[VOL-4442] grpc streaming connection monitoring

Change-Id: I8a361473a252f6d2b64578a97980b2b7b3618f55
diff --git a/internal/pkg/core/openonuInterAdapter.go b/internal/pkg/core/openonuInterAdapter.go
new file mode 100644
index 0000000..8e9bdec
--- /dev/null
+++ b/internal/pkg/core/openonuInterAdapter.go
@@ -0,0 +1,125 @@
+/*
+ * 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 core provides the utility for onu devices, flows and statistics
+package core
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/golang/protobuf/ptypes/empty"
+	"github.com/opencord/voltha-lib-go/v7/pkg/log"
+	"github.com/opencord/voltha-protos/v5/go/common"
+	"github.com/opencord/voltha-protos/v5/go/health"
+	ia "github.com/opencord/voltha-protos/v5/go/inter_adapter"
+	"github.com/opencord/voltha-protos/v5/go/onu_inter_adapter_service"
+)
+
+//OpenONUACInterAdapter structure holds a reference to ONU adapter
+type OpenONUACInterAdapter struct {
+	onuAdapter  *OpenONUAC
+	exitChannel chan struct{}
+}
+
+//NewOpenONUACAdapter returns a new instance of OpenONUACAdapter
+func NewOpenONUACAdapter(ctx context.Context, onuAdapter *OpenONUAC) *OpenONUACInterAdapter {
+	return &OpenONUACInterAdapter{onuAdapter: onuAdapter, exitChannel: make(chan struct{})}
+}
+
+//Start starts (logs) the adapter
+func (oo *OpenONUACInterAdapter) Start(ctx context.Context) error {
+	logger.Info(ctx, "starting-openonu-inter-adapter")
+	return nil
+}
+
+//OnuIndication redirects the request the the core ONU adapter handler
+func (oo *OpenONUACInterAdapter) OnuIndication(ctx context.Context, onuInd *ia.OnuIndicationMessage) (*empty.Empty, error) {
+	return oo.onuAdapter.OnuIndication(ctx, onuInd)
+}
+
+//OmciIndication redirects the request the the core ONU adapter handler
+func (oo *OpenONUACInterAdapter) OmciIndication(ctx context.Context, msg *ia.OmciMessage) (*empty.Empty, error) {
+	return oo.onuAdapter.OmciIndication(ctx, msg)
+}
+
+//DownloadTechProfile redirects the request the the core ONU adapter handler
+func (oo *OpenONUACInterAdapter) DownloadTechProfile(ctx context.Context, tProfile *ia.TechProfileDownloadMessage) (*empty.Empty, error) {
+	return oo.onuAdapter.DownloadTechProfile(ctx, tProfile)
+}
+
+//DeleteGemPort redirects the request the the core ONU adapter handler
+func (oo *OpenONUACInterAdapter) DeleteGemPort(ctx context.Context, gPort *ia.DeleteGemPortMessage) (*empty.Empty, error) {
+	return oo.onuAdapter.DeleteGemPort(ctx, gPort)
+}
+
+//DeleteTCont redirects the request the the core ONU adapter handler
+func (oo *OpenONUACInterAdapter) DeleteTCont(ctx context.Context, tConf *ia.DeleteTcontMessage) (*empty.Empty, error) {
+	return oo.onuAdapter.DeleteTCont(ctx, tConf)
+}
+
+//Stop terminates the session
+func (oo *OpenONUACInterAdapter) Stop(ctx context.Context) error {
+	close(oo.exitChannel)
+	logger.Info(ctx, "openonu-inter-adapter-stopped")
+	return nil
+}
+
+// GetHealthStatus is used by a OnuInterAdapterService client to detect a connection
+// lost with the gRPC server hosting the OnuInterAdapterService service
+func (oo *OpenONUACInterAdapter) GetHealthStatus(stream onu_inter_adapter_service.OnuInterAdapterService_GetHealthStatusServer) error {
+	ctx := context.Background()
+	logger.Debugw(ctx, "receive-stream-connection", log.Fields{"stream": stream})
+
+	if stream == nil {
+		return fmt.Errorf("conn-is-nil %v", stream)
+	}
+	initialRequestTime := time.Now()
+	var remoteClient *common.Connection
+	var tempClient *common.Connection
+	var err error
+loop:
+	for {
+		tempClient, err = stream.Recv()
+		if err != nil {
+			logger.Warnw(ctx, "received-stream-error", log.Fields{"remote-client": remoteClient, "error": err})
+			break loop
+		}
+		// Send a response back
+		err = stream.Send(&health.HealthStatus{State: health.HealthStatus_HEALTHY})
+		if err != nil {
+			logger.Warnw(ctx, "sending-stream-error", log.Fields{"remote-client": remoteClient, "error": err})
+			break loop
+		}
+
+		remoteClient = tempClient
+		logger.Debugw(ctx, "received-keep-alive", log.Fields{"remote-client": remoteClient})
+		oo.onuAdapter.updateReachabilityFromRemote(context.Background(), remoteClient)
+
+		select {
+		case <-stream.Context().Done():
+			logger.Infow(ctx, "stream-keep-alive-context-done", log.Fields{"remote-client": remoteClient, "error": stream.Context().Err()})
+			break loop
+		case <-oo.exitChannel:
+			logger.Warnw(ctx, "received-stop", log.Fields{"remote-client": remoteClient, "initial-conn-time": initialRequestTime})
+			break loop
+		default:
+		}
+	}
+	logger.Errorw(ctx, "connection-down", log.Fields{"remote-client": remoteClient, "error": err, "initial-conn-time": initialRequestTime})
+	return err
+}