1/* 2 * Copyright © 2008-2011 Kristian Høgsberg 3 * Copyright © 2011 Intel Corporation 4 * Copyright © 2013-2015 Red Hat, Inc. 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a 7 * copy of this software and associated documentation files (the "Software"), 8 * to deal in the Software without restriction, including without limitation 9 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 10 * and/or sell copies of the Software, and to permit persons to whom the 11 * Software is furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice (including the next 14 * paragraph) shall be included in all copies or substantial portions of the 15 * Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 22 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 23 * DEALINGS IN THE SOFTWARE. 24 */ 25 26#include "config.h" 27 28#include <time.h> 29 30#include "util-ratelimit.h" 31#include "util-time.h" 32 33void 34ratelimit_init(struct ratelimit *r, uint64_t ival_us, unsigned int burst) 35{ 36 r->interval = ival_us; 37 r->begin = 0; 38 r->burst = burst; 39 r->num = 0; 40} 41 42/* 43 * Perform rate-limit test. Returns RATELIMIT_PASS if the rate-limited action 44 * is still allowed, RATELIMIT_THRESHOLD if the limit has been reached with 45 * this call, and RATELIMIT_EXCEEDED if you're beyond the threshold. 46 * It's safe to treat the return-value as boolean, if you're not interested in 47 * the exact state. It evaluates to "true" if the threshold hasn't been 48 * exceeded, yet. 49 * 50 * The ratelimit object must be initialized via ratelimit_init(). 51 * 52 * Modelled after Linux' lib/ratelimit.c by Dave Young 53 * <hidave.darkstar@gmail.com>, which is licensed GPLv2. 54 */ 55enum ratelimit_state 56ratelimit_test(struct ratelimit *r) 57{ 58 struct timespec ts; 59 uint64_t utime; 60 61 if (r->interval <= 0 || r->burst <= 0) 62 return RATELIMIT_PASS; 63 64 clock_gettime(CLOCK_MONOTONIC, &ts); 65 utime = s2us(ts.tv_sec) + ns2us(ts.tv_nsec); 66 67 if (r->begin <= 0 || r->begin + r->interval < utime) { 68 /* reset counter */ 69 r->begin = utime; 70 r->num = 1; 71 return RATELIMIT_PASS; 72 } 73 74 if (r->num < r->burst) { 75 /* continue burst */ 76 return (++r->num == r->burst) ? RATELIMIT_THRESHOLD 77 : RATELIMIT_PASS; 78 } 79 80 return RATELIMIT_EXCEEDED; 81} 82