The current "transaction" symlink was introduced to fix issues with
interrupted pulls; normally we assume that if we have a metadata
object, we also have all objects to which it refers.
There used to be a "summary" which had all the available refs, but I
deleted it because it wasn't really used, and was still racy despite
the transaction bits.
We still want the pull process to use the transaction link, so don't
delete the APIs, just relax the restriction on object writing, and
introduce a new ostree_repo_set_ref_immediate().
Rather than having separate write_ref calls, make clients start a
transaction, add some refs, and then commit it. While this doesn't
make it 100% atomic, it makes it easier for us to use an atomic
model, and it means we don't do as much I/O updating the summary
file and such.
https://bugzilla.gnome.org/show_bug.cgi?id=707644
We'll always have "bare" mode for keeping files-as-hardlinks as root.
But "archive" was my second attempt at a format for non-root file
storage, used by the gnome-ostree buildsystem which runs as non-root.
It was really handy to have a "tar" like mode where I can create
tarballs as a user, that contain files owned by root for example.
The "archive" mode stored content files as two pieces in the
filesystem; ".file" contained metadata, and ".filecontent" was the
actual content, uncompressed. The nice thing about this was that to
check out a tree as non-root, you could just hardlink into the repo.
However, archive was fairly bad for serving via HTTP; it required
*two* HTTP requests per content object, greatly magnifing the already
inefficient fetch process. So "archive-z2" was introduced.
To allow gnome-ostree to still check out trees as a user, the
"uncompressed-object-cache" was introduced, and that's how things have
been working for a while.
So we should just be able to kill this code. Specifically note just
how much better the stage_object() function became.
https://bugzilla.gnome.org/show_bug.cgi?id=706057
Colin Walters
Jasper St. Pierre
Tobias Hunger