Module com.lmax.disruptor

Package com.lmax.disruptor

Interface RewindableEventHandler<T>

Type Parameters:

T - event implementation storing the data for sharing during exchange or parallel coordination of an event.

All Superinterfaces:

EventHandlerIdentity

public interface RewindableEventHandler<T>

Callback interface to be implemented for processing events as they become available in the RingBuffer with support for throwing a RewindableException when an even cannot be processed currently but may succeed on retry.

See Also:

if you want to handle exceptions propagated out of the handler.

Method Summary

Modifier and Type	Method	Description
default void	onBatchStart(long batchSize, long queueDepth)	Invoked by BatchEventProcessor prior to processing a batch of events
void	onEvent(T event, long sequence, boolean endOfBatch)	Called when a publisher has published an event to the RingBuffer.
default void	onShutdown()	Called once just before the event processing thread is shutdown.
default void	onStart()	Called once on thread start before first event is available.
default void	onTimeout(long sequence)	Invoked when a BatchEventProcessor's WaitStrategy throws a TimeoutException.

Method Detail

onEvent

void onEvent(T event,
             long sequence,
             boolean endOfBatch)
      throws RewindableException,
             java.lang.Exception

Called when a publisher has published an event to the RingBuffer. The BatchEventProcessor will read messages from the RingBuffer in batches, where a batch is all of the events available to be processed without having to wait for any new event to arrive. This can be useful for event handlers that need to do slower operations like I/O as they can group together the data from multiple events into a single operation. Implementations should ensure that the operation is always performed when endOfBatch is true as the time between that message and the next one is indeterminate.

Parameters:

event - published to the RingBuffer

sequence - of the event being processed

endOfBatch - flag to indicate if this is the last event in a batch from the RingBuffer

Throws:

RewindableException - if the EventHandler would like the batch event processor to process the entire batch again.

java.lang.Exception - if the EventHandler would like the exception handled further up the chain.

onBatchStart

default void onBatchStart(long batchSize,
                          long queueDepth)

Invoked by BatchEventProcessor prior to processing a batch of events

Parameters:

batchSize - the size of the batch that is starting

queueDepth - the total number of queued up events including the batch about to be processed

onStart

default void onStart()

Called once on thread start before first event is available.

onShutdown

default void onShutdown()

Called once just before the event processing thread is shutdown.

Sequence event processing will already have stopped before this method is called. No events will be processed after this message.

onTimeout

default void onTimeout(long sequence)
                throws java.lang.Exception

Invoked when a BatchEventProcessor's WaitStrategy throws a TimeoutException.

Parameters:

sequence - - the last processed sequence.

Throws:

java.lang.Exception - if the implementation is unable to handle this timeout.