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[mum4k]

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[lefred]

Hello,
I´ve created a simple container have a text widget.
What is the best method to update the text (clean and change it) every x seconds or capture a key pressed ?
Thank you.

[mum4k]

Would you be able to explain that a little bit more? It would be the best if you could help me to understand the problem the flush should be solving.

[lefred]

My problem is that I create a new with termdash.KeyboardSubscriber, then if a certain key is pressed, I "change" dashboard where I create a new one (new go function fetching new information every seconds, etc...) that new context also subscribe the keyboard events to be catch the key to exit completely the application or go back to the main dashboard.
That is working. However if I press keys, once I go back in the main dashboard, those keys are again processed. I would like to have the possibility when I close the second created to flush the keyboard queue.

The issue is explained also here: lefred/innotopgo#16

[mum4k]

Thank you for providing the explanation. I suspect that flushing of the queue won't help here, because the delivery of the events is concurrent - some events might still be delivered between the container update and the flush.

This is an interesting problem and something we should solve. I have a couple of ideas, but first I need to understand the issue a bit better:

1. When you say some keys get delivered again - do they get delivered again to the termdash.KeyboardSubscriber, or does a copy of them get delivered to the updated container and some widgets in it? I suspect the latter, but please confirm.
2. Could you provide more details on what do the duplicate keys cause in your application? Ideally, can you point me to the code that defines the termdash.KeyboardSubscriber that processes the first copy of the key and the code that processes the duplicate keys that got delivered again?

This will help me understand what we are dealing with and I should be able to suggest some solutions afterwards.

[lefred]

In this part of the code I wait for the user to pres ESC (to exit) or backspace to close this dashboard:

https://github.com/lefred/innotopgo/blob/9df1f34ccc073f4d27d9b4146a1a42f2a87d530d/innotop/memory.go#L244

If other keys are pressed I don´t want to do anything... however if somebody press a key like ´I´ , then when this dashboard is closed and we go back in the main one:

https://github.com/lefred/innotopgo/blob/9df1f34ccc073f4d27d9b4146a1a42f2a87d530d/innotop/processlist.go#L466

the keys that were pressed previously ( in my example) will then be processed and the action linked to that key will be performed (display of yet another dashboard).

[mum4k]

Thank you for providing the code pointers, turns out this is a different problem than I thought.

The issue is that while your code reinitializes termdash here, it reuses the same instance of tcell created here. The tcell instance has a goroutine that continues to pull keyboard events even while your program switches between the dashboards.

As a quick fix you could try closing tcell and starting a new instance of tcell every time you call termdash.Run. E.g.

t, err := tcell.New()
if err != nil {
    return err
}
termdash.Run(t, ...) // Run the first dashboard.

t.Close() // Close the first tcell instance and create a new one.
t, err = tcell.New()
if err != nil {
    return err
}
termdash.Run(t, ...) // Run the second dashboard with a new instance of tcell.

However I would like to point out that this isn't the most straightforward way of using termdash and if you start restarting tcell as well, you might get some unwanted terminal flickering. The way termdash was intended to be used was to only call termdash.Run once for the lifetime of the application. And when you need to change dashboards, you can use the container.Update method. If you also need to change the behavior of the KeyboardSubscriber, you can define it as a method on an object in your program and that way modify its behavior without calling termdash.Run multiple times.

Please let me know if this helps.