/**
* Copyright 2011 Google Inc.
*
* 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.google.digitalcoin.core;
import java.util.List;
/**
* <p>Implementors can listen to events like blocks being downloaded/transactions being broadcast/connect/disconnects,
* they can pre-filter messages before they are procesesed by a {@link Peer} or {@link PeerGroup}, and they can
* provide transactions to remote peers when they ask for them.</p>
*/
public interface PeerEventListener {
/**
* Called on a Peer thread when a block is received.<p>
*
* The block may have transactions or may be a header only once getheaders is implemented.
*
* @param peer the peer receiving the block
* @param block the downloaded block
* @param blocksLeft the number of blocks left to download
*/
public void onBlocksDownloaded(Peer peer, Block block, int blocksLeft);
/**
* Called when a download is started with the initial number of blocks to be downloaded.
*
* @param peer the peer receiving the block
* @param blocksLeft the number of blocks left to download
*/
public void onChainDownloadStarted(Peer peer, int blocksLeft);
/**
* Called when a peer is connected
*
* @param peer
* @param peerCount the total number of connected peers
*/
public void onPeerConnected(Peer peer, int peerCount);
/**
* Called when a peer is disconnected. Note that this won't be called if the listener is registered on a
* {@link PeerGroup} and the group is in the process of shutting down.
*
* @param peer
* @param peerCount the total number of connected peers
*/
public void onPeerDisconnected(Peer peer, int peerCount);
/**
* Called when a message is received by a peer, before the message is processed. The returned message is
* processed instead. Returning null will cause the message to be ignored by the Peer returning the same message
* object allows you to see the messages received but not change them. The result from one event listeners
* callback is passed as "m" to the next, forming a chain.
*/
public Message onPreMessageReceived(Peer peer, Message m);
/**
* Called when a new transaction is broadcast over the network.
*/
public void onTransaction(Peer peer, Transaction t);
/**
* Called when a peer receives a getdata message, usually in response to an "inv" being broadcast. Return as many
* items as possible which appear in the {@link GetDataMessage}, or null if you're not interested in responding.
*/
public List<Message> getData(Peer peer, GetDataMessage m);
}