[HarfBuzz] caching plans with user features

[Jonathan Kew]

On 29/10/13 23:03, Behdad Esfahbod wrote:
> On 13-10-29 10:10 PM, Jonathan Kew wrote:
>>
>> So I'd suggest it's worth doing something like this - unless of course you
>> want to go the whole way and implement "smart" plan caching with user
>> features, but IMO that sounds like it might be more effort than it's worth.
>
> Thanks Jonathan.  Yes, something along these lines is what I wanted to do.  My
> only hesitation was that plans are cached indefinitely on the face, but if we
> only cache global-only plans, I'm still quite comfortable with that.

I wondered whether perhaps we should limit the number of plans that a 
face can cache - start discarding old plans if the number goes past 
about 10 or so. That would degrade gracefully and avoid uncontrolled 
growth if a badly-coded (or malicious!) site keeps adding random (or 
duplicated) features to the list, but still give the performance boost 
for any normal use-cases.

>
> Will clean up and pick this one.  May take a week or so though as I'll be at
> Iceland Airwaves for the rest of the week.
>
> Cheers,
>