Ticket Created
over 3 years ago

WERETECH-12052

Conflict/race between makeWebRequest and Storage.setValue called from onUpdate on a watchface.

Hi, I was able to reproduce the following problem (both in simulator and in a Descent MK1 using SDK 3.2.5 and 4.0.6):

If the function setValue is called from onUpdate while makeWebRequest is still waiting for the webserver to return data,

the callback function is "lost" (and not called).

The following code reproduce the problem 100% of the time.



using Toybox.Application;
using Toybox.Background;
using Toybox.System;
using Toybox.WatchUi;
using Toybox.Time;
using Toybox.Communications;
using Toybox.Application.Storage;

(:background)
class PiServiceDelegate extends Toybox.System.ServiceDelegate {
  function initialize() {
    System.ServiceDelegate.initialize();
  }
  function onTemporalEvent() {
    // That URI takes about 3 seconds to answer
    var uri = "https://wb.elaine.fi/pi_slow";
    System.println("Before query");
    var options = {
      :methods => Communications.HTTP_REQUEST_METHOD_GET,
      :responseType => Communications.HTTP_RESPONSE_CONTENT_TYPE_JSON
    };
    Communications.makeWebRequest(uri, null, options,
                                  method(:pi_received));
  }
  function pi_received(code, data) {
    System.println(code);
    System.println(data);
    if (code == 200) {
      Background.exit(data);
    }
  }
}

(:background)
class PiWatch extends Application.AppBase {
  public function initialize() {
    AppBase.initialize();
  }
  function onBackgroundData(data) {
    System.println("onBackgroundData: " + data);
  }
  function getServiceDelegate() {
    return [new PiServiceDelegate()];
  }
  function getInitialView() {
    Background.registerForTemporalEvent(new Time.Duration(5 * 60));
    return [new PiWatchView(), new PiWatchDelegate()];
  }
}

class PiWatchView extends WatchUi.WatchFace {
  public function initialize() {
    WatchFace.initialize();
  }
  public function onUpdate(dc) {
    System.println("onUpdate");
    // On simulator, onUpdate is ran every seconds
    // So we will call Storage.setValue between the http request
    // and the result
    // On watch same problem exists
    Storage.setValue("foo", "bar");
    // Note that problem does not exists if Storage.setValue
    // is called in onPartialUpdate
  }
}

class PiWatchDelegate extends WatchUi.WatchFaceDelegate {
  public function initialize() {
    WatchFaceDelegate.initialize();
  }
}


Here is the output:


onUpdate
onUpdate
onUpdate
Background: Before query
onUpdate
onUpdate
onUpdate
Error: Symbol Not Found Error
Details: Failed invoking <symbol>
Stack:
onUpdate
onUpdate
onUpdate



If I comment the setValue line, I get the expected result:

onUpdate
onUpdate
onUpdate
onUpdate
Background: Before query
onUpdate
onUpdate
onUpdate
Background: 200
Background: {pi=>3.140000}
onBackgroundData: {pi=>3.140000}
onUpdate
onUpdate
onUpdate
Parents
  • Hi Jim,

    Well, it is also what I do in real apps (save data in onBackgroundData for later use).

    (That said, onUpdate is called only once a minute on the watch (only simulator call it every sec)).

    The code I've uploaded is the minimal test case to a problem I had and even if it's not a good practice, it is still a real bug.

    The reason I used setValue, in onUpdate, is when some informations are not (yet ?) available because of the dual-CPU issue on 5X/MK1/... So I had to store it (heartzones in my case) when I have a result.

    Jean

Comment
  • Hi Jim,

    Well, it is also what I do in real apps (save data in onBackgroundData for later use).

    (That said, onUpdate is called only once a minute on the watch (only simulator call it every sec)).

    The code I've uploaded is the minimal test case to a problem I had and even if it's not a good practice, it is still a real bug.

    The reason I used setValue, in onUpdate, is when some informations are not (yet ?) available because of the dual-CPU issue on 5X/MK1/... So I had to store it (heartzones in my case) when I have a result.

    Jean

Children
  • yes, I have the same results. but on f5xPlus (dual cpu too), f6p  - there is no problem.

    however whether or not this bug will be fixed I would not dare to save something in onUpdate or onPartialUpdate.

    I had a lot of problem when in view I read from storage and in app save into storage, so now after many protection I read/save data not in the same time and saving only in 3 places app.onStop, app.onBackgroundData and app.makeReq

  • OnUpdate is called every second in a watchface on a real device for 10 seconds after it leaves low power mode (onExitSleep is first called.)  You can switch the sim to every minute with the checkbox for Settings>Low Power.