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Add new StringInfo APIs to allow callers to specify the buffer size.

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Previously StringInfo APIs allocated buffers with fixed initial
allocation size of 1024 bytes. This may be too large and inappropriate
for some callers that can do with smaller memory buffers. To fix this,
introduce new APIs that allow callers to specify initial buffer size.

extern StringInfo makeStringInfoExt(int initsize);
extern void initStringInfoExt(StringInfo str, int initsize);

Existing APIs (makeStringInfo() and initStringInfo()) are changed to
call makeStringInfoExt and initStringInfoExt respectively (via inline
helper functions makeStringInfoInternal and initStringInfoInternal),
with the default buffer size of 1024.

Reviewed-by: Nathan Bossart, David Rowley, Michael Paquier, Gurjeet Singh
Discussion: https://postgr.es/m/20241225.123704.1194662271286702010.ishii%40postgresql.org
This commit is contained in:
Tatsuo Ishii
2025-01-11 08:02:56 +09:00
parent ca9c6a5680
commit a9dcbb4d5c
2 changed files with 89 additions and 11 deletions
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71
src/common/stringinfo.c
View File

@@ -29,6 +29,40 @@
#include "lib/stringinfo.h"
/*
* initStringInfoInternal
*
* Initialize a StringInfoData struct (with previously undefined contents)
* to describe an empty string.
* The initial memory allocation size is specified by 'initsize'.
* The valid range for 'initsize' is 1 to MaxAllocSize.
*/
static inline void
initStringInfoInternal(StringInfo str, int initsize)
{
Assert(initsize >= 1 && initsize <= MaxAllocSize);
str->data = (char *) palloc(initsize);
str->maxlen = initsize;
resetStringInfo(str);
}
/*
* makeStringInfoInternal(int initsize)
*
* Create an empty 'StringInfoData' & return a pointer to it.
* The initial memory allocation size is specified by 'initsize'.
* The valid range for 'initsize' is 1 to MaxAllocSize.
*/
static inline StringInfo
makeStringInfoInternal(int initsize)
{
StringInfo res = (StringInfo) palloc(sizeof(StringInfoData));
initStringInfoInternal(res, initsize);
return res;
}
/*
* makeStringInfo
*
@@ -37,13 +71,20 @@
StringInfo
makeStringInfo(void)
{
StringInfo res;
return makeStringInfoInternal(STRINGINFO_DEFAULT_SIZE);
}
res = (StringInfo) palloc(sizeof(StringInfoData));
initStringInfo(res);
return res;
/*
* makeStringInfoExt(int initsize)
*
* Create an empty 'StringInfoData' & return a pointer to it.
* The initial memory allocation size is specified by 'initsize'.
* The valid range for 'initsize' is 1 to MaxAllocSize.
*/
StringInfo
makeStringInfoExt(int initsize)
{
return makeStringInfoInternal(initsize);
}
/*
@@ -55,11 +96,21 @@ makeStringInfo(void)
void
initStringInfo(StringInfo str)
{
int size = 1024; /* initial default buffer size */
return initStringInfoInternal(str, STRINGINFO_DEFAULT_SIZE);
}
str->data = (char *) palloc(size);
str->maxlen = size;
resetStringInfo(str);
/*
* initStringInfoExt
*
* Initialize a StringInfoData struct (with previously undefined contents)
* to describe an empty string.
* The initial memory allocation size is specified by 'initsize'.
* The valid range for 'initsize' is 1 to MaxAllocSize.
*/
void
initStringInfoExt(StringInfo str, int initsize)
{
initStringInfoInternal(str, initsize);
}
/*