Fix metrics concurrency

Signed-off-by: Artem Glazychev <artem.glazychev@xored.com>

pkg/networkservice/common/metrics/metadata.go

@@ -0,0 +1,33 @@
+// Copyright (c) 2022 Cisco and/or its affiliates.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// 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 metrics
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/metric"
+
+	"github.com/networkservicemesh/sdk/pkg/networkservice/utils/metadata"
+)
+
+type keyType struct{}
+type metricsMap map[string]metric.Int64Histogram
+
+func loadOrStore(ctx context.Context, metrics metricsMap) (value metricsMap, ok bool) {
+	rawValue, ok := metadata.Map(ctx, false).LoadOrStore(keyType{}, metrics)
+	return rawValue.(metricsMap), ok
+}

pkg/networkservice/common/metrics/server.go

@@ -31,15 +31,13 @@ import (
 )
 
 type metricServer struct {
-	recorderMap map[string]metric.Int64Histogram
-	meter       metric.Meter
+	meter metric.Meter
 }
 
 // NewServer returns a new metric server chain element
 func NewServer() networkservice.NetworkServiceServer {
 	return &metricServer{
-		recorderMap: make(map[string]metric.Int64Histogram),
-		meter:       global.Meter(""),
+		meter: global.Meter(""),
 	}
 }
 
@@ -70,19 +68,20 @@ func (t *metricServer) writeMetrics(ctx context.Context, path *networkservice.Pa
 				continue
 			}
 
+			metrics, _ := loadOrStore(ctx, make(map[string]metric.Int64Histogram))
 			for metricName, metricValue := range pathSegment.Metrics {
 				/* Works with integers only */
 				recVal, err := strconv.ParseInt(metricValue, 10, 64)
 				if err != nil {
 					continue
 				}
-				_, ok := t.recorderMap[metricName]
+				_, ok := metrics[metricName]
 				if !ok {
-					t.recorderMap[metricName] = metric.Must(t.meter).NewInt64Histogram(
+					metrics[metricName] = metric.Must(t.meter).NewInt64Histogram(
 						pathSegment.Name + "_" + metricName,
 					)
 				}
-				t.recorderMap[metricName].Record(ctx, recVal, attribute.String("connection", path.GetPathSegments()[0].Id))
+				metrics[metricName].Record(ctx, recVal, attribute.String("connection", path.GetPathSegments()[0].Id))
 			}
 		}
 	}