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/*
* Copyright (c) 1989 Jan-Simon Pendry
* Copyright (c) 1989 Imperial College of Science, Technology & Medicine
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Jan-Simon Pendry at Imperial College, London.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)clock.c 8.1 (Berkeley) 6/6/93
*
* $FreeBSD$
*
*/
/*
* Callouts.
*
* Modelled on kernel object of the same name.
* See usual references.
*
* Use of a heap-based mechanism was rejected:
* 1. more complex implementation needed.
* 2. not obvious that a list is too slow for Amd.
*/
#include "am.h"
typedef struct callout callout;
struct callout {
callout *c_next; /* List of callouts */
void (*c_fn)(); /* Function to call */
voidp c_closure; /* Closure to pass to call */
time_t c_time; /* Time of call */
int c_id; /* Unique identifier */
};
static callout callouts; /* List of pending callouts */
static callout *free_callouts; /* Cache of free callouts */
static int nfree_callouts; /* Number on free list */
static int callout_id; /* Next free callout identifier */
time_t next_softclock; /* Time of next call to softclock() */
/*
* Number of callout slots we keep on the free list
*/
#define CALLOUT_FREE_SLOP 10
/*
* Global assumption: valid id's are non-zero.
*/
#define CID_ALLOC() (++callout_id)
#define CID_UNDEF (0)
static callout *alloc_callout(P_void);
static callout *alloc_callout()
{
callout *cp = free_callouts;
if (cp) {
--nfree_callouts;
free_callouts = free_callouts->c_next;
return cp;
}
return ALLOC(callout);
}
static void free_callout P((callout *cp));
static void free_callout(cp)
callout *cp;
{
if (nfree_callouts > CALLOUT_FREE_SLOP) {
free((voidp) cp);
} else {
cp->c_next = free_callouts;
free_callouts = cp;
nfree_callouts++;
}
}
/*
* Schedule a callout.
*
* (*fn)(closure) will be called at clocktime() + secs
*/
int timeout P((unsigned int secs, void (*fn)(), voidp closure));
int timeout(secs, fn, closure)
unsigned int secs;
void (*fn)();
voidp closure;
{
callout *cp, *cp2;
time_t t = clocktime() + secs;
/*
* Allocate and fill in a new callout structure
*/
callout *cpnew = alloc_callout();
cpnew->c_closure = closure;
cpnew->c_fn = fn;
cpnew->c_time = t;
cpnew->c_id = CID_ALLOC();
if (t < next_softclock)
next_softclock = t;
/*
* Find the correct place in the list
*/
for (cp = &callouts; cp2 = cp->c_next; cp = cp2)
if (cp2->c_time >= t)
break;
/*
* And link it in
*/
cp->c_next = cpnew;
cpnew->c_next = cp2;
/*
* Return callout identifier
*/
return cpnew->c_id;
}
/*
* De-schedule a callout
*/
void untimeout P((int id));
void untimeout(id)
int id;
{
callout *cp, *cp2;
for (cp = &callouts; cp2 = cp->c_next; cp = cp2) {
if (cp2->c_id == id) {
cp->c_next = cp2->c_next;
free_callout(cp2);
break;
}
}
}
/*
* Reschedule after clock changed
*/
void reschedule_timeouts P((time_t now, time_t then));
void reschedule_timeouts(now, then)
time_t now;
time_t then;
{
callout *cp;
for (cp = callouts.c_next; cp; cp = cp->c_next) {
if (cp->c_time >= now && cp->c_time <= then) {
plog(XLOG_WARNING, "job %d rescheduled to run immediately", cp->c_id);
#ifdef DEBUG
dlog("rescheduling job %d back %d seconds",
cp->c_id, cp->c_time - now);
#endif
next_softclock = cp->c_time = now;
}
}
}
/*
* Clock handler
*/
int softclock(P_void);
int softclock()
{
time_t now;
callout *cp;
do {
if (task_notify_todo)
do_task_notify();
now = clocktime();
/*
* While there are more callouts waiting...
*/
while ((cp = callouts.c_next) && cp->c_time <= now) {
/*
* Extract first from list, save fn & closure and
* unlink callout from list and free.
* Finally call function.
*
* The free is done first because
* it is quite common that the
* function will call timeout()
* and try to allocate a callout
*/
void (*fn)() = cp->c_fn;
voidp closure = cp->c_closure;
callouts.c_next = cp->c_next;
free_callout(cp);
#ifdef DEBUG
/*dlog("Calling %#x(%#x)", fn, closure);*/
#endif /* DEBUG */
(*fn)(closure);
}
} while (task_notify_todo);
/*
* Return number of seconds to next event,
* or 0 if there is no event.
*/
if (cp = callouts.c_next)
return cp->c_time - now;
return 0;
}
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