Re: [Task Scheduler] scheduling flexibility

Actually, I think we might need to go further than this. Allowing web apps
to request to be woken up with precise scheduling seems very dangerous from
a battery life perspective. Would it be possible to split this API into two
use cases?

1. An API for precise scheduling, which **requires you to show a
user-visible notification** to prevent developers from abusing it. For use
by calendar notifications, alarm clocks, etc. Could be an extension of Web
Notifications <http://www.w3.org/TR/notifications/>.

2. An API for inexact scheduling (e.g. background syncing). For example,
instead of asking to be woken up at a specific DOMTimeStamp, you would just
give an optional minimum time delay; the system would guarantee not to wake
you up before that, but would choose any convenient moment afterwards. Most
apps would just choose the smallest time delay we offer them (which is
fine, as the convenient moment mechanism would throttle them), but
sometimes an app knows that there's no point in running until some point in
the future, which is when they would provide a non-zero minimum time delay.

Possible heuristics that the system might use to decide what is convenient
time for background execution include:
- batching requests together with other apps
- being on WiFi
- being plugged in to a charger
- the screen being on (or device being awake for some other reason)
- the network being active
- the user not being asleep
- learning at what times of day each app gets used, and prioritizing
syncing etc shortly before the app is likely to be used
- learning in what locations each app gets used, similarly
- how recently/frequently the app has been used
- how recently the device was last used

Of course the heuristics would be implementation-defined, so
implementations can optimize battery life without having to update the spec
each time.

Thanks,
John


On Tue, Nov 5, 2013 at 1:35 PM, Michael van Ouwerkerk <
mvanouwerkerk@chromium.org> wrote:

> How do people feel about allowing for scheduling flexibility in the Task
> Scheduler API? The goal of this feature would be to save battery power. If
> the system has flexibility about when to precisely run a task, it could
> batch multiple tasks together, or only run tasks when the device is awake.
> This way, we could avoid waking up devices too frequently.
>
> Some use cases require precise scheduling e.g. an alarm in the morning, or
> a cooking timer. But there are many tasks that are much less time
> sensitive, these could be scheduled flexibly e.g. syncing a news feed or
> auto-updating to a new version.
>
> Any comments? My apologies if this issue has been discussed previously.
>
> Regards,
>
> Michael van Ouwerkerk
>
>