peerview.java

JXTA&#8482 is a set of open, generalized peer-to-peer (P2P) protocols that allow any networked devi

         * a rdv.
         *
         * - A probe to the peer whose adv we received, because we want
         * confirmation that it's alive.
         *
         * - A response with a random adv from our cache if we're being probed
         *
         * We may send more than one message.
         */

        boolean status;

        if (!isCached) {
            if (!isResponse) {
                // Type 1: Respond to probe
                //
                // We are being probed by an edge peer or peerview member. We respond
                // with our own advertisement.
                status = send(pve, self, true, false);

                if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
                    LOG.fine("Type 1 (Respond with self PVE) : Sent to " + pve + " result =" + status);
                }

                // Type 3: Respond with random entry from our PV when we are probed.
                //
                // Respond with a strategized adv from our view.
                PeerViewElement sendpve = replyStrategy.next();

                if ((sendpve != null) && !pve.equals(sendpve) && !self.equals(sendpve)) {
                    status = send(pve, sendpve, true, false);
                    if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
                        LOG.fine("Type 3 (Respond with random PVE) : Sent " + sendpve + " to " + pve + " result=" + status);
                    }
                }
            } else {
                // Heartbeat: do nothing.
            }
        } else if (isResponse) {
            if (isNewbie && !useOnlySeeds && !isFromEdge) {
                // Type 2: Probe a peer we have just learned about from a referral.
                //
                // If useOnlySeeds, we're not allowed to talk to peers other than our 
                // seeds, so do not probe anything we learn from 3rd party. (Probing of
                // seeds happens as part of the "kick" strategy).
                status = send(pve, self, false, false);

                if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
                    LOG.fine("Type 2 (Probe PVE) : Probed " + pve + " result=" + status);
                }
            } else {
                // Already known or ignoring: do nothing.
            }
        } else {
            // Invalid : do nothing.
        }
    }

    /**
     * {@inheritDoc}
     */
    @SuppressWarnings("fallsthrough")
    public void rendezvousEvent(RendezvousEvent event) {

        if (closed) {
            return;
        }

        boolean notifyFailure = false;

        synchronized (this) {

            int theEventType = event.getType();

            if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
                LOG.fine("[" + group.getPeerGroupName() + "] Processing  " + event);
            }

            refreshSelf();

            if ((RendezvousEvent.BECAMERDV == theEventType) || (RendezvousEvent.BECAMEEDGE == theEventType)) {
                // kill any existing watchdog task
                if (null != watchdogTask) {
                    removeTask(watchdogTask);
                    watchdogTask.cancel();
                    watchdogTask = null;
                }
            }

            switch (theEventType) {
            case RendezvousEvent.RDVCONNECT:
            case RendezvousEvent.RDVRECONNECT:
            case RendezvousEvent.CLIENTCONNECT:
            case RendezvousEvent.CLIENTRECONNECT:
            case RendezvousEvent.RDVFAILED:
            case RendezvousEvent.RDVDISCONNECT:
            case RendezvousEvent.CLIENTFAILED:
            case RendezvousEvent.CLIENTDISCONNECT:
                break;

            case RendezvousEvent.BECAMERDV:
                openWirePipes();
                watchdogTask = new WatchdogTask();
                addTask(watchdogTask, WATCHDOG_PERIOD, WATCHDOG_PERIOD);
                rescheduleKick(true);
                break;

            case RendezvousEvent.BECAMEEDGE:
                openWirePipes();
                if (!localView.isEmpty()) {
                    // FIXME bondolo 20040229 since we likely don't have a
                    // rendezvous connection, it is kind of silly to be sending
                    // this now. probably should wait until we get a rendezvous
                    // connection.
                    notifyFailure = true;
                }
                rescheduleKick(true);
                break;

            default:
                if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
                    LOG.warning("[" + group.getPeerGroupName() + "] Unexpected RDV event : " + event);
                }
                break;
            }
        }

        // we can't do the notification under synchronization.
        if (notifyFailure) {
            notifyFailure(self, true);
        }
    }

    public void start() {// do nothing for now... all the good stuff happens as a result of
        // rendezvous events.
    }

    public void stop() {

        synchronized (this) {
            // Only one thread gets to perform the shutdown.
            if (closed) {
                return;
            }
            closed = true;
        }

        // notify other rendezvous peers that we are going down
        notifyFailure(self, true);

        // From now on we can nullify everything we want. Other threads check
        // the closed flag where it matters.
        synchronized (this) {
            if (watchdogTask != null) {
                removeTask(watchdogTask);
                watchdogTask.cancel();
                watchdogTask = null;
            }

            // Remove message listener.
            endpoint.removeIncomingMessageListener(SERVICE_NAME, uniqueGroupId);

            // Remove rendezvous listener.
            rdvService.removeListener(this);

            // Remove all our pending scheduled tasks
            // Carefull with the indices while removing: do it backwards, it's
            // cheaper and simpler.

            synchronized (scheduledTasks) {
                Iterator<TimerTask> eachTask = scheduledTasks.iterator();

                while (eachTask.hasNext()) {
                    try {
                        TimerTask task = eachTask.next();

                        task.cancel();
                        eachTask.remove();
                    } catch (Exception ez1) {
                        if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
                            LOG.log(Level.WARNING, "Cannot cancel task: ", ez1);
                        }
                    }
                }
            }

            // Make sure that we close our WirePipes
            closeWirePipes();

            // Let go of the up and down peers.
            downPeer = null;
            upPeer = null;
            localView.clear();

            timer.cancel();

            rpvListeners.clear();
        }
    }

    protected void addTask(TimerTask task, long delay, long interval) {

        synchronized (scheduledTasks) {
            if (scheduledTasks.contains(task)) {
                if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
                    LOG.warning("Task list already contains specified task.");
                }
            }
            scheduledTasks.add(task);
        }

        if (interval >= 1) {
            timer.schedule(task, delay, interval);
        } else {
            timer.schedule(task, delay);
        }
    }

    protected void removeTask(TimerTask task) {
        scheduledTasks.remove(task);
    }

    /**
     * Adds the specified URI to the list of seeds. Even if useOnlySeeds is in
     * effect, this seed may now be used, as if it was part of the initial
     * configuration.
     *
     * @param seed the URI of the seed rendezvous.
     */
    public void addSeed(URI seed) {
        if (seedingManager instanceof URISeedingManager) {
            ((URISeedingManager) seedingManager).addSeed(seed);
        }
    }

    /**
     * Probe the specified peer immediately.
     * <p/>
     * Note: If "useOnlySeeds" is in effect and the peer is not a seed, any response to this probe will be ignored.
     */
    public boolean probeAddress(EndpointAddress address, RouteAdvertisement hint) {

        PeerViewElement holdIt;

        synchronized (localView) {
            holdIt = self;
        }

        return send(address, hint, holdIt, false, false);
    }

    /**
     * Send our own advertisement to all of the seed rendezvous.
     */
    public void seed() {
        long reseedRemaining = earliestReseed - TimeUtils.timeNow();

        if (reseedRemaining > 0) {
            // Too early; the previous round is not even done.
            if (Logging.SHOW_INFO && LOG.isLoggable(Level.INFO)) {
                LOG.info("Still Seeding for " + reseedRemaining + "ms.");
            }
            return;
        }

        if (Logging.SHOW_INFO && LOG.isLoggable(Level.INFO)) {
            LOG.info("New Seeding...");
        }

        // Schedule sending propagated query to our local network neighbors.
        send(null, null, self, false, false);

        long iterations = 0;

        if (localView.size() < minHappyPeerView) {
            // We only do these things if we don't have a "happy" Peer View.
            // If the Peer View is already "happy" then we will use only
            // Peer View referrals for learning of new entires.

            List<RouteAdvertisement> seedRdvs = new ArrayList<RouteAdvertisement>(
                    Arrays.asList(seedingManager.getActiveSeedRoutes()));

            while (!seedRdvs.isEmpty()) {
                RouteAdvertisement aSeed = seedRdvs.remove(0);

                if (null == aSeed.getDestPeerID()) {
                    // It is an incomplete route advertisement. We are going to assume that it is only a wrapper for a single ea.
                    Vector<String> seed_eas = aSeed.getDest().getVectorEndpointAddresses();

                    if (!seed_eas.isEmpty()) {
                        EndpointAddress aSeedHost = new EndpointAddress(seed_eas.get(0));

                        // XXX 20061220 bondolo We could check all of our current PVEs to make sure that this address is not already known.

                        send(aSeedHost, null, self, false, false);
                    }
                } else {
                    // We have a full route, send it to the virtual address of the route!
                    // FIXME malveaux 20070816 Second part of conjunct can be removed once 'self' is included in the peerview
                    if ((null == getPeerViewElement(aSeed.getDestPeerID())) && !group.getPeerID().equals(aSeed.getDestPeerID())) {
                        EndpointAddress aSeedHost = new EndpointAddress("jxta", aSeed.getDestPeerID().getUniqueValue().toString(),
                                null, null);

                        send(aSeedHost, aSeed, self, false, false);
                    }
                }
            }

            if (!useOnlySeeds) {
                // If use only seeds, we're not allowed to put in the peerview
                // anything but our seed rdvs. So, we've done everything that
                // was required.

                // Schedule sending propagated query to our advertising group
                if (advertisingGroup != null) {
                    // send it, but not immediately.
                    scheduleAdvertisingGroupQuery(DEFAULT_SEEDING_PERIOD * 2);
                }
            }
        }

        earliestReseed = TimeUtils.toAbsoluteTimeMillis(seedingRdvConnDelay + (DEFAULT_SEEDING_PERIOD * iterations));
    }

    /**
     * Make sure that the PeerView properly changes behavior, when switching
     * from edge mode to rdv mode, and vice-versa.
     * Since openWirePipes() requires some other services such as the Pipe
     * Service, and since updateStatus is invoked this work must happen in
     * background, giving a chance to other services to be started.
     */
    private class OpenPipesTask extends TimerTask {

        /**
         * {@inheritDoc}
         */
        @Override
        public void run() {
            try {
                if (closed) {
                    return;
                }

                openWirePipes();
            } catch (Throwable all) {
                if (Logging.SHOW_SEVERE && LOG.isLoggable(Level.SEVERE)) {
                    LOG.log(Level.SEVERE, "Uncaught Throwable in thread: " + Thread.currentThread().getName(), all);
                }
            } finally {
                removeTask(this);
            }
        }
    }