org.apache.activemq.artemis.shaded.org.jgroups.Receiver Maven / Gradle / Ivy
package org.apache.activemq.artemis.shaded.org.jgroups;
import org.apache.activemq.artemis.shaded.org.jgroups.util.MessageBatch;
import java.io.InputStream;
import java.io.OutputStream;
/**
* Defines the callbacks that are invoked when messages, views etc are received
*
* @see JChannel#setReceiver(Receiver)
* @since 2.0
* @author Bela Ban
*/
public interface Receiver {
/**
* Called when a message is received.
* @param msg The message
*/
default void receive(Message msg) {
}
/**
* Called when a batch of messages is received
* @param batch The message batch
*/
default void receive(MessageBatch batch) {
for(Message msg: batch) {
try {
receive(msg);
}
catch(Throwable t) {
}
}
}
/**
* Called when a change in membership has occurred. No long running actions, sending of messages
* or anything that could block should be done in this callback. If some long running action
* needs to be performed, it should be done in a separate thread.
*
* Note that on reception of the first view (a new member just joined), the channel will not yet
* be in the connected state. This only happens when {@link JChannel#connect(String)} returns.
*/
default void viewAccepted(View new_view) {}
/**
* Called (usually by the {@link org.apache.activemq.artemis.shaded.org.jgroups.protocols.pbcast.FLUSH} protocol), as an indication that the member
* should stop sending messages. Any messages sent after returning from this callback might get blocked by the FLUSH
* protocol. When the FLUSH protocol is done, and messages can be sent again, the FLUSH protocol
* will simply unblock all pending messages. If a callback for unblocking is desired, implement
* {@link org.apache.activemq.artemis.shaded.org.jgroups.Receiver#unblock()}.
*/
default void block() {}
/**
* Called after the FLUSH protocol has unblocked previously blocked senders, and
* messages can be sent again.
*
* Note that during new view installation we provide guarantee that unblock invocation strictly
* follows view installation at some node A belonging to that view. However, some other message
* M may squeeze in between view and unblock callbacks.
* For more details see https://jira.jboss.org/jira/browse/JGRP-986
*/
default void unblock() {}
/**
* Allows an application to write the state to an OutputStream. After the state has
* been written, the OutputStream doesn't need to be closed as stream closing is automatically
* done when a calling thread returns from this callback.
*
* @param output The OutputStream
* @throws Exception If the streaming fails, any exceptions should be thrown so that the state requester
* can re-throw them and let the caller know what happened
*/
default void getState(OutputStream output) throws Exception {
throw new UnsupportedOperationException("getState() needs to be overridden by applications");
}
/**
* Allows an application to read the state from an InputStream. After the state has been
* read, the InputStream doesn't need to be closed as stream closing is automatically done when a
* calling thread returns from this callback.
*
* @param input The InputStream
* @throws Exception If the streaming fails, any exceptions should be thrown so that the state requester
* can catch them and thus know what happened
*/
default void setState(InputStream input) throws Exception {
throw new UnsupportedOperationException("setState() needs to be overridden by applications");
}
}