[lttng-ust.git] / liblttng-ust / clock.h

/*
 * Copyright (C) 2010  Pierre-Marc Fournier
 * Copyright (C) 2011  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; version 2.1 of
 * the License.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
 */

#ifndef _UST_CLOCK_H
#define _UST_CLOCK_H

#include <time.h>
#include <sys/time.h>
#include <stdint.h>
#include <stddef.h>
#include <stdio.h>
#include "lttng-ust-uuid.h"

/* TRACE CLOCK */

/*
 * Currently using the kernel MONOTONIC clock, waiting for kernel-side
 * LTTng to implement mmap'd trace clock.
 */

/* Choosing correct trace clock */

static __inline__
uint64_t trace_clock_read64(void)
{
	struct timespec ts;

	clock_gettime(CLOCK_MONOTONIC, &ts);
	return ((uint64_t) ts.tv_sec * 1000000000ULL) + ts.tv_nsec;
}

static __inline__
uint64_t trace_clock_freq(void)
{
	return 1000000000ULL;
}

static __inline__
int trace_clock_uuid(char *uuid)
{
	int ret = 0;
	size_t len;
	FILE *fp;

	/*
	 * boot_id needs to be read once before being used concurrently
	 * to deal with a Linux kernel race. A fix is proposed for
	 * upstream, but the work-around is needed for older kernels.
	 */
	fp = fopen("/proc/sys/kernel/random/boot_id", "r");
	if (!fp) {
		return -ENOENT;
	}
	len = fread(uuid, 1, LTTNG_UST_UUID_STR_LEN - 1, fp);
	if (len < LTTNG_UST_UUID_STR_LEN - 1) {
		ret = -EINVAL;
		goto end;
	}
	uuid[LTTNG_UST_UUID_STR_LEN - 1] = '\0';
end:
	fclose(fp);
	return ret;
}

#endif /* _UST_CLOCK_H */
Commit	Line	Data
	1	/*
	2	* Copyright (C) 2010 Pierre-Marc Fournier
	3	* Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	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
	7	* License as published by the Free Software Foundation; version 2.1 of
	8	* the License.
	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
	20	#ifndef _UST_CLOCK_H
	21	#define _UST_CLOCK_H
	22
	23	#include <time.h>
	24	#include <sys/time.h>
	25	#include <stdint.h>
	26	#include <stddef.h>
	27	#include <stdio.h>
	28	#include "lttng-ust-uuid.h"
	29
	30	/* TRACE CLOCK */
	31
	32	/*
	33	* Currently using the kernel MONOTONIC clock, waiting for kernel-side
	34	* LTTng to implement mmap'd trace clock.
	35	*/
	36
	37	/* Choosing correct trace clock */
	38
	39	static __inline__
	40	uint64_t trace_clock_read64(void)
	41	{
	42	struct timespec ts;
	43
	44	clock_gettime(CLOCK_MONOTONIC, &ts);
	45	return ((uint64_t) ts.tv_sec * 1000000000ULL) + ts.tv_nsec;
	46	}
	47
	48	static __inline__
	49	uint64_t trace_clock_freq(void)
	50	{
	51	return 1000000000ULL;
	52	}
	53
	54	static __inline__
	55	int trace_clock_uuid(char *uuid)
	56	{
	57	int ret = 0;
	58	size_t len;
	59	FILE *fp;
	60
	61	/*
	62	* boot_id needs to be read once before being used concurrently
	63	* to deal with a Linux kernel race. A fix is proposed for
	64	* upstream, but the work-around is needed for older kernels.
	65	*/
	66	fp = fopen("/proc/sys/kernel/random/boot_id", "r");
	67	if (!fp) {
	68	return -ENOENT;
	69	}
	70	len = fread(uuid, 1, LTTNG_UST_UUID_STR_LEN - 1, fp);
	71	if (len < LTTNG_UST_UUID_STR_LEN - 1) {
	72	ret = -EINVAL;
	73	goto end;
	74	}
	75	uuid[LTTNG_UST_UUID_STR_LEN - 1] = '\0';
	76	end:
	77	fclose(fp);
	78	return ret;
	79	}
	80
	81	#endif /* _UST_CLOCK_H */