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