From 5a30d36b175e1ec75bb6f21234bf2d359d3b1a72 Mon Sep 17 00:00:00 2001
From: Steve Yen <steve.yen@gmail.com>
Date: Thu, 29 Jan 2015 11:01:51 -0800
Subject: [PATCH] cznicb KVStore uses Put() for faster read-modify-write

---
 index/store/cznicb/cznicb.go | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/index/store/cznicb/cznicb.go b/index/store/cznicb/cznicb.go
index 0e7d0921..9dce8e2d 100644
--- a/index/store/cznicb/cznicb.go
+++ b/index/store/cznicb/cznicb.go
@@ -220,20 +220,17 @@ func (w *Batch) Execute() (err error) {
 	t := w.s.t
 	for key, mc := range w.ms {
 		k := []byte(key)
-		b := []byte(nil)
-		v, ok := t.Get(k)
-		if ok && v != nil {
-			b = v.([]byte)
-		}
-		b, err := mc.Merge(k, b)
-		if err != nil {
-			return err
-		}
-		if b != nil {
-			t.Set(k, b)
-		} else {
-			t.Delete(k)
-		}
+		t.Put(k, func(oldV interface{}, exists bool) (newV interface{}, write bool) {
+			b := []byte(nil)
+			if exists && oldV != nil {
+				b = oldV.([]byte)
+			}
+			b, err := mc.Merge(k, b)
+			if err != nil {
+				return nil, false
+			}
+			return b, b != nil
+		})
 	}
 
 	for _, op := range w.ops {