Use initial terminal size when creating a terminal

[amisevsk]

Description

When creating a new terminal, queue the initial number of rows/columns in the resize channel after starting to ensure the terminal uses the correct initial size (this requires making the channel buffered).

This should fix eclipse-che/che#22584, except when testing it in the Code editor, the initialDimensions sent to machine-exec are wrong -- resizing the terminal pane by even a few pixels shows the new computed size is 7-9 characters wider.

How to test

These changes are built into quay.io/amisevsk/che-code:terminal-size (with some additional logging to allow debugging terminal size issues).

To test these changes:

1. Start a Che workspace
2. In the Code terminal, run the following command to change the che-code image:

   oc get dwt che-code-$DEVWORKSPACE_NAME -o yaml | sed 's|quay.io/che-incubator/che-code.*|quay.io/amisevsk/che-code:terminal-size|' | oc apply -f -
   

3. Restart the workspace (e.g. using F1 -> restart workspace)
4. Verify terminal width and height are set correctly in new terminals created via "New terminal (Select a container)" -- text should wrap as normal (see linked issue for the original bug)

[azatsarynnyy]

I tested the PR following the provided steps and can't reproduce eclipse-che/che#22584.
Thanks @amisevsk for fixing it! 👍

[amisevsk]

@azatsarynnyy Great to hear, thanks! Sounds like you're not seeing the additional bug (terminal width is off by ~6 chars).

I suspect that my still having the wrapping issue in testing is due to some font rendering weirdness on my system, given its consistency. What I think is happening is:

1. I click to open a terminal
2. Code gets the size of the terminal panel and computes a character width based on the pixel width of each monospace character
3. Code attempts to initialize a terminal using this width
4. Once the terminal is rendered, for some reason (???) the characters are rendered slightly narrower than the computed pixel width in step 2, so the width is still wrong
5. On further resize, Code now uses the correct pixel width for the font to get a new width, which is correct.

What I'm still not clear on is why this doesn't occur for the built in terminal, but if it's just a me problem then it might be fine to merge (this should fix the problem in the majority of cases, at least)

[azatsarynnyy]

@amisevsk I tested it more thoroughly and I noticed that the behavior is different depending on what container I opened the terminal to. See the screencast below:

Screen.Recording.2023-11-27.at.11.25.37.mov

Here ^^ I used the Java Sprint Boot sample from the Dashboard.
Changing the editor image to quay.io/amisevsk/che-code:terminal-size has no effect 🤷

[amisevsk]

This is the same issue I was facing. If you check the output tab for the Che Terminal plugin, you can see that the computed terminal width changes after it's initialized.

For example, here I open a terminal (14 pt font, 129 columns, has wrapping issue), then change the font size to 16 and back to 14pt only to see the newest resize to be 136 columns (still 14pt font, panel width has not changed).

terminal-width.mp4

As far as I can tell, this is coming from somewhere within Code itself; I don't know if it's something we can fix.

[amisevsk]

Testing it on my end, the mariaDB container also wraps correctly from the start, but the initial terminal size (e.g. 106 chars) is 6 less than the actual size (e.g. 112 chars). However, in the mariaDB container, it seems this wrapping is ignored?

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