local_timer.c

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/*
 * $Id: local_timer.c,v 1.1 2007/11/22 13:43:09 andrei Exp $
 *
 * Copyright (C) 2007 iptelorg GmbH
 *
 * This file is part of ser, a free SIP server.
 *
 * ser 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; either version 2 of the License, or
 * (at your option) any later version
 *
 * For a license to use the ser software under conditions
 * other than those described here, or to purchase support for this
 * software, please contact iptel.org by e-mail at the following addresses:
 *    info@iptel.org
 *
 * ser 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, write to the Free Software 
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
/* local, per process timer routines
 * WARNING: this should be used only within the same process, the timers
 *  are not multi-process safe or multi-thread safe
 *  (there are no locks)
 *
 * History:
 * --------
 *  2006-02-03  created by andrei
 */


#include "timer.h"
#include "timer_funcs.h"
#include "dprint.h"
#include "tcp_conn.h"
#include "mem/mem.h"
#include "compiler_opt.h"

#include "local_timer.h"



/* init a local_timer handle
 * returns 0 on success, -1 on error */
int init_local_timer(struct local_timer *t, ticks_t crt_ticks)
{
        int r;
        
        /* initial values */
        memset(t, 0, sizeof(*t));
        t->prev_ticks=crt_ticks;
        /* init timer structures */
        for (r=0; r<H0_ENTRIES; r++)
                _timer_init_list(&t->timer_lst.h0[r]);
        for (r=0; r<H1_ENTRIES; r++)
                _timer_init_list(&t->timer_lst.h1[r]);
        for (r=0; r<H2_ENTRIES; r++)
                _timer_init_list(&t->timer_lst.h2[r]);
        _timer_init_list(&t->timer_lst.expired);
        DBG("init_local_timer: timer_list between %p and %p\n",
                        &t->timer_lst.h0[0], &t->timer_lst.h2[H2_ENTRIES]);
        return 0;
}



void destroy_local_timer(struct local_timer* lt)
{
}



/* generic add timer entry to the timer lists function (see _timer_add)
 * tl->expire must be set previously, delta is the difference in ticks
 * from current time to the timer desired expire (should be tl->expire-*tick)
 * If you don't know delta, you probably want to call _timer_add instead.
 */
static inline int _local_timer_dist_tl(struct local_timer* h, 
                                                                                struct timer_ln* tl, ticks_t delta)
{
        if (likely(delta<H0_ENTRIES)){
                if (unlikely(delta==0)){
                        LOG(L_WARN, "WARNING: local_timer: add_timeout: 0 expire timer"
                                                " added\n");
                        _timer_add_list(&h->timer_lst.expired, tl);
                }else{
                        _timer_add_list( &h->timer_lst.h0[tl->expire & H0_MASK], tl);
                }
        }else if (likely(delta<(H0_ENTRIES*H1_ENTRIES))){
                _timer_add_list(&h->timer_lst.h1[(tl->expire & H1_H0_MASK)>>H0_BITS],
                                                        tl);
        }else{
                _timer_add_list(&h->timer_lst.h2[tl->expire>>(H1_BITS+H0_BITS)], tl);
        }
        return 0;
}



static inline void local_timer_redist(struct local_timer* l,
                                                                                ticks_t t, struct timer_head *h)
{
        struct timer_ln* tl;
        struct timer_ln* tmp;
        
        timer_foreach_safe(tl, tmp, h){
                _local_timer_dist_tl(l, tl, tl->expire-t);
        }
        /* clear the current list */
        _timer_init_list(h);
}



/* local timer add function (no lock, not multithread or multiprocess safe,
 * designed for local process use only)
 * t = current ticks
 * tl must be filled (the intial_timeout and flags must be set)
 * returns -1 on error, 0 on success */
static inline int _local_timer_add(struct local_timer *h, ticks_t t,
                                                                        struct timer_ln* tl)
{
        ticks_t delta;
        
        delta=tl->initial_timeout;
        tl->expire=t+delta;
        return _local_timer_dist_tl(h, tl, delta);
}



/* "public", safe timer add functions (local process use only)
 * adds a timer at delta ticks from the current time
 * returns -1 on error, 0 on success
 * WARNING: to re-add a deleted or expired timer you must call
 *          timer_reinit(tl) prior to timer_add
 *          The default behaviour allows timer_add to add a timer only if it
 *          has never been added before.*/
int local_timer_add(struct local_timer* h, struct timer_ln* tl, ticks_t delta,
                                                ticks_t crt_ticks)
{
        int ret;
        
        if (unlikely(tl->flags & F_TIMER_ACTIVE)){
                DBG("timer_add called on an active timer %p (%p, %p),"
                                        " flags %x\n", tl, tl->next, tl->prev, tl->flags);
                ret=-1; /* refusing to add active or non-reinit. timer */
                goto error;
        }
        tl->initial_timeout=delta;
        if (unlikely((tl->next!=0) || (tl->prev!=0))){
                LOG(L_CRIT, "BUG: tcp_timer_add: called with linked timer:"
                                " %p (%p, %p)\n", tl, tl->next, tl->prev);
                ret=-1;
                goto error;
        }
        tl->flags|=F_TIMER_ACTIVE;
        ret=_local_timer_add(h, crt_ticks, tl);
error:
        return ret;
}



/* safe timer delete
 * deletes tl and inits the list pointer to 0
 * WARNING: to be able to reuse a deleted timer you must call
 *          timer_reinit(tl) on it
 * 
 */
void local_timer_del(struct local_timer* h, struct timer_ln* tl)
{
        /* quick exit if timer inactive */
        if (unlikely(!(tl->flags & F_TIMER_ACTIVE))){
                DBG("timer_del called on an inactive timer %p (%p, %p),"
                                        " flags %x\n", tl, tl->next, tl->prev, tl->flags);
                return;
        }
        if (likely((tl->next!=0)&&(tl->prev!=0))){
                _timer_rm_list(tl); /* detach */
                tl->next=tl->prev=0;
        }else{
                DBG("timer_del: (f) timer %p (%p, %p) flags %x "
                        "already detached\n",
                        tl, tl->next, tl->prev, tl->flags);
        }
}



/* called from timer_handle*/
inline static void local_timer_list_expire(struct local_timer* l, 
                                                                                        ticks_t t, struct timer_head* h)
{
        struct timer_ln * tl;
        ticks_t ret;
        
        /*DBG("timer_list_expire @ ticks = %lu, list =%p\n",
                        (unsigned long) *ticks, h);
        */
        while(h->next!=(struct timer_ln*)h){
                tl=h->next;
                _timer_rm_list(tl); /* detach */
                        tl->next=tl->prev=0; /* debugging */
                                /*FIXME: process tcpconn */
                                ret=tl->f(t, tl, tl->data);
                                if (ret!=0){
                                        /* not one-shot, re-add it */
                                        if (ret!=(ticks_t)-1) /* ! periodic */
                                                tl->initial_timeout=ret;
                                        _local_timer_add(l, t, tl);
                                }
        }
}



/* run all the handler that expire at t ticks */
static inline void local_timer_expire(struct local_timer* h, ticks_t t)
{
        /* trust the compiler for optimizing */
        if (unlikely((t & H0_MASK)==0)){              /*r1*/
                if (unlikely((t & H1_H0_MASK)==0)){        /*r2*/
                        local_timer_redist(h, t, &h->timer_lst.h2[t>>(H0_BITS+H1_BITS)]);
                }
                
                local_timer_redist(h, t, &h->timer_lst.h1[(t & H1_H0_MASK)>>H0_BITS]);
                                                                                                                        /*r2 >> H0*/
        }
        /* run handler immediately, no need to move it to the expired list
         * (since no locks are used) */
        local_timer_list_expire(h, t, &h->timer_lst.h0[t & H0_MASK]);
}



/* "main" local timer routine, should be called with a proper ticks value
 * WARNING: it should never be called twice for the same ticks value
 * (it could cause too fast expires for long timers), ticks must be also
 *  always increasing */
void local_timer_run(struct local_timer* lt, ticks_t saved_ticks)
{
        
                /* protect against time running backwards */
                if (unlikely(lt->prev_ticks>=saved_ticks)){
                        LOG(L_CRIT, "BUG: local_timer: backwards or still time\n");
                        /* try to continue */
                        lt->prev_ticks=saved_ticks-1;
                        return;
                }
                /* go through all the "missed" ticks, taking a possible overflow
                 * into account */
                for (lt->prev_ticks=lt->prev_ticks+1; lt->prev_ticks!=saved_ticks; 
                                                                                                                        lt->prev_ticks++)
                        local_timer_expire(lt, lt->prev_ticks);
                local_timer_expire(lt, lt->prev_ticks); /* do it for saved_ticks too */
        local_timer_list_expire(lt, saved_ticks, &lt->timer_lst.expired);
        /* WARNING: add_timer(...,0) must go directly to expired list, since
         * otherwise there is a race between timer running and adding it
         * (it could expire it H0_ENTRIES ticks later instead of 'now')*/
}

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