Addresses #903

Created function that peeks at both key and value at the same time
(to avoid repeated OMT calls).
This was worth 4-5% performance in scanscan --lwc --prelock --prelockflag


git-svn-id: file:///svn/tokudb@5386 c7de825b-a66e-492c-adef-691d508d4ae1

newbrt/brt.c

@@ -3198,6 +3198,15 @@ DBT *brt_cursor_peek_prev_val(BRT_CURSOR cursor)
     return &cursor->prevval;
 }
 
+void brt_cursor_peek_current(BRT_CURSOR cursor, const DBT **pkey, const DBT **pval)
+// Effect: Retrieves a pointer to the DBTs for the current key and value.
+// Requires:  The caller may not modify the DBTs or the memory at which they points.
+{
+    if (cursor->current_in_omt) load_dbts_from_omt(cursor, &cursor->key, &cursor->val);
+    *pkey = &cursor->key;
+    *pval = &cursor->val;
+}
+
 DBT *brt_cursor_peek_current_key(BRT_CURSOR cursor)
 // Effect: Return a pointer to a DBT for the current key.  
 // Requires:  The caller may not modify that DBT or the memory at which it points.

newbrt/brt.h

@@ -84,6 +84,7 @@ DBT *brt_cursor_peek_prev_key(BRT_CURSOR cursor);
 DBT *brt_cursor_peek_prev_val(BRT_CURSOR cursor);
 DBT *brt_cursor_peek_current_key(BRT_CURSOR cursor);
 DBT *brt_cursor_peek_current_val(BRT_CURSOR cursor);
+void brt_cursor_peek_current(BRT_CURSOR cursor, const DBT **pkey, const DBT **pval);
 void brt_cursor_restore_state_from_prev(BRT_CURSOR cursor);
 
 typedef struct brtenv *BRTENV;

src/ydb.c

@@ -1801,10 +1801,7 @@ static int toku_c_getf_next(DBC *c, u_int32_t flag, void(*f)(DBT const *key, DBT
                                            txn);
     if (c_get_result!=0 && c_get_result!=DB_NOTFOUND) { r = c_get_result; goto cleanup; }
     int found = c_get_result==0;
-    if (found) {
-        pkey = brt_cursor_peek_current_key(c->i->c);
-        pval = brt_cursor_peek_current_val(c->i->c);
-    }
+    if (found) brt_cursor_peek_current(c->i->c, &pkey, &pval);
     if (do_locking) {
 
 	DBT *prevkey = found ? brt_cursor_peek_prev_key(c->i->c) : brt_cursor_peek_current_key(c->i->c);