/*******************************************************************************
* Copyright 2015 Klaus Pfeiffer <klaus@allpiper.com>
*
* 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.jfastnet.processors;
import com.jfastnet.messages.Message;
import lombok.EqualsAndHashCode;
import java.util.HashMap;
import java.util.Map;
/** @author Klaus Pfeiffer - klaus@allpiper.com */
public class DiscardMessagesHandler implements IMessageReceiverPreProcessor{
// TODO potentially growing over time
private Map<Object, Message> msgs = new HashMap<>();
@Override
public Message beforeReceive(Message incomingMessage) {
Object discardableKey = incomingMessage.getDiscardableKey();
if (discardableKey != null) {
Message message = msgs.get(discardableKey);
if (message == null) {
msgs.put(discardableKey, incomingMessage);
return incomingMessage;
} else {
long incomingMessageTimestamp = incomingMessage.getTimestamp();
long existingMessageTimestamp = message.getTimestamp();
if (incomingMessageTimestamp >= existingMessageTimestamp) {
// incoming message is newer
msgs.put(discardableKey, incomingMessage);
return incomingMessage;
} else {
// discard message, because incoming message is older than
// already retrieved message
return null;
}
}
}
return incomingMessage;
}
/** Can be used to discard messages of a certain class and a certain key. */
@EqualsAndHashCode
public static class ClassKey {
private Class clazz;
private Object key;
public ClassKey(Class clazz, Object key) {
this.clazz = clazz;
this.key = key;
}
}
}