edu.snu.coral.common

Class StateMachine

java.lang.Object

edu.snu.coral.common.StateMachine

public final class StateMachine
extends Object

A finite state machine that can be created with user defined states and transitions.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	StateMachine.Builder Builder that builds a StateMachine.

Method Summary

Modifier and Type	Method and Description
void	checkState(Enum expectedCurrentState) Checks whether the current state is same as the expectedCurrentState.
boolean	compareAndSetState(Enum expectedCurrentState, Enum state) Atomically sets the state to the given updated state if the current state equals to the expected state.
Enum	getCurrentState()
static StateMachine.Builder	newBuilder()
void	setState(Enum state) Sets the current state as a certain state.
String	toString()

Methods inherited from class java.lang.Object

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

Method Detail

checkState

public void checkState(Enum expectedCurrentState)

Checks whether the current state is same as the expectedCurrentState.

Parameters:

expectedCurrentState - the expected current state

Throws:

RuntimeException - if the expectedCurrentState is not same as the actual current state

setState

public void setState(Enum state)

Sets the current state as a certain state.

Parameters:

state - a state

Throws:

RuntimeException - if the state is unknown state, or the transition from the current state to the specified state is illegal

compareAndSetState

public boolean compareAndSetState(Enum expectedCurrentState,
                                  Enum state)

Atomically sets the state to the given updated state if the current state equals to the expected state.

Parameters:

expectedCurrentState - an expected state

state - a state

Returns:

true if successful. false indicates that the actual value was not equal to the expected value.

Throws:

RuntimeException - if the state is unknown state, or the transition from the current state to the specified state is illegal

getCurrentState

public Enum getCurrentState()

Returns:

the name of the current state.

toString

public String toString()

Overrides:

toString in class Object

newBuilder

public static StateMachine.Builder newBuilder()

Returns:

a builder of StateMachine