snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

examples/features/stats_monitoring/statshandler/handler.go

@@ -0,0 +1,93 @@
+/*
+ *
+ * Copyright 2022 gRPC authors.
+ *
+ * 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 statshandler is an example pkg to illustrate the use of the stats handler.
+package statshandler
+
+import (
+	"context"
+	"log"
+	"net"
+	"path/filepath"
+
+	"google.golang.org/grpc/stats"
+)
+
+// Handler implements [stats.Handler](https://pkg.go.dev/google.golang.org/grpc/stats#Handler) interface.
+type Handler struct{}
+
+type connStatCtxKey struct{}
+
+// TagConn can attach some information to the given context.
+// The context used in HandleConn for this connection will be derived from the context returned.
+// In the gRPC client:
+// The context used in HandleRPC for RPCs on this connection will be the user's context and NOT derived from the context returned here.
+// In the gRPC server:
+// The context used in HandleRPC for RPCs on this connection will be derived from the context returned here.
+func (st *Handler) TagConn(ctx context.Context, stat *stats.ConnTagInfo) context.Context {
+	log.Printf("[TagConn] [%T]: %+[1]v", stat)
+	return context.WithValue(ctx, connStatCtxKey{}, stat)
+}
+
+// HandleConn processes the Conn stats.
+func (st *Handler) HandleConn(ctx context.Context, stat stats.ConnStats) {
+	var rAddr net.Addr
+	if s, ok := ctx.Value(connStatCtxKey{}).(*stats.ConnTagInfo); ok {
+		rAddr = s.RemoteAddr
+	}
+
+	if stat.IsClient() {
+		log.Printf("[server addr: %s] [HandleConn] [%T]: %+[2]v", rAddr, stat)
+	} else {
+		log.Printf("[client addr: %s] [HandleConn] [%T]: %+[2]v", rAddr, stat)
+	}
+}
+
+type rpcStatCtxKey struct{}
+
+// TagRPC can attach some information to the given context.
+// The context used for the rest lifetime of the RPC will be derived from the returned context.
+func (st *Handler) TagRPC(ctx context.Context, stat *stats.RPCTagInfo) context.Context {
+	log.Printf("[TagRPC] [%T]: %+[1]v", stat)
+	return context.WithValue(ctx, rpcStatCtxKey{}, stat)
+}
+
+// HandleRPC processes the RPC stats. Note: All stat fields are read-only.
+func (st *Handler) HandleRPC(ctx context.Context, stat stats.RPCStats) {
+	var sMethod string
+	if s, ok := ctx.Value(rpcStatCtxKey{}).(*stats.RPCTagInfo); ok {
+		sMethod = filepath.Base(s.FullMethodName)
+	}
+
+	var cAddr net.Addr
+	// for gRPC clients, key connStatCtxKey{} will not be present in HandleRPC's context.
+	if s, ok := ctx.Value(connStatCtxKey{}).(*stats.ConnTagInfo); ok {
+		cAddr = s.RemoteAddr
+	}
+
+	if stat.IsClient() {
+		log.Printf("[server method: %s] [HandleRPC] [%T]: %+[2]v", sMethod, stat)
+	} else {
+		log.Printf("[client addr: %s] [HandleRPC] [%T]: %+[2]v", cAddr, stat)
+	}
+}
+
+// New returns a new implementation of [stats.Handler](https://pkg.go.dev/google.golang.org/grpc/stats#Handler) interface.
+func New() *Handler {
+	return &Handler{}
+}