b4ca1db968
The option tells the command to expire older reflog entries that refer to commits that are no longer reachable from the tip of the ref the reflog is associated with. To avoid repeated merge_base() invocations, we used to mark commits that are known to be reachable by walking the history from the tip until we hit commits that are older than expire-total (which is the timestamp before which all the reflog entries are expired). However, it is a different matter if a commit is _not_ known to be reachable and the commit is known to be unreachable. Because you can rewind a ref to an ancient commit and then reset it back to the original tip, a recent reflog entry can point at a commit that older than the expire-total timestamp and we shouldn't expire it. For that reason, we had to run merge-base computation when a commit is _not_ known to be reachable. This introduces a lazy/on-demand traversal of the history to mark reachable commits in steps. As before, we mark commits that are newer than expire-total to optimize the normal case before walking reflog, but we dig deeper from the commits the initial step left off when we encounter a commit that is not known to be reachable. Signed-off-by: Junio C Hamano <gitster@pobox.com>
////////////////////////////////////////////////////////////////
GIT - the stupid content tracker
////////////////////////////////////////////////////////////////
"git" can mean anything, depending on your mood.
- random three-letter combination that is pronounceable, and not
actually used by any common UNIX command. The fact that it is a
mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the
dictionary of slang.
- "global information tracker": you're in a good mood, and it actually
works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks
Git is a fast, scalable, distributed revision control system with an
unusually rich command set that provides both high-level operations
and full access to internals.
Git is an Open Source project covered by the GNU General Public License.
It was originally written by Linus Torvalds with help of a group of
hackers around the net. It is currently maintained by Junio C Hamano.
Please read the file INSTALL for installation instructions.
See Documentation/gittutorial.txt to get started, then see
Documentation/everyday.txt for a useful minimum set of commands, and
Documentation/git-commandname.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with "man gittutorial" or "git help tutorial", and the
documentation of each command with "man git-commandname" or "git help
commandname".
CVS users may also want to read Documentation/gitcvs-migration.txt
("man gitcvs-migration" or "git help cvs-migration" if git is
installed).
Many Git online resources are accessible from http://git-scm.com/
including full documentation and Git related tools.
The user discussion and development of Git take place on the Git
mailing list -- everyone is welcome to post bug reports, feature
requests, comments and patches to git@vger.kernel.org. To subscribe
to the list, send an email with just "subscribe git" in the body to
majordomo@vger.kernel.org. The mailing list archives are available at
http://marc.theaimsgroup.com/?l=git and other archival sites.
The messages titled "A note from the maintainer", "What's in
git.git (stable)" and "What's cooking in git.git (topics)" and
the discussion following them on the mailing list give a good
reference for project status, development direction and
remaining tasks.