net.kuujo.catalog.server

Class StateMachine

java.lang.Object

net.kuujo.catalog.server.StateMachine

All Implemented Interfaces:

AutoCloseable

public abstract class StateMachine
extends Object
implements AutoCloseable

Base class for user-provided Raft state machines.

Users should extend this class to create a state machine for use within a RaftServer.

State machines are responsible for handling operations submitted to the Raft cluster and filtering committed operations out of the Raft log. The most important rule of state machines is that state machines must be deterministic in order to maintain Catalog's consistency guarantees. That is, state machines must not change their behavior based on external influences and have no side effects. Users should never use System time to control behavior within a state machine.

When commands and queries are submitted to the Raft cluster, the RaftServer will log and replicate them as necessary and, once complete, apply them to the configured state machine.

Author:

Jordan Halterman

See Also:

Commit

Method Summary

Modifier and Type	Method and Description
void	close() Closes the state machine.
void	close(Session session) Called when a session is closed.
abstract void	configure(StateMachineExecutor executor) Configures the state machine.
void	expire(Session session) Called when a session is expired.
void	init(StateMachineContext context) Initializes the state machine.
void	register(Session session) Called when a new session is registered.

Methods inherited from class java.lang.Object

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

Method Detail

init

public void init(StateMachineContext context)

Initializes the state machine.

Parameters:

context - The state machine context.

Throws:

NullPointerException - if context is null

configure

public abstract void configure(StateMachineExecutor executor)

Configures the state machine.

Parameters:

executor - The state machine executor.

register

public void register(Session session)

Called when a new session is registered.

Parameters:

session - The session that was registered.

expire

public void expire(Session session)

Called when a session is expired.

Parameters:

session - The expired session.

close

public void close(Session session)

Called when a session is closed.

Parameters:

session - The session that was closed.

close

public void close()

Closes the state machine.

Specified by:

close in interface AutoCloseable