PeriodicDeltaChangeListener (Apache Brooklyn)

java.lang.Object
- brooklyn.entity.rebind.PeriodicDeltaChangeListener

All Implemented Interfaces:

ChangeListener
```
public class PeriodicDeltaChangeListener
extends java.lang.Object
implements ChangeListener
```
A "simple" implementation that periodically persists all entities/locations/policies that have changed since the last periodic persistence. TODO A better implementation would look at a per-entity basis. When the entity was modified, then schedule a write for that entity in X milliseconds time (if not already scheduled). That would prevent hammering the persister when a bunch of entity attributes change (e.g. when the entity has just polled over JMX/http/etc). Such a scheduled-write approach would be similar to the Nagle buffering algorithm in TCP (see tcp_nodelay).

Field Summary
- Fields inherited from interface brooklyn.entity.rebind.ChangeListener
  NOOP

Constructor Summary

Constructors
Constructor and Description
`PeriodicDeltaChangeListener(ExecutionContext executionContext, BrooklynMementoPersister persister, PersistenceExceptionHandler exceptionHandler, PersistenceActivityMetrics metrics, Duration period)`

Method Summary

Methods
Modifier and Type	Method and Description
`PersistenceExceptionHandler`	`getExceptionHandler()`
`void`	`onChanged(BrooklynObject instance)`
`void`	`onManaged(BrooklynObject instance)`
`void`	`onUnmanaged(BrooklynObject instance)`
`boolean`	`persistNowSafely()`
`void`	`start()`
`void`	`waitForPendingComplete(Duration timeout, boolean canTrigger)` Waits for any in-progress writes to be completed then for or any unwritten data to be written.

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PeriodicDeltaChangeListener

public PeriodicDeltaChangeListener(ExecutionContext executionContext,
                           BrooklynMementoPersister persister,
                           PersistenceExceptionHandler exceptionHandler,
                           PersistenceActivityMetrics metrics,
                           Duration period)

Method Detail

start
```
public void start()
```

waitForPendingComplete

public void waitForPendingComplete(Duration timeout,
                          boolean canTrigger)
                            throws java.lang.InterruptedException,
                                   java.util.concurrent.TimeoutException

Waits for any in-progress writes to be completed then for or any unwritten data to be written.

Throws:: java.lang.InterruptedException; java.util.concurrent.TimeoutException

persistNowSafely
```
public boolean persistNowSafely()
```

onManaged
```
public void onManaged(BrooklynObject instance)
```
Specified by:

onManaged in interface ChangeListener

onUnmanaged
```
public void onUnmanaged(BrooklynObject instance)
```
Specified by:

onUnmanaged in interface ChangeListener

onChanged
```
public void onChanged(BrooklynObject instance)
```
Specified by:

onChanged in interface ChangeListener

getExceptionHandler

public PersistenceExceptionHandler getExceptionHandler()

Class PeriodicDeltaChangeListener

Field Summary

Fields inherited from interface brooklyn.entity.rebind.ChangeListener

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

PeriodicDeltaChangeListener

Method Detail

start

waitForPendingComplete

persistNowSafely

onManaged

onUnmanaged

onChanged

getExceptionHandler