Package io.grpc.util

Class OutlierDetectionLoadBalancer

java.lang.Object

io.grpc.LoadBalancer

io.grpc.util.OutlierDetectionLoadBalancer

@Internal
public final class OutlierDetectionLoadBalancer
extends LoadBalancer

Wraps a child LoadBalancer while monitoring for outlier backends and removing them from the use of the child LB.

This implements the outlier detection gRFC: https://github.com/grpc/proposal/blob/master/A50-xds-outlier-detection.md

The implementation maintains two maps. Each endpoint status is tracked using an EndpointTracker. E.g. for two endpoints with these address list and their tracker: Endpoint e1 : [a1, a2] is tracked with EndpointTracker t1 Endpoint e2 : [a3] is tracked with EndpointTracker t2 The two maps are: First, addressMap maps from socket address -> endpoint tracker : [a1 -> t1, a2 -> t1, a3 -> t2] EndpointTracker has reference to all the subchannels of the corresponding endpoint. Second, trackerMap maps from unordered address set -> endpoint tracker. Updated upon address updates.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) class	OutlierDetectionLoadBalancer.ChildHelper	This child helper wraps the provided helper so that it can hand out wrapped OutlierDetectionLoadBalancer.OutlierDetectionSubchannels and manage the address info map.
(package private) class	OutlierDetectionLoadBalancer.DetectionTimer	This timer will be invoked periodically, according to configuration, and it will look for any outlier subchannels.
(package private) static class	OutlierDetectionLoadBalancer.EndpointTracker	Tracks additional information about the endpoint needed for outlier detection.
(package private) static class	OutlierDetectionLoadBalancer.EndpointTrackerMap	Maintains a mapping from endpoint (a set of addresses) to their trackers.
(package private) static class	OutlierDetectionLoadBalancer.FailurePercentageOutlierEjectionAlgorithm
static final class	OutlierDetectionLoadBalancer.OutlierDetectionLoadBalancerConfig	The configuration for OutlierDetectionLoadBalancer.
(package private) class	OutlierDetectionLoadBalancer.OutlierDetectionPicker	This picker delegates the actual picking logic to a wrapped delegate, but associates a ClientStreamTracer with each pick to track the results of each subchannel stream.
(package private) class	OutlierDetectionLoadBalancer.OutlierDetectionSubchannel
(package private) static interface	OutlierDetectionLoadBalancer.OutlierEjectionAlgorithm	Implementations provide different ways of ejecting outlier addresses..
(package private) static class	OutlierDetectionLoadBalancer.SuccessRateOutlierEjectionAlgorithm	This algorithm ejects addresses that don't maintain a required rate of successful calls.

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
(package private) final Map<SocketAddress,OutlierDetectionLoadBalancer.EndpointTracker>	addressMap
private final LoadBalancer.Helper	childHelper
private SynchronizationContext.ScheduledHandle	detectionTimerHandle
private Long	detectionTimerStartNanos
private static final Attributes.Key<OutlierDetectionLoadBalancer.EndpointTracker>	ENDPOINT_TRACKER_KEY
(package private) final OutlierDetectionLoadBalancer.EndpointTrackerMap	endpointTrackerMap
private final ChannelLogger	logger
private final GracefulSwitchLoadBalancer	switchLb
private final SynchronizationContext	syncContext
private TimeProvider	timeProvider
private final ScheduledExecutorService	timeService

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
OutlierDetectionLoadBalancer(LoadBalancer.Helper helper, TimeProvider timeProvider)	Creates a new instance of OutlierDetectionLoadBalancer.

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 static boolean	hasSingleAddress(List<EquivalentAddressGroup> addressGroups)	Counts how many addresses are in a given address group.
void	shutdown()	The channel asks the load-balancer to shutdown.
private static List<OutlierDetectionLoadBalancer.EndpointTracker>	trackersWithVolume(OutlierDetectionLoadBalancer.EndpointTrackerMap trackerMap, int volume)	Returns only the trackers that have the minimum configured volume to be considered.

Methods inherited from class io.grpc.LoadBalancer

canHandleEmptyAddressListFromNameResolution, handleResolvedAddresses, handleSubchannelState, requestConnection

Methods inherited from class java.lang.Object

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

Field Details

endpointTrackerMap

final OutlierDetectionLoadBalancer.EndpointTrackerMap endpointTrackerMap

addressMap

final Map<SocketAddress,OutlierDetectionLoadBalancer.EndpointTracker> addressMap

syncContext

private final SynchronizationContext syncContext

childHelper

private final LoadBalancer.Helper childHelper

switchLb

private final GracefulSwitchLoadBalancer switchLb

timeProvider

private TimeProvider timeProvider

timeService

private final ScheduledExecutorService timeService

detectionTimerHandle

private SynchronizationContext.ScheduledHandle detectionTimerHandle

detectionTimerStartNanos

private Long detectionTimerStartNanos

logger

private final ChannelLogger logger

ENDPOINT_TRACKER_KEY

private static final Attributes.Key<OutlierDetectionLoadBalancer.EndpointTracker> ENDPOINT_TRACKER_KEY

Constructor Details

OutlierDetectionLoadBalancer

public OutlierDetectionLoadBalancer(LoadBalancer.Helper helper,
 TimeProvider timeProvider)

Creates a new instance of OutlierDetectionLoadBalancer.

Method Details

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

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

trackersWithVolume

private static List<OutlierDetectionLoadBalancer.EndpointTracker> trackersWithVolume(OutlierDetectionLoadBalancer.EndpointTrackerMap trackerMap,
 int volume)

Returns only the trackers that have the minimum configured volume to be considered.

hasSingleAddress

private static boolean hasSingleAddress(List<EquivalentAddressGroup> addressGroups)

Counts how many addresses are in a given address group.