Code review comment for lp:~compiz-team/compiz/compiz.performance_1027211.2

On Mon, Dec 10, 2012 at 2:41 PM, Daniel van Vugt
<email address hidden> wrote:
> Also, without too much verbosity, why is it we need to implement window movement completely synchronously? My understanding is that waiting and locking should never be required when the user moves a window.
>
> A window move should simply involve two events:
> 1. Motion event -> move plugin -> send request to X server (XConfigureWindow I think).
> and some time later (should not care when):
> 2. XConfigureNotify (or whatever) -> core plugin -> compiz window position updated.
>
> I mean; my understanding of lazy positioning is that we update the compiz position without waiting for the server to tell us it's done. Therefore the above method counts as non-lazy movement, but also does not require any waiting or locking. I think this is contrary to the proposed and established non-lazy algorithm that does sync for some reason.
>
> If we want to keep lazy mode as an option and it does bypass the server as I suspect then OK. However I think at least non-lazy mode should be implemented as above, so that either way you never need to lock or sync to move a window.

Ah, I think there's a mixup of terminology here.

We're still completely async, both this branch and before this branch.
ConfigureWindow requests are in themselves async, you can post as many
as you want. There's absolutely no waiting for the server.

The problem is that the nvidia driver can't handle it. So instead of
sending it lots and lots of ConfigureWindow requests, we let plugins
"lock out" core from doing that until it makes sense for us to do it.
This means that:

1. In the case of "lazy positioning" being disabled, we just wait
until just before the next frame and post the request
2. In the case of "lazy positioning" enabled, we wait until the window
is ungrabbed.

Both are overridden in cases where we have to ask the server
something. But that's not too often.

> --
> https://code.launchpad.net/~compiz-team/compiz/compiz.performance_1027211.2/+merge/138800
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--
Sam Spilsbury