92b1551b1d
Before committing ref updates, split symbolic ref updates into two parts: an update to the underlying ref, and a log-only update to the symbolic ref. This ensures that both references are locked correctly during the transaction, including while their reflogs are updated. Similarly, if the reference pointed to by HEAD is modified directly, add a separate log-only update to HEAD, rather than leaving the job of updating HEAD's reflog to commit_ref_update(). This change ensures that HEAD is locked correctly while its reflog is being modified, as well as being cheaper (HEAD only needs to be resolved once). This makes use of a new function, lock_raw_ref(), which is analogous to read_raw_ref(), but acquires a lock on the reference before reading it. This change still has two problems: * There are redundant read_ref_full() reference lookups. * It is still possible to get incorrect reflogs for symbolic references if there is a concurrent update by another process, since the old_oid of a symref is determined before the lock on the pointed-to ref is held. Both problems will soon be fixed. Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> WIP
Git - fast, scalable, distributed revision control system
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 version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from http://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see Documentation/giteveryday.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).
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 (read Documentation/SubmittingPatches for instructions on patch submission). 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://news.gmane.org/gmane.comp.version-control.git/, http://marc.info/?l=git and other archival sites.
The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (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