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kern_rate.c revision 1.1.4.2 
      1  1.1.4.2  skrll /*	$NetBSD: kern_rate.c,v 1.1.4.2 2008/10/10 22:34:14 skrll Exp $	*/
      2  1.1.4.2  skrll 
      3  1.1.4.2  skrll /*-
      4  1.1.4.2  skrll  * Copyright (c) 2000, 2004, 2005, 2007, 2008 The NetBSD Foundation, Inc.
      5  1.1.4.2  skrll  * All rights reserved.
      6  1.1.4.2  skrll  *
      7  1.1.4.2  skrll  * This code is derived from software contributed to The NetBSD Foundation
      8  1.1.4.2  skrll  * by Christopher G. Demetriou.
      9  1.1.4.2  skrll  *
     10  1.1.4.2  skrll  * Redistribution and use in source and binary forms, with or without
     11  1.1.4.2  skrll  * modification, are permitted provided that the following conditions
     12  1.1.4.2  skrll  * are met:
     13  1.1.4.2  skrll  * 1. Redistributions of source code must retain the above copyright
     14  1.1.4.2  skrll  *    notice, this list of conditions and the following disclaimer.
     15  1.1.4.2  skrll  * 2. Redistributions in binary form must reproduce the above copyright
     16  1.1.4.2  skrll  *    notice, this list of conditions and the following disclaimer in the
     17  1.1.4.2  skrll  *    documentation and/or other materials provided with the distribution.
     18  1.1.4.2  skrll  *
     19  1.1.4.2  skrll  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  1.1.4.2  skrll  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  1.1.4.2  skrll  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  1.1.4.2  skrll  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  1.1.4.2  skrll  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  1.1.4.2  skrll  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  1.1.4.2  skrll  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  1.1.4.2  skrll  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  1.1.4.2  skrll  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  1.1.4.2  skrll  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  1.1.4.2  skrll  * POSSIBILITY OF SUCH DAMAGE.
     30  1.1.4.2  skrll  */
     31  1.1.4.2  skrll 
     32  1.1.4.2  skrll #include <sys/cdefs.h>
     33  1.1.4.2  skrll __KERNEL_RCSID(0, "$NetBSD: kern_rate.c,v 1.1.4.2 2008/10/10 22:34:14 skrll Exp $");
     34  1.1.4.2  skrll 
     35  1.1.4.2  skrll #include <sys/param.h>
     36  1.1.4.2  skrll #include <sys/time.h>
     37  1.1.4.2  skrll 
     38  1.1.4.2  skrll /*
     39  1.1.4.2  skrll  * ratecheck(): simple time-based rate-limit checking.  see ratecheck(9)
     40  1.1.4.2  skrll  * for usage and rationale.
     41  1.1.4.2  skrll  */
     42  1.1.4.2  skrll int
     43  1.1.4.2  skrll ratecheck(struct timeval *lasttime, const struct timeval *mininterval)
     44  1.1.4.2  skrll {
     45  1.1.4.2  skrll 	struct timeval tv, delta;
     46  1.1.4.2  skrll 	int rv = 0;
     47  1.1.4.2  skrll 
     48  1.1.4.2  skrll 	getmicrouptime(&tv);
     49  1.1.4.2  skrll 	timersub(&tv, lasttime, &delta);
     50  1.1.4.2  skrll 
     51  1.1.4.2  skrll 	/*
     52  1.1.4.2  skrll 	 * check for 0,0 is so that the message will be seen at least once,
     53  1.1.4.2  skrll 	 * even if interval is huge.
     54  1.1.4.2  skrll 	 */
     55  1.1.4.2  skrll 	if (timercmp(&delta, mininterval, >=) ||
     56  1.1.4.2  skrll 	    (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
     57  1.1.4.2  skrll 		*lasttime = tv;
     58  1.1.4.2  skrll 		rv = 1;
     59  1.1.4.2  skrll 	}
     60  1.1.4.2  skrll 
     61  1.1.4.2  skrll 	return (rv);
     62  1.1.4.2  skrll }
     63  1.1.4.2  skrll 
     64  1.1.4.2  skrll /*
     65  1.1.4.2  skrll  * ppsratecheck(): packets (or events) per second limitation.
     66  1.1.4.2  skrll  */
     67  1.1.4.2  skrll int
     68  1.1.4.2  skrll ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
     69  1.1.4.2  skrll {
     70  1.1.4.2  skrll 	struct timeval tv, delta;
     71  1.1.4.2  skrll 	int rv;
     72  1.1.4.2  skrll 
     73  1.1.4.2  skrll 	getmicrouptime(&tv);
     74  1.1.4.2  skrll 	timersub(&tv, lasttime, &delta);
     75  1.1.4.2  skrll 
     76  1.1.4.2  skrll 	/*
     77  1.1.4.2  skrll 	 * check for 0,0 is so that the message will be seen at least once.
     78  1.1.4.2  skrll 	 * if more than one second have passed since the last update of
     79  1.1.4.2  skrll 	 * lasttime, reset the counter.
     80  1.1.4.2  skrll 	 *
     81  1.1.4.2  skrll 	 * we do increment *curpps even in *curpps < maxpps case, as some may
     82  1.1.4.2  skrll 	 * try to use *curpps for stat purposes as well.
     83  1.1.4.2  skrll 	 */
     84  1.1.4.2  skrll 	if ((lasttime->tv_sec == 0 && lasttime->tv_usec == 0) ||
     85  1.1.4.2  skrll 	    delta.tv_sec >= 1) {
     86  1.1.4.2  skrll 		*lasttime = tv;
     87  1.1.4.2  skrll 		*curpps = 0;
     88  1.1.4.2  skrll 	}
     89  1.1.4.2  skrll 	if (maxpps < 0)
     90  1.1.4.2  skrll 		rv = 1;
     91  1.1.4.2  skrll 	else if (*curpps < maxpps)
     92  1.1.4.2  skrll 		rv = 1;
     93  1.1.4.2  skrll 	else
     94  1.1.4.2  skrll 		rv = 0;
     95  1.1.4.2  skrll 
     96  1.1.4.2  skrll #if 1 /*DIAGNOSTIC?*/
     97  1.1.4.2  skrll 	/* be careful about wrap-around */
     98  1.1.4.2  skrll 	if (*curpps + 1 > *curpps)
     99  1.1.4.2  skrll 		*curpps = *curpps + 1;
    100  1.1.4.2  skrll #else
    101  1.1.4.2  skrll 	/*
    102  1.1.4.2  skrll 	 * assume that there's not too many calls to this function.
    103  1.1.4.2  skrll 	 * not sure if the assumption holds, as it depends on *caller's*
    104  1.1.4.2  skrll 	 * behavior, not the behavior of this function.
    105  1.1.4.2  skrll 	 * IMHO it is wrong to make assumption on the caller's behavior,
    106  1.1.4.2  skrll 	 * so the above #if is #if 1, not #ifdef DIAGNOSTIC.
    107  1.1.4.2  skrll 	 */
    108  1.1.4.2  skrll 	*curpps = *curpps + 1;
    109  1.1.4.2  skrll #endif
    110  1.1.4.2  skrll 
    111  1.1.4.2  skrll 	return (rv);
    112  1.1.4.2  skrll }
    113