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// -*-c++-*-
/* $Id: backoff.h,v 1.6 2001/03/25 09:01:55 dm Exp $ */
/*
*
* Copyright (C) 1998 David Mazieres (dm@uun.org)
*
* This program 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, or (at
* your option) any later version.
*
* This program 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
*
*/
#ifndef _BACKOFF_H_
#define _BACKOFF_H_ 1
template<class T>
#ifndef NO_TEMPLATE_FRIENDS
class
#else /* NO_TEMPLATE_FRIENDS */
struct
#endif /* NO_TEMPLATE_FRIENDS */
tmoq_entry {
u_int qno;
time_t tm;
T *next;
T **pprev;
public:
tmoq_entry () : qno ((u_int) -1) {}
#ifndef NO_TEMPLATE_FRIENDS
template<class U, tmoq_entry<U> U::*field,
u_int minto, u_int maxsend> friend class tmoq;
#endif /* NO_TEMPLATE_FRIENDS */
};
template<class T, tmoq_entry<T> T::*field, u_int minto = 2, u_int maxsend = 5>
class tmoq {
struct head {
T *first;
T **plast;
head () {first = NULL; plast = &first;}
};
head queue[maxsend];
bool pending[maxsend];
static void tcb (tmoq *tq, u_int qn) {
tq->pending[qn] = false;
tq->runq (qn);
tq->schedq (qn);
}
void schedq (u_int qn) {
T *p;
if (!pending[qn] && (p = queue[qn].first)) {
pending[qn] = true;
timecb ((p->*field).tm, wrap (tcb, this, qn));
}
}
void runq (u_int qn) {
time_t now = time (NULL);
T *p;
while ((p = queue[qn].first) && (p->*field).tm <= now) {
remove (p);
if (qn < maxsend - 1)
insert (p, qn + 1, now);
else {
(p->*field).qno = maxsend;
p->timeout ();
}
}
}
void insert (T *p, u_int qn, time_t now = 0) {
(p->*field).qno = qn;
(p->*field).tm = (now ? now : time (NULL)) + (minto << qn);
(p->*field).next = NULL;
(p->*field).pprev = queue[qn].plast;
*queue[qn].plast = p;
queue[qn].plast = &(p->*field).next;
schedq (qn);
p->xmit (qn);
}
public:
tmoq () {
for (size_t i = 0; i < maxsend; i++)
pending[i] = false;
}
void start (T *p) { insert (p, 0); }
void remove (T *p) {
if ((p->*field).qno < maxsend) {
if ((p->*field).next)
((p->*field).next->*field).pprev = (p->*field).pprev;
else
queue[(p->*field).qno].plast = (p->*field).pprev;
*(p->*field).pprev = (p->*field).next;
}
}
};
#endif /* !_BACKOFF_H_ */
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