Updated pmmetrics package to support for VOL-1091 and VOL-1381, This is to collect PMMetics for OLT.
Updated with SendKPIevent2 method
Updated with review comments

Change-Id: Ib2461f1fa6003a74372737c08e3bc2305667f2ce
diff --git a/pkg/adapters/adapterif/core_proxy_if.go b/pkg/adapters/adapterif/core_proxy_if.go
index 196f356..615452c 100644
--- a/pkg/adapters/adapterif/core_proxy_if.go
+++ b/pkg/adapters/adapterif/core_proxy_if.go
@@ -37,6 +37,7 @@
 	DeviceStateUpdate(ctx context.Context, deviceID string,
 		connStatus voltha.ConnectStatus_ConnectStatus, operStatus voltha.OperStatus_OperStatus) error
 
+	DevicePMConfigUpdate(ctx context.Context, pmConfigs *voltha.PmConfigs) error
 	ChildDeviceDetected(ctx context.Context, parentDeviceID string, parentPortNo int,
 		childDeviceType string, channelID int, vendorID string, serialNumber string, onuID int64) (*voltha.Device, error)
 
diff --git a/pkg/adapters/adapterif/events_proxy_if.go b/pkg/adapters/adapterif/events_proxy_if.go
index 00a86a5..1f70f27 100644
--- a/pkg/adapters/adapterif/events_proxy_if.go
+++ b/pkg/adapters/adapterif/events_proxy_if.go
@@ -24,6 +24,8 @@
 type EventProxy interface {
 	SendDeviceEvent(deviceEvent *voltha.DeviceEvent, category EventCategory,
 		subCategory EventSubCategory, raisedTs int64) error
+	SendKpiEvent(id string, deviceEvent *voltha.KpiEvent2, category EventCategory,
+		subCategory EventSubCategory, raisedTs int64) error
 }
 
 const (
diff --git a/pkg/adapters/common/events_proxy.go b/pkg/adapters/common/events_proxy.go
index 0f966d3..b35d145 100644
--- a/pkg/adapters/common/events_proxy.go
+++ b/pkg/adapters/common/events_proxy.go
@@ -102,6 +102,28 @@
 
 }
 
+func (ep *EventProxy) SendKpiEvent(id string, kpiEvent *voltha.KpiEvent2, category adapterif.EventCategory, subCategory adapterif.EventSubCategory, raisedTs int64) error {
+	if kpiEvent == nil {
+		log.Error("Recieved empty kpi event")
+		return errors.New("KPI event nil")
+	}
+	var event voltha.Event
+	var de voltha.Event_KpiEvent2
+	de.KpiEvent2 = kpiEvent
+	event.Header = ep.getEventHeader(id, category, subCategory, voltha.EventType_KPI_EVENT2, raisedTs)
+	event.EventType = &de
+	if err := ep.sendEvent(&event); err != nil {
+		log.Errorw("Failed to send kpi event to KAFKA bus", log.Fields{"device-event": kpiEvent})
+		return err
+	}
+	log.Infow("Successfully sent kpi event to KAFKA", log.Fields{"Id": event.Header.Id, "Category": event.Header.Category,
+		"SubCategory": event.Header.SubCategory, "Type": event.Header.Type, "TypeVersion": event.Header.TypeVersion,
+		"ReportedTs": event.Header.ReportedTs, "KpiEventName": "STATS_EVENT"})
+
+	return nil
+
+}
+
 /* TODO: Send out KPI events*/
 
 func (ep *EventProxy) sendEvent(event *voltha.Event) error {
diff --git a/pkg/pmmetrics/performance_metrics.go b/pkg/pmmetrics/performance_metrics.go
new file mode 100644
index 0000000..4bd0446
--- /dev/null
+++ b/pkg/pmmetrics/performance_metrics.go
@@ -0,0 +1,97 @@
+/*
+ * Copyright 2019-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 pmmetrics
+
+import (
+	"github.com/opencord/voltha-protos/go/voltha"
+)
+
+// PmMetrics structure holds metric and device info
+type PmMetrics struct {
+	deviceID          string
+	frequency         uint32
+	grouped           bool
+	frequencyOverride bool
+	metrics           map[string]*voltha.PmConfig
+}
+
+type PmMetricsOption func(*PmMetrics)
+
+// Frequency is to poll stats at this interval
+func Frequency(frequency uint32) PmMetricsOption {
+	return func(args *PmMetrics) {
+		args.frequency = frequency
+	}
+}
+
+// GetSubscriberMetrics will return the metrics subscribed for the device.
+func (pm *PmMetrics) GetSubscriberMetrics() map[string]*voltha.PmConfig {
+	if pm == nil {
+		return nil
+	}
+	return pm.metrics
+}
+
+func Grouped(grouped bool) PmMetricsOption {
+	return func(args *PmMetrics) {
+		args.grouped = grouped
+	}
+}
+
+func FrequencyOverride(frequencyOverride bool) PmMetricsOption {
+	return func(args *PmMetrics) {
+		args.frequencyOverride = frequencyOverride
+	}
+}
+
+// Metrics will store the PMMetric params
+func Metrics(pmNames []string) PmMetricsOption {
+	return func(args *PmMetrics) {
+		args.metrics = make(map[string]*voltha.PmConfig)
+		for _, name := range pmNames {
+			args.metrics[name] = &voltha.PmConfig{
+				Name:    name,
+				Type:    voltha.PmConfig_COUNTER,
+				Enabled: true,
+			}
+		}
+	}
+}
+
+// NewPmMetrics will return the pmmetric object
+func NewPmMetrics(deviceID string, opts ...PmMetricsOption) *PmMetrics {
+	pm := &PmMetrics{}
+	pm.deviceID = deviceID
+	for _, option := range opts {
+		option(pm)
+	}
+	return pm
+}
+
+// ToPmConfigs will enable the defined pmmetric
+func (pm *PmMetrics) ToPmConfigs() *voltha.PmConfigs {
+	pmConfigs := &voltha.PmConfigs{
+		Id:           pm.deviceID,
+		DefaultFreq:  pm.frequency,
+		Grouped:      pm.grouped,
+		FreqOverride: pm.frequencyOverride,
+	}
+	for _, v := range pm.metrics {
+		pmConfigs.Metrics = append(pmConfigs.Metrics, &voltha.PmConfig{Name: v.Name, Type: v.Type, Enabled: v.Enabled})
+	}
+	return pmConfigs
+}