Package io.grpc.internal

Class PickFirstLoadBalancer

java.lang.Object

io.grpc.LoadBalancer

io.grpc.internal.PickFirstLoadBalancer

final class PickFirstLoadBalancer
extends LoadBalancer

A LoadBalancer that provides no load-balancing over the addresses from the NameResolver. The channel's default behavior is used, which is walking down the address list and sticking to the first that works.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	PickFirstLoadBalancer.Picker	No-op picker which doesn't add any custom picking logic.
static class	PickFirstLoadBalancer.PickFirstLoadBalancerConfig
private class	PickFirstLoadBalancer.RequestConnectionPicker	Picker that requests connection during the first pick, and returns noResult.

Nested classes/interfaces inherited from class io.grpc.LoadBalancer

LoadBalancer.CreateSubchannelArgs, LoadBalancer.ErrorPicker, LoadBalancer.Factory, LoadBalancer.FixedResultPicker, LoadBalancer.Helper, LoadBalancer.PickDetailsConsumer, LoadBalancer.PickResult, LoadBalancer.PickSubchannelArgs, LoadBalancer.ResolvedAddresses, LoadBalancer.Subchannel, LoadBalancer.SubchannelPicker, LoadBalancer.SubchannelStateListener

Field Summary

Fields

Modifier and Type	Field	Description
private ConnectivityState	currentState
private LoadBalancer.Helper	helper
private LoadBalancer.Subchannel	subchannel

Fields inherited from class io.grpc.LoadBalancer

ATTR_HEALTH_CHECKING_CONFIG, DISABLE_SUBCHANNEL_RECONNECT_KEY, EMPTY_PICKER, HAS_HEALTH_PRODUCER_LISTENER_KEY, HEALTH_CONSUMER_LISTENER_ARG_KEY, IS_PETIOLE_POLICY

Constructor Summary

Constructors

Constructor	Description
PickFirstLoadBalancer(LoadBalancer.Helper helper)

Method Summary

Modifier and Type	Method	Description
Status	acceptResolvedAddresses(LoadBalancer.ResolvedAddresses resolvedAddresses)	Accepts newly resolved addresses from the name resolution system.
void	handleNameResolutionError(Status error)	Handles an error from the name resolution system.
private void	processSubchannelState(LoadBalancer.Subchannel subchannel, ConnectivityStateInfo stateInfo)
void	requestConnection()	The channel asks the LoadBalancer to establish connections now (if applicable) so that the upcoming RPC may then just pick a ready connection without waiting for connections.
void	shutdown()	The channel asks the load-balancer to shutdown.
private void	updateBalancingState(ConnectivityState state, LoadBalancer.SubchannelPicker picker)

Methods inherited from class io.grpc.LoadBalancer

canHandleEmptyAddressListFromNameResolution, handleResolvedAddresses, handleSubchannelState

Methods inherited from class java.lang.Object

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

Field Detail

helper

private final LoadBalancer.Helper helper

subchannel

private LoadBalancer.Subchannel subchannel

currentState

private ConnectivityState currentState

Constructor Detail

PickFirstLoadBalancer

PickFirstLoadBalancer(LoadBalancer.Helper helper)

Method Detail

acceptResolvedAddresses

public Status acceptResolvedAddresses(LoadBalancer.ResolvedAddresses resolvedAddresses)

Description copied from class: LoadBalancer

Accepts newly resolved addresses from the name resolution system. The EquivalentAddressGroup addresses should be considered equivalent but may be flattened into a single list if needed.

Implementations can choose to reject the given addresses by returning false.

Implementations should not modify the given addresses.

Overrides:

acceptResolvedAddresses in class LoadBalancer

Parameters:

resolvedAddresses - the resolved server addresses, attributes, and config.

Returns:

true if the resolved addresses were accepted. false if rejected.

handleNameResolutionError

public void handleNameResolutionError(Status error)

Description copied from class: LoadBalancer

Handles an error from the name resolution system.

Specified by:

handleNameResolutionError in class LoadBalancer

Parameters:

error - a non-OK status

processSubchannelState

private void processSubchannelState(LoadBalancer.Subchannel subchannel,
                                    ConnectivityStateInfo stateInfo)

updateBalancingState

private void updateBalancingState(ConnectivityState state,
                                  LoadBalancer.SubchannelPicker picker)

shutdown

public void shutdown()

Description copied from class: LoadBalancer

The channel asks the load-balancer to shutdown. No more methods on this class will be called after this method. The implementation should shutdown all Subchannels and OOB channels, and do any other cleanup as necessary.

Specified by:

shutdown in class LoadBalancer

requestConnection

public void requestConnection()

Description copied from class: LoadBalancer

The channel asks the LoadBalancer to establish connections now (if applicable) so that the upcoming RPC may then just pick a ready connection without waiting for connections. This is triggered by ManagedChannel.getState(true).

If LoadBalancer doesn't override it, this is no-op. If it infeasible to create connections given the current state, e.g. no Subchannel has been created yet, LoadBalancer can ignore this request.

Overrides:

requestConnection in class LoadBalancer