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Power Management in Symbian

Are there any "best practices" for writing a power-efficient background application in Symbian?

Specifically, is there any way (i.e. API) for a Symbian app to hint the OS regarding its current state in order to reduce battery consumption? In Android, for instance, there is the notion of Wake Locks, which prevents the device from going into standby mode - Is there anything similar in Symbian?

EDIT:
Are there any implications when running code as a separate thread with the Open-C library, and not as "native" Symbian C++, using Active Objects etc.? (the Open-C code is blocking on IO most of the time).

Solution
    1. You can check user (in-)activity with a RTimer::Inactivity() method. This way is described in Forum Nokia Wiki page. There it's also described how you can reset inactivity timer.
    2. You can check whether device screen is turned on or off using HAL API. See classes HAL and HALData. You may use such a call:

    TInt displayState; HAL::Get(HALData::EDisplayState, displayState); And the displayState will hold either 0 if display is turned off or 1 in other case.

    With these APIs you will know whether user is active now, so you'll be able to change behavior of your background service to reduce its power consumption.

    You can also use Nokia Energy Profiler application to record power consumption of handset, with different power saving options of your background service. Also please refer to Nokia's document describing best practices to save power of device. This document is quite straightforward, but useful nonetheless.

    Hope this helps.

    EDIT: About separate thread and Open C. As far as I know, Open C is just a plugin and deep down all the implementations are still "native Symbian". So, as far as you avoid periodic polling of some resource and just use usual blocking IO, your code is quite same economical on power as standard Symbian Active Objects techniques (which use Symbian-specific semaphores to block threads).