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