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 | |