Repository: grpc/grpc-go
File: internal/xds/xds.go (Go)

Code before:
// handshakeClusterNameKey is the type used as the key to store cluster name in
// the Attributes field of resolver.Address.
type handshakeClusterNameKey struct{}

// SetXDSHandshakeClusterName returns a copy of addr in which the Attributes field
// is updated with the cluster name.
func SetXDSHandshakeClusterName(addr resolver.Address, clusterName string) resolver.Address {
	addr.Attributes = addr.Attributes.WithValue(handshakeClusterNameKey{}, clusterName)
	return addr
}

// GetXDSHandshakeClusterName returns cluster name stored in attr.
func GetXDSHandshakeClusterName(attr *attributes.Attributes) (string, bool) {
	v := attr.Value(handshakeClusterNameKey{})
	name, ok := v.(string)
	return name, ok
}

// xdsHashKey is the type used as the key to store request hash in the context
// used when combining the Ring Hash load balancing policy with xDS.
type xdsHashKey struct{}

// GetXDSRequestHash returns the request hash in the context and true if it was set
// from the xDS config selector. If the xDS config selector has not set the hash,
// it returns 0 and false.
func GetXDSRequestHash(ctx context.Context) (uint64, bool) {
	requestHash := ctx.Value(xdsHashKey{})
	if requestHash == nil {
		return 0, false
	}
	return requestHash.(uint64), true
}

// SetXDSRequestHash adds the request hash to the context for use in Ring Hash
// Load Balancing using xDS route hash_policy.
func SetXDSRequestHash(ctx context.Context, requestHash uint64) context.Context {
	return context.WithValue(ctx, xdsHashKey{}, requestHash)
}


Review comment (suggestion):
For those two functions I decided to follow the convention established above with Get/SetXDSHandshakeClusterName despite the redundancy with the xds package name.

XDSHeaderName violates the rule that says that function names should not start with the package name, so I added the Get prefix, but I could also go with `xds.SetRequestHash` and `xds.RequestHash`. Let me know if you have a preference.

Code after:
/*
 * Copyright 2021 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 xds contains methods to Get/Set handshake cluster names. It is separated
// out from the top level /internal package to avoid circular dependencies.
package xds

import (
	"google.golang.org/grpc/attributes"
	"google.golang.org/grpc/resolver"
)

// handshakeClusterNameKey is the type used as the key to store cluster name in
// the Attributes field of resolver.Address.
type handshakeClusterNameKey struct{}

// SetXDSHandshakeClusterName returns a copy of addr in which the Attributes field
// is updated with the cluster name.
func SetXDSHandshakeClusterName(addr resolver.Address, clusterName string) resolver.Address {
	addr.Attributes = addr.Attributes.WithValue(handshakeClusterNameKey{}, clusterName)
	return addr
}

// GetXDSHandshakeClusterName returns cluster name stored in attr.
func GetXDSHandshakeClusterName(attr *attributes.Attributes) (string, bool) {
	v := attr.Value(handshakeClusterNameKey{})
	name, ok := v.(string)
	return name, ok
}