clientv3: embed api version in metadata

ref.
https://github.com/etcd-io/etcd/pull/11687

Signed-off-by: Gyuho Lee <leegyuho@amazon.com>

clientv3: fix racy writes to context key

=== RUN   TestWatchOverlapContextCancel

==================

WARNING: DATA RACE

Write at 0x00c42110dd40 by goroutine 99:

  runtime.mapassign()

      /usr/local/go/src/runtime/hashmap.go:485 +0x0

  github.com/coreos/etcd/clientv3.metadataSet()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/ctx.go:61 +0x8c

  github.com/coreos/etcd/clientv3.withVersion()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/ctx.go:47 +0x137

  github.com/coreos/etcd/clientv3.newStreamClientInterceptor.func1()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/client.go:309 +0x81

  google.golang.org/grpc.NewClientStream()

      /go/src/github.com/coreos/etcd/gopath/src/google.golang.org/grpc/stream.go:101 +0x10e

  github.com/coreos/etcd/etcdserver/etcdserverpb.(*watchClient).Watch()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/etcdserver/etcdserverpb/rpc.pb.go:3193 +0xe9

  github.com/coreos/etcd/clientv3.(*watchGrpcStream).openWatchClient()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/watch.go:788 +0x143

  github.com/coreos/etcd/clientv3.(*watchGrpcStream).newWatchClient()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/watch.go:700 +0x5c3

  github.com/coreos/etcd/clientv3.(*watchGrpcStream).run()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/watch.go:431 +0x12b

Previous read at 0x00c42110dd40 by goroutine 130:

  reflect.maplen()

      /usr/local/go/src/runtime/hashmap.go:1165 +0x0

  reflect.Value.MapKeys()

      /usr/local/go/src/reflect/value.go:1090 +0x43b

  fmt.(*pp).printValue()

      /usr/local/go/src/fmt/print.go:741 +0x1885

  fmt.(*pp).printArg()

      /usr/local/go/src/fmt/print.go:682 +0x1b1

  fmt.(*pp).doPrintf()

      /usr/local/go/src/fmt/print.go:998 +0x1cad

  fmt.Sprintf()

      /usr/local/go/src/fmt/print.go:196 +0x77

  github.com/coreos/etcd/clientv3.streamKeyFromCtx()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/watch.go:825 +0xc8

  github.com/coreos/etcd/clientv3.(*watcher).Watch()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/watch.go:265 +0x426

  github.com/coreos/etcd/clientv3/integration.testWatchOverlapContextCancel.func1()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/integration/watch_test.go:959 +0x23e

Goroutine 99 (running) created at:

  github.com/coreos/etcd/clientv3.(*watcher).newWatcherGrpcStream()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/watch.go:236 +0x59d

  github.com/coreos/etcd/clientv3.(*watcher).Watch()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/watch.go:278 +0xbb6

  github.com/coreos/etcd/clientv3/integration.testWatchOverlapContextCancel.func1()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/integration/watch_test.go:959 +0x23e

Goroutine 130 (running) created at:

  github.com/coreos/etcd/clientv3/integration.testWatchOverlapContextCancel()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/integration/watch_test.go:979 +0x76d

  github.com/coreos/etcd/clientv3/integration.TestWatchOverlapContextCancel()

      /go/src/github.com/coreos/etcd/gopath/src/github.com/coreos/etcd/clientv3/integration/watch_test.go:922 +0x44

  testing.tRunner()

      /usr/local/go/src/testing/testing.go:657 +0x107

==================

Signed-off-by: Gyuho Lee <leegyuho@amazon.com>

clientv3/client.go

@@ -32,7 +32,6 @@ import (
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/keepalive"
-	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
 )
 
@@ -269,7 +268,11 @@ func (c *Client) dialSetupOpts(endpoint string, dopts ...grpc.DialOption) (opts
 		}
 		return conn, err
 	}
-	opts = append(opts, grpc.WithDialer(f))
+	opts = append(opts,
+		grpc.WithDialer(f),
+		grpc.WithUnaryInterceptor(newUnaryClientInterceptor()),
+		grpc.WithStreamInterceptor(newStreamClientInterceptor()),
+	)
 
 	creds := c.creds
 	if _, _, scheme := parseEndpoint(endpoint); len(scheme) != 0 {
@@ -284,6 +287,30 @@ func (c *Client) dialSetupOpts(endpoint string, dopts ...grpc.DialOption) (opts
 	return opts
 }
 
+func newUnaryClientInterceptor() grpc.UnaryClientInterceptor {
+	return func(ctx context.Context,
+		method string,
+		req, reply interface{},
+		cc *grpc.ClientConn,
+		invoker grpc.UnaryInvoker,
+		opts ...grpc.CallOption) error {
+		ctx = withVersion(ctx)
+		return invoker(ctx, method, req, reply, cc, opts...)
+	}
+}
+
+func newStreamClientInterceptor() grpc.StreamClientInterceptor {
+	return func(ctx context.Context,
+		desc *grpc.StreamDesc,
+		cc *grpc.ClientConn,
+		method string,
+		streamer grpc.Streamer,
+		opts ...grpc.CallOption) (grpc.ClientStream, error) {
+		ctx = withVersion(ctx)
+		return streamer(ctx, desc, cc, method, opts...)
+	}
+}
+
 // Dial connects to a single endpoint using the client's config.
 func (c *Client) Dial(endpoint string) (*grpc.ClientConn, error) {
 	return c.dial(endpoint)
@@ -356,13 +383,6 @@ func (c *Client) dial(endpoint string, dopts ...grpc.DialOption) (*grpc.ClientCo
 	return conn, nil
 }
 
-// WithRequireLeader requires client requests to only succeed
-// when the cluster has a leader.
-func WithRequireLeader(ctx context.Context) context.Context {
-	md := metadata.Pairs(rpctypes.MetadataRequireLeaderKey, rpctypes.MetadataHasLeader)
-	return metadata.NewOutgoingContext(ctx, md)
-}
-
 func newClient(cfg *Config) (*Client, error) {
 	if cfg == nil {
 		cfg = &Config{}

clientv3/ctx.go

@@ -0,0 +1,64 @@
+// Copyright 2020 The etcd 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 clientv3
+
+import (
+	"context"
+	"strings"
+
+	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
+	"github.com/coreos/etcd/version"
+	"google.golang.org/grpc/metadata"
+)
+
+// WithRequireLeader requires client requests to only succeed
+// when the cluster has a leader.
+func WithRequireLeader(ctx context.Context) context.Context {
+	md, ok := metadata.FromOutgoingContext(ctx)
+	if !ok { // no outgoing metadata ctx key, create one
+		md = metadata.Pairs(rpctypes.MetadataRequireLeaderKey, rpctypes.MetadataHasLeader)
+		return metadata.NewOutgoingContext(ctx, md)
+	}
+	copied := md.Copy() // avoid racey updates
+	// overwrite/add 'hasleader' key/value
+	metadataSet(copied, rpctypes.MetadataRequireLeaderKey, rpctypes.MetadataHasLeader)
+	return metadata.NewOutgoingContext(ctx, copied)
+}
+
+// embeds client version
+func withVersion(ctx context.Context) context.Context {
+	md, ok := metadata.FromOutgoingContext(ctx)
+	if !ok { // no outgoing metadata ctx key, create one
+		md = metadata.Pairs(rpctypes.MetadataClientAPIVersionKey, version.APIVersion)
+		return metadata.NewOutgoingContext(ctx, md)
+	}
+	copied := md.Copy() // avoid racey updates
+	// overwrite/add version key/value
+	metadataSet(copied, rpctypes.MetadataClientAPIVersionKey, version.APIVersion)
+	return metadata.NewOutgoingContext(ctx, copied)
+}
+
+func metadataGet(md metadata.MD, k string) []string {
+	k = strings.ToLower(k)
+	return md[k]
+}
+
+func metadataSet(md metadata.MD, k string, vals ...string) {
+	if len(vals) == 0 {
+		return
+	}
+	k = strings.ToLower(k)
+	md[k] = vals
+}

clientv3/ctx_test.go

@@ -0,0 +1,67 @@
+// Copyright 2020 The etcd 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 clientv3
+
+import (
+	"context"
+	"reflect"
+	"testing"
+
+	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
+	"github.com/coreos/etcd/version"
+	"google.golang.org/grpc/metadata"
+)
+
+func TestMetadataWithRequireLeader(t *testing.T) {
+	ctx := context.TODO()
+	md, ok := metadata.FromOutgoingContext(ctx)
+	if ok {
+		t.Fatal("expected no outgoing metadata ctx key")
+	}
+
+	// add a conflicting key with some other value
+	md = metadata.Pairs(rpctypes.MetadataRequireLeaderKey, "invalid")
+	// add a key, and expect not be overwritten
+	metadataSet(md, "hello", "1", "2")
+	ctx = metadata.NewOutgoingContext(ctx, md)
+
+	// expect overwrites but still keep other keys
+	ctx = WithRequireLeader(ctx)
+	md, ok = metadata.FromOutgoingContext(ctx)
+	if !ok {
+		t.Fatal("expected outgoing metadata ctx key")
+	}
+	if ss := metadataGet(md, rpctypes.MetadataRequireLeaderKey); !reflect.DeepEqual(ss, []string{rpctypes.MetadataHasLeader}) {
+		t.Fatalf("unexpected metadata for %q %v", rpctypes.MetadataRequireLeaderKey, ss)
+	}
+	if ss := metadataGet(md, "hello"); !reflect.DeepEqual(ss, []string{"1", "2"}) {
+		t.Fatalf("unexpected metadata for 'hello' %v", ss)
+	}
+}
+
+func TestMetadataWithClientAPIVersion(t *testing.T) {
+	ctx := withVersion(WithRequireLeader(context.TODO()))
+
+	md, ok := metadata.FromOutgoingContext(ctx)
+	if !ok {
+		t.Fatal("expected outgoing metadata ctx key")
+	}
+	if ss := metadataGet(md, rpctypes.MetadataRequireLeaderKey); !reflect.DeepEqual(ss, []string{rpctypes.MetadataHasLeader}) {
+		t.Fatalf("unexpected metadata for %q %v", rpctypes.MetadataRequireLeaderKey, ss)
+	}
+	if ss := metadataGet(md, rpctypes.MetadataClientAPIVersionKey); !reflect.DeepEqual(ss, []string{version.APIVersion}) {
+		t.Fatalf("unexpected metadata for %q %v", rpctypes.MetadataClientAPIVersionKey, ss)
+	}
+}