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Git over HTTPS has a high request startup latency, since the SSL negotiation can take up to a second. In order to reduce this latency, connections should be left open to the Git server across requests (or invocations of the git commandline). Reduce SSL startup latency by running a daemon job that keeps connections open to a Git server. The daemon job (git-remote-persistent-https--proxy) is started on the first request through the client binary (git-remote-persistent-https) and remains running for 24 hours after the last request, or until a new daemon binary is placed in the PATH. The client determines the daemon's HTTP address by communicating over a UNIX socket with the daemon. From there, the rest of the Git protocol work is delegated to the "git-remote-http" binary, with the environment's http_proxy set to the daemon. Accessing /pub/scm/linux/kernel/git/torvalds/linux repository hosted at kernel.googlesource.com with "git ls-remote" over https:// and persistent-https:// 5 times shows that the first request takes about the same time (0.193s vs 0.208s---there is a slight set-up cost for the local proxy); as expected, the other four requests are much faster (~0.18s vs ~0.08s). Incidentally, this also has the benefit of HTTP keep-alive working across Git command invocations. Its common for servers to use a 5 minute keep-alive on an HTTP 1.1 connection. Git-over-HTTP commonly uses Transfer-Encoding: chunked on replies, so keep-alive will generally just work, even though a pack stream's length isn't known in advance. Because the helper is an external process holding that connection open, we also benefit from being able to reuse an existing TCP connection to the server. The same "git ls-remote" test against http:// vs persistent-https:// URL shows that the former takes ~0.09s while the first request for the latter is about 0.134s with set-up cost, and subsequent requests are ~0.065s, shaving around one RTT to the server. Signed-off-by: Colby Ranger <cranger@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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GIT - the stupid content tracker
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"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 (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://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.