/** begins an http failover. */
  private void checkForStaleUpdateAndMaybeDoHttpFailover() {
    LOG.debug("checking for timeout http failover");
    long monthAgo = clock.now() - ONE_MONTH;
    if (UpdateSettings.LAST_UPDATE_TIMESTAMP.getValue() < monthAgo
        && // more than a month ago
        UpdateSettings.LAST_HTTP_FAILOVER.getValue() < monthAgo
        && // and last failover too
        !httpRequestControl.requestQueued(
            HttpRequestControl.RequestReason.TIMEOUT)) { // and we're not already doing a failover

      long when = (connectionServices.isConnected() ? 1 : 5) * 60 * 1000;
      if (LOG.isDebugEnabled()) LOG.debug("scheduling http failover in " + when);

      backgroundExecutor.schedule(
          new Runnable() {
            public void run() {
              try {
                launchHTTPUpdate(timeoutUpdateLocation);
              } catch (URISyntaxException e) {
                httpRequestControl.requestFinished();
                httpRequestControl.cancelRequest();
                LOG.warn(e.toString(), e);
              }
            }
          },
          when,
          TimeUnit.MILLISECONDS);
    }
  }
  /**
   * Stores the given data to disk & posts an update to neighboring connections. Starts the download
   * of any updates
   */
  private void storeAndUpdate(byte[] data, UpdateCollection uc, UpdateType updateType) {
    if (LOG.isTraceEnabled())
      LOG.trace("Retrieved new data from: " + updateType + ", storing & updating.");
    if (uc.getId() == IGNORE_ID && updateType == UpdateType.FROM_NETWORK)
      throw new IllegalStateException("shouldn't be here!");

    // If an http max request is pending, don't even bother with this stuff.
    // We want to get it straight from the source...
    if (updateType == UpdateType.FROM_NETWORK
        && httpRequestControl.isRequestPending()
        && httpRequestControl.getRequestReason() == HttpRequestControl.RequestReason.MAX) return;

    _lastId = uc.getId();

    _lastTimestamp = uc.getTimestamp();
    UpdateSettings.LAST_UPDATE_TIMESTAMP.setValue(_lastTimestamp);

    long delay = UpdateSettings.UPDATE_DOWNLOAD_DELAY.getValue();
    long random = Math.abs(RANDOM.nextLong() % delay);
    _nextDownloadTime = _lastTimestamp + random;

    _lastBytes = data;

    if (updateType != UpdateType.FROM_DISK) {
      // cancel any http and pretend we just updated.
      if (httpRequestControl.getRequestReason() == HttpRequestControl.RequestReason.TIMEOUT)
        httpRequestControl.cancelRequest();
      UpdateSettings.LAST_HTTP_FAILOVER.setValue(clock.now());

      FileUtils.verySafeSave(CommonUtils.getUserSettingsDir(), FILENAME, data);
      capabilitiesVMFactory.updateCapabilities();
      connectionManager.get().sendUpdatedCapabilities();
    }

    Version limeV;
    try {
      limeV = new Version(LimeWireUtils.getLimeWireVersion());
    } catch (VersionFormatException vfe) {
      LOG.warn("Invalid LimeWire version", vfe);
      return;
    }

    Version javaV = null;
    try {
      javaV = new Version(VersionUtils.getJavaVersion());
    } catch (VersionFormatException vfe) {
      LOG.warn("Invalid java version", vfe);
    }

    // don't allow someone to set the style to be above major.
    int style = Math.min(UpdateStyle.STYLE_MAJOR, UpdateSettings.UPDATE_STYLE.getValue());

    UpdateData updateInfo =
        uc.getUpdateDataFor(
            limeV, ApplicationSettings.getLanguage(), LimeWireUtils.isPro(), style, javaV);

    List<DownloadInformation> updatesToDownload = uc.getUpdatesWithDownloadInformation();
    _killingObsoleteNecessary = true;

    // if we have an update for our machine, prepare the command line
    // and move our update to the front of the list of updates
    if (updateInfo != null && updateInfo.getUpdateURN() != null) {
      prepareUpdateCommand(updateInfo);
      updatesToDownload = new LinkedList<DownloadInformation>(updatesToDownload);
      updatesToDownload.add(0, updateInfo);
    }

    _updateInfo = updateInfo;
    _updatesToDownload = updatesToDownload;

    downloadUpdates(updatesToDownload, null);
    if (updateInfo == null) {
      LOG.warn("No relevant update info to notify about.");
      return;
    } else if (updateInfo.getUpdateURN() == null || isHopeless(updateInfo)) {
      if (LOG.isDebugEnabled())
        LOG.debug(
            "we have an update, but it doesn't need a download.  "
                + "or all our updates are hopeles. Scheduling URL notification...");

      updateInfo.setUpdateCommand(null);

      backgroundExecutor.schedule(
          new NotificationFailover(_lastId),
          delay(clock.now(), uc.getTimestamp()),
          TimeUnit.MILLISECONDS);
    } else if (isMyUpdateDownloaded(updateInfo)) {
      LOG.debug("there is an update for me, but I happen to have it on disk");
      fireUpdate(updateInfo);
    } else LOG.debug("we have an update, it needs a download.  Rely on callbacks");
  }