On Tue, Jul 7, 2009 at 10:08 PM, Matthew Toseland<[email protected]> wrote: > On Tuesday 07 July 2009 20:41:54 sashee wrote: >> Maybe I don't see something, but I think it is much more simpler. Here it is: >> >> When the processing of RequestElement starts, the ClientRequest object >> is already activated, because FCPClient:305 activates all requests, >> and puts to the v List, and those object are the very same objects >> RequestElement works with. So they are initialized, but maybe the >> Fetch(Insert)Context isn't. So activate it. And also the EventProducer >> if not activated. As the constructor has the ObjectContainer object, >> it can activate. As I see this is used at ClientGet:785. invoked from >> RequestElement:122 , and it seems to be working. > > Yes. But these objects may become deactivated shortly after the constructor > ends.
Why can they deactivated? They are actively fetching a file, so they are needed. Where are they deactivated? >> >> The only problem seems to be that these listeners shouldn't be >> persisted, they aren't supposed to survive a restart. So I think I >> should create a mechanism for transient eventlisteners. > > Which is pretty much what I was saying. You can't just add a listener to each > request because it may be deactivated. But if you add it at e.g. the > FCPClient level, you can get a callback while it is active. >> >> What you think about it? >> >> sashee >> >> On Tue, Jul 7, 2009 at 7:56 PM, Matthew >> Toseland<[email protected]> wrote: >> > On Tuesday 07 July 2009 18:50:58 Matthew Toseland wrote: >> >> On Tuesday 07 July 2009 18:26:40 Matthew Toseland wrote: >> >> > public void addEventListener(ClientEventListener cel) { >> >> > + if(listeners==null){ >> >> > + //Don't know how it can happen, but it did, and >> >> > checking for null isn't going to hurt anything >> >> > + listeners=new Vector<ClientEventListener>(); >> >> > + } >> >> > if(cel != null) >> >> > listeners.addElement(cel); >> >> > else >> >> > throw new IllegalArgumentException("Adding a null >> >> > listener!"); >> >> > } >> >> > >> >> > It can't happen for transient requests. For persistent requests, a >> >> > persistence-related bug in the code might well cause it to happen >> >> > however. :( >> >> > >> >> Okay, now I see what is going on ... >> >> >> >> + public RequestElement(ClientRequest clientRequest, int[] columns, >> >> String path, ObjectContainer container, boolean advancedModeEnabled, >> >> String[] priorityClasses, boolean isUpload, ToadletContext ctx) { >> >> ... >> >> + if (clientRequest instanceof ClientGet) { >> >> + if (((ClientGet) >> >> clientRequest).getFetchContext().eventProducer != null) ((ClientGet) >> >> clientRequest).getFetchContext().eventProducer.addEventListener(progressListener); >> >> + } else if (clientRequest instanceof ClientPutBase) { >> >> + if (((ClientPutBase) >> >> clientRequest).getInsertContext().eventProducer != null) ((ClientPutBase) >> >> clientRequest).getInsertContext().eventProducer.addEventListener(progressListener); >> >> + } else { >> >> + System.err.println("Dont know this type! type:" + >> >> clientRequest.getClass()); >> >> + } >> >> + >> >> clientRequest.getClient().addRequestCompletionCallback(progressListener); >> >> + } >> >> >> >> >> >> Anything on the download/upload page is a persistent request. A >> >> persistent request is either persistence=reboot or persistence=forever, >> >> but the latter is far more common. These requests are *stored in a >> >> database*, and are not always in memory. Using them as variables will >> >> cause them to be pinned in memory but will not ensure they stay >> >> "activated" i.e. that all their fields are loaded and non-null. The only >> >> safe way to access them is to schedule a job on the database thread (the >> >> DBJobRunner, aka NodeClientCore). Hence, the SimpleEventProducer may well >> >> be null, and even if it isn't, it may not be activated, meaning the >> >> listeners array may be null. >> >> >> >> Hence subscribing to the SimpleEventProducer and listening for events is >> >> not going to be sufficient. You need to implement some sort of global >> >> hook, so that when an event is generated against a request in the global >> >> queue (only the global queue is shown on the downloads/uploads pages), >> >> you get a notification, at that point, while the request is still active. >> >> >> >> What you need to do is as follows: >> >> - FCPServer.globalRebootClient is the half of the global queue that is >> >> persistence=reboot, that is, the part that isn't persisted to the >> >> database. You can ignore it for all practical purposes, but you should >> >> really deal with it when you get around to it. >> >> - FCPServer.globalForeverClient is the half of the global queue that is >> >> persistence=forever, and in practice has almost all global requests >> >> (requests or inserts shown on the downloads/uploads pages). It is never >> >> deactivated. >> >> - This is an FCPClient. >> >> - You need to create a callback method and a registry of listeners on >> >> FCPClient that gets fed every FCP event, at the time it is created, along >> >> with the ClientRequest which created it. This happens in >> >> ClientGet.receive, ClientPutBase.receive, and probably that's about it; >> >> check the call hierarchy for the constructors for e.g. >> >> SimpleProgressMessage if you are concerned. This always happens on the >> >> database thread, or at least, if it's not on the database thread, it >> >> schedules a job on the database thread to send the message (e.g. in >> >> ClientPutBase.trySendProgressMessage). So call the callback at that point. >> >> - The callback should go to some sort of manager object, which determines >> >> which RequestElement(s) want the message. Or you can just register all of >> >> them but it will be slower that way. >> >> - Don't store the pointers, store the UID of the request (this is because >> >> we don't want to pin the request object in memory). This is an long value >> >> for a specific request in the database which doesn't change unless we >> >> defrag (which is an offline operation). You can get it by: >> >> >> >> container.ext().getID(<object>). >> >> >> >> Please let me know if you need any more information on this! The db4o zip >> >> file contains javadocs, you can get it from db4o.com, we use version 7.4. >> >> >> > Also, you should not store the ObjectContainer, and should not access the >> > database except on the database thread (i.e. when an ObjectContainer has >> > been passed in ultimately from a DBJob). >> > >> > _______________________________________________ >> > Devl mailing list >> > [email protected] >> > http://emu.freenetproject.org/cgi-bin/mailman/listinfo/devl >> > >> _______________________________________________ >> Devl mailing list >> [email protected] >> http://emu.freenetproject.org/cgi-bin/mailman/listinfo/devl >> >> > > > _______________________________________________ Devl mailing list [email protected] http://emu.freenetproject.org/cgi-bin/mailman/listinfo/devl
