Version 2.0.7
[lttng-ust.git] / liblttng-ust / clock.h
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1/*
2 * Copyright (C) 2010 Pierre-Marc Fournier
3 * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
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7 * License as published by the Free Software Foundation; version 2.1 of
8 * the License.
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9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
18 */
19
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20#ifndef _UST_CLOCK_H
21#define _UST_CLOCK_H
518d7abb 22
ca4525b5 23#include <time.h>
518d7abb 24#include <sys/time.h>
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25#include <stdint.h>
26#include <stddef.h>
939950af 27#include <stdio.h>
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28
29/*
30 * Includes final \0.
31 */
32#define CLOCK_UUID_LEN 37
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33
34/* TRACE CLOCK */
35
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36/*
37 * Currently using the kernel MONOTONIC clock, waiting for kernel-side
38 * LTTng to implement mmap'd trace clock.
39 */
518d7abb 40
9c6bb081 41/* Choosing correct trace clock */
518d7abb 42
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43static __inline__
44uint64_t trace_clock_read64(void)
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45{
46 struct timespec ts;
9c6bb081 47
8d8a24c8 48 clock_gettime(CLOCK_MONOTONIC, &ts);
dc190cc1 49 return ((uint64_t) ts.tv_sec * 1000000000ULL) + ts.tv_nsec;
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50}
51
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52static __inline__
53uint64_t trace_clock_freq(void)
518d7abb 54{
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55 return 1000000000ULL;
56}
57
58static __inline__
95c5cc3c 59const int trace_clock_uuid(char *uuid)
28b12049 60{
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61 int ret = 0;
62 size_t len;
63 FILE *fp;
64
65 /*
66 * boot_id needs to be read once before being used concurrently
67 * to deal with a Linux kernel race. A fix is proposed for
68 * upstream, but the work-around is needed for older kernels.
69 */
70 fp = fopen("/proc/sys/kernel/random/boot_id", "r");
71 if (!fp) {
72 return -ENOENT;
73 }
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74 len = fread(uuid, 1, CLOCK_UUID_LEN - 1, fp);
75 if (len < CLOCK_UUID_LEN - 1) {
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76 ret = -EINVAL;
77 goto end;
78 }
578ce73a 79 uuid[CLOCK_UUID_LEN - 1] = '\0';
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80end:
81 fclose(fp);
82 return ret;
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83}
84
9c6bb081 85#endif /* _UST_CLOCK_H */
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