From ecf49fc0738105e87d20e29aa82c403b666ff0b4 Mon Sep 17 00:00:00 2001
From: siddontang <siddontang@gmail.com>
Date: Wed, 29 Oct 2014 23:12:19 +0800
Subject: [PATCH] update area

---
 arena/arena.go | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/arena/arena.go b/arena/arena.go
index ceec084..2ca98aa 100644
--- a/arena/arena.go
+++ b/arena/arena.go
@@ -3,26 +3,28 @@ package arena
 type Arena struct {
 	buf []byte
 
-	size int
+	offset int
 }
 
 func NewArena(size int) *Arena {
 	a := new(Arena)
 
-	a.size = size
 	a.buf = make([]byte, size, size)
+	a.offset = 0
 
 	return a
 }
 
 func (a *Arena) Make(size int) []byte {
-	if a.size < size {
+	if len(a.buf) < size || len(a.buf)-a.offset < size {
 		return make([]byte, size)
-	} else if len(a.buf) < size {
-		a.buf = make([]byte, a.size)
 	}
 
-	b := a.buf[0:size]
-	a.buf = a.buf[size:]
+	b := a.buf[a.offset : size+a.offset]
+	a.offset += size
 	return b
 }
+
+func (a *Arena) Reset() {
+	a.offset = 0
+}