gitbase: use a shared zlib encoder

Signed-off-by: Miguel Molina <[email protected]>

Author: erizocosmico

index.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"sync"
 
 	errors "gopkg.in/src-d/go-errors.v1"
 	"gopkg.in/src-d/go-mysql-server.v0/sql"
@@ -26,25 +27,42 @@ type Indexable interface {
 	gitBase
 }
 
-func encodeIndexKey(k indexKey) ([]byte, error) {
-	bs, err := k.encode()
-	if err != nil {
-		return nil, err
-	}
+type zlibEncoder struct {
+	w   *zlib.Writer
+	mut sync.Mutex
+}
+
+func (e *zlibEncoder) encode(data []byte) ([]byte, error) {
+	e.mut.Lock()
+	defer e.mut.Unlock()
 
 	var buf bytes.Buffer
-	gz := zlib.NewWriter(&buf)
-	if _, err := gz.Write(bs); err != nil {
+	e.w.Reset(&buf)
+
+	if _, err := e.w.Write(data); err != nil {
 		return nil, err
 	}
 
-	if err := gz.Close(); err != nil {
+	if err := e.w.Close(); err != nil {
 		return nil, err
 	}
 
 	return buf.Bytes(), nil
 }
 
+var encoder = func() *zlibEncoder {
+	return &zlibEncoder{w: zlib.NewWriter(bytes.NewBuffer(nil))}
+}()
+
+func encodeIndexKey(k indexKey) ([]byte, error) {
+	bs, err := k.encode()
+	if err != nil {
+		return nil, err
+	}
+
+	return encoder.encode(bs)
+}
+
 func decodeIndexKey(data []byte, k indexKey) error {
 	gz, err := zlib.NewReader(bytes.NewReader(data))
 	if err != nil {