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Re: [Public WebGL] Extension proposal: WEBGL_lose_context



On Thu, Dec 16, 2010 at 8:55 AM, Alexey Marinichev
<amarinichev@google.com> wrote:
> Chromium has code that detects if the context is lost, it does it by
> checking if it can properly communicate with the GPU process.
> Javascript code cannot affect the communication channel to the GPU
> process, so you cannot trigger the context recovery code.
>
> If lost context extension is implemented as "kill the GPU process and
> hope for the best", you'll be able to see if the browser will be able
> to synthesize lost and recovered events properly.
>
> I don't see a need in restoreContext function, the context should be
> recreated automatically, that's what we are testing anyway.

The way this extension is phrased, the context couldn't recover until
the restoreContext function is called. In Chromium we could still kill
the GPU process to implement loseContext (which would be very useful
for increasing the testing coverage), and the GPU process could
automatically restart; we would just need to add another gate which
prevents the WebGLRenderingContext from thinking the context has
restored until restoreContext() is called.

-Ken

> On Thu, Dec 16, 2010 at 11:54 AM, Gregg Tavares (wrk) <gman@google.com> wrote:
>>
>>
>> On Wed, Dec 15, 2010 at 6:53 PM, Adrienne Walker <enne@google.com> wrote:
>>>
>>> El día 15 de diciembre de 2010 15:59, Gregg Tavares (wrk)
>>> <gman@google.com> escribió:
>>> > Here's the other problem I have with this extension.
>>> > #1) For a JavaScript app to be able to test they handle lost context
>>> >    as pointed out, they can use JavaScript for this
>>> > #2) To be able to write lost context conformance tests
>>> > #3) To test the browser's handing of lost context.
>>> > The problem with but #2 and #3 is that this extension WILL NOT ACHIEVE
>>> > EITHER OF THOSE GOALS.
>>>
>>> Failing to test absolutely everything does not imply a failure to test
>>> anything.  Again, why are you arguing so strongly against increased
>>> test coverage?
>>
>> I'm not arguing against increased test coverage. I'm arguing against an
>> extension that will not actually provide any actual test coverage.
>> The only way you can really test your actual implementation is to wrap all
>> calls to OpenGL (not webgl) and then at some number of calls, start ignoring
>> the calls and returning lost context from eglSwapBuffers or eglMakeCurrent
>> The extension proposed doesn't do this. It will test almost zero paths
>> through an actual WebGL implementation.
>>
>>>
>>> I'd love to hear any suggestions you have for testing the cases that
>>> you bring up in an automated fashion.  It's frustrating that the only
>>> way so far that we've had to make code that uses glGet more robust was
>>> to have you spend your time performing code inspection at potential
>>> failure sites.
>>>
>>> -Adrienne
>>
>>
>

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