[SailfishDevel] QML Timer stops running

[Luca Donaggio]

I'm in a  similar situation: I've written a small app for my personal use
that periodically download some stats from one of my company's web servers.
I'm perfectly fine with it not doing anything while in deep-sleep, but I
would like to do a forced update as soon as the device wakes up.
How can I detect such event from C++ side (my app is run as a daemon
actually, so no qml involved)? Is there some DBus signal I can listen to?

Thanks,

Luca Donaggio


On Wed, Jan 15, 2014 at 9:26 AM, Jonni Rainisto <jonni.rainisto at jolla.com>wrote:

> Hi,
>
> For the love of ***, dont use libiphb every 5 seconds, that will kill
> batterylife for suspend (store QA will reject apps that eat battery). Its
> more meant to be triggered every 10, 15, 30 etc. minutes. So if you want to
> make 25 minute timer that works even while suspended, then you should do
> libiphb to wake up after 25 minutes.
>
> Or if you want to make libiphb to wake up device every 10 minutes, you can
> make your application to check how much time has really passed since last
> wakeup by checking hw clock (as that is the only clock which is updated
> even while beeing suspended) timestamps like this:
>
> static void tv_get_monotime(struct timeval *tv)
> {
> #if defined(CLOCK_BOOTTIME)
>   struct timespec ts;
>   if (clock_gettime(CLOCK_BOOTTIME, &ts) < 0)
>       if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0)
>           qFatal("Can't clock_gettime!");
>   TIMESPEC_TO_TIMEVAL(tv, &ts);
> #endif
> }
>
>
> ________________________________________
> From: devel-bounces at lists.sailfishos.org [
> devel-bounces at lists.sailfishos.org] on behalf of Thomas Tanghus [
> thomas at tanghus.net]
> Sent: Tuesday, January 14, 2014 4:11 PM
> To: Sailfish OS Developers
> Subject: Re: [SailfishDevel] QML Timer stops running
>
> On Tuesday 14 January 2014 13:05 Graham Cobb wrote:
> > On 14/01/14 01:14, Thomas Tanghus wrote:
> > > On Tuesday 14 January 2014 01:53 Ove Kåven wrote:
> > >> No matter what OS or platform you're on, counting the number of times
> > >> your timer callback is called is *never* a good idea, even on desktop
> > >> PCs. Timer callbacks can be skipped for any number of reasons (heavy
> > >> system load, laptop suspend, etc).
> >
> > > Good point. That will also at least work around the issue when in
> > > "pre-deep- sleep".
> >
> > I agree with Ove (that is how every timer function I have ever worked on
> > works, from interrupt handlers in embedded system kernels through to the
> > GPE Calendar app) -- repeating timers are a convenience, but are never
> > treated as accurate.
> >
> > But I would also suggest that for any apps that do timing, when the app
> > is not being displayed (and so the screen doesn't need to be updated),
> > the code should switch to using a single-shot timer set to the time when
> > the next event happens, instead of using repeating timers.  If the
> > kitchen timer is set for 25 minutes and the screen is blank you don't
> > want your app waking up every second.  Of course, it is a little bit
> > tedious to write the code to cancel the long timer and restart short
> > timers when the screen is turned back on but the user will thank you for
> it.
>
> It sounds like a good idea, and should be fairly easy to implement. I just
> don't know how to detect when the screen is off (this is my first
> baby-steps
> in mobile coding). We have the applicationActive property, but the cover
> can
> still be active and visible while it is false.
>
> > Unfortunately, I have no idea how you actually set up a single shot
> > timer that will fire correctly in deep sleep from the Qt environment
> > (the last time I implemented that logic was on Maemo).
>
> Rainisto pointed to libiphb[1] which I have now implemented with a crude
> wakeup every 5-10 seconds. Not optimal, but I'm OK with it for v 0.1.1 ;)
>
> [1] http://talk.maemo.org/showpost.php?p=1401318&postcount=2
>
> --
> Med venlig hilsen / Best Regards
>
> Thomas Tanghus
> _______________________________________________
> SailfishOS.org Devel mailing list
> _______________________________________________
> SailfishOS.org Devel mailing list
>



-- 
Luca Donaggio
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