How to send a message in OnApplicationQuit about ardity HOT 10 CLOSED

Hi Jakub,

Indeed, that behaviour is expected because of the execution order of MonoBehaviours' functions:

1. When a game is finishing it invokes the OnDisable method of the GameObject that controls the COM port, and then the COM port is closed.
2. Then, Unity invokes the OnApplicationQuit method, but by then the COM port is already closed, so your message will never arrive at the other side.

Check here the order of execution of the functions: https://docs.unity3d.com/Manual/ExecutionOrder.html

Now, there are some solutions:

1. If you can guarantee the OnDisable of other of the scripts of that GameObject gets invoked before the SerialController.OnDisable then you can send your custom message from there (be sure of adding a delay after sending the message).
2. I will modify the library to include a "tear-down" function, as I think yours will be a pretty common use-case.

Do you want to try with the first option in the meantime? I can add the new functionality later on the weekend.

from ardity.

Thanks for fast response. I'll start with OnDisable solution. But how can I add a delay and be sure that the app will wait until it closes? Is adding a coroutine with WaitForSeconds(1); in OnDisable enough?

from ardity.

It turns out you cannot place coroutines in OnDisable, and the fact that I'm using Robotlegs Sharp doesn't help either. I'll wait for your "tear-down" implementation, unless you have any other advices for me :)

from ardity.

Hi,
I am at this moment making the last tests for the library to ensure the tear-down works correctly (so far, it does).

It seems weekend arrived earlier than expected 😃

from ardity.

Alright, the feature is finished.

Could you give it a try and let me know if it works well for you too?
I put in the README another sample Arduino program, the one I used for testing this feature.
Also, there is a new scene called "DemoSceneUserPoll_ReadWrite_TearDown" where I use the tear-down functionality.
The Unity package was also updated with this change.

from ardity.

It works with the device in your supplied test scene. I'll have time to check it in my applilcation tomorrow.

from ardity.

Hello.
Did it work?

from ardity.

Sorry for not writing you back. I'm in the middle of a project and it's a little hot in here :) Your teardown method worked for me. Since I'm a fresh C#/Unity programmer i was wondering what's the diffrence between calling:
void OnDisable() { SendSerialMessage("@REL#0@"); ...

and

void OnDisable() { if (userDefinedTearDownFunction != null) userDefinedTearDownFunction(); ...
and userDefinedTearDownFunction calling SendSerialMessage("@REL#0@"); on SerialController? Do delegates hold the execution stack or something?

from ardity.

For this to work:

void OnDisable() { SendSerialMessage("@REL#0@");

you must modify the SerialController file, which is not a good idea with 3rd-party libraries as you will have trouble when upgrading to a new version. Other than that, the lines behave exactly in the same way.

Now, if you meant putting:

void OnDisable() { SendSerialMessage("@REL#0@");

in a different file, then it won't necessarily work as it depends on which OnDisable gets executed first. If SerialController's execute first then by the time the OnDisable of your class gets executed, the COM port is already closed.

from ardity.

And about you last question, no, delegates don't hold the execution stack or anything like that, they are plain function pointers.

I guess your question is why it works now, check at the SerialThread class, it has an additional change there that was needed so the tear-down worked:

Now, the OnDisable puts something in the "out-queue", and the thread ensures that it doesn't exit while there is something in that queue, so you can think of the queue being the one that holds down the execution of the other OnDisable's.

from ardity.