Fix race conditions as mentioned in #148

[1lann]

This PR resolves the race conditions mentioned in #148.

The race condition was causing rendering glitches with prompts for me, it annoyed me sufficiently that I decided to investigate why the rendering was glitching and wrote a fix. Here's a PR for it if you'd like.

In summary what happens in most cases is when you hit "enter" in a prompt, an "ioloop" goroutine in the readline package dispatches the event to both the listen handler, and to the code that returns from .Readline() simultaneously. Because both the listen handler and the code that occurs after .Readline() returns in promptui mutate the readline screen buffer without synchronization, a data race occurs, and can cause rendering glitches depending on the order of execution (not to mention the data race itself is unsafe anyway).

This fix adds a mutex to synchronize the access between the listen handler and the after .Readline() return handling, additionally a closing variable is used to indicate to the listen handler when it should stop processing events as the prompt is quitting as to prevent the incorrect final text from being displayed.

I've tested this code on the example provided in #148, and with my own code, and it appears to be functioning great now without any rendering glitches in prompts, nor any warnings from Go's race detector when running with -race.

Reminder that after merging and testing, you'll probably want to release this as an update.

[CLAassistant]

All committers have signed the CLA.

[aschrijver]

Liking the project, but would be great to see this merged. I just upgraded from v0.3.2 to do the bell fix, but now with duplicate prompt lines and inconsistent formatting (prompt bold, not bold, at random) that results from this it feels a bit like a step backwards.

[viccuad]

I would be glad to help in merging this PR, as I depend on it to use the module.

[kylecarbs]

What's left to get this merged?

[johnmanjiro13]

I want you to merge this PR.

[kumailn]

@1lann when will this be merged?

[1lann]

@kumailn I do not have push access to this repository, if I could merge it I would, the best I can do is resolve the merge conflict (which I have now done). You'd have to go poke the maintainers of this repository if you want to get this merged. Alternatively you can use my fork at https://github.com/1lann/promptui, I haven't tested it however so use at your own risk. Alternatively you can use a library that is better maintained like bubletea which is what I've ended up doing. A text input example is here, you might want to write a helper to make it more elegant to use.

[AaronCrawfis]

@jbowes @louisbranch would you be able to take a look at this? Would love to fix an issue we have for double prompts on Windows. Thanks!!

[ish-xyz]

@jbowes @louisbranch can you please have a look here?