add stream assign server side implementation

weed/server/master_grpc_server_assign.go

@@ -3,6 +3,7 @@ package weed_server
 import (
 	"context"
 	"fmt"
+	"github.com/seaweedfs/seaweedfs/weed/glog"
 	"time"
 
 	"github.com/seaweedfs/raft"
@@ -15,6 +16,24 @@ import (
 	"github.com/seaweedfs/seaweedfs/weed/topology"
 )
 
+func (ms *MasterServer) StreamAssign(server master_pb.Seaweed_StreamAssignServer) error {
+	for {
+		req, err := server.Recv()
+		if err != nil {
+			glog.Errorf("StreamAssign failed to receive: %v", err)
+			return err
+		}
+		resp, err := ms.Assign(context.Background(), req)
+		if err != nil {
+			glog.Errorf("StreamAssign failed to assign: %v", err)
+			return err
+		}
+		if err = server.Send(resp); err != nil {
+			glog.Errorf("StreamAssign failed to send: %v", err)
+			return err
+		}
+	}
+}
 func (ms *MasterServer) Assign(ctx context.Context, req *master_pb.AssignRequest) (*master_pb.AssignResponse, error) {
 
 	if !ms.Topo.IsLeader() {