NetBSD/sys/kern/kern_rate.c

113 lines
3.4 KiB
C

/* $NetBSD: kern_rate.c,v 1.2 2012/12/12 11:10:56 pooka Exp $ */
/*-
* Copyright (c) 2000, 2004, 2005, 2007, 2008 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Christopher G. Demetriou.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_rate.c,v 1.2 2012/12/12 11:10:56 pooka Exp $");
#include <sys/param.h>
#include <sys/time.h>
/*
* ratecheck(): simple time-based rate-limit checking. see ratecheck(9)
* for usage and rationale.
*/
int
ratecheck(struct timeval *lasttime, const struct timeval *mininterval)
{
struct timeval tv, delta;
int rv = 0;
getmicrouptime(&tv);
timersub(&tv, lasttime, &delta);
/*
* check for 0,0 is so that the message will be seen at least once,
* even if interval is huge.
*/
if (timercmp(&delta, mininterval, >=) ||
(lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
*lasttime = tv;
rv = 1;
}
return (rv);
}
/*
* ppsratecheck(): packets (or events) per second limitation.
*/
int
ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
{
struct timeval tv, delta;
int rv;
getmicrouptime(&tv);
timersub(&tv, lasttime, &delta);
/*
* check for 0,0 is so that the message will be seen at least once.
* if more than one second have passed since the last update of
* lasttime, reset the counter.
*
* we do increment *curpps even in *curpps < maxpps case, as some may
* try to use *curpps for stat purposes as well.
*/
if ((lasttime->tv_sec == 0 && lasttime->tv_usec == 0) ||
delta.tv_sec >= 1) {
*lasttime = tv;
*curpps = 0;
}
if (maxpps < 0)
rv = 1;
else if (*curpps < maxpps)
rv = 1;
else
rv = 0;
#if 1 /*DIAGNOSTIC?*/
/* be careful about wrap-around */
if (__predict_true(*curpps != INT_MAX))
*curpps = *curpps + 1;
#else
/*
* assume that there's not too many calls to this function.
* not sure if the assumption holds, as it depends on *caller's*
* behavior, not the behavior of this function.
* IMHO it is wrong to make assumption on the caller's behavior,
* so the above #if is #if 1, not #ifdef DIAGNOSTIC.
*/
*curpps = *curpps + 1;
#endif
return (rv);
}