io.grpc.util

Class ForwardingLoadBalancerHelper

java.lang.Object

io.grpc.LoadBalancer.Helper

io.grpc.util.ForwardingLoadBalancerHelper

@ExperimentalApi(value="https://github.com/grpc/grpc-java/issues/1771")
public abstract class ForwardingLoadBalancerHelper
extends LoadBalancer.Helper

Constructor Summary

Constructors

Constructor and Description
ForwardingLoadBalancerHelper()

Method Summary

Modifier and Type	Method and Description
ManagedChannel	createOobChannel(EquivalentAddressGroup eag, String authority) Out-of-band channel for LoadBalancer’s own RPC needs, e.g., talking to an external load-balancer service.
LoadBalancer.Subchannel	createSubchannel(List<EquivalentAddressGroup> addrs, Attributes attrs) Creates a Subchannel, which is a logical connection to the given group of addresses which are considered equivalent.
protected abstract LoadBalancer.Helper	delegate() Returns the underlying helper.
String	getAuthority() Returns the authority string of the channel, which is derived from the DNS-style target name.
ChannelLogger	getChannelLogger() Returns the ChannelLogger for the Channel served by this LoadBalancer.
NameResolver.Factory	getNameResolverFactory() Returns the NameResolver of the channel.
ScheduledExecutorService	getScheduledExecutorService() Returns a ScheduledExecutorService for scheduling delayed tasks.
SynchronizationContext	getSynchronizationContext() Returns a SynchronizationContext that runs tasks in the same Synchronization Context as that the callback methods on the LoadBalancer interface are run in.
void	refreshNameResolution() Call NameResolver.refresh() on the channel's resolver.
void	runSerialized(Runnable task) Deprecated.
String	toString()
void	updateBalancingState(ConnectivityState newState, LoadBalancer.SubchannelPicker newPicker) Set a new state with a new picker to the channel.
void	updateOobChannelAddresses(ManagedChannel channel, EquivalentAddressGroup eag) Updates the addresses used for connections in the Channel.
void	updateSubchannelAddresses(LoadBalancer.Subchannel subchannel, List<EquivalentAddressGroup> addrs) Replaces the existing addresses used with subchannel.

Methods inherited from class io.grpc.LoadBalancer.Helper

createSubchannel, updateSubchannelAddresses

Methods inherited from class java.lang.Object

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

Constructor Detail

ForwardingLoadBalancerHelper

public ForwardingLoadBalancerHelper()

Method Detail

delegate

protected abstract LoadBalancer.Helper delegate()

Returns the underlying helper.

createSubchannel

public LoadBalancer.Subchannel createSubchannel(List<EquivalentAddressGroup> addrs,
                                                Attributes attrs)

Description copied from class: LoadBalancer.Helper

Creates a Subchannel, which is a logical connection to the given group of addresses which are considered equivalent. The attrs are custom attributes associated with this Subchannel, and can be accessed later through Subchannel.getAttributes().

It is recommended you call this method from the Synchronization Context, otherwise your logic around the creation may race with LoadBalancer.handleSubchannelState(io.grpc.LoadBalancer.Subchannel, io.grpc.ConnectivityStateInfo). See #5015 for more discussions.

The LoadBalancer is responsible for closing unused Subchannels, and closing all Subchannels within LoadBalancer.shutdown().

Overrides:

createSubchannel in class LoadBalancer.Helper

updateSubchannelAddresses

public void updateSubchannelAddresses(LoadBalancer.Subchannel subchannel,
                                      List<EquivalentAddressGroup> addrs)

Description copied from class: LoadBalancer.Helper

Replaces the existing addresses used with subchannel. This method is superior to LoadBalancer.Helper.createSubchannel(io.grpc.EquivalentAddressGroup, io.grpc.Attributes) when the new and old addresses overlap, since the subchannel can continue using an existing connection.

Overrides:

updateSubchannelAddresses in class LoadBalancer.Helper

createOobChannel

public ManagedChannel createOobChannel(EquivalentAddressGroup eag,
                                       String authority)

Description copied from class: LoadBalancer.Helper

Out-of-band channel for LoadBalancer’s own RPC needs, e.g., talking to an external load-balancer service.

The LoadBalancer is responsible for closing unused OOB channels, and closing all OOB channels within LoadBalancer.shutdown().

Specified by:

createOobChannel in class LoadBalancer.Helper

updateOobChannelAddresses

public void updateOobChannelAddresses(ManagedChannel channel,
                                      EquivalentAddressGroup eag)

Description copied from class: LoadBalancer.Helper

Updates the addresses used for connections in the Channel. This is supperior to LoadBalancer.Helper.createOobChannel(io.grpc.EquivalentAddressGroup, java.lang.String) when the old and new addresses overlap, since the channel can continue using an existing connection.

Overrides:

updateOobChannelAddresses in class LoadBalancer.Helper

updateBalancingState

public void updateBalancingState(ConnectivityState newState,
                                 LoadBalancer.SubchannelPicker newPicker)

Description copied from class: LoadBalancer.Helper

Set a new state with a new picker to the channel.

When a new picker is provided via updateBalancingState(), the channel will apply the picker on all buffered RPCs, by calling LoadBalancer.SubchannelPicker.pickSubchannel( LoadBalancer.PickSubchannelArgs).

The channel will hold the picker and use it for all RPCs, until updateBalancingState() is called again and a new picker replaces the old one. If updateBalancingState() has never been called, the channel will buffer all RPCs until a picker is provided.

The passed state will be the channel's new state. The SHUTDOWN state should not be passed and its behavior is undefined.

Specified by:

updateBalancingState in class LoadBalancer.Helper

refreshNameResolution

public void refreshNameResolution()

Description copied from class: LoadBalancer.Helper

Call NameResolver.refresh() on the channel's resolver.

Overrides:

refreshNameResolution in class LoadBalancer.Helper

runSerialized

@Deprecated
public void runSerialized(Runnable task)

Deprecated.

Description copied from class: LoadBalancer.Helper

Schedule a task to be run in the Synchronization Context, which serializes the task with the callback methods on the LoadBalancer interface.

Overrides:

runSerialized in class LoadBalancer.Helper

getNameResolverFactory

public NameResolver.Factory getNameResolverFactory()

Description copied from class: LoadBalancer.Helper

Returns the NameResolver of the channel.

Specified by:

getNameResolverFactory in class LoadBalancer.Helper

getAuthority

public String getAuthority()

Description copied from class: LoadBalancer.Helper

Returns the authority string of the channel, which is derived from the DNS-style target name.

Specified by:

getAuthority in class LoadBalancer.Helper

getSynchronizationContext

public SynchronizationContext getSynchronizationContext()

Description copied from class: LoadBalancer.Helper

Returns a SynchronizationContext that runs tasks in the same Synchronization Context as that the callback methods on the LoadBalancer interface are run in.

Pro-tip: in order to call SynchronizationContext.schedule(java.lang.Runnable, long, java.util.concurrent.TimeUnit, java.util.concurrent.ScheduledExecutorService), you need to provide a ScheduledExecutorService. LoadBalancer.Helper.getScheduledExecutorService() is provided for your convenience.

Overrides:

getSynchronizationContext in class LoadBalancer.Helper

getScheduledExecutorService

public ScheduledExecutorService getScheduledExecutorService()

Description copied from class: LoadBalancer.Helper

Returns a ScheduledExecutorService for scheduling delayed tasks.

This service is a shared resource and is only meant for quick tasks. DO NOT block or run time-consuming tasks.

The returned service doesn't support shutdown() and shutdownNow(). They will throw if called.

Overrides:

getScheduledExecutorService in class LoadBalancer.Helper

getChannelLogger

public ChannelLogger getChannelLogger()

Description copied from class: LoadBalancer.Helper

Returns the ChannelLogger for the Channel served by this LoadBalancer.

Overrides:

getChannelLogger in class LoadBalancer.Helper

toString

public String toString()

Overrides:

toString in class Object