1000));
 
        /* return next event time in milliseconds (24days max wait) */
        return (rettime.tv_sec * 1000) + (rettime.tv_usec / 1000);
}
 
/* exported interface documented in schedule.h */
void list_schedule(void)
{
        struct timeval tv;
        struct nscallback *cur_nscb;
 
        gettimeofday(&tv, NULL);
 
        NSLOG(netsurf, INFO, "schedule list at %ld:%ld", tv.tv_sec, tv.tv_usec);
 
        cur_nscb = schedule_list;
 
        while (cur_nscb != NULL) {
                NSLOG(netsurf, INFO,
                      "Schedule %p at %ld:%ld",
                      cur_nscb,
                      cur_nscb->tv.tv_sec,
                      cur_nscb->tv.tv_usec);
                cur_nscb = cur_nscb->next;
        }
}
 
 
/*
 * Local Variables:
 * c-basic-offset:8
 * End:
 */