Re: [PATCH] winex11: Don't create a temporary context each time X11DRV_wglBindTexImageARB is called.

[Ken Thomases]

On Feb 26, 2016, at 5:29 PM, Miklós Máté  wrote:
> @@ -2320,6 +2322,7 @@ static BOOL X11DRV_wglDestroyPbufferARB( struct wgl_pbuffer *object )
>     TRACE("(%p)\n", object);
> pglXDestroyPbuffer(gdi_display, object->drawable);
> - pglXDestroyContext(gdi_display, object->tmp_context);

I think you need to check if object->tmp_context is non-zero before calling glXDestroyContext() to avoid a GLXBadContext error.
> -
>    if (!object->tmp_context) {
> -
>        object->tmp_context = pglXCreateNewContext(gdi_display, object->fmt->fbconfig, object->fmt->render_type, prev_context, True);
> -
>        object->prev_context = prev_context;
> -
>    } else if (object->prev_context != prev_context) {
> -
>        pglXDestroyContext(gdi_display, object->tmp_context);
> -
>        object->tmp_context = pglXCreateNewContext(gdi_display, object->fmt->fbconfig, object->fmt->render_type, prev_context, True);
> -
>        object->prev_context = prev_context;
> -
>    }

Those two branches are mostly the same.  This could be reduced to:

if (!object->tmp_context || object->prev_context != prev_context) {
            if (object->tmp_context)
                pglXDestroyContext(gdi_display, object->tmp_context);
            object->tmp_context = pglXCreateNewContext(gdi_display, object->fmt->fbconfig, object->fmt->render_type, prev_context, True);
            object->prev_context = prev_context;
        }

Is it necessary, when a context is destroyed, to go through all wgl_pbuffer structs looking for any whose prev_context matches the one being destroyed and clear it?  Otherwise, you risk having a stale reference that could be reused for a different context and not realize you need to recreate tmp_context.  Of course, enumerating all of them in a thread-safe manner is going to require a lot of added infrastructure and complexity.

-Ken