otelgrpc: stats handlers record durations in ms instead of ns (#4548)

Author: Sovietaced

CHANGELOG.md

@@ -16,6 +16,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 - Fix `StreamClientInterceptor` in `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc` to end the spans synchronously. (#4537)
 - Fix data race in stats handlers when processing messages received and sent metrics in `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc`. (#4577)
+- The stats handlers `NewClientHandler`, `NewServerHandler` in `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc` now records RPC durations in `ms` instead of `ns`. (#4548)
 
 ## [1.21.0/0.46.0/0.15.0/0.1.0] - 2023-11-10
 

instrumentation/google.golang.org/grpc/otelgrpc/interceptor.go

@@ -340,9 +340,11 @@ func UnaryServerInterceptor(opts ...Option) grpc.UnaryServerInterceptor {
 		grpcStatusCodeAttr := statusCodeAttr(s.Code())
 		span.SetAttributes(grpcStatusCodeAttr)
 
-		elapsedTime := time.Since(before).Milliseconds()
+		// Use floating point division here for higher precision (instead of Millisecond method).
+		elapsedTime := float64(time.Since(before)) / float64(time.Millisecond)
+
 		metricAttrs = append(metricAttrs, grpcStatusCodeAttr)
-		cfg.rpcDuration.Record(ctx, float64(elapsedTime), metric.WithAttributes(metricAttrs...))
+		cfg.rpcDuration.Record(ctx, elapsedTime, metric.WithAttributes(metricAttrs...))
 
 		return resp, err
 	}

instrumentation/google.golang.org/grpc/otelgrpc/stats_handler.go

@@ -194,10 +194,13 @@ func (c *config) handleRPC(ctx context.Context, rs stats.RPCStats) {
 		span.End()
 
 		metricAttrs = append(metricAttrs, rpcStatusAttr)
-		c.rpcDuration.Record(wctx, float64(rs.EndTime.Sub(rs.BeginTime)), metric.WithAttributes(metricAttrs...))
+
+		// Use floating point division here for higher precision (instead of Millisecond method).
+		elapsedTime := float64(rs.EndTime.Sub(rs.BeginTime)) / float64(time.Millisecond)
+
+		c.rpcDuration.Record(wctx, elapsedTime, metric.WithAttributes(metricAttrs...))
 		c.rpcRequestsPerRPC.Record(wctx, atomic.LoadInt64(&gctx.messagesReceived), metric.WithAttributes(metricAttrs...))
 		c.rpcResponsesPerRPC.Record(wctx, atomic.LoadInt64(&gctx.messagesSent), metric.WithAttributes(metricAttrs...))
-
 	default:
 		return
 	}