import { SubchannelRef } from "./channelz";
import { ConnectivityState } from "./connectivity-state";
import { Subchannel } from "./subchannel";
export declare type ConnectivityStateListener = (subchannel: SubchannelInterface, previousState: ConnectivityState, newState: ConnectivityState) => void;
/**
* This is an interface for load balancing policies to use to interact with
* subchannels. This allows load balancing policies to wrap and unwrap
* subchannels.
*
* Any load balancing policy that wraps subchannels must unwrap the subchannel
* in the picker, so that other load balancing policies consistently have
* access to their own wrapper objects.
*/
export interface SubchannelInterface {
getConnectivityState(): ConnectivityState;
addConnectivityStateListener(listener: ConnectivityStateListener): void;
removeConnectivityStateListener(listener: ConnectivityStateListener): void;
startConnecting(): void;
getAddress(): string;
ref(): void;
unref(): void;
getChannelzRef(): SubchannelRef;
/**
* If this is a wrapper, return the wrapped subchannel, otherwise return this
*/
getRealSubchannel(): Subchannel;
}
export declare abstract class BaseSubchannelWrapper implements SubchannelInterface {
protected child: SubchannelInterface;
constructor(child: SubchannelInterface);
getConnectivityState(): ConnectivityState;
addConnectivityStateListener(listener: ConnectivityStateListener): void;
removeConnectivityStateListener(listener: ConnectivityStateListener): void;
startConnecting(): void;
getAddress(): string;
ref(): void;
unref(): void;
getChannelzRef(): SubchannelRef;
getRealSubchannel(): Subchannel;
}