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Attached is a patch that replaces a bunch of places where StringInfos

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are unnecessarily allocated on the heap rather than the stack. If the
StringInfo doesn't outlive the stack frame in which it is created,
there is no need to allocate it on the heap via makeStringInfo() --
stack allocation is faster.  While it's not a big deal unless the
code is in a critical path, I don't see a reason not to save a few
cycles -- using stack allocation is not less readable.

I also cleaned up a bit of code along the way: moved variable
declarations into a more tightly-enclosing scope where possible,
fixed some pointless copying of strings in dblink, etc.
This commit is contained in:
Neil Conway
2006-03-01 06:51:01 +00:00
parent 8e5a10d46c
commit 0d9742f99a
5 changed files with 126 additions and 140 deletions
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51
contrib/tablefunc/tablefunc.c
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@ -1260,13 +1260,10 @@ build_tuplestore_recursively(char *key_fld,
{
TupleDesc tupdesc = attinmeta->tupdesc;
MemoryContext oldcontext;
StringInfo sql = makeStringInfo();
int ret;
int proc;
int serial_column;
StringInfo branchstr = NULL;
StringInfo chk_branchstr = NULL;
StringInfo chk_current_key = NULL;
StringInfoData sql;
char **values;
char *current_key;
char *current_key_parent;
@ -1278,17 +1275,12 @@ build_tuplestore_recursively(char *key_fld,
if (max_depth > 0 && level > max_depth)
return tupstore;
/* start a new branch */
branchstr = makeStringInfo();
/* need these to check for recursion */
chk_branchstr = makeStringInfo();
chk_current_key = makeStringInfo();
initStringInfo(&sql);
/* Build initial sql statement */
if (!show_serial)
{
appendStringInfo(sql, "SELECT %s, %s FROM %s WHERE %s = %s AND %s IS NOT NULL AND %s <> %s",
appendStringInfo(&sql, "SELECT %s, %s FROM %s WHERE %s = %s AND %s IS NOT NULL AND %s <> %s",
key_fld,
parent_key_fld,
relname,
@ -1299,7 +1291,7 @@ build_tuplestore_recursively(char *key_fld,
}
else
{
appendStringInfo(sql, "SELECT %s, %s FROM %s WHERE %s = %s AND %s IS NOT NULL AND %s <> %s ORDER BY %s",
appendStringInfo(&sql, "SELECT %s, %s FROM %s WHERE %s = %s AND %s IS NOT NULL AND %s <> %s ORDER BY %s",
key_fld,
parent_key_fld,
relname,
@ -1359,7 +1351,7 @@ build_tuplestore_recursively(char *key_fld,
}
/* Retrieve the desired rows */
ret = SPI_execute(sql->data, true, 0);
ret = SPI_execute(sql.data, true, 0);
proc = SPI_processed;
/* Check for qualifying tuples */
@ -1369,6 +1361,9 @@ build_tuplestore_recursively(char *key_fld,
SPITupleTable *tuptable = SPI_tuptable;
TupleDesc spi_tupdesc = tuptable->tupdesc;
int i;
StringInfoData branchstr;
StringInfoData chk_branchstr;
StringInfoData chk_current_key;
/* First time through, do a little more setup */
if (level == 0)
@ -1389,28 +1384,35 @@ build_tuplestore_recursively(char *key_fld,
for (i = 0; i < proc; i++)
{
/* start a new branch */
initStringInfo(&branchstr);
/* need these to check for recursion */
initStringInfo(&chk_branchstr);
initStringInfo(&chk_current_key);
/* initialize branch for this pass */
appendStringInfo(branchstr, "%s", branch);
appendStringInfo(chk_branchstr, "%s%s%s", branch_delim, branch, branch_delim);
appendStringInfo(&branchstr, "%s", branch);
appendStringInfo(&chk_branchstr, "%s%s%s", branch_delim, branch, branch_delim);
/* get the next sql result tuple */
spi_tuple = tuptable->vals[i];
/* get the current key and parent */
current_key = SPI_getvalue(spi_tuple, spi_tupdesc, 1);
appendStringInfo(chk_current_key, "%s%s%s", branch_delim, current_key, branch_delim);
appendStringInfo(&chk_current_key, "%s%s%s", branch_delim, current_key, branch_delim);
current_key_parent = pstrdup(SPI_getvalue(spi_tuple, spi_tupdesc, 2));
/* get the current level */
sprintf(current_level, "%d", level);
/* check to see if this key is also an ancestor */
if (strstr(chk_branchstr->data, chk_current_key->data))
if (strstr(chk_branchstr.data, chk_current_key.data))
elog(ERROR, "infinite recursion detected");
/* OK, extend the branch */
appendStringInfo(branchstr, "%s%s", branch_delim, current_key);
current_branch = branchstr->data;
appendStringInfo(&branchstr, "%s%s", branch_delim, current_key);
current_branch = branchstr.data;
/* build a tuple */
values[0] = pstrdup(current_key);
@ -1461,14 +1463,9 @@ build_tuplestore_recursively(char *key_fld,
tupstore);
/* reset branch for next pass */
xpfree(branchstr->data);
initStringInfo(branchstr);
xpfree(chk_branchstr->data);
initStringInfo(chk_branchstr);
xpfree(chk_current_key->data);
initStringInfo(chk_current_key);
xpfree(branchstr.data);
xpfree(chk_branchstr.data);
xpfree(chk_current_key.data);
}
}