timestamp.c

postgresql8.3.4源码,开源数据库

									 IntervalOffsets[precision]) /
									IntervalScales[precision]) *
								   IntervalScales[precision]);
			}
#else
			interval->time = rint(((double) interval->time) *
								  IntervalScales[precision]) /
				IntervalScales[precision];
#endif
		}
	}

	return;
}


/* EncodeSpecialTimestamp()
 * Convert reserved timestamp data type to string.
 */
static int
EncodeSpecialTimestamp(Timestamp dt, char *str)
{
	if (TIMESTAMP_IS_NOBEGIN(dt))
		strcpy(str, EARLY);
	else if (TIMESTAMP_IS_NOEND(dt))
		strcpy(str, LATE);
	else
		return FALSE;

	return TRUE;
}	/* EncodeSpecialTimestamp() */

Datum
now(PG_FUNCTION_ARGS)
{
	PG_RETURN_TIMESTAMPTZ(GetCurrentTransactionStartTimestamp());
}

Datum
statement_timestamp(PG_FUNCTION_ARGS)
{
	PG_RETURN_TIMESTAMPTZ(GetCurrentStatementStartTimestamp());
}

Datum
clock_timestamp(PG_FUNCTION_ARGS)
{
	PG_RETURN_TIMESTAMPTZ(GetCurrentTimestamp());
}

Datum
pgsql_postmaster_start_time(PG_FUNCTION_ARGS)
{
	PG_RETURN_TIMESTAMPTZ(PgStartTime);
}

/*
 * GetCurrentTimestamp -- get the current operating system time
 *
 * Result is in the form of a TimestampTz value, and is expressed to the
 * full precision of the gettimeofday() syscall
 */
TimestampTz
GetCurrentTimestamp(void)
{
	TimestampTz result;
	struct timeval tp;

	gettimeofday(&tp, NULL);

	result = (TimestampTz) tp.tv_sec -
		((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY);

#ifdef HAVE_INT64_TIMESTAMP
	result = (result * USECS_PER_SEC) + tp.tv_usec;
#else
	result = result + (tp.tv_usec / 1000000.0);
#endif

	return result;
}

/*
 * TimestampDifference -- convert the difference between two timestamps
 *		into integer seconds and microseconds
 *
 * Both inputs must be ordinary finite timestamps (in current usage,
 * they'll be results from GetCurrentTimestamp()).
 *
 * We expect start_time <= stop_time.  If not, we return zeroes; for current
 * callers there is no need to be tense about which way division rounds on
 * negative inputs.
 */
void
TimestampDifference(TimestampTz start_time, TimestampTz stop_time,
					long *secs, int *microsecs)
{
	TimestampTz diff = stop_time - start_time;

	if (diff <= 0)
	{
		*secs = 0;
		*microsecs = 0;
	}
	else
	{
#ifdef HAVE_INT64_TIMESTAMP
		*secs = (long) (diff / USECS_PER_SEC);
		*microsecs = (int) (diff % USECS_PER_SEC);
#else
		*secs = (long) diff;
		*microsecs = (int) ((diff - *secs) * 1000000.0);
#endif
	}
}

/*
 * TimestampDifferenceExceeds -- report whether the difference between two
 *		timestamps is >= a threshold (expressed in milliseconds)
 *
 * Both inputs must be ordinary finite timestamps (in current usage,
 * they'll be results from GetCurrentTimestamp()).
 */
bool
TimestampDifferenceExceeds(TimestampTz start_time,
						   TimestampTz stop_time,
						   int msec)
{
	TimestampTz diff = stop_time - start_time;

#ifdef HAVE_INT64_TIMESTAMP
	return (diff >= msec * INT64CONST(1000));
#else
	return (diff * 1000.0 >= msec);
#endif
}

/*
 * Convert a time_t to TimestampTz.
 *
 * We do not use time_t internally in Postgres, but this is provided for use
 * by functions that need to interpret, say, a stat(2) result.
 */
TimestampTz
time_t_to_timestamptz(time_t tm)
{
	TimestampTz result;

	result = (TimestampTz) tm -
		((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY);

#ifdef HAVE_INT64_TIMESTAMP
	result *= USECS_PER_SEC;
#endif

	return result;
}

/*
 * Convert a TimestampTz to time_t.
 *
 * This too is just marginally useful, but some places need it.
 */
time_t
timestamptz_to_time_t(TimestampTz t)
{
	time_t		result;

#ifdef HAVE_INT64_TIMESTAMP
	result = (time_t) (t / USECS_PER_SEC +
				 ((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY));
#else
	result = (time_t) (t +
				 ((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY));
#endif

	return result;
}

/*
 * Produce a C-string representation of a TimestampTz.
 *
 * This is mostly for use in emitting messages.  The primary difference
 * from timestamptz_out is that we force the output format to ISO.	Note
 * also that the result is in a static buffer, not pstrdup'd.
 */
const char *
timestamptz_to_str(TimestampTz t)
{
	static char buf[MAXDATELEN + 1];
	int			tz;
	struct pg_tm tt,
			   *tm = &tt;
	fsec_t		fsec;
	char	   *tzn;

	if (TIMESTAMP_NOT_FINITE(t))
		EncodeSpecialTimestamp(t, buf);
	else if (timestamp2tm(t, &tz, tm, &fsec, &tzn, NULL) == 0)
		EncodeDateTime(tm, fsec, &tz, &tzn, USE_ISO_DATES, buf);
	else
		strlcpy(buf, "(timestamp out of range)", sizeof(buf));

	return buf;
}


void
dt2time(Timestamp jd, int *hour, int *min, int *sec, fsec_t *fsec)
{
#ifdef HAVE_INT64_TIMESTAMP
	int64		time;
#else
	double		time;
#endif

	time = jd;

#ifdef HAVE_INT64_TIMESTAMP
	*hour = time / USECS_PER_HOUR;
	time -= (*hour) * USECS_PER_HOUR;
	*min = time / USECS_PER_MINUTE;
	time -= (*min) * USECS_PER_MINUTE;
	*sec = time / USECS_PER_SEC;
	*fsec = time - (*sec * USECS_PER_SEC);
#else
	*hour = time / SECS_PER_HOUR;
	time -= (*hour) * SECS_PER_HOUR;
	*min = time / SECS_PER_MINUTE;
	time -= (*min) * SECS_PER_MINUTE;
	*sec = time;
	*fsec = time - *sec;
#endif
}	/* dt2time() */


/*
 * timestamp2tm() - Convert timestamp data type to POSIX time structure.
 *
 * Note that year is _not_ 1900-based, but is an explicit full value.
 * Also, month is one-based, _not_ zero-based.
 * Returns:
 *	 0 on success
 *	-1 on out of range
 *
 * If attimezone is NULL, the global timezone (including possibly brute forced
 * timezone) will be used.
 */
int
timestamp2tm(Timestamp dt, int *tzp, struct pg_tm * tm, fsec_t *fsec, char **tzn, pg_tz *attimezone)
{
	Timestamp	date;
	Timestamp	time;
	pg_time_t	utime;

	/*
	 * If HasCTZSet is true then we have a brute force time zone specified. Go
	 * ahead and rotate to the local time zone since we will later bypass any
	 * calls which adjust the tm fields.
	 */
	if (attimezone == NULL && HasCTZSet && tzp != NULL)
	{
#ifdef HAVE_INT64_TIMESTAMP
		dt -= CTimeZone * USECS_PER_SEC;
#else
		dt -= CTimeZone;
#endif
	}

#ifdef HAVE_INT64_TIMESTAMP
	time = dt;
	TMODULO(time, date, USECS_PER_DAY);

	if (time < INT64CONST(0))
	{
		time += USECS_PER_DAY;
		date -= 1;
	}

	/* add offset to go from J2000 back to standard Julian date */
	date += POSTGRES_EPOCH_JDATE;

	/* Julian day routine does not work for negative Julian days */
	if (date < 0 || date > (Timestamp) INT_MAX)
		return -1;

	j2date((int) date, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
	dt2time(time, &tm->tm_hour, &tm->tm_min, &tm->tm_sec, fsec);
#else
	time = dt;
	TMODULO(time, date, (double) SECS_PER_DAY);

	if (time < 0)
	{
		time += SECS_PER_DAY;
		date -= 1;
	}

	/* add offset to go from J2000 back to standard Julian date */
	date += POSTGRES_EPOCH_JDATE;

recalc_d:
	/* Julian day routine does not work for negative Julian days */
	if (date < 0 || date > (Timestamp) INT_MAX)
		return -1;

	j2date((int) date, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
recalc_t:
	dt2time(time, &tm->tm_hour, &tm->tm_min, &tm->tm_sec, fsec);

	*fsec = TSROUND(*fsec);
	/* roundoff may need to propagate to higher-order fields */
	if (*fsec >= 1.0)
	{
		time = ceil(time);
		if (time >= (double) SECS_PER_DAY)
		{
			time = 0;
			date += 1;
			goto recalc_d;
		}
		goto recalc_t;
	}
#endif

	/* Done if no TZ conversion wanted */
	if (tzp == NULL)
	{
		tm->tm_isdst = -1;
		tm->tm_gmtoff = 0;
		tm->tm_zone = NULL;
		if (tzn != NULL)
			*tzn = NULL;
		return 0;
	}

	/*
	 * We have a brute force time zone per SQL99? Then use it without change
	 * since we have already rotated to the time zone.
	 */
	if (attimezone == NULL && HasCTZSet)
	{
		*tzp = CTimeZone;
		tm->tm_isdst = 0;
		tm->tm_gmtoff = CTimeZone;
		tm->tm_zone = NULL;
		if (tzn != NULL)
			*tzn = NULL;
		return 0;
	}

	/*
	 * If the time falls within the range of pg_time_t, use pg_localtime() to
	 * rotate to the local time zone.
	 *
	 * First, convert to an integral timestamp, avoiding possibly
	 * platform-specific roundoff-in-wrong-direction errors, and adjust to
	 * Unix epoch.	Then see if we can convert to pg_time_t without loss. This
	 * coding avoids hardwiring any assumptions about the width of pg_time_t,
	 * so it should behave sanely on machines without int64.
	 */
#ifdef HAVE_INT64_TIMESTAMP
	dt = (dt - *fsec) / USECS_PER_SEC +
		(POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY;
#else
	dt = rint(dt - *fsec +
			  (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY);
#endif
	utime = (pg_time_t) dt;
	if ((Timestamp) utime == dt)
	{
		struct pg_tm *tx = pg_localtime(&utime,
								 attimezone ? attimezone : session_timezone);

		tm->tm_year = tx->tm_year + 1900;
		tm->tm_mon = tx->tm_mon + 1;
		tm->tm_mday = tx->tm_mday;
		tm->tm_hour = tx->tm_hour;
		tm->tm_min = tx->tm_min;
		tm->tm_sec = tx->tm_sec;
		tm->tm_isdst = tx->tm_isdst;
		tm->tm_gmtoff = tx->tm_gmtoff;
		tm->tm_zone = tx->tm_zone;
		*tzp = -tm->tm_gmtoff;
		if (tzn != NULL)
			*tzn = (char *) tm->tm_zone;
	}
	else
	{
		/*
		 * When out of range of pg_time_t, treat as GMT
		 */
		*tzp = 0;
		/* Mark this as *no* time zone available */
		tm->tm_isdst = -1;
		tm->tm_gmtoff = 0;
		tm->tm_zone = NULL;
		if (tzn != NULL)
			*tzn = NULL;
	}

	return 0;
}


/* tm2timestamp()
 * Convert a tm structure to a timestamp data type.
 * Note that year is _not_ 1900-based, but is an explicit full value.
 * Also, month is one-based, _not_ zero-based.
 *
 * Returns -1 on failure (value out of range).
 */
int
tm2timestamp(struct pg_tm * tm, fsec_t fsec, int *tzp, Timestamp *result)
{
#ifdef HAVE_INT64_TIMESTAMP
	int			date;
	int64		time;
#else
	double		date,
				time;
#endif

	/* Julian day routines are not correct for negative Julian days */
	if (!IS_VALID_JULIAN(tm->tm_year, tm->tm_mon, tm->tm_mday))
	{
		*result = 0;			/* keep compiler quiet */
		return -1;
	}

	date = date2j(tm->tm_year, tm->tm_mon, tm->tm_mday) - POSTGRES_EPOCH_JDATE;
	time = time2t(tm->tm_hour, tm->tm_min, tm->tm_sec, fsec);

#ifdef HAVE_INT64_TIMESTAMP
	*result = date * USECS_PER_DAY + time;
	/* check for major overflow */
	if ((*result - time) / USECS_PER_DAY != date)
	{
		*result = 0;			/* keep compiler quiet */
		return -1;
	}
	/* check for just-barely overflow (okay except time-of-day wraps) */
	if ((*result < 0 && date >= 0) ||
		(*result >= 0 && date < 0))
	{
		*result = 0;			/* keep compiler quiet */
		return -1;
	}
#else
	*result = date * SECS_PER_DAY + time;
#endif
	if (tzp != NULL)
		*result = dt2local(*result, -(*tzp));

	return 0;
}


/* interval2tm()
 * Convert a interval data type to a tm structure.
 */
int
interval2tm(Interval span, struct pg_tm * tm, fsec_t *fsec)
{
#ifdef HAVE_INT64_TIMESTAMP
	int64		time;
	int64		tfrac;
#else
	double		time;
	double		tfrac;
#endif

	tm->tm_year = span.month / MONTHS_PER_YEAR;
	tm->tm_mon = span.month % MONTHS_PER_YEAR;
	tm->tm_mday = span.day;
	time = span.time;

#ifdef HAVE_INT64_TIMESTAMP
	tfrac = time / USECS_PER_HOUR;
	time -= tfrac * USECS_PER_HOUR;
	tm->tm_hour = tfrac;		/* could overflow ... */
	tfrac = time / USECS_PER_MINUTE;
	time -= tfrac * USECS_PER_MINUTE;
	tm->tm_min = tfrac;
	tfrac = time / USECS_PER_SEC;
	*fsec = time - (tfrac * USECS_PER_SEC);
	tm->tm_sec = tfrac;
#else
recalc:
	TMODULO(time, tfrac, (double) SECS_PER_HOUR);
	tm->tm_hour = tfrac;		/* could overflow ... */
	TMODULO(time, tfrac, (double) SECS_PER_MINUTE);
	tm->tm_min = tfrac;
	TMODULO(time, tfrac, 1.0);
	tm->tm_sec = tfrac;
	time = TSROUND(time);
	/* roundoff may need to propagate to higher-order fields */
	if (time >= 1.0)
	{
		time = ceil(span.time);
		goto recalc;
	}
	*fsec = time;
#endif

	return 0;
}

int
tm2interval(struct pg_tm * tm, fsec_t fsec, Interval *span)
{
	span->month = tm->tm_year * MONTHS_PER_YEAR + tm->tm_mon;
	span->day = tm->tm_mday;
#ifdef HAVE_INT64_TIMESTAMP
	span->time = (((((tm->tm_hour * INT64CONST(60)) +
					 tm->tm_min) * INT64CONST(60)) +
				   tm->tm_sec) * USECS_PER_SEC) + fsec;
#else
	span->time = (((tm->tm_hour * (double) MINS_PER_HOUR) +
				   tm->tm_min) * (double) SECS_PER_MINUTE) +
		tm->tm_sec + fsec;
#endif

	return 0;
}

#ifdef HAVE_INT64_TIMESTAMP
static int64
time2t(const int hour, const int min, const int sec, const fsec_t fsec)
{
	return (((((hour * MINS_PER_HOUR) + min) * SECS_PER_MINUTE) + sec) * USECS_PER_SEC) + fsec;
}	/* time2t() */
#else
static double
time2t(const int hour, const int min, const int sec, const fsec_t fsec)
{
	return (((hour * MINS_PER_HOUR) + min) * SECS_PER_MINUTE) + sec + fsec;
}	/* time2t() */
#endif

static Timestamp
dt2local(Timestamp dt, int tz)
{
#ifdef HAVE_INT64_TIMESTAMP
	dt -= (tz * USECS_PER_SEC);
#else
	dt -= tz;
#endif
	return dt;
}	/* dt2local() */


/*****************************************************************************
 *	 PUBLIC ROUTINES														 *
 *****************************************************************************/


Datum
timestamp_finite(PG_FUNCTION_ARGS)
{
	Timestamp	timestamp = PG_GETARG_TIMESTAMP(0);