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Commit4fc115b

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committed
Speed up conversion of signed integers to C strings.
A hand-coded implementation turns out to be much faster than callingprintf(). In passing, add a few more regresion tests.Andres Freund, with assorted, mostly cosmetic changes.
1 parent0f61d4d commit4fc115b

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9 files changed

+157
-18
lines changed

9 files changed

+157
-18
lines changed

‎src/backend/utils/adt/int8.c‎

Lines changed: 3 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -20,6 +20,7 @@
2020
#include"funcapi.h"
2121
#include"libpq/pqformat.h"
2222
#include"utils/int8.h"
23+
#include"utils/builtins.h"
2324

2425

2526
#defineMAXINT8LEN25
@@ -157,13 +158,10 @@ Datum
157158
int8out(PG_FUNCTION_ARGS)
158159
{
159160
int64val=PG_GETARG_INT64(0);
160-
char*result;
161-
intlen;
162161
charbuf[MAXINT8LEN+1];
162+
char*result;
163163

164-
if ((len=snprintf(buf,MAXINT8LEN,INT64_FORMAT,val))<0)
165-
elog(ERROR,"could not format int8");
166-
164+
pg_lltoa(val,buf);
167165
result=pstrdup(buf);
168166
PG_RETURN_CSTRING(result);
169167
}

‎src/backend/utils/adt/numutils.c‎

Lines changed: 102 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -3,8 +3,6 @@
33
* numutils.c
44
* utility functions for I/O of built-in numeric types.
55
*
6-
*integer:pg_atoi, pg_itoa, pg_ltoa
7-
*
86
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
97
* Portions Copyright (c) 1994, Regents of the University of California
108
*
@@ -109,27 +107,118 @@ pg_atoi(char *s, int size, int c)
109107
}
110108

111109
/*
112-
*pg_itoa- converts a short int to its string represention
110+
* pg_itoa: converts a signed 16-bit integer to its string representation
111+
*
112+
* Caller must ensure that 'a' points to enough memory to hold the result
113+
* (at least 7 bytes, counting a leading sign and trailing NUL).
113114
*
114-
*Note:
115-
*previously based on ~ingres/source/gutil/atoi.c
116-
*now uses vendor's sprintf conversion
115+
* It doesn't seem worth implementing this separately.
117116
*/
118117
void
119118
pg_itoa(int16i,char*a)
120119
{
121-
sprintf(a,"%hd", (short)i);
120+
pg_ltoa((int32)i,a);
121+
}
122+
123+
/*
124+
* pg_ltoa: converts a signed 32-bit integer to its string representation
125+
*
126+
* Caller must ensure that 'a' points to enough memory to hold the result
127+
* (at least 12 bytes, counting a leading sign and trailing NUL).
128+
*/
129+
void
130+
pg_ltoa(int32value,char*a)
131+
{
132+
char*start=a;
133+
boolneg= false;
134+
135+
/*
136+
* Avoid problems with the most negative integer not being representable
137+
* as a positive integer.
138+
*/
139+
if (value==INT32_MIN)
140+
{
141+
memcpy(a,"-2147483648",12);
142+
return;
143+
}
144+
elseif (value<0)
145+
{
146+
value=-value;
147+
neg= true;
148+
}
149+
150+
/* Compute the result backwards. */
151+
do
152+
{
153+
int32remainder;
154+
int32oldval=value;
155+
value /=10;
156+
remainder=oldval-value*10;
157+
*a++='0'+remainder;
158+
}while (value!=0);
159+
if (neg)
160+
*a++='-';
161+
162+
/* Add trailing NUL byte. */
163+
*a--='\0';
164+
165+
/* reverse string */
166+
while (start<a)
167+
{
168+
charswap=*start;
169+
*start++=*a;
170+
*a--=swap;
171+
}
122172
}
123173

124174
/*
125-
*pg_ltoa- converts a long intto its stringrepresention
175+
* pg_lltoa: convert a signed 64bit integerto its stringrepresentation
126176
*
127-
*Note:
128-
*previously based on ~ingres/source/gutil/atoi.c
129-
*now uses vendor's sprintf conversion
177+
* Caller must ensure that 'a' points to enough memory to hold the result
178+
* (at least MAXINT8LEN+1 bytes, counting a leading sign and trailing NUL).
130179
*/
131180
void
132-
pg_ltoa(int32l,char*a)
181+
pg_lltoa(int64value,char*a)
133182
{
134-
sprintf(a,"%d",l);
183+
char*start=a;
184+
boolneg= false;
185+
186+
/*
187+
* Avoid problems with the most negative integer not being representable
188+
* as a positive integer.
189+
*/
190+
if (value==INT64_MIN)
191+
{
192+
memcpy(a,"-9223372036854775808",21);
193+
return;
194+
}
195+
elseif (value<0)
196+
{
197+
value=-value;
198+
neg= true;
199+
}
200+
201+
/* Build the string by computing the wanted string backwards. */
202+
do
203+
{
204+
int64remainder;
205+
int64oldval=value;
206+
value /=10;
207+
remainder=oldval-value*10;
208+
*a++='0'+remainder;
209+
}while (value!=0);
210+
211+
if (neg)
212+
*a++='-';
213+
214+
/* Add trailing NUL byte. */
215+
*a--='\0';
216+
217+
/* Reverse string. */
218+
while (start<a)
219+
{
220+
charswap=*start;
221+
*start++=*a;
222+
*a--=swap;
223+
}
135224
}

‎src/include/utils/builtins.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -275,6 +275,7 @@ extern Datum current_schemas(PG_FUNCTION_ARGS);
275275
externint32pg_atoi(char*s,intsize,intc);
276276
externvoidpg_itoa(int16i,char*a);
277277
externvoidpg_ltoa(int32l,char*a);
278+
externvoidpg_lltoa(int64ll,char*a);
278279

279280
/*
280281
*Per-opclass comparison functions for new btrees. These are

‎src/test/regress/expected/int2.out‎

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -242,3 +242,16 @@ SELECT '' AS five, i.f1, i.f1 / int4 '2' AS x FROM INT2_TBL i;
242242
| -32767 | -16383
243243
(5 rows)
244244

245+
-- corner cases
246+
SELECT (1<<15-1)::int2::text;
247+
text
248+
-------
249+
16384
250+
(1 row)
251+
252+
SELECT (-1<<15)::int2::text;
253+
text
254+
--------
255+
-32768
256+
(1 row)
257+

‎src/test/regress/expected/int4.out‎

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -329,3 +329,16 @@ SELECT (2 + 2) / 2 AS two;
329329
2
330330
(1 row)
331331

332+
-- corner cases
333+
SELECT (1<<31-1)::int4::text;
334+
text
335+
------------
336+
1073741824
337+
(1 row)
338+
339+
SELECT (1<<31)::int4::text;
340+
text
341+
-------------
342+
-2147483648
343+
(1 row)
344+

‎src/test/regress/expected/int8.out‎

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -802,3 +802,16 @@ SELECT * FROM generate_series('+4567890123456789'::int8, '+4567890123456799'::in
802802
4567890123456799
803803
(6 rows)
804804

805+
-- corner cases
806+
SELECT (1<<63-1)::int8::text;
807+
text
808+
------------
809+
1073741824
810+
(1 row)
811+
812+
SELECT (1<<63)::int8::text;
813+
text
814+
-------------
815+
-2147483648
816+
(1 row)
817+

‎src/test/regress/sql/int2.sql‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -83,3 +83,7 @@ SELECT '' AS five, i.f1, i.f1 - int4 '2' AS x FROM INT2_TBL i;
8383
SELECT''AS five,i.f1,i.f1/ int2'2'AS xFROM INT2_TBL i;
8484

8585
SELECT''AS five,i.f1,i.f1/ int4'2'AS xFROM INT2_TBL i;
86+
87+
-- corner cases
88+
SELECT (1<<15-1)::int2::text;
89+
SELECT (-1<<15)::int2::text;

‎src/test/regress/sql/int4.sql‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -123,3 +123,7 @@ SELECT 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 AS ten;
123123
SELECT2+2/2AS three;
124124

125125
SELECT (2+2)/2AS two;
126+
127+
-- corner cases
128+
SELECT (1<<31-1)::int4::text;
129+
SELECT (1<<31)::int4::text;

‎src/test/regress/sql/int8.sql‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -190,3 +190,7 @@ SELECT q1, q1 << 2 AS "shl", q1 >> 3 AS "shr" FROM INT8_TBL;
190190
SELECT*FROM generate_series('+4567890123456789'::int8,'+4567890123456799'::int8);
191191
SELECT*FROM generate_series('+4567890123456789'::int8,'+4567890123456799'::int8,0);
192192
SELECT*FROM generate_series('+4567890123456789'::int8,'+4567890123456799'::int8,2);
193+
194+
-- corner cases
195+
SELECT (1<<63-1)::int8::text;
196+
SELECT (1<<63)::int8::text;

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