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examples: add an example to illustrate the usage of stats handler (#5657
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# Stats Monitoring Handler | ||
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This example demonstrates the use of the [`stats`](https://pkg.go.dev/google.golang.org/grpc/stats) package for reporting various | ||
network and RPC stats. | ||
_Note that all fields are READ-ONLY and the APIs of the `stats` package are | ||
experimental_. | ||
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## Try it | ||
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``` | ||
go run server/main.go | ||
``` | ||
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``` | ||
go run client/main.go | ||
``` | ||
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## Explanation | ||
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gRPC provides a mechanism to hook on to various events (phases) of the | ||
request-response network cycle through the [`stats.Handler`](https://pkg.go.dev/google.golang.org/grpc/stats#Handler) interface. To access | ||
these events, a concrete type that implements `stats.Handler` should be passed to | ||
`grpc.WithStatsHandler()` on the client side and `grpc.StatsHandler()` on the | ||
server side. | ||
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The `HandleRPC(context.Context, RPCStats)` method on `stats.Handler` is called | ||
multiple times during a request-response cycle, and various event stats are | ||
passed to its `RPCStats` parameter (an interface). The concrete types that | ||
implement this interface are: `*stats.Begin`, `*stats.InHeader`, `*stats.InPayload`, | ||
`*stats.InTrailer`, `*stats.OutHeader`, `*stats.OutPayload`, `*stats.OutTrailer`, and | ||
`*stats.End`. The order of these events differs on client and server. | ||
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Similarly, the `HandleConn(context.Context, ConnStats)` method on `stats.Handler` | ||
is called twice, once at the beginning of the connection with `*stats.ConnBegin` | ||
and once at the end with `*stats.ConnEnd`. | ||
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The [`stats.Handler`](https://pkg.go.dev/google.golang.org/grpc/stats#Handler) interface also provides | ||
`TagRPC(context.Context, *RPCTagInfo) context.Context` and | ||
`TagConn(context.Context, *ConnTagInfo) context.Context` methods. These methods | ||
are mainly used to attach network related information to the given context. | ||
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The `TagRPC(context.Context, *RPCTagInfo) context.Context` method returns a | ||
context from which the context used for the rest lifetime of the RPC will be | ||
derived. This behavior is consistent between the gRPC client and server. | ||
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The context returned from | ||
`TagConn(context.Context, *ConnTagInfo) context.Context` has varied lifespan: | ||
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- In the gRPC client: | ||
The context used for the rest lifetime of the RPC will NOT be derived from | ||
this context. Hence the information attached to this context can only be | ||
consumed by `HandleConn(context.Context, ConnStats)` method. | ||
- In the gRPC server: | ||
The context used for the rest lifetime of the RPC will be derived from | ||
this context. | ||
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NOTE: The [stats](https://pkg.go.dev/google.golang.org/grpc/stats) package should only be used for network monitoring purposes, | ||
and not as an alternative to [interceptors](https://github.com/grpc/grpc-go/blob/master/examples/features/metadata). |
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/* | ||
* | ||
* 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. | ||
* | ||
*/ | ||
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// Binary client is an example client to illustrate the use of the stats handler. | ||
package main | ||
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import ( | ||
"context" | ||
"flag" | ||
"log" | ||
"time" | ||
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"google.golang.org/grpc" | ||
"google.golang.org/grpc/credentials/insecure" | ||
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echogrpc "google.golang.org/grpc/examples/features/proto/echo" | ||
echopb "google.golang.org/grpc/examples/features/proto/echo" | ||
"google.golang.org/grpc/examples/features/stats_monitoring/statshandler" | ||
) | ||
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var addr = flag.String("addr", "localhost:50051", "the address to connect to") | ||
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func main() { | ||
flag.Parse() | ||
opts := []grpc.DialOption{ | ||
grpc.WithTransportCredentials(insecure.NewCredentials()), | ||
grpc.WithStatsHandler(statshandler.New()), | ||
} | ||
conn, err := grpc.Dial(*addr, opts...) | ||
if err != nil { | ||
log.Fatalf("failed to connect to server %q: %v", *addr, err) | ||
} | ||
defer conn.Close() | ||
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ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second) | ||
defer cancel() | ||
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c := echogrpc.NewEchoClient(conn) | ||
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resp, err := c.UnaryEcho(ctx, &echopb.EchoRequest{Message: "stats handler demo"}) | ||
if err != nil { | ||
log.Fatalf("unexpected error from UnaryEcho: %v", err) | ||
} | ||
log.Printf("RPC response: %s", resp.Message) | ||
} |
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/* | ||
* | ||
* 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. | ||
* | ||
*/ | ||
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// Binary server is an example server to illustrate the use of the stats handler. | ||
package main | ||
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import ( | ||
"context" | ||
"flag" | ||
"fmt" | ||
"log" | ||
"net" | ||
"time" | ||
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"google.golang.org/grpc" | ||
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echogrpc "google.golang.org/grpc/examples/features/proto/echo" | ||
echopb "google.golang.org/grpc/examples/features/proto/echo" | ||
"google.golang.org/grpc/examples/features/stats_monitoring/statshandler" | ||
) | ||
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var port = flag.Int("port", 50051, "the port to serve on") | ||
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type server struct { | ||
echogrpc.UnimplementedEchoServer | ||
} | ||
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func (s *server) UnaryEcho(ctx context.Context, req *echopb.EchoRequest) (*echopb.EchoResponse, error) { | ||
time.Sleep(2 * time.Second) | ||
return &echopb.EchoResponse{Message: req.Message}, nil | ||
} | ||
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func main() { | ||
flag.Parse() | ||
lis, err := net.Listen("tcp", fmt.Sprintf(":%d", *port)) | ||
if err != nil { | ||
log.Fatalf("failed to listen on port %d: %v", *port, err) | ||
} | ||
log.Printf("server listening at %v\n", lis.Addr()) | ||
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s := grpc.NewServer(grpc.StatsHandler(statshandler.New())) | ||
echogrpc.RegisterEchoServer(s, &server{}) | ||
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if err := s.Serve(lis); err != nil { | ||
log.Fatalf("failed to serve: %v", err) | ||
} | ||
} |
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examples/features/stats_monitoring/statshandler/handler.go
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/* | ||
* | ||
* 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. | ||
* | ||
*/ | ||
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// Package statshandler is an example pkg to illustrate the use of the stats handler. | ||
package statshandler | ||
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import ( | ||
"context" | ||
"log" | ||
"net" | ||
"path/filepath" | ||
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"google.golang.org/grpc/stats" | ||
) | ||
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// Handler implements [stats.Handler](https://pkg.go.dev/google.golang.org/grpc/stats#Handler) interface. | ||
type Handler struct{} | ||
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type connStatCtxKey struct{} | ||
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// 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) | ||
} | ||
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// 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 | ||
} | ||
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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) | ||
} | ||
} | ||
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type rpcStatCtxKey struct{} | ||
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// 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) | ||
} | ||
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// 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) | ||
} | ||
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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 | ||
} | ||
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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) | ||
} | ||
} | ||
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// New returns a new implementation of [stats.Handler](https://pkg.go.dev/google.golang.org/grpc/stats#Handler) interface. | ||
func New() *Handler { | ||
return &Handler{} | ||
} |