Re: [PATCH v5 03/15] index-helper: new daemon for caching index and related stuff

On Wed, Apr 20, 2016 at 7:17 PM, Johannes Schindelin
[off-list ref] wrote:

quoted

We keep this daemon's logic as thin as possible. The "brain" stays in
git. So the daemon can read and validate stuff, but that's all it's
allowed to do. It does not add/create new information. It doesn't even
accept direct updates from git.

I like this design. For now. Later, I really think we should add the
ability to update the index via the index-helper.

Later we do. For watchman, index-helper creates and shares a piece of
information retrieved from watchman, which has to be combined back to
the index by git process. But it's still not a _direct_ index update.

I am thinking about a
method similar to watchman where a separate process (that may use the
inotify syscall on Linux, or tap into the NTFS journal on Windows) tells
the index-helper specifically which paths to look at, so that nobody ever
has to look at any files that were not modified at all.

Am I missing something here? I thought watchman could already run on
Windows. We benefit from watchman, which was originally written for
Mercurial. If there's a better way to do inotify equivalent for
Windows, is it possible to do it in watchman so Mercurial can benefit
from it too?

On Wed, Apr 20, 2016 at 7:19 PM, Johannes Schindelin
[off-list ref] wrote:

quoted

On Wed, Apr 20, 2016 at 6:27 AM, David Turner [off-list ref] wrote:

quoted

Shared memory is done by storing files in a per-repository temporary
directory.  This is more portable than shm (which requires
posix-realtime and has various quirks on OS X).  It might even work on
Windows, although this has not been tested.

There's another option, but I'm not sure if it's too clever/tricky to
do. Anyway, on *nix we can send file descriptors over unix socket [2],
then mmap them back to access content.

This sounds too clever to me ;-)

Well. At least we have considered everything (that I'm aware of).
-- 
Duy