software.amazon.kinesis.coordinator

Interface LeaderDecider

All Known Implementing Classes:

DynamoDBLockBasedLeaderDecider, MigrationAdaptiveLeaderDecider

public interface LeaderDecider

Used in conjunction with periodic shard sync. Implement this interface to allow KCL to decide if the current worker should execute shard sync. When periodic shard sync is enabled, PeriodicShardSyncManager periodically checks if the current worker is one of the leaders designated to execute shard-sync and then acts accordingly.

Field Summary

Fields

Modifier and Type	Field and Description
static String	METRIC_OPERATION_LEADER_DECIDER
static String	METRIC_OPERATION_LEADER_DECIDER_IS_LEADER

Method Summary

Modifier and Type	Method and Description
default void	initialize() Performs initialization tasks for decider if any.
Boolean	isLeader(String workerId) Method invoked to check the given workerId corresponds to one of the workers designated to execute shard-syncs periodically.
default void	releaseLeadershipIfHeld() If the current worker is the leader, then releases the leadership else does nothing.
void	shutdown() Can be invoked, if needed, to shutdown any clients/thread-pools being used in the LeaderDecider implementation.

Field Detail

METRIC_OPERATION_LEADER_DECIDER

static final String METRIC_OPERATION_LEADER_DECIDER

See Also:

Constant Field Values

METRIC_OPERATION_LEADER_DECIDER_IS_LEADER

static final String METRIC_OPERATION_LEADER_DECIDER_IS_LEADER

See Also:

Constant Field Values

Method Detail

isLeader

Boolean isLeader(String workerId)

Method invoked to check the given workerId corresponds to one of the workers designated to execute shard-syncs periodically.

Parameters:

workerId - ID of the worker

Returns:

True if the worker with ID workerId can execute shard-sync. False otherwise.

shutdown

void shutdown()

Can be invoked, if needed, to shutdown any clients/thread-pools being used in the LeaderDecider implementation.

initialize

default void initialize()

Performs initialization tasks for decider if any.

releaseLeadershipIfHeld

default void releaseLeadershipIfHeld()

If the current worker is the leader, then releases the leadership else does nothing. This might not be relevant for some implementations, for e.g. DeterministicShuffleShardSyncLeaderDecider does not have mechanism to release leadership. Current worker if leader releases leadership, it's possible that the current worker assume leadership sometime later again in future elections.