Package cz.o2.proxima.direct.core.commitlog

Class CommitLogObservers.ForwardingObserver

java.lang.Object

cz.o2.proxima.direct.core.commitlog.CommitLogObservers.ForwardingObserver

All Implemented Interfaces:

CommitLogObserver, LogObserver<Offset,CommitLogObserver.OnNextContext>

Enclosing class:

CommitLogObservers

public static class CommitLogObservers.ForwardingObserver
extends java.lang.Object
implements CommitLogObserver

A @{link LogObserver} that delegates calls to underlying delegate. Useful for overriding specific methods before passing to delegate.

Nested Class Summary

Nested classes/interfaces inherited from interface cz.o2.proxima.direct.core.commitlog.CommitLogObserver

CommitLogObserver.OffsetCommitter, CommitLogObserver.OnIdleContext, CommitLogObserver.OnNextContext, CommitLogObserver.OnRepartitionContext

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ForwardingObserver(CommitLogObserver delegate)

Method Summary

Modifier and Type	Method	Description
void	onCancelled()	Notify that the processing has been canceled.
void	onCompleted()	Notify that the processing has gracefully ended.
boolean	onError(java.lang.Throwable error)	Called to notify there was an error in the commit reader.
boolean	onException(java.lang.Exception exception)	Called to notify there was an exception in the commit reader.
boolean	onFatalError(java.lang.Error error)	Called to notify there was an error in the commit reader.
void	onIdle(CommitLogObserver.OnIdleContext context)	Called when the observer is idle.
boolean	onNext(StreamElement element, CommitLogObserver.OnNextContext context)	Process next record in the commit log.
void	onRepartition(CommitLogObserver.OnRepartitionContext context)	Callback to notify of automatic repartitioning.

Methods inherited from class java.lang.Object

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

Constructor Detail

ForwardingObserver

protected ForwardingObserver(CommitLogObserver delegate)

Method Detail

onRepartition

public void onRepartition(CommitLogObserver.OnRepartitionContext context)

Description copied from interface: CommitLogObserver

Callback to notify of automatic repartitioning. This method is always called first before any LogObserver.onNext(cz.o2.proxima.core.storage.StreamElement, ContextT) call happens.

Specified by:

onRepartition in interface CommitLogObserver

Parameters:

context - context of the repartition

onIdle

public void onIdle(CommitLogObserver.OnIdleContext context)

Description copied from interface: CommitLogObserver

Called when the observer is idle. Note that the definition of idle is commit-log dependent and it even might NOT be called at all, if the commit log guarantees that as long as there are *any* data flowing in, then LogObserver.onNext(cz.o2.proxima.core.storage.StreamElement, ContextT) will be called eventually.

Typical example of commit log with no need to call CommitLogObserver.onIdle(cz.o2.proxima.direct.core.commitlog.CommitLogObserver.OnIdleContext) is google PubSub, having virtually single shared partition which loads balances incoming data.

Specified by:

onIdle in interface CommitLogObserver

Parameters:

context - the context for on idle processing

onCompleted

public void onCompleted()

Description copied from interface: LogObserver

Notify that the processing has gracefully ended.

Specified by:

onCompleted in interface LogObserver<Offset,CommitLogObserver.OnNextContext>

onCancelled

public void onCancelled()

Description copied from interface: LogObserver

Notify that the processing has been canceled.

Specified by:

onCancelled in interface LogObserver<Offset,CommitLogObserver.OnNextContext>

onError

public boolean onError(java.lang.Throwable error)

Description copied from interface: LogObserver

Called to notify there was an error in the commit reader.

Specified by:

onError in interface LogObserver<Offset,CommitLogObserver.OnNextContext>

Parameters:

error - error caught during processing

Returns:

true to restart processing from last committed position, false to stop processing

onException

public boolean onException(java.lang.Exception exception)

Description copied from interface: LogObserver

Called to notify there was an exception in the commit reader. There is no guarantee this method gets called, if LogObserver.onError(Throwable) is overridden.

Specified by:

onException in interface LogObserver<Offset,CommitLogObserver.OnNextContext>

Parameters:

exception - exception caught during processing

Returns:

true to restart processing from last committed position, false to stop processing

onFatalError

public boolean onFatalError(java.lang.Error error)

Description copied from interface: LogObserver

Called to notify there was an error in the commit reader. There is no guarantee this method gets called, if LogObserver.onError(Throwable) is overridden.

Specified by:

onFatalError in interface LogObserver<Offset,CommitLogObserver.OnNextContext>

Parameters:

error - error caught during processing

Returns:

true to restart processing from last committed position, false to stop processing

onNext

public boolean onNext(StreamElement element,
                      CommitLogObserver.OnNextContext context)

Description copied from interface: LogObserver

Process next record in the commit log.

Specified by:

onNext in interface LogObserver<Offset,CommitLogObserver.OnNextContext>

Parameters:

element - the element written to the commit log

context - a context that the application must use to confirm processing of the element. If the application fails to do so, the result is undefined.

Returns:

true if the processing should continue, false otherwise