Package com.linkedin.davinci.helix

Class LeaderFollowerPartitionStateModel

java.lang.Object

org.apache.helix.participant.statemachine.StateModel

com.linkedin.davinci.helix.AbstractPartitionStateModel

com.linkedin.davinci.helix.LeaderFollowerPartitionStateModel

public class LeaderFollowerPartitionStateModel
extends AbstractPartitionStateModel

Venice partition's state model to manage Leader/Follower(Standby) state transitions. Offline (Initial State) -> Follower (ideal state) -> Leader (ideal state) There is only at most one leader at a time and it is elected from the follower. At present, Followers and Leader behave the same in the read path. However, in the write path, leader will take extra work. See LeaderFollowerStoreIngestionTask for more details. There is an optional latch between Offline to Follower transition. The latch is only placed if the version state model served is the current version. (During cluster rebalancing or SN rebouncing) Since Helix rebalancer only refers to state model to determine the rebalancing time. The latch is a safe guard to prevent Helix "over-rebalancing" the cluster and failing the read traffic. The latch is released when ingestion has caught up the lag or the ingestion has reached the last known offset of VT.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	LeaderFollowerPartitionStateModel.LeaderSessionIdChecker	A leader session id checker will be created for each consumer action; server checks whether the session id is still valid before processing the consumer action.

Field Summary

Fields inherited from class com.linkedin.davinci.helix.AbstractPartitionStateModel

logger, WAIT_DROP_PARTITION_TIME_OUT_MS

Fields inherited from class org.apache.helix.participant.statemachine.StateModel

_cancelled, _currentState

Constructor Summary

Constructors

Constructor

Description

LeaderFollowerPartitionStateModel(IngestionBackend ingestionBackend, VeniceStoreVersionConfig storeAndServerConfigs, int partition, LeaderFollowerIngestionProgressNotifier notifier, ReadOnlyStoreRepository metadataRepo, CompletableFuture<HelixPartitionStatusAccessor> partitionPushStatusAccessorFuture, String instanceName, ParticipantStateTransitionStats threadPoolStats, HeartbeatMonitoringService heartbeatMonitoringService)

Method Summary

Modifier and Type	Method	Description
void	onBecomeDroppedFromOffline(org.apache.helix.model.Message message, org.apache.helix.NotificationContext context)
void	onBecomeLeaderFromStandby(org.apache.helix.model.Message message, org.apache.helix.NotificationContext context)
void	onBecomeOfflineFromDropped(org.apache.helix.model.Message message, org.apache.helix.NotificationContext context)
void	onBecomeOfflineFromError(org.apache.helix.model.Message message, org.apache.helix.NotificationContext context)
void	onBecomeOfflineFromStandby(org.apache.helix.model.Message message, org.apache.helix.NotificationContext context)
void	onBecomeStandbyFromLeader(org.apache.helix.model.Message message, org.apache.helix.NotificationContext context)
void	onBecomeStandbyFromOffline(org.apache.helix.model.Message message, org.apache.helix.NotificationContext context)

Methods inherited from class com.linkedin.davinci.helix.AbstractPartitionStateModel

executeStateTransition, executeStateTransition, getIngestionBackend, getPartition, getStoreAndServerConfigs, getStoreIngestionService, getStorePartitionDescription, getStoreRepo, onBecomeDroppedFromError, removeCustomizedState, removePartitionFromStoreGracefully, reset, rollbackOnError, setupNewStorePartition, stopConsumption, waitConsumptionCompleted

Methods inherited from class org.apache.helix.participant.statemachine.StateModel

cancel, defaultTransitionHandler, getCurrentState, isCancelled, onBecomeErrorFromAny, syncState, updateState

Methods inherited from class java.lang.Object

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

Constructor Details

LeaderFollowerPartitionStateModel

public LeaderFollowerPartitionStateModel(IngestionBackend ingestionBackend,
 VeniceStoreVersionConfig storeAndServerConfigs,
 int partition,
 LeaderFollowerIngestionProgressNotifier notifier,
 ReadOnlyStoreRepository metadataRepo,
 CompletableFuture<HelixPartitionStatusAccessor> partitionPushStatusAccessorFuture,
 String instanceName,
 ParticipantStateTransitionStats threadPoolStats,
 HeartbeatMonitoringService heartbeatMonitoringService)

Method Details

onBecomeStandbyFromOffline

public void onBecomeStandbyFromOffline(org.apache.helix.model.Message message,
 org.apache.helix.NotificationContext context)

onBecomeLeaderFromStandby

public void onBecomeLeaderFromStandby(org.apache.helix.model.Message message,
 org.apache.helix.NotificationContext context)

onBecomeStandbyFromLeader

public void onBecomeStandbyFromLeader(org.apache.helix.model.Message message,
 org.apache.helix.NotificationContext context)

onBecomeOfflineFromStandby

public void onBecomeOfflineFromStandby(org.apache.helix.model.Message message,
 org.apache.helix.NotificationContext context)

onBecomeDroppedFromOffline

public void onBecomeDroppedFromOffline(org.apache.helix.model.Message message,
 org.apache.helix.NotificationContext context)

onBecomeOfflineFromDropped

public void onBecomeOfflineFromDropped(org.apache.helix.model.Message message,
 org.apache.helix.NotificationContext context)

onBecomeOfflineFromError

public void onBecomeOfflineFromError(org.apache.helix.model.Message message,
 org.apache.helix.NotificationContext context)