| package com.google.code.gossip.manager; |
| |
| import java.io.IOException; |
| import java.net.DatagramPacket; |
| import java.net.DatagramSocket; |
| import java.net.InetSocketAddress; |
| import java.net.SocketAddress; |
| import java.net.SocketException; |
| import java.util.ArrayList; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| |
| import org.json.JSONArray; |
| import org.json.JSONException; |
| import org.json.JSONObject; |
| |
| import com.google.code.gossip.GossipMember; |
| import com.google.code.gossip.GossipService; |
| import com.google.code.gossip.RemoteGossipMember; |
| |
| /** |
| * [The passive thread: reply to incoming gossip request.] This class handles the passive cycle, |
| * where this client has received an incoming message. For now, this message is always the |
| * membership list, but if you choose to gossip additional information, you will need some logic to |
| * determine the incoming message. |
| */ |
| abstract public class PassiveGossipThread implements Runnable { |
| |
| /** The socket used for the passive thread of the gossip service. */ |
| private DatagramSocket _server; |
| |
| private GossipManager _gossipManager; |
| |
| private AtomicBoolean _keepRunning; |
| |
| public PassiveGossipThread(GossipManager gossipManager) { |
| _gossipManager = gossipManager; |
| try { |
| SocketAddress socketAddress = new InetSocketAddress(_gossipManager.getMyself().getHost(), |
| _gossipManager.getMyself().getPort()); |
| _server = new DatagramSocket(socketAddress); |
| GossipService.LOGGER.info("Gossip service successfully initialized on port " |
| + _gossipManager.getMyself().getPort()); |
| GossipService.LOGGER.debug("I am " + _gossipManager.getMyself()); |
| } catch (SocketException ex) { |
| GossipService.LOGGER.error(ex); |
| _server = null; |
| throw new RuntimeException(ex); |
| } |
| _keepRunning = new AtomicBoolean(true); |
| } |
| |
| @Override |
| public void run() { |
| while (_keepRunning.get()) { |
| try { |
| byte[] buf = new byte[_server.getReceiveBufferSize()]; |
| DatagramPacket p = new DatagramPacket(buf, buf.length); |
| _server.receive(p); |
| GossipService.LOGGER.debug("A message has been received from " + p.getAddress() + ":" |
| + p.getPort() + "."); |
| |
| int packet_length = 0; |
| for (int i = 0; i < 4; i++) { |
| int shift = (4 - 1 - i) * 8; |
| packet_length += (buf[i] & 0x000000FF) << shift; |
| } |
| |
| // Check whether the package is smaller than the maximal packet length. |
| // A package larger than this would not be possible to be send from a GossipService, |
| // since this is check before sending the message. |
| // This could normally only occur when the list of members is very big, |
| // or when the packet is misformed, and the first 4 bytes is not the right in anymore. |
| // For this reason we regards the message. |
| if (packet_length <= GossipManager.MAX_PACKET_SIZE) { |
| byte[] json_bytes = new byte[packet_length]; |
| for (int i = 0; i < packet_length; i++) { |
| json_bytes[i] = buf[i + 4]; |
| } |
| String receivedMessage = new String(json_bytes); |
| GossipService.LOGGER.debug("Received message (" + packet_length + " bytes): " |
| + receivedMessage); |
| try { |
| ArrayList<GossipMember> remoteGossipMembers = new ArrayList<GossipMember>(); |
| RemoteGossipMember senderMember = null; |
| GossipService.LOGGER.debug("Received member list:"); |
| JSONArray jsonArray = new JSONArray(receivedMessage); |
| for (int i = 0; i < jsonArray.length(); i++) { |
| JSONObject memberJSONObject = jsonArray.getJSONObject(i); |
| if (memberJSONObject.length() == 4) { |
| RemoteGossipMember member = new RemoteGossipMember( |
| memberJSONObject.getString(GossipMember.JSON_HOST), |
| memberJSONObject.getInt(GossipMember.JSON_PORT), |
| memberJSONObject.getString(GossipMember.JSON_ID), |
| memberJSONObject.getInt(GossipMember.JSON_HEARTBEAT)); |
| GossipService.LOGGER.debug(member.toString()); |
| // This is the first member found, so this should be the member who is communicating |
| // with me. |
| if (i == 0) { |
| senderMember = member; |
| } |
| remoteGossipMembers.add(member); |
| } else { |
| GossipService.LOGGER |
| .error("The received member object does not contain 4 objects:\n" |
| + memberJSONObject.toString()); |
| } |
| |
| } |
| |
| // Merge our list with the one we just received |
| mergeLists(_gossipManager, senderMember, remoteGossipMembers); |
| } catch (JSONException e) { |
| GossipService.LOGGER |
| .error("The received message is not well-formed JSON. The following message has been dropped:\n" |
| + receivedMessage); |
| } |
| |
| } else { |
| GossipService.LOGGER |
| .error("The received message is not of the expected size, it has been dropped."); |
| } |
| |
| } catch (IOException e) { |
| e.printStackTrace(); |
| _keepRunning.set(false); |
| } |
| } |
| shutdown(); |
| } |
| |
| public void shutdown() { |
| _server.close(); |
| } |
| |
| /** |
| * Abstract method for merging the local and remote list. |
| * |
| * @param gossipManager |
| * The GossipManager for retrieving the local members and dead members list. |
| * @param senderMember |
| * The member who is sending this list, this could be used to send a response if the |
| * remote list contains out-dated information. |
| * @param remoteList |
| * The list of members known at the remote side. |
| */ |
| abstract protected void mergeLists(GossipManager gossipManager, RemoteGossipMember senderMember, |
| ArrayList<GossipMember> remoteList); |
| } |