software.amazon.kinesis.coordinator.migration

Class MigrationClientVersionStateInitializer

java.lang.Object

software.amazon.kinesis.coordinator.migration.MigrationClientVersionStateInitializer

@ThreadSafe
public class MigrationClientVersionStateInitializer
extends Object

Initializer to determine start state of the state machine which identifies the state to initialize KCL when it is starting up. The initial state is determined based on the customer configured CoordinatorConfig.ClientVersionConfig and the current MigrationState in DDB, as follows: ClientVersionConfig | MigrationState (DDB) | initial client version -------------------------+---------------------------------+---------------------------------------------- COMPATIBLE_WITH_2X_PHASE1| Does not exist | CLIENT_VERSION_INIT (local only, not written to DDB) COMPATIBLE_WITH_2X | Does not exist | CLIENT_VERSION_UPGRADE_FROM_2X 3X | Does not exist | CLIENT_VERSION_3X COMPATIBLE_WITH_2X_PHASE1| CLIENT_VERSION_3X_WITH_ROLLBACK | CLIENT_VERSION_3X_WITH_ROLLBACK COMPATIBLE_WITH_2X | CLIENT_VERSION_3X_WITH_ROLLBACK | CLIENT_VERSION_3X_WITH_ROLLBACK 3X | CLIENT_VERSION_3X_WITH_ROLLBACK | CLIENT_VERSION_3X any | CLIENT_VERSION_2X | CLIENT_VERSION_2X any | CLIENT_VERSION_UPGRADE_FROM_2X | CLIENT_VERSION_UPGRADE_FROM_2X any | CLIENT_VERSION_3X | CLIENT_VERSION_3X Phase 1 COMPATIBLE_WITH_2X_PHASE1 does not write any state to DDB. When CLIENT_VERSION_INIT is returned, the migration state machine remains inactive and KCL operates in pure 2.x

Constructor Summary

Constructors

Constructor and Description
MigrationClientVersionStateInitializer()

Method Summary

Modifier and Type	Method and Description
ClientVersion	getClientVersionForInitialization(MigrationState migrationState)
AbstractMap.SimpleEntry<ClientVersion,MigrationState>	getInitialState() Determine the initial client version by reading the current state from DDB and applying the configured client version policy.

Methods inherited from class java.lang.Object

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

Constructor Detail

MigrationClientVersionStateInitializer

public MigrationClientVersionStateInitializer()

Method Detail

getInitialState

public AbstractMap.SimpleEntry<ClientVersion,MigrationState> getInitialState()
                                                                      throws DependencyException

Determine the initial client version by reading the current state from DDB and applying the configured client version policy. This is a READ-ONLY operation — no state is written to DDB. The DDB write happens in the state's enter() method.

If the read fails, Scheduler's retry loop will re-invoke the entire initialization.

Returns:

the initial client version and the migration state read from DDB

Throws:

DependencyException - if reading from DDB fails

getClientVersionForInitialization

public ClientVersion getClientVersionForInitialization(MigrationState migrationState)