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Go

/*
*
* 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{}
}