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Add idl_find binary search routine, used by idl_insert and idl_split_block

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instead of linear search.
This commit is contained in:
Howard Chu 2001-09-21 20:30:27 +00:00
parent 2f6b7e3d43
commit b52795c283
1 changed files with 34 additions and 8 deletions
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42
servers/slapd/back-ldbm/idl.c
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@ -296,6 +296,31 @@ idl_store(
return( rc );
}
/* Binary search for id in block, return index
* an index is always returned, even with no match. If no
* match, the returned index is the insertion point.
*/
static unsigned int
idl_find(
ID_BLOCK *b,
ID id
)
{
unsigned int lo=0, hi=ID_BLOCK_NIDS(b)-1, nr;
for (;lo<=hi;)
{
nr = ( lo + hi ) / 2;
if (ID_BLOCK_ID(b, nr) == id)
break;
if (ID_BLOCK_ID(b, nr) > id)
hi = nr - 1;
else
lo = nr + 1;
}
return nr;
}
/* split the block at id
* locate ID greater than or equal to id.
*/
@ -309,9 +334,10 @@ idl_split_block(
{
unsigned int nr, nl;
/* find where to split the block *//* XXX linear search XXX */
for ( nr = 0; nr < ID_BLOCK_NIDS(b) && id > ID_BLOCK_ID(b, nr); nr++ )
; /* NULL */
/* find where to split the block */
nr = idl_find(b, id);
if ( ID_BLOCK_ID(b,nr) < id )
nr++;
nl = ID_BLOCK_NIDS(b) - nr;
@ -771,13 +797,13 @@ idl_insert( ID_BLOCK **idl, ID id, unsigned int maxids )
return( 2 ); /* already there */
}
/* is it already there? *//* XXX linear search XXX */
for ( i = 0; i < ID_BLOCK_NIDS(*idl) && id > ID_BLOCK_ID(*idl, i); i++ ) {
; /* NULL */
}
if ( i < ID_BLOCK_NIDS(*idl) && ID_BLOCK_ID(*idl, i) == id ) {
/* is it already there? */
i = idl_find(*idl, id);
if ( ID_BLOCK_ID(*idl, i) == id ) {
return( 2 ); /* already there */
}
if ( ID_BLOCK_ID(*idl, i) < id )
i++;
/* do we need to make room for it? */
if ( ID_BLOCK_NIDS(*idl) == ID_BLOCK_NMAX(*idl) ) {