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
avahi_timeval_compare(const struct timeval * a,const struct timeval * b)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
avahi_timeval_diff(const struct timeval * a,const struct timeval * b)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
avahi_timeval_add(struct timeval * a,AvahiUsec usec)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
avahi_age(const struct timeval * a)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
avahi_elapse_time(struct timeval * tv,unsigned msec,unsigned jitter)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