Starting 'runConsoleEventLoop' from a secondary thread.

Issue #215 resolved
WayneK
created an issue

Hi,

First, thanks for a extremely useful library, kudos.

I have a CoreBluetooth based BLE advertisement scanner working with PyObjc all ok. As I am putting this into a (multi-platform) Python module and I would like the main loop to be kicked off from a secondary thread created by the library, so to stay out of the way of users code.

In order to start the RunLoop using 'AppHelper.runConsoleEventLoop' on a thread I have created an Autorelease pool within the thread but am not receiving Bluetooth events.
I /think/ I need to create and pass a new dispatch queue to 'CoreBluetooth.CBCentralManager.initWithDelegate_queue_options_' created within the same thread, the but PyObjC doesn't support dispatch_queue_t yet.

I've read that starting a runloop on a secondary thread /should/ be possible.. is it really true for Objc? is it really possible in PyObc C ?

Do I really need a dispatch_queue_t? Is there an rough estimate as to when it will be added?

Thanks, Wayne

Comments (11)

  1. Ronald Oussoren repo owner

    Eventloops on secondary threads should work fine, but I don't know if CBCentralManager works on a secondary thread.

    I don't know when I'll add dispach_queue_t wrappers, but those are fairly high on my list because more and more APIs use them.

  2. WayneK reporter

    Hi,

    It would appear that to run CoreBluetooth on a secondary thread then using a dispach_queue_t is necessary.

    "If you want to use a different thread to do more sophisticated things, then you need to create a queue and pass it..."

    Source: https://www.invasivecode.com/weblog/core-bluetooth-for-ios-6-core-bluetooth-was/

    I was wondering what level the complexity in dispach_queue_t wrappers might be?
    By that I mean to understand could the wrapper be a simple API 'pass-thru' style? Such that a novice to this could 'have a go', or, do they need to be more complex (e.g. stateful and Py/ObjC thread aware) and require more pervasive changes to PyObjC, so better left to someone more experienced?

    Thanks Wayne

  3. WayneK reporter

    Is my attempt at trying to pass the ctypes dispatch_queue_t opaque pointer failing because it's not of a type supported by the PyObjC parameter proxying mechanism ?

  4. Ronald Oussoren repo owner

    FWIW, I've started work on libdispatch bindings.

    Those will work on macOS 10.10 or later, because the libdispatch types are Objective-C classes starting at that release and that makes wrapping a lot easier.

    The initial commit is in the branch add-libdispatch-bindings, and is incomplete. Once I'm happy with those bindings I'll update the metadata for other APIs using libdispatch types and everything should then work out of the box.

  5. WayneK reporter

    fantastic, great news. I will keep an eye on it and test when/where I can to give feedback.
    Is there an dedicated task/issue I can 'watch' to get notifications? (assuming this one isn't the right place)

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