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Clone with local alternates?

Subject: Clone with local alternates?

## tl;dr

7 messages between Apr 18, 2006 and Apr 19, 2006.

replies: 6people: 3as markdown or json

David Woodhouse· Apr 18, 2006, 23:48 UTC · lore

Often I want to clone a remote repository but would like to use an existing local source tree as 'alternates'.

One way of doing this is to clone the local tree with 'git-clone -l -s', find the latest common commit shared with the remote tree to be fetched, revert to that with 'git-reset --head $last' and then pulling from the remote.

Is that _really_ the best way of doing it though? It would be better if we just had a '--local-alternates=/foo' option to git-clone when cloning a remote repository.

-- 
dwmw2
Shawn Pearce· Apr 18, 2006, 23:56 UTC · re: David Woodhouse · lore

Re: Clone with local alternates?

David Woodhouse <dwmw2@infradead.org> wrote:
Show 11 quoted lines
> Often I want to clone a remote repository but would like to use an
> existing local source tree as 'alternates'. 
> 
> One way of doing this is to clone the local tree with 'git-clone -l -s',
> find the latest common commit shared with the remote tree to be fetched,
> revert to that with 'git-reset --head $last' and then pulling from the
> remote. 
> 
> Is that _really_ the best way of doing it though? It would be better if
> we just had a '--local-alternates=/foo' option to git-clone when cloning
> a remote repository.
  git clone --reference=/foo git://remote/foo

would do the trick. This is new in 1.3.0. I just noticed its also not documented in 1.3.0. :-)

-- 
Shawn.
David Woodhouse· Apr 18, 2006, 23:59 UTC · re: Shawn Pearce · lore

Re: Clone with local alternates?

On Tue, 2006-04-18 at 19:56 -0400, Shawn Pearce wrote:
>   git clone --reference=/foo git://remote/foo
> 
> would do the trick.  This is new in 1.3.0.  I just noticed its also
> not documented in 1.3.0.  :-)
Aha. Thanks.
-- 
dwmw2
Shawn Pearce· Apr 19, 2006, 00:19 UTC · re: Shawn Pearce · lore

[PATCH] Document git-clone --reference

The new --reference flag introduced to git-clone in GIT 1.3.0 was not documented but is rather handy. So document it.

Also corrected a minor issue with the documentation for the -s flag; the info/alternates file name was spelled wrong.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
---
  Shawn Pearce <spearce@spearce.org> wrote:
  >   git clone --reference=/foo git://remote/foo
  > 
  > would do the trick.  This is new in 1.3.0.  I just noticed its also
  > not documented in 1.3.0.  :-)
 Documentation/git-clone.txt |   21 ++++++++++++++++++++-
 1 files changed, 20 insertions(+), 1 deletions(-)

base 6625864c8ce9868ba4ab41165d97084f3f04bbed last 66a5bd88d2a8d9d64d86733852fbaba9caa756b0

diff --git a/Documentation/git-clone.txt b/Documentation/git-clone.txt
index 9ac54c2..131e445 100644
--- a/Documentation/git-clone.txt
+++ b/Documentation/git-clone.txt
@@ -10,6 +10,7 @@ SYNOPSIS
 --------
 [verse]
 'git-clone' [-l [-s]] [-q] [-n] [--bare] [-o <name>] [-u <upload-pack>]
+	  [--reference <repository>]
 	  <repository> [<directory>]
 
 DESCRIPTION
@@ -46,10 +47,18 @@ OPTIONS
 -s::
 	When the repository to clone is on the local machine,
 	instead of using hard links, automatically setup
-	.git/objects/info/alternatives to share the objects
+	.git/objects/info/alternates to share the objects
 	with the source repository.  The resulting repository
 	starts out without any object of its own.
 
+--reference <repository>::
+	If the reference repository is on the local machine
+	automatically setup .git/objects/info/alternates to
+	obtain objects from the reference repository.  Using
+	an already existing repository as an alternate will
+	require less objects to be copied from the repository
+	being cloned, reducing network and local storage costs.
+
 --quiet::
 -q::
 	Operate quietly.  This flag is passed to "rsync" and
@@ -112,6 +121,16 @@ Make a local clone that borrows from the
 ------------
 
 
+Clone from upstream while borrowing from an existing local directory::
++
+------------
+$ git clone --reference my2.6 \
+	git://git.kernel.org/pub/scm/.../linux-2.7 \
+	my2.7
+$ cd my2.7
+------------
+
+
 Create a bare repository to publish your changes to the public::
 +
 ------------

-- 
1.3.0.rc4.g8060
David Woodhouse· Apr 19, 2006, 08:39 UTC · re: Shawn Pearce · lore

Re: Clone with local alternates?

On Tue, 2006-04-18 at 19:56 -0400, Shawn Pearce wrote:
>   git clone --reference=/foo git://remote/foo

That's nice. What would be even _nicer_ is if I could enforce its usage on the server. I keep a clean copy of Linus' kernel tree on the machine with the git dæmon, so I'd like to make it refuse to send any objects which are in that tree and which people should already have fetched from elsewhere anyway.

-- 
dwmw2
Eric W. Biederman· Apr 19, 2006, 09:42 UTC · re: David Woodhouse · lore

Re: Clone with local alternates?

David Woodhouse <dwmw2@infradead.org> writes:
Show 8 quoted lines
> On Tue, 2006-04-18 at 19:56 -0400, Shawn Pearce wrote:
>>   git clone --reference=/foo git://remote/foo
>
> That's nice. What would be even _nicer_ is if I could enforce its usage
> on the server. I keep a clean copy of Linus' kernel tree on the machine
> with the git dæmon, so I'd like to make it refuse to send any objects
> which are in that tree and which people should already have fetched from
> elsewhere anyway.
Given how large the linux kernel archive is I can see the desire.

At git startup there is an exchange of common commits. to find the best place to build the pack from so what you want is possible. I haven't a clue how you would describe it though in the face of multiple branches, coming off the trunk at different times.

Eric
Eric W. Biederman· Apr 19, 2006, 09:36 UTC · re: David Woodhouse · lore

Re: Clone with local alternates?

David Woodhouse <dwmw2@infradead.org> writes:
Show 7 quoted lines
> Often I want to clone a remote repository but would like to use an
> existing local source tree as 'alternates'. 
>
> One way of doing this is to clone the local tree with 'git-clone -l -s',
> find the latest common commit shared with the remote tree to be fetched,
> revert to that with 'git-reset --head $last' and then pulling from the
> remote.

Simpler than the git-reset you can simply do git-fetch remote branch:branch and git will find common ancestor for you and create a new branch that mirrors the old one.

I mention this because it can be interesting to have branches from several remote repositories all in one local repository.

Eric

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