database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-03 09:13:20 +03:00
Code Activity

Improve speed of timestamp/time/date output functions.

Browse Source 
It seems that sprintf(), at least in glibc's version, is unreasonably slow
compared to hand-rolled code for printing integers.  Replacing most uses of
sprintf() in the datetime.c output functions with special-purpose code
turns out to give more than a 2X speedup in COPY of a table with a single
timestamp column; which is pretty impressive considering all the other
logic in that code path.

David Rowley and Andres Freund, reviewed by Peter Geoghegan and myself
This commit is contained in:
Tom Lane
2016-02-06 23:11:28 -05:00
parent b921aeb167
commit aa2387e2fd
3 changed files with 424 additions and 128 deletions
Download Patch File Download Diff File Expand all files Collapse all files

399
src/backend/utils/adt/datetime.c
View File

@@ -43,8 +43,12 @@ static int DecodeTime(char *str, int fmask, int range,
static const datetkn *datebsearch(const char *key, const datetkn *base, int nel);
static int DecodeDate(char *str, int fmask, int *tmask, bool *is2digits,
struct pg_tm * tm);
static void TrimTrailingZeros(char *str);
static void AppendSeconds(char *cp, int sec, fsec_t fsec,
#ifndef HAVE_INT64_TIMESTAMP
static char *TrimTrailingZeros(char *str);
#endif /* HAVE_INT64_TIMESTAMP */
static char *AppendSeconds(char *cp, int sec, fsec_t fsec,
int precision, bool fillzeros);
static void AdjustFractSeconds(double frac, struct pg_tm * tm, fsec_t *fsec,
int scale);
@@ -398,57 +402,121 @@ GetCurrentTimeUsec(struct pg_tm * tm, fsec_t *fsec, int *tzp)
/* TrimTrailingZeros()
* ... resulting from printing numbers with full precision.
*
* Returns a pointer to the new end of string. No NUL terminator is put
* there; callers are responsible for NUL terminating str themselves.
*
* Before Postgres 8.4, this always left at least 2 fractional digits,
* but conversations on the lists suggest this isn't desired
* since showing '0.10' is misleading with values of precision(1).
*/
static void
#ifndef HAVE_INT64_TIMESTAMP
static char *
TrimTrailingZeros(char *str)
{
int len = strlen(str);
while (len > 1 && *(str + len - 1) == '0' && *(str + len - 2) != '.')
{
len--;
*(str + len) = '\0';
return str + len;
}
#endif /* HAVE_INT64_TIMESTAMP */
/*
* Append seconds and fractional seconds (if any) at *cp.
*
* precision is the max number of fraction digits, fillzeros says to
* pad to two integral-seconds digits.
*
* Returns a pointer to the new end of string. No NUL terminator is put
* there; callers are responsible for NUL terminating str themselves.
*
* Note that any sign is stripped from the input seconds values.
*/
static char *
AppendSeconds(char *cp, int sec, fsec_t fsec, int precision, bool fillzeros)
{
Assert(precision >= 0);
#ifdef HAVE_INT64_TIMESTAMP
/* fsec_t is just an int32 */
if (fillzeros)
cp = pg_ltostr_zeropad(cp, Abs(sec), 2);
else
cp = pg_ltostr(cp, Abs(sec));
if (fsec != 0)
{
int32 value = Abs(fsec);
char *end = &cp[precision + 1];
bool gotnonzero = false;
*cp++ = '.';
/*
* Append the fractional seconds part. Note that we don't want any
* trailing zeros here, so since we're building the number in reverse
* we'll skip appending zeros until we've output a non-zero digit.
*/
while (precision--)
{
int32 oldval = value;
int32 remainder;
value /= 10;
remainder = oldval - value * 10;
/* check if we got a non-zero */
if (remainder)
gotnonzero = true;
if (gotnonzero)
cp[precision] = '0' + remainder;
else
end = &cp[precision];
}
/*
* Append sections and fractional seconds (if any) at *cp.
* precision is the max number of fraction digits, fillzeros says to
* pad to two integral-seconds digits.
* Note that any sign is stripped from the input seconds values.
* If we still have a non-zero value then precision must have not been
* enough to print the number. We punt the problem to pg_ltostr(),
* which will generate a correct answer in the minimum valid width.
*/
static void
AppendSeconds(char *cp, int sec, fsec_t fsec, int precision, bool fillzeros)
{
if (value)
return pg_ltostr(cp, Abs(fsec));
return end;
}
else
return cp;
#else
/* fsec_t is a double */
if (fsec == 0)
{
if (fillzeros)
sprintf(cp, "%02d", abs(sec));
return pg_ltostr_zeropad(cp, Abs(sec), 2);
else
sprintf(cp, "%d", abs(sec));
return pg_ltostr(cp, Abs(sec));
}
else
{
#ifdef HAVE_INT64_TIMESTAMP
if (fillzeros)
sprintf(cp, "%02d.%0*d", abs(sec), precision, (int) Abs(fsec));
else
sprintf(cp, "%d.%0*d", abs(sec), precision, (int) Abs(fsec));
#else
if (fillzeros)
sprintf(cp, "%0*.*f", precision + 3, precision, fabs(sec + fsec));
else
sprintf(cp, "%.*f", precision, fabs(sec + fsec));
#endif
TrimTrailingZeros(cp);
return TrimTrailingZeros(cp);
}
#endif /* HAVE_INT64_TIMESTAMP */
}
/* Variant of above that's specialized to timestamp case */
static void
/*
* Variant of above that's specialized to timestamp case.
*
* Returns a pointer to the new end of string. No NUL terminator is put
* there; callers are responsible for NUL terminating str themselves.
*/
static char *
AppendTimestampSeconds(char *cp, struct pg_tm * tm, fsec_t fsec)
{
/*
@@ -459,7 +527,7 @@ AppendTimestampSeconds(char *cp, struct pg_tm * tm, fsec_t fsec)
if (tm->tm_year <= 0)
fsec = 0;
#endif
AppendSeconds(cp, tm->tm_sec, fsec, MAX_TIMESTAMP_PRECISION, true);
return AppendSeconds(cp, tm->tm_sec, fsec, MAX_TIMESTAMP_PRECISION, true);
}
/*
@@ -3831,9 +3899,12 @@ datebsearch(const char *key, const datetkn *base, int nel)
}
/* EncodeTimezone()
* Append representation of a numeric timezone offset to str.
* Copies representation of a numeric timezone offset to str.
*
* Returns a pointer to the new end of string. No NUL terminator is put
* there; callers are responsible for NUL terminating str themselves.
*/
static void
static char *
EncodeTimezone(char *str, int tz, int style)
{
int hour,
@@ -3846,16 +3917,26 @@ EncodeTimezone(char *str, int tz, int style)
hour = min / MINS_PER_HOUR;
min -= hour * MINS_PER_HOUR;
str += strlen(str);
/* TZ is negated compared to sign we wish to display ... */
*str++ = (tz <= 0 ? '+' : '-');
if (sec != 0)
sprintf(str, "%02d:%02d:%02d", hour, min, sec);
{
str = pg_ltostr_zeropad(str, hour, 2);
*str++ = ':';
str = pg_ltostr_zeropad(str, min, 2);
*str++ = ':';
str = pg_ltostr_zeropad(str, sec, 2);
}
else if (min != 0 || style == USE_XSD_DATES)
sprintf(str, "%02d:%02d", hour, min);
{
str = pg_ltostr_zeropad(str, hour, 2);
*str++ = ':';
str = pg_ltostr_zeropad(str, min, 2);
}
else
sprintf(str, "%02d", hour);
str = pg_ltostr_zeropad(str, hour, 2);
return str;
}
/* EncodeDateOnly()
@@ -3871,48 +3952,70 @@ EncodeDateOnly(struct pg_tm * tm, int style, char *str)
case USE_ISO_DATES:
case USE_XSD_DATES:
/* compatible with ISO date formats */
if (tm->tm_year > 0)
sprintf(str, "%04d-%02d-%02d",
tm->tm_year, tm->tm_mon, tm->tm_mday);
else
sprintf(str, "%04d-%02d-%02d %s",
-(tm->tm_year - 1), tm->tm_mon, tm->tm_mday, "BC");
str = pg_ltostr_zeropad(str,
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1), 4);
*str++ = '-';
str = pg_ltostr_zeropad(str, tm->tm_mon, 2);
*str++ = '-';
str = pg_ltostr_zeropad(str, tm->tm_mday, 2);
break;
case USE_SQL_DATES:
/* compatible with Oracle/Ingres date formats */
if (DateOrder == DATEORDER_DMY)
sprintf(str, "%02d/%02d", tm->tm_mday, tm->tm_mon);
{
str = pg_ltostr_zeropad(str, tm->tm_mday, 2);
*str++ = '/';
str = pg_ltostr_zeropad(str, tm->tm_mon, 2);
}
else
sprintf(str, "%02d/%02d", tm->tm_mon, tm->tm_mday);
if (tm->tm_year > 0)
sprintf(str + 5, "/%04d", tm->tm_year);
else
sprintf(str + 5, "/%04d %s", -(tm->tm_year - 1), "BC");
{
str = pg_ltostr_zeropad(str, tm->tm_mon, 2);
*str++ = '/';
str = pg_ltostr_zeropad(str, tm->tm_mday, 2);
}
*str++ = '/';
str = pg_ltostr_zeropad(str,
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1), 4);
break;
case USE_GERMAN_DATES:
/* German-style date format */
sprintf(str, "%02d.%02d", tm->tm_mday, tm->tm_mon);
if (tm->tm_year > 0)
sprintf(str + 5, ".%04d", tm->tm_year);
else
sprintf(str + 5, ".%04d %s", -(tm->tm_year - 1), "BC");
str = pg_ltostr_zeropad(str, tm->tm_mday, 2);
*str++ = '.';
str = pg_ltostr_zeropad(str, tm->tm_mon, 2);
*str++ = '.';
str = pg_ltostr_zeropad(str,
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1), 4);
break;
case USE_POSTGRES_DATES:
default:
/* traditional date-only style for Postgres */
if (DateOrder == DATEORDER_DMY)
sprintf(str, "%02d-%02d", tm->tm_mday, tm->tm_mon);
{
str = pg_ltostr_zeropad(str, tm->tm_mday, 2);
*str++ = '-';
str = pg_ltostr_zeropad(str, tm->tm_mon, 2);
}
else
sprintf(str, "%02d-%02d", tm->tm_mon, tm->tm_mday);
if (tm->tm_year > 0)
sprintf(str + 5, "-%04d", tm->tm_year);
else
sprintf(str + 5, "-%04d %s", -(tm->tm_year - 1), "BC");
{
str = pg_ltostr_zeropad(str, tm->tm_mon, 2);
*str++ = '-';
str = pg_ltostr_zeropad(str, tm->tm_mday, 2);
}
*str++ = '-';
str = pg_ltostr_zeropad(str,
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1), 4);
break;
}
if (tm->tm_year <= 0)
{
memcpy(str, " BC", 3); /* Don't copy NUL */
str += 3;
}
*str = '\0';
}
@@ -3927,13 +4030,14 @@ EncodeDateOnly(struct pg_tm * tm, int style, char *str)
void
EncodeTimeOnly(struct pg_tm * tm, fsec_t fsec, bool print_tz, int tz, int style, char *str)
{
sprintf(str, "%02d:%02d:", tm->tm_hour, tm->tm_min);
str += strlen(str);
AppendSeconds(str, tm->tm_sec, fsec, MAX_TIME_PRECISION, true);
str = pg_ltostr_zeropad(str, tm->tm_hour, 2);
*str++ = ':';
str = pg_ltostr_zeropad(str, tm->tm_min, 2);
*str++ = ':';
str = AppendSeconds(str, tm->tm_sec, fsec, MAX_TIME_PRECISION, true);
if (print_tz)
EncodeTimezone(str, tz, style);
str = EncodeTimezone(str, tz, style);
*str = '\0';
}
@@ -3971,106 +4075,129 @@ EncodeDateTime(struct pg_tm * tm, fsec_t fsec, bool print_tz, int tz, const char
case USE_ISO_DATES:
case USE_XSD_DATES:
/* Compatible with ISO-8601 date formats */
if (style == USE_ISO_DATES)
sprintf(str, "%04d-%02d-%02d %02d:%02d:",
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1),
tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min);
else
sprintf(str, "%04d-%02d-%02dT%02d:%02d:",
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1),
tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min);
AppendTimestampSeconds(str + strlen(str), tm, fsec);
str = pg_ltostr_zeropad(str,
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1), 4);
*str++ = '-';
str = pg_ltostr_zeropad(str, tm->tm_mon, 2);
*str++ = '-';
str = pg_ltostr_zeropad(str, tm->tm_mday, 2);
*str++ = (style == USE_ISO_DATES) ? ' ' : 'T';
str = pg_ltostr_zeropad(str, tm->tm_hour, 2);
*str++ = ':';
str = pg_ltostr_zeropad(str, tm->tm_min, 2);
*str++ = ':';
str = AppendTimestampSeconds(str, tm, fsec);
if (print_tz)
EncodeTimezone(str, tz, style);
if (tm->tm_year <= 0)
sprintf(str + strlen(str), " BC");
str = EncodeTimezone(str, tz, style);
break;
case USE_SQL_DATES:
/* Compatible with Oracle/Ingres date formats */
if (DateOrder == DATEORDER_DMY)
sprintf(str, "%02d/%02d", tm->tm_mday, tm->tm_mon);
{
str = pg_ltostr_zeropad(str, tm->tm_mday, 2);
*str++ = '/';
str = pg_ltostr_zeropad(str, tm->tm_mon, 2);
}
else
sprintf(str, "%02d/%02d", tm->tm_mon, tm->tm_mday);
sprintf(str + 5, "/%04d %02d:%02d:",
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1),
tm->tm_hour, tm->tm_min);
AppendTimestampSeconds(str + strlen(str), tm, fsec);
{
str = pg_ltostr_zeropad(str, tm->tm_mon, 2);
*str++ = '/';
str = pg_ltostr_zeropad(str, tm->tm_mday, 2);
}
*str++ = '/';
str = pg_ltostr_zeropad(str,
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1), 4);
*str++ = ' ';
str = pg_ltostr_zeropad(str, tm->tm_hour, 2);
*str++ = ':';
str = pg_ltostr_zeropad(str, tm->tm_min, 2);
*str++ = ':';
str = AppendTimestampSeconds(str, tm, fsec);
/*
* Note: the uses of %.*s in this function would be risky if the
* timezone names ever contain non-ASCII characters. However, all
* TZ abbreviations in the Olson database are plain ASCII.
* TZ abbreviations in the IANA database are plain ASCII.
*/
if (print_tz)
{
if (tzn)
sprintf(str + strlen(str), " %.*s", MAXTZLEN, tzn);
else
EncodeTimezone(str, tz, style);
{
sprintf(str, " %.*s", MAXTZLEN, tzn);
str += strlen(str);
}
else
str = EncodeTimezone(str, tz, style);
}
if (tm->tm_year <= 0)
sprintf(str + strlen(str), " BC");
break;
case USE_GERMAN_DATES:
/* German variant on European style */
sprintf(str, "%02d.%02d", tm->tm_mday, tm->tm_mon);
sprintf(str + 5, ".%04d %02d:%02d:",
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1),
tm->tm_hour, tm->tm_min);
AppendTimestampSeconds(str + strlen(str), tm, fsec);
str = pg_ltostr_zeropad(str, tm->tm_mday, 2);
*str++ = '.';
str = pg_ltostr_zeropad(str, tm->tm_mon, 2);
*str++ = '.';
str = pg_ltostr_zeropad(str,
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1), 4);
*str++ = ' ';
str = pg_ltostr_zeropad(str, tm->tm_hour, 2);
*str++ = ':';
str = pg_ltostr_zeropad(str, tm->tm_min, 2);
*str++ = ':';
str = AppendTimestampSeconds(str, tm, fsec);
if (print_tz)
{
if (tzn)
sprintf(str + strlen(str), " %.*s", MAXTZLEN, tzn);
else
EncodeTimezone(str, tz, style);
{
sprintf(str, " %.*s", MAXTZLEN, tzn);
str += strlen(str);
}
else
str = EncodeTimezone(str, tz, style);
}
if (tm->tm_year <= 0)
sprintf(str + strlen(str), " BC");
break;
case USE_POSTGRES_DATES:
default:
/* Backward-compatible with traditional Postgres abstime dates */
day = date2j(tm->tm_year, tm->tm_mon, tm->tm_mday);
tm->tm_wday = j2day(day);
memcpy(str, days[tm->tm_wday], 3);
strcpy(str + 3, " ");
str += 3;
*str++ = ' ';
if (DateOrder == DATEORDER_DMY)
sprintf(str + 4, "%02d %3s", tm->tm_mday, months[tm->tm_mon - 1]);
{
str = pg_ltostr_zeropad(str, tm->tm_mday, 2);
*str++ = ' ';
memcpy(str, months[tm->tm_mon - 1], 3);
str += 3;
}
else
sprintf(str + 4, "%3s %02d", months[tm->tm_mon - 1], tm->tm_mday);
sprintf(str + 10, " %02d:%02d:", tm->tm_hour, tm->tm_min);
AppendTimestampSeconds(str + strlen(str), tm, fsec);
sprintf(str + strlen(str), " %04d",
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1));
{
memcpy(str, months[tm->tm_mon - 1], 3);
str += 3;
*str++ = ' ';
str = pg_ltostr_zeropad(str, tm->tm_mday, 2);
}
*str++ = ' ';
str = pg_ltostr_zeropad(str, tm->tm_hour, 2);
*str++ = ':';
str = pg_ltostr_zeropad(str, tm->tm_min, 2);
*str++ = ':';
str = AppendTimestampSeconds(str, tm, fsec);
*str++ = ' ';
str = pg_ltostr_zeropad(str,
(tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1), 4);
if (print_tz)
{
if (tzn)
sprintf(str + strlen(str), " %.*s", MAXTZLEN, tzn);
{
sprintf(str, " %.*s", MAXTZLEN, tzn);
str += strlen(str);
}
else
{
/*
@@ -4079,15 +4206,19 @@ EncodeDateTime(struct pg_tm * tm, fsec_t fsec, bool print_tz, int tz, const char
* avoid formatting something which would be rejected by
* the date/time parser later. - thomas 2001-10-19
*/
sprintf(str + strlen(str), " ");
EncodeTimezone(str, tz, style);
*str++ = ' ';
str = EncodeTimezone(str, tz, style);
}
}
break;
}
if (tm->tm_year <= 0)
sprintf(str + strlen(str), " BC");
break;
{
memcpy(str, " BC", 3); /* Don't copy NUL */
str += 3;
}
*str = '\0';
}
@@ -4242,7 +4373,8 @@ EncodeInterval(struct pg_tm * tm, fsec_t fsec, int style, char *str)
day_sign, abs(mday),
sec_sign, abs(hour), abs(min));
cp += strlen(cp);
AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
cp = AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
*cp = '\0';
}
else if (has_year_month)
{
@@ -4252,13 +4384,15 @@ EncodeInterval(struct pg_tm * tm, fsec_t fsec, int style, char *str)
{
sprintf(cp, "%d %d:%02d:", mday, hour, min);
cp += strlen(cp);
AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
cp = AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
*cp = '\0';
}
else
{
sprintf(cp, "%d:%02d:", hour, min);
cp += strlen(cp);
AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
cp = AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
*cp = '\0';
}
}
break;
@@ -4284,8 +4418,7 @@ EncodeInterval(struct pg_tm * tm, fsec_t fsec, int style, char *str)
{
if (sec < 0 || fsec < 0)
*cp++ = '-';
AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, false);
cp += strlen(cp);
cp = AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, false);
*cp++ = 'S';
*cp++ = '\0';
}
@@ -4311,7 +4444,8 @@ EncodeInterval(struct pg_tm * tm, fsec_t fsec, int style, char *str)
(minus ? "-" : (is_before ? "+" : "")),
abs(hour), abs(min));
cp += strlen(cp);
AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
cp = AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
*cp = '\0';
}
break;
@@ -4337,8 +4471,7 @@ EncodeInterval(struct pg_tm * tm, fsec_t fsec, int style, char *str)
}
else if (is_before)
*cp++ = '-';
AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, false);
cp += strlen(cp);
cp = AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, false);
sprintf(cp, " sec%s",
(abs(sec) != 1 || fsec != 0) ? "s" : "");
is_zero = FALSE;

161
src/backend/utils/adt/numutils.c
View File

@@ -227,3 +227,164 @@ pg_lltoa(int64 value, char *a)
*a-- = swap;
}
}
/*
* pg_ltostr_zeropad
* Converts 'value' into a decimal string representation stored at 'str'.
* 'minwidth' specifies the minimum width of the result; any extra space
* is filled up by prefixing the number with zeros.
*
* Returns the ending address of the string result (the last character written
* plus 1). Note that no NUL terminator is written.
*
* The intended use-case for this function is to build strings that contain
* multiple individual numbers, for example:
*
* str = pg_ltostr_zeropad(str, hours, 2);
* *str++ = ':';
* str = pg_ltostr_zeropad(str, mins, 2);
* *str++ = ':';
* str = pg_ltostr_zeropad(str, secs, 2);
* *str = '\0';
*
* Note: Caller must ensure that 'str' points to enough memory to hold the
* result.
*/
char *
pg_ltostr_zeropad(char *str, int32 value, int32 minwidth)
{
char *start = str;
char *end = &str[minwidth];
int32 num = value;
Assert(minwidth > 0);
/*
* Handle negative numbers in a special way. We can't just write a '-'
* prefix and reverse the sign as that would overflow for INT32_MIN.
*/
if (num < 0)
{
*start++ = '-';
minwidth--;
/*
* Build the number starting at the last digit. Here remainder will
* be a negative number, so we must reverse the sign before adding '0'
* in order to get the correct ASCII digit.
*/
while (minwidth--)
{
int32 oldval = num;
int32 remainder;
num /= 10;
remainder = oldval - num * 10;
start[minwidth] = '0' - remainder;
}
}
else
{
/* Build the number starting at the last digit */
while (minwidth--)
{
int32 oldval = num;
int32 remainder;
num /= 10;
remainder = oldval - num * 10;
start[minwidth] = '0' + remainder;
}
}
/*
* If minwidth was not high enough to fit the number then num won't have
* been divided down to zero. We punt the problem to pg_ltostr(), which
* will generate a correct answer in the minimum valid width.
*/
if (num != 0)
return pg_ltostr(str, value);
/* Otherwise, return last output character + 1 */
return end;
}
/*
* pg_ltostr
* Converts 'value' into a decimal string representation stored at 'str'.
*
* Returns the ending address of the string result (the last character written
* plus 1). Note that no NUL terminator is written.
*
* The intended use-case for this function is to build strings that contain
* multiple individual numbers, for example:
*
* str = pg_ltostr(str, a);
* *str++ = ' ';
* str = pg_ltostr(str, b);
* *str = '\0';
*
* Note: Caller must ensure that 'str' points to enough memory to hold the
* result.
*/
char *
pg_ltostr(char *str, int32 value)
{
char *start;
char *end;
/*
* Handle negative numbers in a special way. We can't just write a '-'
* prefix and reverse the sign as that would overflow for INT32_MIN.
*/
if (value < 0)
{
*str++ = '-';
/* Mark the position we must reverse the string from. */
start = str;
/* Compute the result string backwards. */
do
{
int32 oldval = value;
int32 remainder;
value /= 10;
remainder = oldval - value * 10;
/* As above, we expect remainder to be negative. */
*str++ = '0' - remainder;
} while (value != 0);
}
else
{
/* Mark the position we must reverse the string from. */
start = str;
/* Compute the result string backwards. */
do
{
int32 oldval = value;
int32 remainder;
value /= 10;
remainder = oldval - value * 10;
*str++ = '0' + remainder;
} while (value != 0);
}
/* Remember the end+1 and back up 'str' to the last character. */
end = str--;
/* Reverse string. */
while (start < str)
{
char swap = *start;
*start++ = *str;
*str-- = swap;
}
return end;
}

2
src/include/utils/builtins.h
View File

@@ -290,6 +290,8 @@ extern int32 pg_atoi(const char *s, int size, int c);
extern void pg_itoa(int16 i, char *a);
extern void pg_ltoa(int32 l, char *a);
extern void pg_lltoa(int64 ll, char *a);
extern char *pg_ltostr_zeropad(char *str, int32 value, int32 minwidth);
extern char *pg_ltostr(char *str, int32 value);
/*
* Per-opclass comparison functions for new btrees. These are