forked from apache/beam
/
metadata.go
54 lines (48 loc) · 1.86 KB
/
metadata.go
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// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to You 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 grpcx contains utilities for working with gRPC.
package grpcx
import (
"context"
"github.com/apache/beam/sdks/go/pkg/beam/internal/errors"
"google.golang.org/grpc/metadata"
)
const idKey = "worker_id"
// ReadWorkerID reads the worker ID from an incoming gRPC request context.
func ReadWorkerID(ctx context.Context) (string, error) {
md, ok := metadata.FromIncomingContext(ctx)
if !ok {
return "", errors.New("failed to read metadata from context")
}
id, ok := md[idKey]
if !ok || len(id) < 1 {
return "", errors.Errorf("failed to find worker id in metadata %v", md)
}
if len(id) > 1 {
return "", errors.Errorf("multiple worker ids in metadata: %v", id)
}
return id[0], nil
}
// WriteWorkerID write the worker ID to an outgoing gRPC request context. It
// merges the information with any existing gRPC metadata.
func WriteWorkerID(ctx context.Context, id string) context.Context {
md := metadata.New(map[string]string{
idKey: id,
})
if old, ok := metadata.FromOutgoingContext(ctx); ok {
md = metadata.Join(md, old)
}
return metadata.NewOutgoingContext(ctx, md)
}