Use d_ino (struct dirent) only when available.
Implement a mode for scanning just maildirs (ie. the dirs with cur / new
in them). Use d_type (if available) to optimize that.
On rotational devices (HDD) processing direntries is much faster when
doing so sorted by i-node for the dir-entries. This is an old
optimization (perhaps mu <= 1.6 or so?) that was implemented yet after
indexing changed, likely because my systems use SDDs instead!
But, let's restore that optimization; the sorting is fast enough that we
don't care for SDDs; on HDD it should be quite a bit faster.
Update all cc code using .clang-format; please do so as well for future PRs
etc.; emacs has a handy 'clang-format' mode to make this automatic.
For comparing old changes with git blame, we can disregard this one using
--ignore-rev
(see https://www.moxio.com/blog/43/ignoring-bulk-change-commits-with-git-blame )
We got many reports where the 'lazy check' didn't work too well for
people... so make it a bit less lazy, so it'll just work for more
people.
In practice, never skip _directories_ unless they're leaf directories;
this avoids the mtime-does-not-bubble-up problem.
Implement a new message indexer consisting of a single-threaded scanner
and a multi-threaded indexer.
This allows for a number of optimizations as well as background
indexing, though this initial version should be behave similar to the
old indexer.
