implement grpc metrics for ceph-csi

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

vendor/github.com/grpc-ecosystem/go-grpc-prometheus/server_reporter.go

@@ -0,0 +1,46 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_prometheus
+
+import (
+	"time"
+
+	"google.golang.org/grpc/codes"
+)
+
+type serverReporter struct {
+	metrics     *ServerMetrics
+	rpcType     grpcType
+	serviceName string
+	methodName  string
+	startTime   time.Time
+}
+
+func newServerReporter(m *ServerMetrics, rpcType grpcType, fullMethod string) *serverReporter {
+	r := &serverReporter{
+		metrics: m,
+		rpcType: rpcType,
+	}
+	if r.metrics.serverHandledHistogramEnabled {
+		r.startTime = time.Now()
+	}
+	r.serviceName, r.methodName = splitMethodName(fullMethod)
+	r.metrics.serverStartedCounter.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Inc()
+	return r
+}
+
+func (r *serverReporter) ReceivedMessage() {
+	r.metrics.serverStreamMsgReceived.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Inc()
+}
+
+func (r *serverReporter) SentMessage() {
+	r.metrics.serverStreamMsgSent.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Inc()
+}
+
+func (r *serverReporter) Handled(code codes.Code) {
+	r.metrics.serverHandledCounter.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName, code.String()).Inc()
+	if r.metrics.serverHandledHistogramEnabled {
+		r.metrics.serverHandledHistogram.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Observe(time.Since(r.startTime).Seconds())
+	}
+}