modify idl_search to use binary search algorithm

diff --git a/servers/slapd/back-bdb/idl.c b/servers/slapd/back-bdb/idl.c
index 6415d8728d203121320fb9c9ace753780d77034a..d68fe317bf9a18bbe3354eb83325be12892a4de4 100644 (file)
--- a/servers/slapd/back-bdb/idl.c
+++ b/servers/slapd/back-bdb/idl.c
@@ -20,19 +20,42 @@
 
 #define BDB_IS_ALLIDS(ids)     ((ids)[0] == NOID)
 
+#define IDL_CMP(x,y)   ( x < y ? -1 : ( x > y ? 1 : 0 ) )
+
 static int idl_search( ID *ids, ID id )
 {
-       /* we should replace this a binary search as ids is sorted */
-       int i;
-       int n = (int) ids[0];
-
-       for( i = 1; i <= n; i++ ) {
-               if( id <= ids[i] ) {
-                       return i;
+       /*
+        * binary search of id in ids
+        * if found, returns position of id
+        * if not found, returns first postion greater than id
+        */
+       int base = 0;
+       int cursor;
+       int val;
+       int n = ids[0];
+
+       while( 0 < n ) {
+               int pivot = n >> 1;
+               cursor = base + pivot;
+               val = IDL_CMP( id, ids[cursor + 1] );
+
+               if( val < 0 ) {
+                       n = pivot;
+
+               } else if ( val > 0 ) {
+                       base = cursor + 1;
+                       n -= pivot + 1;
+
+               } else {
+                       return cursor + 1;
                }
        }
-
-       return 0;
+       
+       if( val < 0 ) {
+               return cursor + 1;
+       } else {
+               return cursor + 2;
+       }
 }
 
 static int idl_insert( ID *ids, ID id )