D477: revlog: add option to mmap revlog index

[durin42 (Augie Fackler)]

durin42 requested changes to this revision.
durin42 added inline comments.
This revision now requires changes to proceed.

INLINE COMMENTS

> revlog.py:348
> +                    self.opener.fstat(f).st_size >= mmapindexthreshold):
> +                indexdata = util.buffer(util.mmapread(f))
> +            else:

This makes me very uncomfortable, because util.mmapread() returns the empty string if it doesn't like the file descriptor. I'd be less worried if util.mmapread() crashed, or if this was more cautious about the mmapread failing for some reason.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D477

To: mbthomas, #fbhgext, indygreg, #hg-reviewers, durin42, quark
Cc: durham, quark, durin42, simonfar, mercurial-devel