/** * An event is to be sent down the stack. The layer may want to examine its type and perform some * action on it, depending on the event's type. If the event is a message MSG, then the layer may * need to add a header to it (or do nothing at all) before sending it down the stack using <code> * PassDown</code>. In case of a GET_ADDRESS event (which tries to retrieve the stack's address * from one of the bottom layers), the layer may need to send a new response event back up the * stack using <code>up_prot.up()</code>. The PING protocol is interested in several different * down events, Event.FIND_INITIAL_MBRS - sent by the GMS layer and expecting a GET_MBRS_OK * Event.TMP_VIEW and Event.VIEW_CHANGE - a view change event Event.BECOME_SERVER - called after * client has joined and is fully working group member Event.CONNECT, Event.DISCONNECT. */ @SuppressWarnings("unchecked") public Object down(Event evt) { switch (evt.getType()) { case Event.FIND_INITIAL_MBRS: // sent by GMS layer case Event.FIND_ALL_VIEWS: // sends the GET_MBRS_REQ to all members, waits 'timeout' ms or until 'num_initial_members' // have been retrieved long start = System.currentTimeMillis(); boolean find_all_views = evt.getType() == Event.FIND_ALL_VIEWS; Promise<JoinRsp> promise = (Promise<JoinRsp>) evt.getArg(); List<PingData> rsps = find_all_views ? findAllViews(promise) : findInitialMembers(promise); long diff = System.currentTimeMillis() - start; if (log.isTraceEnabled()) log.trace("discovery took " + diff + " ms: responses: " + Util.printPingData(rsps)); return rsps; case Event.TMP_VIEW: case Event.VIEW_CHANGE: List<Address> tmp; view = (View) evt.getArg(); if ((tmp = view.getMembers()) != null) { synchronized (members) { members.clear(); members.addAll(tmp); } } current_coord = !members.isEmpty() ? members.get(0) : null; is_coord = current_coord != null && local_addr != null && current_coord.equals(local_addr); return down_prot.down(evt); case Event.BECOME_SERVER: // called after client has joined and is fully working group member down_prot.down(evt); is_server = true; return null; case Event.SET_LOCAL_ADDRESS: local_addr = (Address) evt.getArg(); return down_prot.down(evt); case Event.CONNECT: case Event.CONNECT_WITH_STATE_TRANSFER: case Event.CONNECT_USE_FLUSH: case Event.CONNECT_WITH_STATE_TRANSFER_USE_FLUSH: is_leaving = false; group_addr = (String) evt.getArg(); Object ret = down_prot.down(evt); handleConnect(); return ret; case Event.DISCONNECT: is_leaving = true; handleDisconnect(); return down_prot.down(evt); default: return down_prot.down(evt); // Pass on to the layer below us } }