amichair commented on code in PR #93: URL: https://github.com/apache/aries-rsa/pull/93#discussion_r3151543320
########## discovery/tcp/src/main/java/org/apache/aries/rsa/discovery/tcp/TcpConnectionManager.java: ########## @@ -0,0 +1,228 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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 org.apache.aries.rsa.discovery.tcp; + +import org.apache.aries.rsa.discovery.tcp.TcpMessage.*; +import org.osgi.service.remoteserviceadmin.EndpointDescription; +import org.osgi.service.remoteserviceadmin.EndpointEvent; +import org.osgi.service.remoteserviceadmin.EndpointEventListener; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.io.IOException; +import java.net.*; +import java.util.*; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; + +import static org.apache.aries.rsa.discovery.tcp.TcpDiscovery.toURI; + +/** + * Manages all TCP connections for this provider, as well as + * the higher-level TCP discovery protocol logic. + * <p> + * This includes accepting incoming connections on a server socket, + * initiating outgoing connections to configured (or discovered) peers, + * connection retry logic after unexpected disconnection, handling + * incoming messages from connections and handling gossip-discovered peers. + * <p> + * In addition to the protocol-level functionality, it keeps track of + * all known local endpoints and notifies all remote peers about them. + */ +public class TcpConnectionManager implements EndpointEventListener { + private static final Logger LOG = LoggerFactory.getLogger(TcpConnectionManager.class); + + private final InterestManager interestManager; + private final String localAddress; + private final String localUuid; + private final long reconnectDelay; + private final boolean gossip; + + private final ExecutorService executor = Executors.newCachedThreadPool(); // for connect/accept threads + private final Set<TcpConnection> connections = ConcurrentHashMap.newKeySet(); // all connections, including before handshake + private final Map<String, TcpConnection> connectionsByUuid = new ConcurrentHashMap<>(); // connections after handshake (known uuid) + private final Map<String, EndpointDescription> localEndpoints = new ConcurrentHashMap<>(); + private final Set<String> peers = ConcurrentHashMap.newKeySet(); // all configured and discovered (gossip) peer addresses + + private ServerSocket serverSocket; + private volatile boolean closing; + + public TcpConnectionManager(InterestManager interestManager, String localAddress, + String localUuid, long reconnectDelay, boolean gossip) { + this.interestManager = interestManager; + this.localAddress = localAddress; + this.localUuid = localUuid; + this.reconnectDelay = reconnectDelay; + this.gossip = gossip; + } + + public void open(String bindAddress, int port, Collection<String> peers) throws IOException { + serverSocket = new ServerSocket(); + serverSocket.setReuseAddress(true); + serverSocket.bind(new InetSocketAddress(bindAddress, port)); + executor.submit(this::acceptLoop); + addPeers(peers); + } + + public void close() throws IOException { + closing = true; + serverSocket.close(); // acceptLoop will get SocketException + connections.forEach(TcpConnection::close); + executor.shutdownNow(); + } + + private void addPeers(Collection<String> peers) { + peers.stream() + .filter(peer -> !this.peers.contains(peer)) // only new ones + .filter(peer -> !localAddress.equals(peer)) // exclude ourself + .forEach(peer -> { + LOG.info("Adding peer {}", peer); + this.peers.add(peer); + executor.submit(() -> connectLoop(peer)); + }); + } + + private void acceptLoop() { + while (true) { + try { + Socket socket = serverSocket.accept(); + executor.submit(() -> onConnected(socket, null)); + } catch (IOException ioe) { + return; // socket closed + } catch (Throwable t) { + LOG.error("Unexpected error in accept loop - shutting down", t); + return; + } + } + } + + private void connectLoop(String address) { + URI uri = toURI(address); + while (!closing) { + try { + Socket socket = new Socket(uri.getHost(), uri.getPort()); + onConnected(socket, address); + return; // connection established; onConnectionClosed will restart this loop if needed + } catch (IOException ioe) { + try { + Thread.sleep(reconnectDelay); + } catch (InterruptedException ie) { + // end loop (shutting down) + return; + } + } catch (Throwable t) { + LOG.error("Unexpected error in connect loop - shutting down", t); + return; + } + } + } + + private void onConnected(Socket socket, String address) { + try { + TcpConnection conn = new TcpConnection(socket, address, this::onMessage, this::onClosed); + connections.add(conn); + conn.send(new HandshakeMessage(localUuid, localAddress, new ArrayList<>(peers))); + // don't send known endpoints yet, only after receiving handshake + } catch (IOException ioe) { + LOG.error("error initializing accepted connection", ioe); + } + } + + public void onClosed(TcpConnection conn) { + connections.remove(conn); + String peerUuid = conn.getPeerUuid(); + if (peerUuid != null) { // passed the handshake + boolean removed = connectionsByUuid.remove(peerUuid, conn); // remove if this is the active connection + if (removed && !closing) { + interestManager.removePeer(peerUuid); // no active connections with peer + } + } + // re-start the connect retry thread if necessary: + // only if we're the outbound peer, and not in the process of shutting down, + // and there isn't already an active (reverse?) connection with the same peer, + // or we don't know who the peer is yet (before handshake) + if (conn.isOutbound() && !closing && (peerUuid == null || !connectionsByUuid.containsKey(peerUuid))) { + executor.submit(() -> connectLoop(conn.getPeerAddress())); + } + } + + private void onMessage(TcpConnection conn, TcpMessage message) { + if (message instanceof HandshakeMessage) { + HandshakeMessage h = (HandshakeMessage) message; + // update the peer data + conn.setPeerAddress(h.getAddress()); + conn.setPeerUuid(h.getUuid()); + // if gossip is enabled, try adding all of this peer's peers, + // as well as the peer itself (in case it found us via its + // own gossip, and we haven't met before) + if (gossip) { + addPeers(h.getPeers()); + addPeers(Collections.singleton(h.getAddress())); + } + // if we already have another connection with this peer (e.g. reverse direction) + // then we keep the old one (which is already in use) and close the new one + boolean existing = connectionsByUuid.putIfAbsent(h.getUuid(), conn) != null; + if (existing) { + // both sides can check if a connection between them already exists, but + // there is a possible race condition where one peer receives the handshake + // and closes the connection before it even had a chance to send its handshake - + // so the other peer will never know the connection is intentionally closed + // and not experiencing connection errors. If it is the outbound side, it will + // keep retrying to connect. to solve this, only the outbound peer is the one + // that closes the connection. The inbound side just doesn't use it until then. + if (conn.isOutbound()) { + conn.close(); + } + return; + } + // send all of our known local endpoints to the new peer + localEndpoints.values().forEach(endpoint -> conn.send(new UpdateMessage(endpoint.getProperties()))); + } else if (message instanceof UpdateMessage) { + UpdateMessage u = (UpdateMessage) message; + EndpointDescription endpoint = new EndpointDescription(u.getProperties()); + interestManager.addEndpoint(endpoint); + } else if (message instanceof RemoveMessage) { Review Comment: In the current design the TcpMessage class is just the lower-level serialized class holding the data, and the TcpConnection is the one processing the higher-level logic of sent and received messages, so I don't see how one would be updated without the other... Anyway, I added it. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
