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

[Miklós Máté]

On 02/29/2016 06:10 PM, Matteo Bruni wrote:
> 2016-02-29 3:59 GMT+01:00 Ken Thomases <ken at codeweavers.com>:
>> On Feb 26, 2016, at 5:29 PM, Miklós Máté <mtmkls at gmail.com> 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.
Mesa handles ctx=0 by doing nothing. I guess the blob drivers do the same.

>>
>>
>>> +        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;
>>          }
I don't think this improves readability, but whatever.

>>
>>
>> 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.
> Good point, that's necessary in principle and it shouldn't be too hard
> to do by keeping a wgl_pbuffers list (similarly to context_list for
> wgl_context, you should probably reuse the same context_section
> critical section for synchronization).
>
> The other points brought up by Ken are valid too of course.
If a context is destroyed, and a new context is created, what are the 
chances that the two pointers end up being the same?

MM