First Commit of Voltha-Go-Controller from Radisys

Change-Id: I8e2e908e7ab09a4fe3d86849da18b6d69dcf4ab0
diff --git a/internal/pkg/vpagent/connection.go b/internal/pkg/vpagent/connection.go
new file mode 100644
index 0000000..607f7f3
--- /dev/null
+++ b/internal/pkg/vpagent/connection.go
@@ -0,0 +1,88 @@
+/*
+* Copyright 2022-present Open Networking Foundation
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+ */
+
+package vpagent
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"github.com/golang/protobuf/ptypes/empty"
+	"github.com/opencord/voltha-lib-go/v7/pkg/log"
+	"github.com/opencord/voltha-lib-go/v7/pkg/probe"
+	"github.com/opencord/voltha-protos/v5/go/voltha"
+	"google.golang.org/grpc"
+)
+
+//GrpcMaxSize Max size of grpc message
+const GrpcMaxSize int = 17455678
+
+func (vpa *VPAgent) establishConnectionToVoltha(ctx context.Context, p *probe.Probe) error {
+	if p != nil {
+		p.UpdateStatus(ctx, "voltha", probe.ServiceStatusPreparing)
+	}
+
+	if vpa.volthaConnection != nil {
+		vpa.volthaConnection.Close()
+	}
+
+	vpa.volthaConnection = nil
+	vpa.volthaClient.Clear()
+	try := 1
+	for vpa.ConnectionMaxRetries == 0 || try < vpa.ConnectionMaxRetries {
+		conn, err := grpc.Dial(vpa.VolthaAPIEndPoint, grpc.WithInsecure(), grpc.WithDefaultCallOptions(grpc.MaxCallRecvMsgSize(GrpcMaxSize)))
+		if err == nil {
+			svc := voltha.NewVolthaServiceClient(conn)
+			if svc != nil {
+				if _, err = svc.GetVoltha(context.Background(), &empty.Empty{}); err == nil {
+					logger.Debugw(ctx, "Established connection to Voltha",
+						log.Fields{
+							"VolthaApiEndPoint": vpa.VolthaAPIEndPoint,
+						})
+					vpa.volthaConnection = conn
+					vpa.volthaClient.Set(svc)
+					if p != nil {
+						p.UpdateStatus(ctx, "voltha", probe.ServiceStatusRunning)
+					}
+					vpa.events <- vpaEventVolthaConnected
+					return nil
+				}
+			}
+		}
+		logger.Warnw(ctx, "Failed to connect to voltha",
+			log.Fields{
+				"VolthaApiEndPoint": vpa.VolthaAPIEndPoint,
+				"error":             err.Error(),
+			})
+		if vpa.ConnectionMaxRetries == 0 || try < vpa.ConnectionMaxRetries {
+			if vpa.ConnectionMaxRetries != 0 {
+				try++
+			}
+			time.Sleep(vpa.ConnectionRetryDelay)
+		}
+	}
+	if p != nil {
+		p.UpdateStatus(ctx, "voltha", probe.ServiceStatusFailed)
+	}
+	return errors.New("failed-to-connect-to-voltha")
+}
+
+// CloseConnectionToVoltha closes the grpc connection to VOLTHA
+func (vpa *VPAgent) CloseConnectionToVoltha() {
+	//Close the grpc connection to voltha
+	logger.Debug(ctx, "Closing voltha grpc connection")
+	vpa.volthaConnection.Close()
+}