[HarfBuzz] Making harfbuzz more appealing for mupdf project

[Behdad Esfahbod]

Thanks Ebrahim.  Hi Robin,

I'm confused.  HarfBuzz definitely IS completely threadsafe to the best of
my knowledge.  That was one of the strong design goals. I have had to
maintain, debug, and fix threadsafety issues in FreeType, fontconfig, and
Pango over the years, so I definitely know the issues and tried to address
them all in HarfBuzz.

* It is utterly thread unsafe. It uses statics to hold
* structures in, meaning that if it is ever called from
* more than one thread at a time, access to such
* structures can race.

This can't be farther from true.  I use compare-and-exchange to safely
implement singleton initializations or prepend-only linked-lists as
caches.  How is that not threadsafe?

Runtime-configurable custom allocators are different issue.  I don't
believe they are a useful feature and have not yet seen a compelling
usecase.

Since Robin is not on the mailing list, let's continue on github:
https://github.com/behdad/harfbuzz/issues/497

behdad

PS. Sometime I think about shutting down the list and using github
exclusively.  What do people think?

On Thu, Jun 15, 2017 at 12:18 PM, Ebrahim Byagowi <ebraminio at gmail.com>
wrote:

> Hi!
>
> Thanks for your encouraging words :)
>
> forwarding to hb mailing list
>
>
> On Thu, Jun 15, 2017 at 3:46 AM, Robin Watts <robin.watts at artifex.com>
> wrote:
>
>> On 14/06/2017 21:37, Ebrahim Byagowi wrote:
>>
>>> I wonder if is possible to turn this <https://github.com/ccxvii/mup
>>> df/blob/master/source/fitz/harfbuzz.c#L12> comment about harfbuzz on
>>> mupdf project into some doable/trackable tasks on harfbuzz bug tracker or
>>> are they just might not possible to solve because of ABI compatibility (or
>>> fixed already)? Thanks
>>>
>>> (bcc'ed the author to this thread also)
>>>
>>
>> Hi.
>>
>> I'd LOVE to see Harfbuzz fixed. It's a brilliant library, let down by
>> this major flaw.
>>
>> My experience of fixing such issues in several projects is that fixing it
>> in involves extensive, but ultimately simple, plumbing through of a context
>> field.
>>
>> It's not brain surgery, but it's tedious, and it's not something I'd
>> undertake myself without knowing in advance that it would stand a good
>> chance of being accepted.
>>
>> I'd love to work with anyone that would be prepared to try to fix this.
>>
>> Sadly, I believe that such things would involve a break to the ABI
>> though...
>>
>> (I fear this may bounce because I'm not on the harfbuzz list...)
>>
>> Robin
>>
>
>
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>


-- 
behdad
http://behdad.org/
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