/*
 *
 * Copyright 2020 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 client

import (
	"time"
)

type ldsUpdate struct {
	routeName string
}
type ldsCallbackFunc func(ldsUpdate, error)

// watchLDS starts a listener watcher for the service..
//
// Note that during race (e.g. an xDS response is received while the user is
// calling cancel()), there's a small window where the callback can be called
// after the watcher is canceled. The caller needs to handle this case.
func (c *Client) watchLDS(serviceName string, cb ldsCallbackFunc) (cancel func()) {
	wi := &watchInfo{
		c:           c,
		typeURL:     ldsURL,
		target:      serviceName,
		ldsCallback: cb,
	}

	wi.expiryTimer = time.AfterFunc(defaultWatchExpiryTimeout, func() {
		wi.timeout()
	})
	return c.watch(wi)
}