git-p4 - Perforce <-> Git converter using git-fast-import
Usage
=====
git-p4 can be used in two different ways:
1) To import changes from Perforce to a Git repository, using "git-p4 sync".
2) To submit changes from Git back to Perforce, using "git-p4 submit".
Importing
=========
Simply start with
git-p4 clone //depot/path/project
or
git-p4 clone //depot/path/project myproject
This will:
1) Create an empty git repository in a subdirectory called "project" (or
"myproject" with the second command)
2) Import the head revision from the given Perforce path into a git branch
called "p4" (remotes/p4 actually)
3) Create a master branch based on it and check it out.
If you want the entire history (not just the head revision) then you can simply
append a "@all" to the depot path:
git-p4 clone //depot/project/main@all myproject
If you want more control you can also use the git-p4 sync command directly:
mkdir repo-git
cd repo-git
git init
git-p4 sync //path/in/your/perforce/depot
This will import the current head revision of the specified depot path into a
"remotes/p4/master" branch of your git repository. You can use the
--branch=mybranch option to import into a different branch.
If you want to import the entire history of a given depot path simply use:
git-p4 sync //path/in/depot@all
Note:
To achieve optimal compression you may want to run 'git repack -a -d -f' after
a big import. This may take a while.
Incremental Imports
===================
After an initial import you can continue to synchronize your git repository
with newer changes from the Perforce depot by just calling
git-p4 sync
in your git repository. By default the "remotes/p4/master" branch is updated.
Advanced Setup
==============
Suppose you have a periodically updated git repository somewhere, containing a
complete import of a Perforce project. This repository can be cloned and used
with git-p4. When updating the cloned repository with the "sync" command,
git-p4 will try to fetch changes from the original repository first. The git
protocol used with this is usually faster than importing from Perforce
directly.
This behaviour can be disabled by setting the "git-p4.syncFromOrigin" git
configuration variable to "false".
Updating
========
A common working pattern is to fetch the latest changes from the Perforce depot
and merge them with local uncommitted changes. The recommended way is to use
git's rebase mechanism to preserve linear history. git-p4 provides a convenient
git-p4 rebase
command that calls git-p4 sync followed by git rebase to rebase the current
working branch.
Submitting
==========
git-p4 has support for submitting changes from a git repository back to the
Perforce depot. This requires a Perforce checkout separate from your git
repository. To submit all changes that are in the current git branch but not in
the "p4" branch (or "origin" if "p4" doesn't exist) simply call
git-p4 submit
in your git repository. If you want to submit changes in a specific branch that
is not your current git branch you can also pass that as an argument:
git-p4 submit mytopicbranch
You can override the reference branch with the --origin=mysourcebranch option.
If a submit fails you may have to "p4 resolve" and submit manually. You can
continue importing the remaining changes with
git-p4 submit --continue
Example
=======
# Clone a repository
git-p4 clone //depot/path/project
# Enter the newly cloned directory
cd project
# Do some work...
vi foo.h
# ... and commit locally to gi
git commit foo.h
# In the meantime somebody submitted changes to the Perforce depot. Rebase your latest
# changes against the latest changes in Perforce:
git-p4 rebase
# Submit your locally committed changes back to Perforce
git-p4 submit
# ... and synchronize with Perforce
git-p4 rebase
Configuration parameters
========================
git-p4.user ($P4USER)
Allows you to specify the username to use to connect to the Perforce repository.
git config [--global] git-p4.user public
git-p4.password ($P4PASS)
Allows you to specify the password to use to connect to the Perforce repository.
Warning this password will be visible on the command-line invocation of the p4 binary.
git config [--global] git-p4.password public1234
git-p4.port ($P4PORT)
Specify the port to be used to contact the Perforce server. As this will be passed
directly to the p4 binary, it may be in the format host:port as well.
git config [--global] git-p4.port codes.zimbra.com:2666
git-p4.host ($P4HOST)
Specify the host to contact for a Perforce repository.
git config [--global] git-p4.host perforce.example.com
git-p4.client ($P4CLIENT)
Specify the client name to use
git config [--global] git-p4.client public-view
git-p4.allowSubmit
git config [--global] git-p4.allowSubmit false
git-p4.syncFromOrigin
A useful setup may be that you have a periodically updated git repository
somewhere that contains a complete import of a Perforce project. That git
repository can be used to clone the working repository from and one would
import from Perforce directly after cloning using git-p4. If the connection to
the Perforce server is slow and the working repository hasn't been synced for a
while it may be desirable to fetch changes from the origin git repository using
the efficient git protocol. git-p4 supports this setup by calling "git fetch origin"
by default if there is an origin branch. You can disable this using:
git config [--global] git-p4.syncFromOrigin false
git-p4.useclientspec
git config [--global] git-p4.useclientspec false
The P4CLIENT environment variable should be correctly set for p4 to be
able to find the relevant client. This client spec will be used to
both filter the files cloned by git and set the directory layout as
specified in the client (this implies --keep-path style semantics).
Implementation Details...
=========================
* Changesets from Perforce are imported using git fast-import.
* The import does not require anything from the Perforce client view as it just uses
"p4 print //depot/path/file#revision" to get the actual file contents.
* Every imported changeset has a special [git-p4...] line at the
end of the log message that gives information about the corresponding
Perforce change number and is also used by git-p4 itself to find out
where to continue importing when doing incremental imports.
Basically when syncing it extracts the perforce change number of the
latest commit in the "p4" branch and uses "p4 changes //depot/path/...@changenum,#head"
to find out which changes need to be imported.
* git-p4 submit uses "git rev-list" to pick the commits between the "p4" branch
and the current branch.
The commits themselves are applied using git diff/format-patch ... | git apply