AbstractCircuitBreaker

public abstract class org.apache.commons.lang3.concurrent.AbstractCircuitBreaker<T> implements CircuitBreaker<T>

Base class for circuit breakers.

Parameters:

<T> – The type of the value monitored by this circuit breaker

Since:

3.5

Constructors

AbstractCircuitBreaker()

Creates an AbstractCircuitBreaker.

public AbstractCircuitBreaker()

Creates an AbstractCircuitBreaker. It also creates an internal PropertyChangeSupport.

Fields and constants

PROPERTY_NAME	The name of the open property as it is passed to registered change listeners.
state	The current state of this circuit breaker.

public static final String PROPERTY_NAME = "open"

The name of the open property as it is passed to registered change listeners.

protected final AtomicReference<AbstractCircuitBreaker.State> state

The current state of this circuit breaker.

Methods

addChangeListener(PropertyChangeListener)	Adds a change listener to this circuit breaker.
changeState(State)	Changes the internal state of this circuit breaker.
checkState()	Checks the state of this circuit breaker and changes it if necessary.
close()	Closes this circuit breaker.
incrementAndCheckState(Object)	Increments the monitored value and performs a check of the current state of this circuit breaker.
isClosed()	Tests the current closed state of this circuit breaker.
isOpen()	Tests the current open state of this circuit breaker.
isOpen(State)	Tests whether the given state represents an open circuit breaker.
open()	Opens this circuit breaker.
removeChangeListener(PropertyChangeListener)	Removes the specified change listener from this circuit breaker.

public void addChangeListener(PropertyChangeListener listener)

Adds a change listener to this circuit breaker. This listener is notified whenever the state of this circuit breaker changes. If the listener is null, it is silently ignored.

Parameters:

listener – The listener to be added

protected void changeState(AbstractCircuitBreaker.State newState)

Changes the internal state of this circuit breaker. If there is actually a change of the state value, all registered change listeners are notified.

Parameters:

newState – The new state to be set

@Override public abstract boolean checkState()

Checks the state of this circuit breaker and changes it if necessary. The return value indicates whether the circuit breaker is now in state closed; a value of true typically means that the current operation can continue.

Returns:

true if the circuit breaker is now closed; false otherwise.

@Override public void close()

Closes this circuit breaker. Its state is changed to closed. If this circuit breaker is already closed, this method has no effect.

@Override public abstract boolean incrementAndCheckState(T increment)

Increments the monitored value and performs a check of the current state of this circuit breaker. This method works like #checkState(), but the monitored value is incremented before the state check is performed.

Parameters:

increment – value to increment in the monitored value of the circuit breaker

Returns:

true if the circuit breaker is now closed; false otherwise

@Override public boolean isClosed()

Tests the current closed state of this circuit breaker. A return value of true means that the circuit breaker is currently closed. This means that everything is okay with the monitored subsystem.

Returns:

The current closed state of this circuit breaker.

@Override public boolean isOpen()

Tests the current open state of this circuit breaker. A return value of true means that the circuit breaker is currently open indicating a problem in the monitored subsystem.

Returns:

The current open state of this circuit breaker.

protected static boolean isOpen(AbstractCircuitBreaker.State state)

Tests whether the given state represents an open circuit breaker.

Parameters:

state – The state to be converted

Returns:

The boolean open flag

@Override public void open()

Opens this circuit breaker. Its state is changed to open. Depending on a concrete implementation, it may close itself again if the monitored subsystem becomes available. If this circuit breaker is already open, this method has no effect.

public void removeChangeListener(PropertyChangeListener listener)

Removes the specified change listener from this circuit breaker.

Parameters:

listener – The listener to be removed