Add idl_find binary search routine, used by idl_insert and idl_split_block

instead of linear search.

diff --git a/servers/slapd/back-ldbm/idl.c b/servers/slapd/back-ldbm/idl.c
index 9b235440bd85f8685e02611b3c2bcbf07592f51f..fd38d323e877bbb07eaca357c0ba4ac292d567a1 100644 (file)
--- a/servers/slapd/back-ldbm/idl.c
+++ b/servers/slapd/back-ldbm/idl.c
@@ -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) ) {