Package com.tangosol.util.fsm

Class NonBlockingFiniteStateMachine<S extends Enum<S>>

java.lang.Object

com.tangosol.util.fsm.NonBlockingFiniteStateMachine<S>

All Implemented Interfaces:

ExecutionContext, FiniteStateMachine<S>

public class NonBlockingFiniteStateMachine<S extends Enum<S>>
extends Object
implements FiniteStateMachine<S>, ExecutionContext

An NonBlockingFiniteStateMachine is a specialized FiniteStateMachine implementation that performs transitions asynchronously to the threads that request state changes. That is, threads that request state transitions are never blocked. Instead their requests are queued for a single thread to later perform the appropriate transition to the requested state.

Since:

Coherence 12.2.1

Author:

Brian Oliver

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	NonBlockingFiniteStateMachine.CoalescedEvent<S extends Enum<S>>	A NonBlockingFiniteStateMachine.CoalescedEvent is a LifecycleAwareEvent that coalesces other (wrapped) Events with the same discriminator so that only one Event actually executes.
static class	NonBlockingFiniteStateMachine.DefaultTaskDependencies	Implementation of Dependencies for Task
static class	NonBlockingFiniteStateMachine.DelayedTransitionTo<S extends Enum<S>>	A NonBlockingFiniteStateMachine.DelayedTransitionTo is a specialized Instruction for NonBlockingFiniteStateMachines that enables a StateEntryAction to request a delayed transition to another state, unlike a Instruction.TransitionTo Instruction which occurs immediately.
static class	NonBlockingFiniteStateMachine.ProcessEventLater<S extends Enum<S>>	A specialized Instruction for NonBlockingFiniteStateMachines that enables a StateEntryAction to request an Event to be processed at some point in the future.
static class	NonBlockingFiniteStateMachine.SubsequentEvent<S extends Enum<S>>	A NonBlockingFiniteStateMachine.SubsequentEvent is an Event that ensures that another (wrapped) Event to occur if an only if the FiniteStateMachine is at a certain transition count.
protected class	NonBlockingFiniteStateMachine.Task	A PriorityTask implementation to process a requested event.
static interface	NonBlockingFiniteStateMachine.TaskDependencies	Dependencies for Task.

Constructor Summary

Constructors

Constructor	Description
NonBlockingFiniteStateMachine(String sName, Model<S> model, S stateInitial, com.tangosol.internal.util.DaemonPoolDependencies daemonPoolDeps, boolean fIgnoreExceptions, NonBlockingFiniteStateMachine.TaskDependencies deps)	Construct an NonBlockingFiniteStateMachine given a Model.

Method Summary

Modifier and Type	Method	Description
void	addListener(FiniteStateMachineListener<S> listener)	Add a FiniteStateMachineListener to the FiniteStateMachine.
String	getName()	Obtains the name of the FiniteStateMachine.
S	getState()	Obtains the current state of the FiniteStateMachine.
long	getTransitionCount()	Obtains the number of transitions that have occurred in the FiniteStateMachine.
boolean	hasPendingEvents()	Determines if there are any pending Events for the FiniteStateMachine to process.
void	process(Event<S> event)	Request the FiniteStateMachine to process the specified Event.
void	processLater(Event<S> event)	Request the FiniteStateMachine to process the specified Event as soon as possible.
void	processLater(Event<S> event, long duration, TimeUnit timeUnit)	Request the FiniteStateMachine to process the specified Event at some point in the future (represented as a duration to wait from the moment the method is called).
boolean	quiesceThenStop()	Requests the FiniteStateMachine to stop accepting new Events to process, wait for any existing queued Events to be processed and then stop.
void	removeListener(FiniteStateMachineListener<S> listener)	Remove a FiniteStateMachineListener from the FiniteStateMachine.
boolean	start()	Start the FiniteStateMachine and enter the initial state.
boolean	stop()	Stops the FiniteStateMachine as soon as possible.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Details

NonBlockingFiniteStateMachine

public NonBlockingFiniteStateMachine(String sName,
 Model<S> model,
 S stateInitial,
 com.tangosol.internal.util.DaemonPoolDependencies daemonPoolDeps,
 boolean fIgnoreExceptions,
 NonBlockingFiniteStateMachine.TaskDependencies deps)

Construct an NonBlockingFiniteStateMachine given a Model.

Parameters:

sName - the name of the NonBlockingFiniteStateMachine

model - the Model of the NonBlockingFiniteStateMachine

stateInitial - the initial state

daemonPoolDeps - Optional DaemonPoolDependencies for Daemon Pool that will be used for scheduling Transitions

fIgnoreExceptions - when true RuntimeExceptions will be ignored, when false RuntimeExceptions will immediately stop the NonBlockingFiniteStateMachine

deps - the NonBlockingFiniteStateMachine.TaskDependencies specifies the event processing configs.

Method Details

addListener

public void addListener(FiniteStateMachineListener<S> listener)

Add a FiniteStateMachineListener to the FiniteStateMachine.

Note that unique instances of FiniteStateMachineListener are identified via their equals and hashCode implementations.

Specified by:

addListener in interface FiniteStateMachine<S extends Enum<S>>

Parameters:

listener - the listener to be added

removeListener

public void removeListener(FiniteStateMachineListener<S> listener)

Remove a FiniteStateMachineListener from the FiniteStateMachine.

Note that unique instances of FiniteStateMachineListener are identified via their equals and hashCode implementations.

Specified by:

removeListener in interface FiniteStateMachine<S extends Enum<S>>

Parameters:

listener - the listener to be removed

getName

public String getName()

Obtains the name of the FiniteStateMachine. This is primarily used for display/logging/monitoring purposes.

Specified by:

getName in interface ExecutionContext

Specified by:

getName in interface FiniteStateMachine<S extends Enum<S>>

Returns:

the name of the FiniteStateMachine

getState

public S getState()

Obtains the current state of the FiniteStateMachine.

Note: After returning the current state there's no guarantee that the state will be the same because a Transition may be executing asynchronously in the background on another thread.

Specified by:

getState in interface FiniteStateMachine<S extends Enum<S>>

Returns:

the current state of the FiniteStateMachine

getTransitionCount

public long getTransitionCount()

Obtains the number of transitions that have occurred in the FiniteStateMachine.

Note: After returning the count there's no guarantee that the count will be the same on the next request because a Transition may be executing asynchronously in the background on another thread.

Specified by:

getTransitionCount in interface ExecutionContext

Specified by:

getTransitionCount in interface FiniteStateMachine<S extends Enum<S>>

Returns:

the number of transitions that have occurred in the FiniteStateMachine

start

public boolean start()

Start the FiniteStateMachine and enter the initial state.

Note: Once stopped a FiniteStateMachine can't be restarted; instead a new FiniteStateMachine should be created.

Specified by:

start in interface FiniteStateMachine<S extends Enum<S>>

Returns:

true if the start was successful or the FiniteStateMachine is already stated, false if it has been stopped

stop

public boolean stop()

Stops the FiniteStateMachine as soon as possible.

Note: Once stopped a FiniteStateMachine can't be restarted; instead a new FiniteStateMachine should be created.

Specified by:

stop in interface FiniteStateMachine<S extends Enum<S>>

Returns:

true if the stop was successful, false if it's already stopped

quiesceThenStop

public boolean quiesceThenStop()

Requests the FiniteStateMachine to stop accepting new Events to process, wait for any existing queued Events to be processed and then stop.

Note: Once stopped a FiniteStateMachine can't be restarted. Instead a new FiniteStateMachine should be created.

Returns:

true if the FiniteStateMachine was stopped or false if it was already stopped

Throws:

IllegalStateException - if the FiniteStateMachine was never started

toString

public String toString()

Overrides:

toString in class Object

process

public void process(Event<S> event)

Request the FiniteStateMachine to process the specified Event.

Note: There's no guarantee that the Event will be processed because:

1. the Transition to be performed for the Event is invalid as the FiniteStateMachine is not in the required starting state.
2. the FiniteStateMachine may have been stopped.

Specified by:

process in interface FiniteStateMachine<S extends Enum<S>>

Parameters:

event - the Event for the FiniteStateMachine to process

processLater

public void processLater(Event<S> event)

Request the FiniteStateMachine to process the specified Event as soon as possible.

Note: This method is semantically equivalent to process(Event).

Parameters:

event - the Event for the FiniteStateMachine to process

processLater

public void processLater(Event<S> event,
 long duration,
 TimeUnit timeUnit)

Request the FiniteStateMachine to process the specified Event at some point in the future (represented as a duration to wait from the moment the method is called).

Note: There's no guarantee that the Event will processed because:

1. the Transition to be performed for the Event is invalid as the FiniteStateMachine is not in the required starting state.
2. the FiniteStateMachine may have been stopped.

Parameters:

event - the Event for the FiniteStateMachine to process

duration - the amount of the TimeUnit to wait before the Event is processed

timeUnit - the TimeUnit

hasPendingEvents

public boolean hasPendingEvents()

Determines if there are any pending Events for the FiniteStateMachine to process.

Note: If the FiniteStateMachine can no longer process Events false will be returned.

Returns:

true if there are pending Events and Events can be processed, false otherwise