com.lmax.disruptor.EventHandler Maven / Gradle / Ivy
/*
* Copyright 2011 LMAX Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.lmax.disruptor;
/**
* Callback interface to be implemented for processing events as they become available in the {@link RingBuffer}
*
* @param event implementation storing the data for sharing during exchange or parallel coordination of an event.
* @see BatchEventProcessor#setExceptionHandler(ExceptionHandler) if you want to handle exceptions propagated out of the handler.
*/
public interface EventHandler
{
/**
* Called when a publisher has published an event to the {@link RingBuffer}. The {@link BatchEventProcessor} will
* read messages from the {@link 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 an the next one is inderminate.
*
* @param event published to the {@link RingBuffer}
* @param sequence of the event being processed
* @param endOfBatch flag to indicate if this is the last event in a batch from the {@link RingBuffer}
* @throws Exception if the EventHandler would like the exception handled further up the chain.
*/
void onEvent(T event, long sequence, boolean endOfBatch) throws Exception;
}