| 1 | /* $NetBSD: kern_rate.c,v 1.2 2012/12/12 11:10:56 pooka Exp $ */ |
| 2 | |
| 3 | /*- |
| 4 | * Copyright (c) 2000, 2004, 2005, 2007, 2008 The NetBSD Foundation, Inc. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * This code is derived from software contributed to The NetBSD Foundation |
| 8 | * by Christopher G. Demetriou. |
| 9 | * |
| 10 | * Redistribution and use in source and binary forms, with or without |
| 11 | * modification, are permitted provided that the following conditions |
| 12 | * are met: |
| 13 | * 1. Redistributions of source code must retain the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer. |
| 15 | * 2. Redistributions in binary form must reproduce the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer in the |
| 17 | * documentation and/or other materials provided with the distribution. |
| 18 | * |
| 19 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
| 20 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| 21 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 22 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
| 23 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 24 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 25 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 26 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 27 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 28 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 29 | * POSSIBILITY OF SUCH DAMAGE. |
| 30 | */ |
| 31 | |
| 32 | #include <sys/cdefs.h> |
| 33 | __KERNEL_RCSID(0, "$NetBSD: kern_rate.c,v 1.2 2012/12/12 11:10:56 pooka Exp $" ); |
| 34 | |
| 35 | #include <sys/param.h> |
| 36 | #include <sys/time.h> |
| 37 | |
| 38 | /* |
| 39 | * ratecheck(): simple time-based rate-limit checking. see ratecheck(9) |
| 40 | * for usage and rationale. |
| 41 | */ |
| 42 | int |
| 43 | ratecheck(struct timeval *lasttime, const struct timeval *mininterval) |
| 44 | { |
| 45 | struct timeval tv, delta; |
| 46 | int rv = 0; |
| 47 | |
| 48 | getmicrouptime(&tv); |
| 49 | timersub(&tv, lasttime, &delta); |
| 50 | |
| 51 | /* |
| 52 | * check for 0,0 is so that the message will be seen at least once, |
| 53 | * even if interval is huge. |
| 54 | */ |
| 55 | if (timercmp(&delta, mininterval, >=) || |
| 56 | (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) { |
| 57 | *lasttime = tv; |
| 58 | rv = 1; |
| 59 | } |
| 60 | |
| 61 | return (rv); |
| 62 | } |
| 63 | |
| 64 | /* |
| 65 | * ppsratecheck(): packets (or events) per second limitation. |
| 66 | */ |
| 67 | int |
| 68 | ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps) |
| 69 | { |
| 70 | struct timeval tv, delta; |
| 71 | int rv; |
| 72 | |
| 73 | getmicrouptime(&tv); |
| 74 | timersub(&tv, lasttime, &delta); |
| 75 | |
| 76 | /* |
| 77 | * check for 0,0 is so that the message will be seen at least once. |
| 78 | * if more than one second have passed since the last update of |
| 79 | * lasttime, reset the counter. |
| 80 | * |
| 81 | * we do increment *curpps even in *curpps < maxpps case, as some may |
| 82 | * try to use *curpps for stat purposes as well. |
| 83 | */ |
| 84 | if ((lasttime->tv_sec == 0 && lasttime->tv_usec == 0) || |
| 85 | delta.tv_sec >= 1) { |
| 86 | *lasttime = tv; |
| 87 | *curpps = 0; |
| 88 | } |
| 89 | if (maxpps < 0) |
| 90 | rv = 1; |
| 91 | else if (*curpps < maxpps) |
| 92 | rv = 1; |
| 93 | else |
| 94 | rv = 0; |
| 95 | |
| 96 | #if 1 /*DIAGNOSTIC?*/ |
| 97 | /* be careful about wrap-around */ |
| 98 | if (__predict_true(*curpps != INT_MAX)) |
| 99 | *curpps = *curpps + 1; |
| 100 | #else |
| 101 | /* |
| 102 | * assume that there's not too many calls to this function. |
| 103 | * not sure if the assumption holds, as it depends on *caller's* |
| 104 | * behavior, not the behavior of this function. |
| 105 | * IMHO it is wrong to make assumption on the caller's behavior, |
| 106 | * so the above #if is #if 1, not #ifdef DIAGNOSTIC. |
| 107 | */ |
| 108 | *curpps = *curpps + 1; |
| 109 | #endif |
| 110 | |
| 111 | return (rv); |
| 112 | } |
| 113 | |