Make protobuf client and request handler write protobuf length and data in one call to write to avoid race conditions

src/coordinator/protobuf_client.go

@@ -110,12 +110,12 @@ func (self *ProtobufClient) MakeRequest(request *protocol.Request, responseStrea
 		}
 
 		conn.SetWriteDeadline(time.Now().Add(self.writeTimeout))
-		err = binary.Write(conn, binary.LittleEndian, uint32(len(data)))
+		buff := bytes.NewBuffer(make([]byte, 0, len(data)+8))
+		binary.Write(buff, binary.LittleEndian, uint32(len(data)))
+		_, err = conn.Write(append(buff.Bytes(), data...))
+
 		if err == nil {
-			_, err = conn.Write(data)
-			if err == nil {
-				return nil
-			}
+			return nil
 		}
 		log.Error("ProtobufClient: error making request: %s", err)
 		// TODO: do something smarter here based on whatever the error is.

src/coordinator/protobuf_request_handler.go

@@ -1,6 +1,7 @@
 package coordinator
 
 import (
+	"bytes"
 	"cluster"
 	log "code.google.com/p/log4go"
 	"common"
@@ -122,13 +123,9 @@ func (self *ProtobufRequestHandler) WriteResponse(conn net.Conn, response *proto
 		return self.WriteResponse(conn, response)
 	}
 
-	err = binary.Write(conn, binary.LittleEndian, uint32(len(data)))
-	if err != nil {
-		log.Error("error writing response length: %s", err)
-		return err
-	}
-
-	_, err = conn.Write(data)
+	buff := bytes.NewBuffer(make([]byte, 0, len(data)+8))
+	binary.Write(buff, binary.LittleEndian, uint32(len(data)))
+	_, err = conn.Write(append(buff.Bytes(), data...))
 	if err != nil {
 		log.Error("error writing response: %s", err)
 		return err