fg_time.h File Reference

Timing related routines used by Flowgrind. More...

#include "config.h"
#include <sys/time.h>
#include <time.h>
#include <stdbool.h>

Go to the source code of this file.

Macros
#define	NSEC_PER_SEC   1000000000L
	Number of nanoseconds per second. More...

Functions
const char *	ctimenow (bool ns)
	Returns the current wall-clock time as null-terminated string. More...
const char *	ctimenow_r (char *buf, size_t size, bool ns)
	Returns the current wall-clock time as null-terminated string. More...
const char *	ctimespec (const struct timespec *tp, bool ns)
	Converts timespec struct tp into a null-terminated string. More...
const char *	ctimespec_r (const struct timespec *tp, char *buf, size_t size, bool ns)
	Converts timespec struct tp into a null-terminated string. More...
int	gettime (struct timespec *tp)
	Returns the current wall-clock time with nanosecond precision. More...
bool	normalize_tp (struct timespec *tp)
	Normalizes timespec struct tp. More...
void	time_add (struct timespec *tp, double seconds)
	Add an amount of time seconds to a specific point in time tp. More...
double	time_diff (const struct timespec *tp1, const struct timespec *tp2)
	Returns the time difference between two the specific points in time tp1 and tp2. More...
double	time_diff_now (const struct timespec *tp)
	Returns time difference between now and the specific point in time tp. More...
bool	time_is_after (const struct timespec *tp1, const struct timespec *tp2)
	Returns true if second point in time tp2 is chronologically after the first point in time tp1. More...

Detailed Description

Timing related routines used by Flowgrind.

Definition in file fg_time.h.

Macro Definition Documentation

NSEC_PER_SEC

#define NSEC_PER_SEC   1000000000L

Number of nanoseconds per second.

Definition at line 41 of file fg_time.h.

Function Documentation

ctimenow()

const char* ctimenow

(

bool

ns

)

Returns the current wall-clock time as null-terminated string.

The function returns a pointer to static data and hence is not thread-safe. The thread-safe version is ctimenow_r().

Parameters

[in]

ns

if returned time string should have nanosecond precision

Returns

string of the form '2013-12-09-12:00:48[.34369902]'

See also

ctimenow_r

Definition at line 56 of file fg_time.c.

{
        struct timespec now;
 
        gettime(&now);
 
        return ctimespec(&now, ns);
}

ctimenow_r()

const char* ctimenow_r	(	char *	buf,
		size_t	size,
		bool	ns
	)

Returns the current wall-clock time as null-terminated string.

It stores the string in a user-supplied buffer buf.

Parameters

[out]	buf	buffer with room for at least 30 bytes
[in]	size	size of the buffer
[in]	ns	if returned time string should have nanosecond precision

Returns

string of the form '2013-12-09-12:00:48[.34369902]'

Definition at line 47 of file fg_time.c.

{
        struct timespec now;
 
        gettime(&now);
 
        return ctimespec_r(&now, buf, size, ns);
}

ctimespec()

const char* ctimespec	(	const struct timespec *	tp,
		bool	ns
	)

Converts timespec struct tp into a null-terminated string.

The function returns a pointer to static data and hence is not thread-safe. The thread-safe version is ctimespec_r().

Parameters

[in]	tp	point in time
[in]	ns	if returned time string should have nanosecond precision

Returns

string of the form '2013-12-09-12:00:48[.34369902]'

See also

ctimespec_r

Definition at line 86 of file fg_time.c.

{
        static char buf[30];
 
        ctimespec_r(tp, buf, sizeof(buf), ns);
 
        return buf;
}

ctimespec_r()

const char* ctimespec_r	(	const struct timespec *	tp,
		char *	buf,
		size_t	size,
		bool	ns
	)

Converts timespec struct tp into a null-terminated string.

It stores the string in a user-supplied buffer buf.

Parameters

[in]	tp	point in time
[out]	buf	buffer with room for at least 30 bytes
[in]	size	size of the buffer
[in]	ns	if returned time string should have nanosecond precision

Returns

string of the form '2013-12-09-12:00:48i[.34369902]'

Definition at line 66 of file fg_time.c.

{
        struct tm tm;
 
        /* Converts the calendar time to broken-down time representation,
         * expressed relative to the user's specified timezone */
        tzset();
        localtime_r(&tp->tv_sec, &tm);
 
        /* Converts broken-down time representation into a string */
        size_t len = strftime(buf, size, "%F-%T", &tm);
 
        /* Append nanoseconds to string */
        if (ns)
                snprintf(buf+len, size-len, ".%09ld", tp->tv_nsec);
 
        return buf;
}

gettime()

int gettime

(

struct timespec *

tp

)

Returns the current wall-clock time with nanosecond precision.

Since the returned time is retrieved from a system-wide clock that measures real time, the time is may be affected by discontinuous jumps in the system time (e.g., if admin manually changes the clock), and by the incremental adjustments performed by NTP.

Parameters

[out]

tp

current time in seconds and nanoseconds since the Epoch

Returns

return 0 for success, or -1 for failure

Definition at line 145 of file fg_time.c.

{
        static struct timespec res = {.tv_sec = 0, .tv_nsec = 0};
 
        /* Find out clock resolution. Will only be retrieved on first call */
        if (!res.tv_sec && !res.tv_nsec) {
                clock_getres(CLOCK_REALTIME, &res);
                /* Clock resolution is lower than expected (1ns) */
                assert(res.tv_nsec == 1);
        }
 
        /* Get wall-clock time */
        return clock_gettime(CLOCK_REALTIME, tp);
}

normalize_tp()

bool normalize_tp

(

struct timespec *

tp

)

Normalizes timespec struct tp.

Ensures that the equation 0 <= tp->tv_nsec < NSEC_PER_SEC holds, meaning that the amount of nanoseconds is not negative less than one second.

Parameters

[in,out]

tp

point in time

Returns

true if timespec struct was already normalized, otherwise false

Definition at line 119 of file fg_time.c.

{
        bool normalized = true;
 
        while (tp->tv_nsec >= (long) NSEC_PER_SEC) {
                tp->tv_nsec -= (long) NSEC_PER_SEC;
                tp->tv_sec++;
                normalized = false;
        }
        while (tp->tv_nsec < 0) {
                tp->tv_nsec += (long) NSEC_PER_SEC;
                tp->tv_sec--;
                normalized = false;
        }
        return normalized;
}

time_add()

void time_add	(	struct timespec *	tp,
		double	seconds
	)

Add an amount of time seconds to a specific point in time tp.

Parameters

[in,out]	tp	point in time
[in]	seconds	amount of time in seconds

Definition at line 136 of file fg_time.c.

{
        tp->tv_sec += (time_t) seconds;
        tp->tv_nsec += (long) ((seconds - (time_t) seconds) * (long) NSEC_PER_SEC);
        normalize_tp(tp);
}

time_diff()

double time_diff	(	const struct timespec *	tp1,
		const struct timespec *	tp2
	)

Returns the time difference between two the specific points in time tp1 and tp2.

Negative if the first point in time is chronologically after the second one.

Parameters

[in]	tp1	point in time
[in]	tp2	point in time

Returns

time difference in nanoseconds

Definition at line 95 of file fg_time.c.

{
        return (double) (tp2->tv_sec - tp1->tv_sec)
                + (double) (tp2->tv_nsec - tp1->tv_nsec) / (long) NSEC_PER_SEC;
}

time_diff_now()

double time_diff_now

(

const struct timespec *

tp

)

Returns time difference between now and the specific point in time tp.

Parameters

[in]

tp

point in time

Returns

time difference in nanoseconds

Definition at line 101 of file fg_time.c.

{
        struct timespec now;
 
        gettime(&now);
        return (double) (now.tv_sec - tp->tv_sec)
                + (double) (now.tv_nsec - tp->tv_nsec) / (long) NSEC_PER_SEC;
}

time_is_after()

bool time_is_after	(	const struct timespec *	tp1,
		const struct timespec *	tp2
	)

Returns true if second point in time tp2 is chronologically after the first point in time tp1.

Parameters

[in]	tp1	point in time
[in]	tp2	point in time

Returns

true or false

Definition at line 110 of file fg_time.c.

{
        if (tp1->tv_sec > tp2->tv_sec)
                return true;
        if (tp1->tv_sec < tp2->tv_sec)
                return false;
        return tp1->tv_nsec > tp2->tv_nsec;
}