[Issue]: Mouse movement tracking consumes a lot of CPU

[Caellian]

Description

As noted by siliconsniffer in #1742, tracking global mouse movements with XInput consumes a lot of resources (50% of CPU in their case).

This might come from some different change in 1.19.7, but I think XInput is the cause because it produces a lot of events (almost one for every pixel of movement).

I'd like to discuss possible solutions:

• Disable XInput support by default (fallback code is already in place, inaccurate enter/leave tracking on most WMs).
• Throttle processed events
  • Track last event time. Avoiding forwarding to lua handlers could help a lot.
• Simplify logic for enter/leave checking.

Version

1.19.7

[siliconsniffer]

#1745 fixed the issue from #1742 for me, as stated in #1748 .

[Caellian]

@siliconsniffer So conky no longer uses 50% of your CPU?

If you have xcb-util-errors installed, your local build will be different from official arch package (which is compiled without it). Building from source even without the PRs completely avoids problematic code if you have xcb-util-errors as conky detects it at compile time.

[siliconsniffer]

Nope, no 50% CPU usage anymore, except only if I move my mouse very quickly between the windows, but that's probably my compositor or wm, not a conky issue (I think).

I don't have this installed, how does it avoid problematic code?

[Caellian]

Because conky detects xcb-util-errors at compile time and uses it for error reporting (nice, descriptive error messages) instead of a manual implementation (raw error codes) which previously used wrong buffer sizes for formatting (thus buffer overflow).

It might be just that the error callback was slow.