[Kde-pim] Akonadi Resource - setOnline troubles

[Christian Mollekopf]

On Wednesday 19 February 2014 17.31:13 Daniel Vrátil wrote:
> On Tuesday 18 of February 2014 16:41:35 Kevin Krammer wrote:
> > On Tuesday, 2014-02-18, 16:31:43, Daniel Vrátil wrote:
> > > On Monday 17 of February 2014 22:21:09 Martin Koller wrote:
> > > > In the patch I created for the DAV resource (to make it automatically
> > > > offline when it can not reach the server) I see a problem with the
> > > > online/offline switching:
> > > > When I use setOnline(false), the baseclass stores this as "desired
> > > > status
> > > > == offline", which also means whenever the network goes away (e.g.
> > > > suspend Laptop) and comes again (resume Laptop) detected by Solid, it
> > > > would not automatically try to set the resource to online, because the
> > > > baseclass still thinks, my desire is to have it offline.
> > > > 
> > > > How can I overcome this ?
> > > > 
> > > > I want to set the resource to "temporarily offline" and therefore to
> > > > activate the change recorder, but as soon as possible (either via my
> > > > QTimer
> > > > or when Solid detects network activation) I want that the resource
> > > > retries
> > > > to go online.
> > > > 
> > > > I could also listen to the Solid events, but I see this as an ugly
> > > > solution, as this is something every network needing resource should
> > > > do.
> > > > 
> > > > What about a new method in AgentBase ?, e.g.
> > > > void setTemporaryOffline() { setOnlineInternal(false); }  // not
> > > > storing
> > > > state as desired state
> > > 
> > > Yup, this sounds reasonable. Maybe setTemporaryOffline could even take
> > > an
> > > argument for timeout, set up a timer internally and then emit a signal,
> > > that resource implementations would connect to to check whether we are
> > > online already. Afaik this is pretty much what you've done in the DAV
> > > resource and similar solution would be used in other resources too, so
> > > having this as part of ResourceBase would prevent some code duplication.
> > 
> > I think we have discussed something similar before, i.e. the need to have
> > more states than just online/offline.
> > 
> > The earlier discussion was mostly about distingushing different forms of
> > "offline", i.e. whether the resource or the user is the originator of the
> > state.
> 
> I found the (rather long :) email from Andreas from December 2012.  What I
> understand from the proposal is to have following states:
> 
> TurnedOff
> Akonadi is not allowed to talked to the resource and the resource does
> nothing. But how does the resource get into this state? And when should it
> recover? Is this set by user, server or resource itself?
> 

By the user typically (or an application that deems it suitable), just like 
StayDisconnected.

> StayDisconnected
> Resource was set offline by user or application. Akonadi can talk to it, but
> resource is not allowed to talk to it's storage (IMAP server, maildir...).
> Resource has to be switched to Connected state manually by user or
> application again.
> In this state any attempt to retrieve data from the resource will result in
> ItemRetrievalException on the server, user will be shown a weird error (we
> seriously need Akonadi server to send reasonable error messages we can show
> to users) and KMail will get stuck on "Retrieving email...", because it can
> only tell that ItemFetchJob failed, but does not know why (or has this been
> fixed already?)
> 
> Disconnected
> Resource requires access to network, but no network is available.
> ResourceBase automatically moves between Disconnected and Connected states
> based on network availability reported by Solid. There is the same problem
> with data retrieval as in StayDisconnected.
> 
> TemporaryDisconnected ( == BackendNotAvailable? )
> Network is available,  but connection to server cannot be established (or
> maildir folder is not available because it's not mounted for instance).
> Resource sets itself to this state and will attempt to reach the backend
> periodically (ResourceBase will emit a "tryReconnect" signal in configurable
> intervals). Once it succeeds, it will switch itself back to Connected.
> 
> Connected
> Everything is fine.
> 
> 
> Is this +- what you and Andreas had in mind?
> 

Sounds good to me.

We really need to avoid that the resources disable themselves (Turned Off, Stay 
Disconnected). I don't know how many times I had mails stuck in my outbox 
because Local Folders somehow went offline.


> > Maybe this is just another good reason to get this rolling? :)
> 
> Right, I doubt I'll get to do it anytime soon, so if Martin is willing do
> dig deeper into kdepimlibs, why not :-)
> 
That would be awesome indeed =)

Cheers,
Christian

_______________________________________________
KDE PIM mailing list kde-pim at kde.org
https://mail.kde.org/mailman/listinfo/kde-pim
KDE PIM home page at http://pim.kde.org/