Task gets queued despite higher priority

[Cycneus]

I’m working on a profile to let Tasker handle photo geotagging, and it’s coming together pretty nicely but for one strange issue I’m having with task priority. Here’s a sketch of what the profile looks like:

      Profile: [App] Camera

    Priority: 25 Restore: no Enforce: no

    Application: Camera

      Enter: Camera on

    A1: Variable Set [ Name:%LATEST_photo To:%FOTO Do Maths:Off Append:Off ]

    A2: Perform Task [ Name:Sound off Priority:%priority ]



      Exit: Camera off

    Abort Existing Task

    A1: Perform Task [ Name:Sound on Priority:%priority ]

    A2: Perform Task [ Name:Geotag photos Priority:5 ] If [ %LATEST_photo neq %FOTO ]

When I launch the Camera app, the enter task runs as expected and executes the ”Sound off” sub-task (which puts the phone in silent mode to prevent annoying shutter sounds). If I then take a photo and close the camera app, the exit task will fire as expected and (1) restore audio settings before (2) starting the ”Geotag photos” sub-task. This one takes a while to finish, mostly because of a GPS location request action.

Now, here’s the problem. If I re-open the Camera app while the geotagging task is running, the profile becomes active, but the enter task (priority: 25) will not run until the geotagging task (priority: 5) is finished; only then does the ”Sound off” routine in the enter task execute. What gives?

I know what many of you are probably thinking, but no, ”Enforce Task Order” is not enabled in the profile settings. I know, too, that according to the user manual all exit tasks have a priority of %priority+1001 by default; but you’ll notice that I’ve deliberately set the last ”Perform Task” in the exit task to have a priority of 5, thus letting the exit task finish before the geotagging one is executed. And as for the ”Sound on” task, it’s pretty much instantaneous, so the priority shouldn’t be a problem.

Any idea what I might be missing?

[Wayne Longford]

Could you post the Run Log please. 

First make sure it's turned on by going to Menu / More / Run Log. 

Then trigger the profile as usual and afterwards go back to the Run Log and select Menu / External Viewer and copy the log here. Thanks.

[Cycneus]

Sure thing:

20160105 19.30.42 P Active   ID163    [App] Camera
20160105 19.30.42 E Start    ID0:0.0  TaskService
20160105 19.30.42 T Running  ID165    Camera On
20160105 19.30.42 A OK       ID165.1  Camera On.Var Set, %LATEST_photo=DCIM/Camera/PANO_2..
20160105 19.30.42 T Running  ID3:2    Sound Off
20160105 19.30.42 A OK       ID165.2  Camera On.Perform Task, Sound Off
20160105 19.30.42 T ExitOK   ID165    Camera On
20160105 19.30.42 A OK       ID3:2.1  Sound Off.Var Set, %LATEST_sound=all
20160105 19.30.42 A OK       ID3:2.2  Sound Off.Do Not Disturb
20160105 19.30.42 T ExitOK   ID3:2    Sound Off
20160105 19.30.42 E Stop     ID0:0.0  TaskService
20160105 19.30.49 P Inactive ID163    [App] Camera
20160105 19.30.49 E Start    ID0:0.0  TaskService
20160105 19.30.49 T Running  ID166    Camera Off
20160105 19.30.49 T Running  ID21:2   Sound On
20160105 19.30.49 A OK       ID166.1  Camera Off.Perform Task, Sound On
20160105 19.30.49 A OK       ID21:2.1 Sound On.If
20160105 19.30.49 A OK       ID21:2.2 Sound On.Do Not Disturb
20160105 19.30.49 A OK       ID21:2.3 Sound On.Else
20160105 19.30.49 T ExitOK   ID21:2   Sound On
20160105 19.30.49 T Running  ID167:3  Geotag Photos
20160105 19.30.49 A OK       ID166.2  Camera Off.Perform Task, Geotag Photos
20160105 19.30.49 T ExitOK   ID166    Camera Off
20160105 19.30.49 A OK       ID167:3.1 Geotag Photos.Get Location
20160105 19.30.51 P Active   ID163    [App] Camera
20160105 19.30.51 T Running  ID165:4  Camera On
20160105 19.30.56 P Inactive ID163    [App] Camera
20160105 19.30.56 T Running  ID166:5  Camera Off
20160105 19.30.56 T Running  ID21:6   Sound On
20160105 19.30.56 A OK       ID166:5.1 Camera Off.Perform Task, Sound On
20160105 19.30.56 A OK       ID21:6.1 Sound On.If
20160105 19.30.56 A OK       ID21:6.2 Sound On.Do Not Disturb
20160105 19.30.56 A OK       ID21:6.3 Sound On.Else
20160105 19.30.56 T ExitOK   ID21:6   Sound On
20160105 19.30.56 T ExitRep  ID167:3  Geotag Photos
20160105 19.30.56 T Running  ID167:7  Geotag Photos
20160105 19.30.56 A OK       ID166:5.2 Camera Off.Perform Task, Geotag Photos
20160105 19.30.56 T ExitOK   ID166:5  Camera Off
20160105 19.30.58 A OK       ID167:7.1 Geotag Photos.Get Location
20160105 19.31.04 T ExitOK   ID167:7  Geotag Photos
20160105 19.31.04 A OK       ID165:4.1 Camera On.Var Set, %LATEST_photo=DCIM/Camera/PANO_2..
20160105 19.31.04 T Running  ID3:8    Sound Off
20160105 19.31.04 A OK       ID165:4.2 Camera On.Perform Task, Sound Off
20160105 19.31.04 T ExitOK   ID165:4  Camera On
20160105 19.31.04 A OK       ID3:8.1  Sound Off.Var Set, %LATEST_sound=all
20160105 19.31.04 A OK       ID3:8.2  Sound Off.Do Not Disturb
20160105 19.31.05 T ExitOK   ID3:8    Sound Off
20160105 19.31.05 E Stop     ID0:0.0  TaskService

[Wayne Longford]

If an action is in progress then it can't generally be interrupted by another action despite its priority. Priority only determines whereabouts an action will be inserted in the queue of scheduled actions.

With the Get Location action, by default, Tasker considers this action to be in progress until a fix is acquired or it times-out (the default timeout value is 100 seconds). Therefore no other action will start until after this point. 

You can change this behaviour for the Get Location action by selecting the Continue Task Immediately option within the action edit screen. With this option set, Tasker will perform the next queued action without waiting for a location fix to complete.

[Cycneus]

Thanks for the info. I suppose I was thrown off by the part in the user manual that states: "If you want a particular task to always interrupt other tasks that may be executing, give it a high priority". But now that you mention it, it does make sense that a running action won't be interfered with. Unfortunately, the point of the Get Location action in this particular task is to get a GPS fix before going on to geotag a photo, so the "Continue Task" workaround would defeat the purpose.

Here's an interesting thing, though: I managed to get things working anyway, by selecting "Continue Task" like you suggested, but then—somewhat on a hunch—adding a "Wait Until" action that looks for (%TIMES - %LOCTMS) / 60 < 1. In other words, the task continues immediately after the Get Location action, but will wait until the latest GPS fix time is less than one minute before going to the next action. That way, my enter task suddenly was allowed to interfere and run in spite of everything. I believe it has something to do with the special way in which "Wait" actions are handled in terms of task scheduling.

[Rich D]

> Thanks for the info. I suppose I was thrown off by the part in the user manual that states: "If you want a particular task to always interrupt other tasks that may be executing, give it a high priority". But now that you mention it, it does make sense that a running action won't be interfered with.

Correct.  It does say interrupt 'Tasks' not 'actions'  and somewhere in the guide it states that once started a action will not get interupted..  :)

>
> Here's an interesting thing, though: I managed to get things working anyway, by selecting "Continue Task" like you suggested, but then—somewhat on a hunch

Nice hunch,  that is exactly how to handle it.

I believe it has something to do with the special way in which "Wait" actions are handled in terms of task scheduling.
>

Correct.  A wait action will always give other tasks a chance to run. Even tasks with lower priorities will run when a Higher priority task encounters a wait action.

Interesting project..  can I ask why not just start the 'get location' action as soon as the camera app is opened  I would imagine that is how the camera app does it.

I believe you will face the same challenge I found when making a app that saves pics to predesignated folders.  When you quickly take several pictures in a row there is not enough time to manipulate the %FOTO variable before it is reset to the next pic.

I tried many different approaches so to hopefully save you some time this is the one I found to work the best. I never missed a pic with it. It used a camera 'APP' context.

Pic Taken On (1006)
<start>
A1: Anchor
A2: Stop [ With Error:Off Task: ] If [ %WIN !~ %Cameralabel ]
A3: Variable Set [ Name:%foto To:%FOTO Do Maths:Off Append:Off ]
A4: Variable Search Replace [ Variable:%foto Search:/ Ignore Case:On Multi-Line:On One Match Only:Off Store Matches In: Replace Matches:On Replace With: ]
A5: Wait [ MS:542 Seconds:0 Minutes:0 Hours:0 Days:0 ]
A6: Goto [ Type:Action Label Number:1 Label:start ] If [ %foto ~ %Photo ]
A7: If [ %foto !~ %Photo ]
A8: Copy File [ From:%FOTO To:%Picfilename Use Root:Off ]
A9: Variable Set [ Name:%Apicname To:%FOTO Do Maths:Off Append:Off ]
A10: Flash [ Text:Pic saved Long:Off ]
A11: End If
A12: Variable Set [ Name:%Photo To:%FOTO Do Maths:Off Append:Off ]
A13: Variable Search Replace [ Variable:%Photo Search:/ Ignore Case:On Multi-Line:On One Match Only:Off Store Matches In: Replace Matches:On Replace With: ]
A14: Goto [ Type:Action Label Number:1 Label:start ]

Let me know if you have any questions about the task.

Just a suggestion but this is how I would see the flow working.

- Camera app starts
  -- get location (continue task)
  -- start monitoring loop for %FOTO
      --  if %FOTO changes
         --   push %FOTO into a local array
         --  you could check here to see if the location has changed. This would be in case you stop taking pics and leave the camera app open and change locations then start taking pics again.
         --  stop loop if camera app closes
   -- end for loop

-- wait until you have a location fix
--  set the location to all pics in local array ( set the geo tags)

You will want to set this collision settings to ' run together'  in case you open the camera and take more pics while setting the geo tags.. 

Rich...

 

[Cycneus]

Thanks for the info and tips, Rich. It's most appreciated.

The way I solved the issue you mention is kind of clunky, but actually seems to work very well. I chose to eschew %FOTO completely and instead set the profile up to do something like this:

Camera app starts
    - list files in DCIM/Camera
    - write list to Photos.txt

Camera app exits
    - read Photos.txt into %photolist_old array
    - list files in DCIM/Camera to %photolist_new array
    - compare %photolist_old() with %photolist_new() and save differing (new) file paths to %photos_new array
    - if %photos_new1 is set
        - get location
        - geotag new photos

can I ask why not just start the 'get location' action as soon as the camera app is opened

 I prefer to only fire the resource-hungry location action if there actually are new photos to geotag. Sometimes you miss and delete shots, sometimes you record videos, etc.

I should very much like to try your elegant solution—keeping everything in the enter task by pushing new values of %FOTO into a local array—but for some strange reason, %FOTO has stopped updating on my end, even though it worked fine only a couple of days ago. To be continued, I guess!

[Rich D]

> Thanks for the info and tips, Rich. It's most appreciated.
>
> The way I solved the issue you mention is kind of clunky, but actually seems to work very well. I chose to eschew %FOTO completely and instead set the profile up to do something like this:
>
> Camera app starts
>     - list files in DCIM/Camera
>     - write list to Photos.txt
>
> Camera app exits
>     - read Photos.txt into %photolist_old array
>     - list files in DCIM/Camera to %photolist_new array
>     - compare %photolist_old() with %photolist_new() and save differing (new) file paths to %photos_new array
>     - if %photos_new1 is set
>         - get location
>         - geotag new photos

but for some strange reason, %FOTO has stopped updating on my end.

Huh..  the only reason I suggested the %FOTO approach was I saw you were already using it and assumed it was working for you. As I stated the above approach   worked on my device for a long time. However I wanted to make a app out of my project and there are 2 issues with using %FOTO across multiple devices.

1. %FOTO will not work if you have your camera saving the pics to your external sd card.

2. Some users have reported %FOTO not working correctly on their particular device.

So I did change my approach to something similar to what you are using.  It might be a bit simpler and more reliable (if you have "a LOT" of pics in DCIM camera)

It uses a shell find command.  The way it works is I write to a file called 'timestamp.txt' when the camera app opens then to retrieve all the files in 'DCIM/Camera' that have been modified since that file was accessed I use the following shell find command.

This goes in the enter task

A1: Write File [ File:timestamp.txt Text:a Append:Off Add Newline:On ]

And this goes in the exit task

A2: Run Shell [ Command:find %DCIM_path -newer /storage/sdcard0/timestamp.txt Timeout (Seconds):0 Use Root:Off Store Output In:%picpath Store Errors In: Store Result In: ]

This will give you a line feed separated list of all the files from when 'timestamp.txt' was modified to the current time.

Here is the entire exit task.

Pic Taken 2 (1119)
Run Both Together
<start>
A1: Anchor
A2: Variable Set [ Name:%ret To:

Do Maths:Off Append:Off ]

<find files>
A3: Run Shell [ Command:find %DCIM_path -newer /storage/sdcard0/timestamp.txt Timeout (Seconds):0 Use Root:Off Store Output In:%picpath Store Errors In: Store Result In: ]
A4: Variable Add [ Name:%count Value:1 Wrap Around:0 ]
A5: Goto [ Type:Action Label Number:1 Label:find files ] If [ %picpath !Set & %count < 3 ]

///  I found it necessary to to loop this 3 times to give the camera time to save the pics//

A6: Stop [ With Error:Off Task: ] If [ %picpath !Set ]

//// This will stop the task if no pics were taken /////

A7: Variable Search Replace [ Variable:%picpath Search:%ret Ignore Case:Off Multi-Line:Off One Match Only:Off Store Matches In: Replace Matches:On Replace With: ]

/// remove line feeds ///

A8: Variable Split [ Name:%picpath Splitter:/ Delete Base:Off ]
A9: Variable Set [ Name:%index To:%picpath(#?*jpg*) Do Maths:Off Append:Off ]

/// %index now contains the indices of the array elements  that contain just the file name ( not the path) of all files with a jpg extension. ///

A10: Variable Split [ Name:%index Splitter:, Delete Base:Off ]
A11: For [ Variable:%item Items:%index(:) ]
<copy>
A12: Copy File [ From:%DCIM_path%picpath(%item) To:%Picfilename Use Root:Off Continue Task After Error:On ]
A13: Move [ From:%DCIM_path%picpath(%item) To:%camera_path_deleted Use Root:Off ]
A14: End For

It sounds like you might want to avoid %FOTO as well :)

!>> can I ask why not just start the 'get location' action as soon as the camera app is opened

>
>
>  I prefer to only fire the resource-hungry location action if there actually are new photos to geotag. Sometimes you miss and delete shots, sometimes you record videos, etc.
>

Ah, I see your point.. 

[Cycneus]

The timestamp + shell method works perfectly, thank you for that! Away goes both %FOTO and bulky file lists.

[Rich D]

> The timestamp + shell method works perfectly, thank you for that! Away goes both %FOTO and bulky file lists.

Glad its working for you..

While I was posting this I came across one issue with my approach. If I take 20 pics in a row then exit the camera and immediately re-open the camera and take another pic the enter task is not allowed to run so the time stamp file is not updated.  The reason for this is a bit complex but the issue is that I had 'enforce task order' selected in the profile properties. You would think this would give the enter task priority over the exit task. However it only ensures the enter task will finish before the exit task can run "In this iteration of the profile" so it has no effect if a exit task is running and the profile fires again and starts the enter task. In this case the exit task has a much higher priority. To fix the problem I put in 2 wait actions in the exit task with a condition of %TRUN~'the name of my enter task'  so when the profile goes active again it will 'start' the enter task (but it will not run because the exit task has a higher priority) however now the wait action will run and this will let the enter task run.   Simple aye..... :)

   If you do a search of this group for "Enforce Task Order, How Exactly Does It Work " it should shed some light on it.   Here is my full exit task with the changes.

Pic Taken 2 (1171)

Run Both Together
<start>
A1: Anchor

A2: Flash [ Text:%priority Long:On ]
A3: Variable Set [ Name:%camera_path_deleted To:%DCIM_path Do Maths:Off Append:Off ]
A4: Variable Set [ Name:%camera_path_deleted To:Deleted pics/ Do Maths:Off Append:On ]
A5: Variable Set [ Name:%ret To:

Do Maths:Off Append:Off ]

A6: Destroy Scene [ Name:Camera Overlay ]
<find files>
A7: Run Shell [ Command:find %DCIM_path -newer /storage/sdcard0/timestamp.txt Timeout (Seconds):0 Use Root:Off Store Output In:%picpath Store Errors In: Store Result In: ]
A8: Wait [ MS:0 Seconds:1 Minutes:0 Hours:0 Days:0 ] If [ %TRUN ~ *,pic taken on,* ]
A9: Variable Add [ Name:%count Value:1 Wrap Around:0 ]
A10: Goto [ Type:Action Label Number:1 Label:find files ] If [ %picpath !Set & %count < 3 ]
A11: Stop [ With Error:Off Task: ] If [ %picpath !Set ]
A12: Variable Search Replace [ Variable:%picpath Search:%ret Ignore Case:Off Multi-Line:Off One Match Only:Off Store Matches In: Replace Matches:On Replace With: ]
A13: Variable Split [ Name:%picpath Splitter:/ Delete Base:Off ]
A14: Variable Set [ Name:%index To:%picpath(#?*jpg*) Do Maths:Off Append:Off ]
A15: Variable Split [ Name:%index Splitter:, Delete Base:Off ]
A16: For [ Variable:%item Items:%index(:) ]
A17: Wait [ MS:0 Seconds:1 Minutes:0 Hours:0 Days:0 ] If [ %TRUN ~ *,pic taken on,* ]
<copy>
A18: Copy File [ From:%DCIM_path%picpath(%item) To:%Picfilename Use Root:Off Continue Task After Error:On ]
A19: Move [ From:%DCIM_path%picpath(%item) To:%camera_path_deleted Use Root:Off ]
A20: End For

[Rich D]

Correction...

  It was a bit late when I was posting last knight.....  :)

However it only ensures the enter task will finish before the exit task can run "In this iteration of the profile" so it has no effect if a exit task is running and the profile fires again and starts the enter task.

This is incorrect.  If a exit task is running from a previous activation of a profile and the profile goes active again,  the 'enforce task order' will not allow the new enter task to run until the exit task has finished.

So I had to de-selected the 'enforce task order' for the profile. You still need the waits in the exit task because a exit task will have a higher priority then a enter task.  

Sorry for the confusion....

[Cycneus]

Thanks for the heads up. I had solved that particular issue by deselecting "Enforce Task Order" in the profile settings and calling a separate "Geotag Photos" task in the exit task, with the priority of this "Perform Task" action set lower than the enter task. This should (1) let the high priority exit task finish before starting the Geotag task, and so (2) allow the enter task to intervene while that one is running. Also, in the Geotag task, I have a "Wait Until: %TIMES - %LOCTMS < 10" immediately after the Get Location action (with "Continue Task Immediately" checked), which should also let the enter task run even while location is being established. I've seen no issues with this setup so far.