Usage
=====
-git-p4 supports two main modes: Importing from Perforce to a Git repository is
-done using "git-p4 sync". Submitting changes from Git back to Perforce is
-done using "git-p4 submit".
+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
=========
-You can simply start with
+Simply start with
git-p4 clone //depot/path/project
git-p4 clone //depot/path/project myproject
-This will create an empty git repository in a subdirectory called "project" (or
-"myproject" with the second command), import the head revision from the
-specified perforce path into a git "p4" branch, create a master branch off 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:
+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
git-p4 sync //path/in/your/perforce/depot
This will import the current head revision of the specified depot path into a
-"p4" branch of your git repository. You can use the --branch=mybranch option
-to use a different branch.
+"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 just use
+If you want to import the entire history of a given depot path simply use:
git-p4 sync //path/in/depot@all
-To achieve optimal compression you may want to run 'git repack -a -d -f' after
-a big import. This may take a while.
-Support for Perforce integrations is still work in progress. Don't bother
-trying it unless you want to hack on it :)
+Note:
-For convenience there's also the git-p4 clone command that works similar to
-git-clone and combines the creation of the git repository with the the initial
-import and the branch setup
+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 easily synchronize your git repository with
-newer changes from the Perforce depot by just calling
+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 "p4" branch is updated.
+in your git repository. By default the "remotes/p4/master" branch is updated.
+
+Advanced Setup
+==============
-It is recommended to run 'git repack -a -d -f' from time to time when using
-incremental imports to optimally combine the individual git packs that each
-incremental import creates through the use of git-fast-import.
+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
========
==========
git-p4 has support for submitting changes from a git repository back to the
-Perforce depot. This requires a Perforce checkout separate to your git
+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 --continue
-After submitting you should sync your perforce import branch ("p4" or "origin")
-from Perforce using git-p4's sync command.
+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
+
+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
+