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First day of [Kickstarter funded work](http://www.kickstarter.com/projects/joeyh/git-annex-assistant-like-dropbox-but-with-your-own/)!
Worked on [[inotify]] today. The `watch` branch in git now does a pretty
good job of following changes made to the directory, annexing files
as they're added and staging other changes into git. Here's a quick
transcript of it in action:
joey@gnu:~/tmp>mkdir demo
joey@gnu:~/tmp>cd demo
joey@gnu:~/tmp/demo>git init
Initialized empty Git repository in /home/joey/tmp/demo/.git/
joey@gnu:~/tmp/demo>git annex init demo
init demo ok
(Recording state in git...)
joey@gnu:~/tmp/demo>git annex watch &
[1] 3284
watch . (scanning...) (started)
joey@gnu:~/tmp/demo>dd if=/dev/urandom of=bigfile bs=1M count=2
add ./bigfile 2+0 records in
2+0 records out
2097152 bytes (2.1 MB) copied, 0.835976 s, 2.5 MB/s
(checksum...) ok
(Recording state in git...)
joey@gnu:~/tmp/demo>ls -la bigfile
lrwxrwxrwx 1 joey joey 188 Jun 4 15:36 bigfile -> .git/annex/objects/Wx/KQ/SHA256-s2097152--e5ced5836a3f9be782e6da14446794a1d22d9694f5c85f3ad7220b035a4b82ee/SHA256-s2097152--e5ced5836a3f9be782e6da14446794a1d22d9694f5c85f3ad7220b035a4b82ee
joey@gnu:~/tmp/demo>git status -s
A bigfile
joey@gnu:~/tmp/demo>mkdir foo
joey@gnu:~/tmp/demo>mv bigfile foo
"del ./bigfile"
joey@gnu:~/tmp/demo>git status -s
AD bigfile
A foo/bigfile
Due to Linux's inotify interface, this is surely some of the most subtle,
race-heavy code that I'll need to deal with while developing the git annex
assistant. But I can't start wading, need to jump off the deep end to make
progress!
The hardest problem today involved the case where a directory is moved
outside of the tree that's being watched. Inotify will still send events
for such directories, but it doesn't make sense to continue to handle them.
Ideally I'd stop inotify watching such directories, but a lot of state
would need to be maintained to know which inotify handle to stop watching.
(Seems like Haskell's inotify API makes this harder than it needs to be...)
Instead, I put in a hack that will make it detect inotify events from
directories moved away, and ignore them. This is probably acceptable,
since this is an unusual edge case.
----
The notable omission in the inotify code, which I'll work on next, is
staging deleting of files. This is tricky because adding a file to the
annex happens to cause a deletion event. I need to make sure there are no
races where that deletion event causes data loss.
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