Java tutorial
/** * diqube: Distributed Query Base. * * Copyright (C) 2015 Bastian Gloeckle * * This file is part of diqube. * * diqube is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as * published by the Free Software Foundation, either version 3 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package org.diqube.ui.ticket; import java.lang.reflect.InvocationTargetException; import java.util.List; import java.util.concurrent.atomic.AtomicBoolean; import javax.annotation.PreDestroy; import javax.inject.Inject; import org.apache.thrift.TException; import org.apache.thrift.protocol.TCompactProtocol; import org.apache.thrift.protocol.TMultiplexedProtocol; import org.apache.thrift.protocol.TProtocol; import org.apache.thrift.transport.TFramedTransport; import org.apache.thrift.transport.TSocket; import org.apache.thrift.transport.TTransport; import org.apache.thrift.transport.TTransportException; import org.diqube.context.AutoInstatiate; import org.diqube.remote.query.IdentityServiceConstants; import org.diqube.remote.query.thrift.IdentityService; import org.diqube.remote.query.thrift.TicketInfo; import org.diqube.ticket.TicketValidityService; import org.diqube.ui.DiqubeServletConfig; import org.diqube.ui.DiqubeServletConfig.ServletConfigListener; import org.diqube.ui.websocket.WebSocketEndpoint.WebSocketEndpointListener; import org.diqube.util.Pair; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Subscribes for logout-events sent by diqube-servers (see * {@link IdentityService.Iface#registerCallback(org.diqube.thrift.base.thrift.RNodeAddress)} and takes care of * regularily fetching updates on invalidated tickets. * * @author Bastian Gloeckle */ @AutoInstatiate public class TicketValiditySubscriber implements WebSocketEndpointListener, TicketsAcceptableProvider, ServletConfigListener { private static final Logger logger = LoggerFactory.getLogger(TicketValiditySubscriber.class); /** * Re-subscribe to updates received from diqube-servers after this amount of minutes. This is needed, since * diqube-server will automatically remove our registration after about 1h. */ private static final long RESUBSCRIBE_MIN = 19; @Inject private DiqubeServletConfig config; @Inject private TicketValidityService ticketValidityService; private volatile long nextTimestampToFetchListFromServer = 0L; private volatile long nextTimestampToResubscribeToServer = 0L; private AtomicBoolean lastFetchSuccessful = new AtomicBoolean(false); @Override public void servletConfigurationAvailable() { // as soon as configuration is available, we try to connect and subscribe. work(); } @PreDestroy public void cleanup() { if (nextTimestampToResubscribeToServer != 0L) // we probably are subscribed. If not any more, it is not bad to call. try { openIdentityService().unregisterCallback(config.createClusterResponseAddr()); } catch (TException e) { throw new RuntimeException("Could not register to receive logout updates."); } } /** * Work method. Gets called pretty often and registers at the server/fetches updated logged out lists. */ private void work() { if (System.currentTimeMillis() > nextTimestampToResubscribeToServer) { synchronized (this) { if (System.currentTimeMillis() > nextTimestampToResubscribeToServer) { try { openIdentityService().registerCallback(config.createClusterResponseAddr()); logger.info("Registered at a diqube server for updates on logged out tickets."); nextTimestampToResubscribeToServer = System.currentTimeMillis() + RESUBSCRIBE_MIN * 60 * 1_000L; } catch (RuntimeException | TException e) { logger.warn("Could not subscribe to logout updates at diqube-servers!", e); } } } } if (System.currentTimeMillis() > nextTimestampToFetchListFromServer) { // This is meant to block all threads until a new list has been fetched! We must not accept anything before we did // not fetch a new list! synchronized (this) { if (System.currentTimeMillis() > nextTimestampToFetchListFromServer) { try { List<TicketInfo> invalidTickets = openIdentityService().getInvalidTicketInfos(); logger.info("Fetched up-to-date list of logged out tickets."); // actually mark tickets as invalid. for (TicketInfo t : invalidTickets) ticketValidityService.markTicketAsInvalid(t); lastFetchSuccessful.set(true); nextTimestampToFetchListFromServer = System.currentTimeMillis() + config.getLogoutTicketFetchSec() * 1_000L; } catch (RuntimeException | TException e) { lastFetchSuccessful.set(false); logger.warn("Could not fetch up-to-date logout list from diqube-server!", e); // retry in 2r seconds nextTimestampToFetchListFromServer = System.currentTimeMillis() + 2 * 1_000L; } } } } } @Override public void socketOpened() { work(); } @Override public void socketMessage() { work(); } @Override public boolean areTicketsAcceptable() { // Only accept any Ticket in the UI if we were able to reach a diqube-server recently and were able to load a // current list of Tickets which seem to be valid, but have been logged out (and therefore are not valid anymore). // If we did not reach any diqube-server, then we will accept NO tickets at all, since they could have been logged // out in the meantime and we simply do not know about it. return lastFetchSuccessful.get(); } private IdentityService.Iface openIdentityService() { IdentityService.Iface identityService = openConnection(IdentityService.Client.class, IdentityServiceConstants.SERVICE_NAME); if (identityService == null) throw new RuntimeException("Could not connect to any cluster node!"); return identityService; } private <T> T openConnection(Class<T> thriftClientClass, String serviceName) { for (Pair<String, Short> node : config.getClusterServers()) { TTransport transport = new TFramedTransport(new TSocket(node.getLeft(), node.getRight())); TProtocol protocol = new TMultiplexedProtocol(new TCompactProtocol(transport), serviceName); T res; try { res = thriftClientClass.getConstructor(TProtocol.class).newInstance(protocol); } catch (InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException | NoSuchMethodException | SecurityException e) { throw new RuntimeException("Could not instantiate thrift client", e); } try { transport.open(); } catch (TTransportException e) { continue; } return res; } return null; } }