net.sf.ehcache.distribution

Class RMISynchronousCacheReplicator

java.lang.Object

net.sf.ehcache.distribution.RMISynchronousCacheReplicator

All Implemented Interfaces:

Cloneable, CacheReplicator, CacheEventListener

Direct Known Subclasses:

RMIAsynchronousCacheReplicator

public class RMISynchronousCacheReplicator
extends Object
implements CacheReplicator

Listens to CacheManager and Cache events and propagates those to CachePeer peers of the Cache.

Version:

$Id: RMISynchronousCacheReplicator.java 5631 2012-05-10 08:31:33Z teck $

Author:

Greg Luck

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	replicatePuts Whether to replicate puts.
protected boolean	replicatePutsViaCopy Whether a put should replicated by copy or by invalidation, (a remove).
protected boolean	replicateRemovals Whether to replicate removes
protected boolean	replicateUpdates Whether to replicate updates.
protected boolean	replicateUpdatesViaCopy Whether an update (a put) should be by copy or by invalidation, (a remove).
protected Status	status The status of the replicator.

Constructor Summary

Constructors

Constructor and Description
RMISynchronousCacheReplicator(boolean replicatePuts, boolean replicatePutsViaCopy, boolean replicateUpdates, boolean replicateUpdatesViaCopy, boolean replicateRemovals) Constructor for internal and subclass use

Method Summary

Modifier and Type	Method and Description
boolean	alive() Checks that the replicator is is STATUS_ALIVE.
Object	clone() Creates a clone of this listener.
void	dispose() Give the replicator a chance to cleanup and free resources when no longer needed
boolean	isReplicateUpdatesViaCopy() Returns whether update is through copy or invalidate
boolean	notAlive() Asserts that the replicator is active.
void	notifyElementEvicted(Ehcache cache, Element element) Called immediately after an element is evicted from the cache.
void	notifyElementExpired(Ehcache cache, Element element) Called immediately after an element is found to be expired.
void	notifyElementPut(Ehcache cache, Element element) Called immediately after an element has been put into the cache.
void	notifyElementRemoved(Ehcache cache, Element element) Called immediately after an attempt to remove an element.
void	notifyElementUpdated(Ehcache cache, Element element) Called immediately after an element has been put into the cache and the element already existed in the cache.
void	notifyRemoveAll(Ehcache cache) Called during Ehcache.removeAll() to indicate that the all elements have been removed from the cache in a bulk operation.
protected static void	replicatePutNotification(Ehcache cache, Element element) Does the actual RMI remote call.
protected static void	replicateRemovalNotification(Ehcache cache, Serializable key) Does the actual RMI remote call.
protected void	replicateRemoveAllNotification(Ehcache cache) Does the actual RMI remote call.

Methods inherited from class java.lang.Object

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

Field Detail

status

protected Status status

The status of the replicator. Only replicates when STATUS_ALIVE

replicatePuts

protected final boolean replicatePuts

Whether to replicate puts.

replicatePutsViaCopy

protected boolean replicatePutsViaCopy

Whether a put should replicated by copy or by invalidation, (a remove).

By copy is best when the entry is expensive to produce. By invalidation is best when we are really trying to force other caches to sync back to a canonical source like a database. An example of a latter usage would be a read/write cache being used in Hibernate.

This setting only has effect if #replicateUpdates is true.

replicateUpdates

protected final boolean replicateUpdates

Whether to replicate updates.

replicateUpdatesViaCopy

protected final boolean replicateUpdatesViaCopy

Whether an update (a put) should be by copy or by invalidation, (a remove).

By copy is best when the entry is expensive to produce. By invalidation is best when we are really trying to force other caches to sync back to a canonical source like a database. An example of a latter usage would be a read/write cache being used in Hibernate.

This setting only has effect if #replicateUpdates is true.

replicateRemovals

protected final boolean replicateRemovals

Whether to replicate removes

Constructor Detail

RMISynchronousCacheReplicator

public RMISynchronousCacheReplicator(boolean replicatePuts,
                                     boolean replicatePutsViaCopy,
                                     boolean replicateUpdates,
                                     boolean replicateUpdatesViaCopy,
                                     boolean replicateRemovals)

Constructor for internal and subclass use

Parameters:

replicatePuts -

replicateUpdates -

replicateUpdatesViaCopy -

replicateRemovals -

Method Detail

notifyElementPut

public void notifyElementPut(Ehcache cache,
                             Element element)
                      throws CacheException

Called immediately after an element has been put into the cache. The Cache.put(net.sf.ehcache.Element) method will block until this method returns.

Implementers may wish to have access to the Element's fields, including value, so the element is provided. Implementers should be careful not to modify the element. The effect of any modifications is undefined.

Specified by:

notifyElementPut in interface CacheEventListener

Parameters:

cache - the cache emitting the notification

element - the element which was just put into the cache.

Throws:

CacheException

replicatePutNotification

protected static void replicatePutNotification(Ehcache cache,
                                               Element element)
                                        throws RemoteCacheException

Does the actual RMI remote call.

If a Throwable occurs a SEVERE log message will be logged, but attempts to replicate to the other peers will continue.

Throws:

RemoteCacheException

notifyElementUpdated

public void notifyElementUpdated(Ehcache cache,
                                 Element element)
                          throws CacheException

Called immediately after an element has been put into the cache and the element already existed in the cache. This is thus an update.

The Cache.put(net.sf.ehcache.Element) method will block until this method returns.

Implementers may wish to have access to the Element's fields, including value, so the element is provided. Implementers should be careful not to modify the element. The effect of any modifications is undefined.

Specified by:

notifyElementUpdated in interface CacheEventListener

Parameters:

cache - the cache emitting the notification

element - the element which was just put into the cache.

Throws:

CacheException

notifyElementRemoved

public void notifyElementRemoved(Ehcache cache,
                                 Element element)
                          throws CacheException

Called immediately after an attempt to remove an element. The remove method will block until this method returns.

This notification is received regardless of whether the cache had an element matching the removal key or not. If an element was removed, the element is passed to this method, otherwise a synthetic element, with only the key set is passed in.

Specified by:

notifyElementRemoved in interface CacheEventListener

Parameters:

cache - the cache emitting the notification

element - the element just deleted, or a synthetic element with just the key set if no element was removed.param element just deleted

Throws:

CacheException

replicateRemovalNotification

protected static void replicateRemovalNotification(Ehcache cache,
                                                   Serializable key)
                                            throws RemoteCacheException

Does the actual RMI remote call.

If a Throwable occurs a SEVERE log message will be logged, but attempts to replicate to the other peers will continue.

Throws:

RemoteCacheException

notifyElementExpired

public final void notifyElementExpired(Ehcache cache,
                                       Element element)

Called immediately after an element is found to be expired. The Cache.remove(Object) method will block until this method returns.

As the Element has been expired, only what was the key of the element is known.

Elements are checked for expiry in ehcache at the following times:

• When a get request is made
• When an element is spooled to the diskStore in accordance with a MemoryStore eviction policy
• In the DiskStore when the expiry thread runs, which by default is Cache.DEFAULT_EXPIRY_THREAD_INTERVAL_SECONDS

If an element is found to be expired, it is deleted and this method is notified.

This implementation does not propagate expiries. It does not need to do anything because the element will expire in the remote cache at the same time. If the remote peer is not configured the same way they should not be in an cache cluster.

Specified by:

notifyElementExpired in interface CacheEventListener

Parameters:

cache - the cache emitting the notification

element - the element that has just expired

Deadlock Warning: expiry will often come from the DiskStore expiry thread. It holds a lock to the DiskStorea the time the notification is sent. If the implementation of this method calls into a synchronized Cache method and that subsequently calls into DiskStore a deadlock will result. Accordingly implementers of this method should not call back into Cache.

notifyElementEvicted

public void notifyElementEvicted(Ehcache cache,
                                 Element element)

Called immediately after an element is evicted from the cache. Evicted in this sense means evicted from one store and not moved to another, so that it exists nowhere in the local cache.

In a sense the Element has been removed from the cache, but it is different, thus the separate notification.

This replicator does not propagate these events

Specified by:

notifyElementEvicted in interface CacheEventListener

Parameters:

cache - the cache emitting the notification

element - the element that has just been evicted

notifyRemoveAll

public void notifyRemoveAll(Ehcache cache)

Called during Ehcache.removeAll() to indicate that the all elements have been removed from the cache in a bulk operation. The usual notifyElementRemoved(net.sf.ehcache.Ehcache,net.sf.ehcache.Element) is not called.

This notification exists because clearing a cache is a special case. It is often not practical to serially process notifications where potentially millions of elements have been bulk deleted.

Specified by:

notifyRemoveAll in interface CacheEventListener

Parameters:

cache - the cache emitting the notification

replicateRemoveAllNotification

protected void replicateRemoveAllNotification(Ehcache cache)

Does the actual RMI remote call. If a Throwable occurs a SEVERE log message will be logged, but attempts to replicate to the other peers will continue.

isReplicateUpdatesViaCopy

public final boolean isReplicateUpdatesViaCopy()

Description copied from interface: CacheReplicator

Returns whether update is through copy or invalidate

Specified by:

isReplicateUpdatesViaCopy in interface CacheReplicator

Returns:

whether update is through copy or invalidate

notAlive

public final boolean notAlive()

Asserts that the replicator is active.

Specified by:

notAlive in interface CacheReplicator

Returns:

true if the status is not STATUS_ALIVE

alive

public final boolean alive()

Checks that the replicator is is STATUS_ALIVE.

Specified by:

alive in interface CacheReplicator

Returns:

true if the replicator is is STATUS_ALIVE, else false.

dispose

public void dispose()

Give the replicator a chance to cleanup and free resources when no longer needed

Specified by:

dispose in interface CacheEventListener

clone

public Object clone()
             throws CloneNotSupportedException

Creates a clone of this listener. This method will only be called by ehcache before a cache is initialized.

This may not be possible for listeners after they have been initialized. Implementations should throw CloneNotSupportedException if they do not support clone.

Specified by:

clone in interface CacheEventListener

Overrides:

clone in class Object

Returns:

a clone

Throws:

CloneNotSupportedException - if the listener could not be cloned.