Re: [iostreams] Interest in multithreaded lzma filter?

From: Mike (mike.dev_at_[hidden])
Date: 2019-05-23 12:39:34

> Gesendet: Mittwoch, 22. Mai 2019 um 23:40 Uhr
> Von: "Jeff Bonyun via Boost" <boost_at_[hidden]>
>
> > ...  How will we detect whether
> > liblzma is capable?  If it is not capable but specified, will we allow
> > the compression anyway?
>
> I've been investigating this. liblzma defines a version macro,
> LZMA_VERSION. It looks like liblzma obtained its multithreaded function
> in 5.1.1 (in 2011). So the idea would be to branch on this macro, and
> fall back to the currently-used single-threaded function for an older
> liblzma version. In that case, requesting any number of threads will
> carry out the operation, but will only use a single thread. This makes
> it tolerant of different versions, but does mark up the code with a few
> #if branches. I'm assuming boost goes for tolerance in this case.

Does a 2019 Boost release really have to be compatible with a Pre 2011
release of liblzma? Is this combination even tested?
I.e. are we sure this would be the only incompatibility?

How about just adding this functionality unconditionally and see if
someone complains?

Mike