s4-ldb: over-allocate index records to save on realloc costs

diff --git a/source4/lib/ldb/ldb_tdb/ldb_index.c b/source4/lib/ldb/ldb_tdb/ldb_index.c
index 501907578d91c9674ce1f07d304633d80797e15f..606c24491ccb1d98d1af193ef5ce397fcc484620 100644 (file)
--- a/source4/lib/ldb/ldb_tdb/ldb_index.c
+++ b/source4/lib/ldb/ldb_tdb/ldb_index.c
@@ -1065,6 +1065,7 @@ static int ltdb_index_add1(struct ldb_module *module, const char *dn,
        int ret;
        const struct ldb_schema_attribute *a;
        struct dn_list *list;
+       unsigned alloc_len;
 
        ldb = ldb_module_get_ctx(module);
 
@@ -1096,7 +1097,10 @@ static int ltdb_index_add1(struct ldb_module *module, const char *dn,
                return LDB_ERR_ENTRY_ALREADY_EXISTS;            
        }
 
-       list->dn = talloc_realloc(list, list->dn, struct ldb_val, list->count+1);
+       /* overallocate the list a bit, to reduce the number of
+        * realloc trigered copies */    
+       alloc_len = ((list->count+1)+7) & ~7;
+       list->dn = talloc_realloc(list, list->dn, struct ldb_val, alloc_len);
        if (list->dn == NULL) {
                talloc_free(list);
                return LDB_ERR_OPERATIONS_ERROR;