Added a recyling pool for bulk strings written in redis client to help performance.

common/redisclient.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"net"
 	"strconv"
+	"sync"
 )
 
 type RedisClient struct {
@@ -30,11 +31,6 @@ func (client *RedisClient) Close() error {
 	return client.conn.Close()
 }
 
-func redisLength(prefix byte, s int) []byte {
-	buf := append(make([]byte, 0, 16), prefix)
-	return append(strconv.AppendInt(buf, int64(s), 10), '\r', '\n')
-}
-
 var (
 	writeArray4 = []byte("*4\r\n")
 	hspatial    = []byte("HSPATIAL")
@@ -42,14 +38,47 @@ var (
 	ignore      = []byte("IGNORE")
 )
 
+// stringPool is a pool to help recycle bulk strings
+// for writing. Experimented with sync.Pool and
+// channel based leaky buffers but the mutex based
+// version performs best in this case.
+type stringPool struct {
+	list [][]byte
+	sync.Mutex
+}
+
+func (sp *stringPool) alloc() (l []byte) {
+	sp.Lock()
+	if n := len(sp.list); n > 0 {
+		l = sp.list[n-1]
+		sp.list[n-1] = nil
+		sp.list = sp.list[:n-1]
+		sp.Unlock()
+	} else {
+		sp.Unlock()
+		l = make([]byte, 0, 32)
+	}
+	return
+}
+
+func (sp *stringPool) free(b []byte) {
+	b = b[:0]
+	sp.Lock()
+	sp.list = append(sp.list, b)
+	sp.Unlock()
+}
+
+var spool stringPool
+
 func (client *RedisClient) writeBulkString(data []byte) (err error) {
-	if _, err = client.conn.Write(redisLength('$', len(data))); err != nil {
-		return
-	}
-	if _, err = client.conn.Write(data); err != nil {
-		return
-	}
-	_, err = client.conn.Write(nl)
+	buf := spool.alloc()
+	buf = append(buf, '$')
+	buf = strconv.AppendInt(buf, int64(len(data)), 10)
+	buf = append(buf, nl...)
+	buf = append(buf, data...)
+	buf = append(buf, nl...)
+	_, err = client.conn.Write(buf)
+	spool.free(buf)
 	return
 }