From 091d20bfe2324518dc8f3e15b0f2e54ce9124718 Mon Sep 17 00:00:00 2001
From: Evan Jones <evan.jones@datadoghq.com>
Date: Tue, 29 Oct 2024 12:07:25 -0400
Subject: [PATCH] server: Only call FromIncomingContext with stats handlers
 (#7781)

---
 server.go | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/server.go b/server.go
index d1e1415a40f9..62a5b04b76e2 100644
--- a/server.go
+++ b/server.go
@@ -1783,17 +1783,20 @@ func (s *Server) handleStream(t transport.ServerTransport, stream *transport.Str
 	service := sm[:pos]
 	method := sm[pos+1:]
 
-	md, _ := metadata.FromIncomingContext(ctx)
-	for _, sh := range s.opts.statsHandlers {
-		ctx = sh.TagRPC(ctx, &stats.RPCTagInfo{FullMethodName: stream.Method()})
-		sh.HandleRPC(ctx, &stats.InHeader{
-			FullMethod:  stream.Method(),
-			RemoteAddr:  t.Peer().Addr,
-			LocalAddr:   t.Peer().LocalAddr,
-			Compression: stream.RecvCompress(),
-			WireLength:  stream.HeaderWireLength(),
-			Header:      md,
-		})
+	// FromIncomingContext is expensive: skip if there are no statsHandlers
+	if len(s.opts.statsHandlers) > 0 {
+		md, _ := metadata.FromIncomingContext(ctx)
+		for _, sh := range s.opts.statsHandlers {
+			ctx = sh.TagRPC(ctx, &stats.RPCTagInfo{FullMethodName: stream.Method()})
+			sh.HandleRPC(ctx, &stats.InHeader{
+				FullMethod:  stream.Method(),
+				RemoteAddr:  t.Peer().Addr,
+				LocalAddr:   t.Peer().LocalAddr,
+				Compression: stream.RecvCompress(),
+				WireLength:  stream.HeaderWireLength(),
+				Header:      md,
+			})
+		}
 	}
 	// To have calls in stream callouts work. Will delete once all stats handler
 	// calls come from the gRPC layer.