Allow disabling coordinator delay

[alex-huff]

Checklist

• I have read through the manual page (man fzf)
• I have searched through the existing issues
• For bug reports, I have checked if the bug is reproducible in the latest version of fzf

Output of fzf --version

0.61 (devel)

OS

• Linux
• macOS
• Windows
• Etc.

Shell

• bash
• zsh
• fish

Problem / Steps to reproduce

I am implementing a window switcher (similar to alt+tab on windows) using fzf and to reduce latency I am using a single kitty/fzf instance instead of creating a new one every time. Whenever I show the window switcher I need to tell fzf to reload it's input using the HTTP server. The problem is that kitty/fzf instantly becomes visible but fzf takes ~100ms to display the reloaded input. This is pretty jarring. I found that disabling this sleep fixed my issue.

fzf/src/core.go

Lines 510 to 515 in d24b58e

	if delay && reading {
	dur := util.DurWithin(
	time.Duration(ticks)*coordinatorDelayStep,
	0, coordinatorDelayMax)
	time.Sleep(dur)
	}

Sadly there is no way to configure this delay using the command line interface.

Before disabling:

fzf-delay-an.mp4

After disabling:

fzf-nodelay-an.mp4

[junegunn]

Can you provide the minimal steps (script) to reproduce the problem you're describing? So that I can experience it on my computer without your full set-up.

[junegunn]

But I can understand what you mean. The delay should be reset to the minimum.

[alex-huff]

fzf --listen '--bind=ctrl-b:first+reload:seq 50 | sort -R'

If you run this command and move up to the second item and press ctrl+b you should be able to feel ~100ms of latency before the list updates. You will instantly see the first item get selected though.

If you press ctrl+b while the first item is focused, it is much harder to notice the latency.

Edit: or just set coordinatorDelayMax to 500 ms and it will be much more obvious
Edit: also you need to trigger some events before you can feel the latency because the sleep duration is based off of ticks

[alex-huff]

Since my fzf instance is running for many hours, it will always sleep for coordinatorDelayMax when reloading.

[junegunn]

Should be fixed in d2c662e.

fzf '--bind=ctrl-b:reload:seq 10000000'

FWIW, the coordinator delay code is over 10 years old that was written well before reload was introduced.

[alex-huff]

Should be fixed in d2c662e.

Yep this resolves my issue. Thanks!