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160 lines
5.5 KiB
Plaintext
160 lines
5.5 KiB
Plaintext
git-p4 - Perforce <-> Git converter using git-fast-import
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Usage
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=====
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git-p4 supports two main modes: Importing from Perforce to a Git repository is
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done using "git-p4 sync" or "git-p4 rebase". Submitting changes from Git back
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to Perforce is done using "git-p4 submit".
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Importing
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=========
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You can simply start with
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git-p4 clone //depot/path/project
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or
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git-p4 clone //depot/path/project myproject
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This will create an empty git repository in a subdirectory called "project" (or
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"myproject" with the second command), import the head revision from the
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specified perforce path into a git "p4" branch (remotes/p4 actually), create a
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master branch off it and check it out. If you want the entire history (not just
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the head revision) then you can simply append a "@all" to the depot path:
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git-p4 clone //depot/project/main@all myproject
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If you want more control you can also use the git-p4 sync command directly:
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mkdir repo-git
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cd repo-git
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git init
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git-p4 sync //path/in/your/perforce/depot
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This will import the current head revision of the specified depot path into a
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"remotes/p4/master" branch of your git repository. You can use the
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--branch=mybranch option to use a different branch.
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If you want to import the entire history of a given depot path just use
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git-p4 sync //path/in/depot@all
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To achieve optimal compression you may want to run 'git repack -a -d -f' after
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a big import. This may take a while.
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Support for Perforce integrations is still work in progress. Don't bother
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trying it unless you want to hack on it :)
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Incremental Imports
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===================
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After an initial import you can easily synchronize your git repository with
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newer changes from the Perforce depot by just calling
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git-p4 sync
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in your git repository. By default the "remotes/p4/master" branch is updated.
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It is recommended to run 'git repack -a -d -f' from time to time when using
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incremental imports to optimally combine the individual git packs that each
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incremental import creates through the use of git-fast-import.
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A useful setup may be that you have a periodically updated git repository
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somewhere that contains a complete import of a Perforce project. That git
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repository can be used to clone the working repository from and one would
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import from Perforce directly after cloning using git-p4. If the connection to
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the Perforce server is slow and the working repository hasn't been synced for a
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while it may be desirable to fetch changes from the origin git repository using
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the efficient git protocol. git-p4 supports this setup by calling "git fetch origin"
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by default if there is an origin branch. You can disable this using
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git config git-p4.syncFromOrigin false
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Updating
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========
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A common working pattern is to fetch the latest changes from the Perforce depot
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and merge them with local uncommitted changes. The recommended way is to use
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git's rebase mechanism to preserve linear history. git-p4 provides a convenient
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git-p4 rebase
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command that calls git-p4 sync followed by git rebase to rebase the current
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working branch.
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Submitting
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==========
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git-p4 has support for submitting changes from a git repository back to the
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Perforce depot. This requires a Perforce checkout separate to your git
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repository. To submit all changes that are in the current git branch but not in
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the "p4" branch (or "origin" if "p4" doesn't exist) simply call
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git-p4 submit
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in your git repository. If you want to submit changes in a specific branch that
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is not your current git branch you can also pass that as an argument:
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git-p4 submit mytopicbranch
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You can override the reference branch with the --origin=mysourcebranch option.
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If a submit fails you may have to "p4 resolve" and submit manually. You can
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continue importing the remaining changes with
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git-p4 submit --continue
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After submitting you should sync your perforce import branch ("p4" or "origin")
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from Perforce using git-p4's sync command.
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If you have changes in your working directory that you haven't committed into
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git yet but that you want to commit to Perforce directly ("quick fixes") then
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you do not have to go through the intermediate step of creating a git commit
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first but you can just call
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git-p4 submit --direct
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Example
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=======
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# Clone a repository
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git-p4 clone //depot/path/project
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# Enter the newly cloned directory
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cd project
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# Do some work...
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vi foo.h
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# ... and commit locally to gi
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git commit foo.h
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# In the meantime somebody submitted changes to the Perforce depot. Rebase your latest
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# changes against the latest changes in Perforce:
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git-p4 rebase
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# Submit your locally committed changes back to Perforce
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git-p4 submit
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# ... and synchronize with Perforce
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git-p4 rebase
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Implementation Details...
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=========================
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* Changesets from Perforce are imported using git fast-import.
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* The import does not require anything from the Perforce client view as it just uses
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"p4 print //depot/path/file#revision" to get the actual file contents.
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* Every imported changeset has a special [git-p4...] line at the
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end of the log message that gives information about the corresponding
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Perforce change number and is also used by git-p4 itself to find out
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where to continue importing when doing incremental imports.
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Basically when syncing it extracts the perforce change number of the
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latest commit in the "p4" branch and uses "p4 changes //depot/path/...@changenum,#head"
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to find out which changes need to be imported.
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* git-p4 submit uses "git rev-list" to pick the commits between the "p4" branch
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and the current branch.
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The commits themselves are applied using git diff/format-patch ... | git apply
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