You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: cluster_proxy.go
    path of file: ./repos/etcd/tests/framework/integration
    
    the code of the file until where you have to start completion: // Copyright 2016 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.

//go:build cluster_proxy

package integration

import (
	"context"
	"sync"

	clientv3 "go.etcd.io/etcd/client/v3"
	"go.etcd.io/etcd/client/v3/namespace"
	"go.etcd.io/etcd/server
    
func ToGRPC(c *clientv3.Client) GrpcAPI {
	pmu.Lock()
	defer pmu.Unlock()

	// dedicated context bound to 'grpc-proxy' lifetype
	// (so in practice lifetime of the client connection to the proxy).
	// TODO: Refactor to a separate clientv3.Client instance instead of the context alone.
	ctx, ctxCancel := context.WithCancel(context.WithValue(context.TODO(), "_name", "grpcProxyContext"))

	lg := c.GetLogger()

	if v, ok := proxies[c]; ok {
		return v.grpc
	}

	// test namespacing proxy
	c.KV = namespace.NewKV(c.KV, proxyNamespace)
	c.Watcher = namespace.NewWatcher(c.Watcher, proxyNamespace)
	c.Lease = namespace.NewLease(c.Lease, proxyNamespace)
	// test coalescing/caching proxy
	kvp, kvpch := grpcproxy.NewKvProxy(c)
	wp, wpch := grpcproxy.NewWatchProxy(ctx, lg, c)
	lp, lpch := grpcproxy.NewLeaseProxy(ctx, c)
	mp := grpcproxy.NewMaintenanceProxy(c)
	clp, _ := grpcproxy.NewClusterProxy(lg, c, "", "") // without registering proxy URLs
	authp := grpcproxy.NewAuthProxy(c)
	lockp := grpcproxy.NewLockProxy(c)
	electp := grpcproxy.NewElectionProxy(c)

	grpc := GrpcAPI{
		adapter.ClusterServerToClusterClient(clp),
		adapter.KvServerToKvClient(kvp),
		adapter.LeaseServerToLeaseClient(lp),
		adapter.WatchServerToWatchClient(wp),
		adapter.MaintenanceServerToMaintenanceClient(mp),
		adapter.AuthServerToAuthClient(authp),
		adapter.LockServerToLockClient(lockp),
		adapter.ElectionServerToElectionClient(electp),
	}
	proxies[c] = grpcClientProxy{ctx: ctx, ctxCancel: ctxCancel, grpc: grpc, wdonec: wpch, kvdonec: kvpch, lpdonec: lpch}
	return grpc
}