From 4fc115b2e981f8c63165ca86a23215380a3fda66 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Fri, 19 Nov 2010 22:13:11 -0500 Subject: [PATCH] Speed up conversion of signed integers to C strings. A hand-coded implementation turns out to be much faster than calling printf(). In passing, add a few more regresion tests. Andres Freund, with assorted, mostly cosmetic changes. --- src/backend/utils/adt/int8.c | 8 +- src/backend/utils/adt/numutils.c | 115 +++++++++++++++++++++++++---- src/include/utils/builtins.h | 1 + src/test/regress/expected/int2.out | 13 ++++ src/test/regress/expected/int4.out | 13 ++++ src/test/regress/expected/int8.out | 13 ++++ src/test/regress/sql/int2.sql | 4 + src/test/regress/sql/int4.sql | 4 + src/test/regress/sql/int8.sql | 4 + 9 files changed, 157 insertions(+), 18 deletions(-) diff --git a/src/backend/utils/adt/int8.c b/src/backend/utils/adt/int8.c index 894110d7a2..91133f7741 100644 --- a/src/backend/utils/adt/int8.c +++ b/src/backend/utils/adt/int8.c @@ -20,6 +20,7 @@ #include "funcapi.h" #include "libpq/pqformat.h" #include "utils/int8.h" +#include "utils/builtins.h" #define MAXINT8LEN 25 @@ -157,13 +158,10 @@ Datum int8out(PG_FUNCTION_ARGS) { int64 val = PG_GETARG_INT64(0); - char *result; - int len; char buf[MAXINT8LEN + 1]; + char *result; - if ((len = snprintf(buf, MAXINT8LEN, INT64_FORMAT, val)) < 0) - elog(ERROR, "could not format int8"); - + pg_lltoa(val, buf); result = pstrdup(buf); PG_RETURN_CSTRING(result); } diff --git a/src/backend/utils/adt/numutils.c b/src/backend/utils/adt/numutils.c index 5f8083f0c5..22bcaf7839 100644 --- a/src/backend/utils/adt/numutils.c +++ b/src/backend/utils/adt/numutils.c @@ -3,8 +3,6 @@ * numutils.c * utility functions for I/O of built-in numeric types. * - * integer: pg_atoi, pg_itoa, pg_ltoa - * * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * @@ -109,27 +107,118 @@ pg_atoi(char *s, int size, int c) } /* - * pg_itoa - converts a short int to its string represention + * pg_itoa: converts a signed 16-bit integer to its string representation + * + * Caller must ensure that 'a' points to enough memory to hold the result + * (at least 7 bytes, counting a leading sign and trailing NUL). * - * Note: - * previously based on ~ingres/source/gutil/atoi.c - * now uses vendor's sprintf conversion + * It doesn't seem worth implementing this separately. */ void pg_itoa(int16 i, char *a) { - sprintf(a, "%hd", (short) i); + pg_ltoa((int32)i, a); +} + +/* + * pg_ltoa: converts a signed 32-bit integer to its string representation + * + * Caller must ensure that 'a' points to enough memory to hold the result + * (at least 12 bytes, counting a leading sign and trailing NUL). + */ +void +pg_ltoa(int32 value, char *a) +{ + char *start = a; + bool neg = false; + + /* + * Avoid problems with the most negative integer not being representable + * as a positive integer. + */ + if (value == INT32_MIN) + { + memcpy(a, "-2147483648", 12); + return; + } + else if (value < 0) + { + value = -value; + neg = true; + } + + /* Compute the result backwards. */ + do + { + int32 remainder; + int32 oldval = value; + value /= 10; + remainder = oldval - value * 10; + *a++ = '0' + remainder; + } while (value != 0); + if (neg) + *a++ = '-'; + + /* Add trailing NUL byte. */ + *a-- = '\0'; + + /* reverse string */ + while (start < a) + { + char swap = *start; + *start++ = *a; + *a-- = swap; + } } /* - * pg_ltoa - converts a long int to its string represention + * pg_lltoa: convert a signed 64bit integer to its string representation * - * Note: - * previously based on ~ingres/source/gutil/atoi.c - * now uses vendor's sprintf conversion + * Caller must ensure that 'a' points to enough memory to hold the result + * (at least MAXINT8LEN+1 bytes, counting a leading sign and trailing NUL). */ void -pg_ltoa(int32 l, char *a) +pg_lltoa(int64 value, char *a) { - sprintf(a, "%d", l); + char *start = a; + bool neg = false; + + /* + * Avoid problems with the most negative integer not being representable + * as a positive integer. + */ + if (value == INT64_MIN) + { + memcpy(a, "-9223372036854775808", 21); + return; + } + else if (value < 0) + { + value = -value; + neg = true; + } + + /* Build the string by computing the wanted string backwards. */ + do + { + int64 remainder; + int64 oldval = value; + value /= 10; + remainder = oldval - value * 10; + *a++ = '0' + remainder; + } while (value != 0); + + if (neg) + *a++ = '-'; + + /* Add trailing NUL byte. */ + *a-- = '\0'; + + /* Reverse string. */ + while (start < a) + { + char swap = *start; + *start++ = *a; + *a-- = swap; + } } diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h index 020ce3ce2e..7b1bb23538 100644 --- a/src/include/utils/builtins.h +++ b/src/include/utils/builtins.h @@ -275,6 +275,7 @@ extern Datum current_schemas(PG_FUNCTION_ARGS); extern int32 pg_atoi(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); /* * Per-opclass comparison functions for new btrees. These are diff --git a/src/test/regress/expected/int2.out b/src/test/regress/expected/int2.out index 8fff981d0a..3bb26b3f48 100644 --- a/src/test/regress/expected/int2.out +++ b/src/test/regress/expected/int2.out @@ -242,3 +242,16 @@ SELECT '' AS five, i.f1, i.f1 / int4 '2' AS x FROM INT2_TBL i; | -32767 | -16383 (5 rows) +-- corner cases +SELECT (1<<15-1)::int2::text; + text +------- + 16384 +(1 row) + +SELECT (-1<<15)::int2::text; + text +-------- + -32768 +(1 row) + diff --git a/src/test/regress/expected/int4.out b/src/test/regress/expected/int4.out index 3fadb7bbdb..42095c7844 100644 --- a/src/test/regress/expected/int4.out +++ b/src/test/regress/expected/int4.out @@ -329,3 +329,16 @@ SELECT (2 + 2) / 2 AS two; 2 (1 row) +-- corner cases +SELECT (1<<31-1)::int4::text; + text +------------ + 1073741824 +(1 row) + +SELECT (1<<31)::int4::text; + text +------------- + -2147483648 +(1 row) + diff --git a/src/test/regress/expected/int8.out b/src/test/regress/expected/int8.out index c8e2dad683..e156067e88 100644 --- a/src/test/regress/expected/int8.out +++ b/src/test/regress/expected/int8.out @@ -802,3 +802,16 @@ SELECT * FROM generate_series('+4567890123456789'::int8, '+4567890123456799'::in 4567890123456799 (6 rows) +-- corner cases +SELECT (1<<63-1)::int8::text; + text +------------ + 1073741824 +(1 row) + +SELECT (1<<63)::int8::text; + text +------------- + -2147483648 +(1 row) + diff --git a/src/test/regress/sql/int2.sql b/src/test/regress/sql/int2.sql index 20d31b6420..8bffe53b03 100644 --- a/src/test/regress/sql/int2.sql +++ b/src/test/regress/sql/int2.sql @@ -83,3 +83,7 @@ SELECT '' AS five, i.f1, i.f1 - int4 '2' AS x FROM INT2_TBL i; SELECT '' AS five, i.f1, i.f1 / int2 '2' AS x FROM INT2_TBL i; SELECT '' AS five, i.f1, i.f1 / int4 '2' AS x FROM INT2_TBL i; + +-- corner cases +SELECT (1<<15-1)::int2::text; +SELECT (-1<<15)::int2::text; diff --git a/src/test/regress/sql/int4.sql b/src/test/regress/sql/int4.sql index 5e84f64360..39bfec1b0d 100644 --- a/src/test/regress/sql/int4.sql +++ b/src/test/regress/sql/int4.sql @@ -123,3 +123,7 @@ SELECT 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 AS ten; SELECT 2 + 2 / 2 AS three; SELECT (2 + 2) / 2 AS two; + +-- corner cases +SELECT (1<<31-1)::int4::text; +SELECT (1<<31)::int4::text; diff --git a/src/test/regress/sql/int8.sql b/src/test/regress/sql/int8.sql index 648563c374..7fff03cd66 100644 --- a/src/test/regress/sql/int8.sql +++ b/src/test/regress/sql/int8.sql @@ -190,3 +190,7 @@ SELECT q1, q1 << 2 AS "shl", q1 >> 3 AS "shr" FROM INT8_TBL; SELECT * FROM generate_series('+4567890123456789'::int8, '+4567890123456799'::int8); SELECT * FROM generate_series('+4567890123456789'::int8, '+4567890123456799'::int8, 0); SELECT * FROM generate_series('+4567890123456789'::int8, '+4567890123456799'::int8, 2); + +-- corner cases +SELECT (1<<63-1)::int8::text; +SELECT (1<<63)::int8::text; -- 2.40.0