cz.o2.proxima.direct.commitlog

Interface LogObserver

All Superinterfaces:

java.io.Serializable

All Known Implementing Classes:

CommitLogReaders.ForwardingLogObserver, LogObservers.AbstractSortedLogObserver, LogObservers.SinglePartitionSortedLogObserver, LogObservers.SortedLogObserver, RetryableLogObserver

@Stable
public interface LogObserver
extends java.io.Serializable

Base interface for bulk and online observers.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	LogObserver.OffsetCommitter Committer for manipulation with offset during consumption.
static interface	LogObserver.OnIdleContext Context passed to onIdle(cz.o2.proxima.direct.commitlog.LogObserver.OnIdleContext).
static interface	LogObserver.OnNextContext Context passed to onNext(cz.o2.proxima.storage.StreamElement, cz.o2.proxima.direct.commitlog.LogObserver.OnNextContext).
static interface	LogObserver.OnRepartitionContext Context passed to onRepartition(cz.o2.proxima.direct.commitlog.LogObserver.OnRepartitionContext).

Method Summary

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

Method Detail

onCompleted

default void onCompleted()

Notify that the processing has gracefully ended.

onCancelled

default void onCancelled()

Notify that the processing has been canceled.

onError

default boolean onError(java.lang.Throwable error)

Called to notify there was an {@link Throwable error) in the commit reader.

Parameters:

error - error caught during processing

Returns:

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

onException

default boolean onException(java.lang.Exception exception)

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

Parameters:

exception - exception caught during processing

Returns:

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

onFatalError

default boolean onFatalError(java.lang.Error error)

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

Parameters:

error - error caught during processing

Returns:

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

onNext

boolean onNext(StreamElement ingest,
               LogObserver.OnNextContext context)

Process next record in the commit log.

Parameters:

ingest - the ingested data written to the commit log

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

Returns:

true if the processing should continue, false otherwise

onRepartition

default void onRepartition(LogObserver.OnRepartitionContext context)

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

Parameters:

context - context of the repartition

onIdle

default void onIdle(LogObserver.OnIdleContext context)

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 onNext(cz.o2.proxima.storage.StreamElement, cz.o2.proxima.direct.commitlog.LogObserver.OnNextContext) will be called eventually.

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

Parameters:

context - the context for on idle processing