io.grpc

Class LoadBalancer<T>

java.lang.Object

io.grpc.LoadBalancer<T>

Type Parameters:

T - the transport type to balance

@ExperimentalApi(value="https://github.com/grpc/grpc-java/issues/1771")
 @ThreadSafe
public abstract class LoadBalancer<T>
extends Object

A pluggable component that receives resolved addresses from NameResolver and provides the channel a usable transport when asked.

Note to implementations: all methods are expected to return quickly. Any work that may block should be done asynchronously.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LoadBalancer.Factory

Constructor Summary

Constructors

Constructor and Description
LoadBalancer()

Method Summary

Modifier and Type	Method and Description
void	handleNameResolutionError(Status error) Handles an error from the name resolution system.
void	handleResolvedAddresses(List<ResolvedServerInfoGroup> servers, Attributes attributes) Handles newly resolved server groups and metadata attributes from name resolution system.
void	handleTransportReady(EquivalentAddressGroup addressGroup) Called when a transport is fully connected and ready to accept traffic.
void	handleTransportShutdown(EquivalentAddressGroup addressGroup, Status s) Called when a transport is shutting down.
abstract T	pickTransport(Attributes affinity) Pick a transport that Channel will use for next RPC.
void	shutdown() Shuts down this LoadBalancer.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LoadBalancer

public LoadBalancer()

Method Detail

pickTransport

@ExperimentalApi(value="https://github.com/grpc/grpc-java/issues/1766")
public abstract T pickTransport(Attributes affinity)

Pick a transport that Channel will use for next RPC.

If called after shutdown() has been called, this method will return a transport that would fail all requests.

Parameters:

affinity - for affinity-based routing

shutdown

public void shutdown()

Shuts down this LoadBalancer.

handleResolvedAddresses

public void handleResolvedAddresses(List<ResolvedServerInfoGroup> servers,
                                    Attributes attributes)

Handles newly resolved server groups and metadata attributes from name resolution system. servers contained in ResolvedServerInfoGroup should be considered equivalent but may be flattened into a single list if needed.

Implementations should not modify the given servers.

Parameters:

servers - the resolved server addresses, never empty.

attributes - extra metadata from naming system.

handleNameResolutionError

public void handleNameResolutionError(Status error)

Handles an error from the name resolution system.

Parameters:

error - a non-OK status

handleTransportReady

public void handleTransportReady(EquivalentAddressGroup addressGroup)

Called when a transport is fully connected and ready to accept traffic.

handleTransportShutdown

public void handleTransportShutdown(EquivalentAddressGroup addressGroup,
                                    Status s)

Called when a transport is shutting down.