1/* $Id$ */ 2 3/*** 4 This file is part of avahi. 5 6 avahi is free software; you can redistribute it and/or modify it 7 under the terms of the GNU Lesser General Public License as 8 published by the Free Software Foundation; either version 2.1 of the 9 License, or (at your option) any later version. 10 11 avahi is distributed in the hope that it will be useful, but WITHOUT 12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General 14 Public License for more details. 15 16 You should have received a copy of the GNU Lesser General Public 17 License along with avahi; if not, write to the Free Software 18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 19 USA. 20***/ 21 22#ifdef HAVE_CONFIG_H 23#include <config.h> 24#endif 25 26#include <pthread.h> 27#include <stdlib.h> 28#include <assert.h> 29 30#include "timeval.h" 31 32int avahi_timeval_compare(const struct timeval *a, const struct timeval *b) { 33 assert(a); 34 assert(b); 35 36 if (a->tv_sec < b->tv_sec) 37 return -1; 38 39 if (a->tv_sec > b->tv_sec) 40 return 1; 41 42 if (a->tv_usec < b->tv_usec) 43 return -1; 44 45 if (a->tv_usec > b->tv_usec) 46 return 1; 47 48 return 0; 49} 50 51AvahiUsec avahi_timeval_diff(const struct timeval *a, const struct timeval *b) { 52 assert(a); 53 assert(b); 54 55 if (avahi_timeval_compare(a, b) < 0) 56 return - avahi_timeval_diff(b, a); 57 58 return ((AvahiUsec) a->tv_sec - b->tv_sec)*1000000 + a->tv_usec - b->tv_usec; 59} 60 61struct timeval* avahi_timeval_add(struct timeval *a, AvahiUsec usec) { 62 AvahiUsec u; 63 assert(a); 64 65 u = usec + a->tv_usec; 66 67 if (u < 0) { 68 a->tv_usec = (long) (1000000 + (u % 1000000)); 69 a->tv_sec += (long) (-1 + (u / 1000000)); 70 } else { 71 a->tv_usec = (long) (u % 1000000); 72 a->tv_sec += (long) (u / 1000000); 73 } 74 75 return a; 76} 77 78AvahiUsec avahi_age(const struct timeval *a) { 79 struct timeval now; 80 81 assert(a); 82 83 gettimeofday(&now, NULL); 84 85 return avahi_timeval_diff(&now, a); 86} 87 88struct timeval *avahi_elapse_time(struct timeval *tv, unsigned msec, unsigned jitter) { 89 assert(tv); 90 91 gettimeofday(tv, NULL); 92 93 if (msec) 94 avahi_timeval_add(tv, (AvahiUsec) msec*1000); 95 96 if (jitter) { 97 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; 98 static int last_rand; 99 static time_t timestamp = 0; 100 101 time_t now; 102 int r; 103 104 now = time(NULL); 105 106 pthread_mutex_lock(&mutex); 107 if (now >= timestamp + 10) { 108 timestamp = now; 109 last_rand = rand(); 110 } 111 112 r = last_rand; 113 114 pthread_mutex_unlock(&mutex); 115 116 /* We use the same jitter for 10 seconds. That way our 117 * time events elapse in bursts which has the advantage that 118 * packet data can be aggregated better */ 119 120 avahi_timeval_add(tv, (AvahiUsec) (jitter*1000.0*r/(RAND_MAX+1.0))); 121 } 122 123 return tv; 124} 125 126