31 lines
1.5 KiB
Text
31 lines
1.5 KiB
Text
|
With yesterday's release, I'm pretty much done with the month's work. Since
|
||
|
|
there was no particular goal this month, it's been a grab bag of features
|
||
|
|
and bugfixes. Quite a lot of them in this last release.
|
||
|
|
|
||
|
|
I'll be away the next couple of days.. But got a start today on the next
|
||
|
|
part of the roadmap, which is planned to be all about Windows and Android
|
||
|
|
porting. Today, it was all about lock files, mostly on Windows.
|
||
|
|
|
||
|
|
Lock files on Windows are horrific. I especially like that programs that
|
||
|
|
want to open a file, for any reason, are encouraged in the official
|
||
|
|
documentation to retry repeatedly if it fails, because some other
|
||
|
|
random program, like a virus checker, might have opened the file first.
|
||
|
|
|
||
|
|
Turns out Windows does support a shared file read mode. This was
|
||
|
|
just barely enough for me to implement both shared and exclusive
|
||
|
|
file locking a-la-flock.
|
||
|
|
|
||
|
|
Couldn't avoid a busy wait in a few places that block on a lock.
|
||
|
|
Luckily, these are few, and the chances the lock will be taken for a long
|
||
|
|
time is small. (I did think about trying to watch the file for close events
|
||
|
|
and detect when the lock was released that way, but it seemed much too
|
||
|
|
complicated and hard to avoid races.)
|
||
|
|
|
||
|
|
Also, Windows only seems to support mandatory locks, while all locking in
|
||
|
|
git-annex needs to be advisory locks. Ie, git-annex's locking shouldn't
|
||
|
|
prevent a program from opening an annexed file! To work around that,
|
||
|
|
I am using dedicated lock files on Windows.
|
||
|
|
|
||
|
|
Also switched direct mode's annexed object locking to use dedicated lock
|
||
|
|
files. AFAICS, this was pretty well broken in direct mode before.
|