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diff --git a/contrib/fast-import/git-p4.txt b/contrib/fast-import/git-p4.txt new file mode 100644 index 0000000000..52003ae904 --- /dev/null +++ b/contrib/fast-import/git-p4.txt @@ -0,0 +1,289 @@ +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. + +The Perforce changelists will be created with the user who ran git-p4. If you +use --preserve-user then git-p4 will attempt to create Perforce changelists +with the Perforce user corresponding to the git commit author. You need to +have sufficient permissions within Perforce, and the git users need to have +Perforce accounts. Permissions can be granted using 'p4 protect'. + +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). + +git-p4.skipSubmitModTimeCheck + + git config [--global] git-p4.skipSubmitModTimeCheck false + +If true, submit will not check if the p4 change template has been modified. + +git-p4.preserveUser + + git config [--global] git-p4.preserveUser false + +If true, attempt to preserve user names by modifying the p4 changelists. See +the "--preserve-user" submit option. + +git-p4.allowMissingPerforceUsers + + git config [--global] git-p4.allowMissingP4Users false + +If git-p4 is setting the perforce user for a commit (--preserve-user) then +if there is no perforce user corresponding to the git author, git-p4 will +stop. With allowMissingPerforceUsers set to true, git-p4 will use the +current user (i.e. the behavior without --preserve-user) and carry on with +the perforce commit. + +git-p4.skipUserNameCheck + + git config [--global] git-p4.skipUserNameCheck false + +When submitting, git-p4 checks that the git commits are authored by the current +p4 user, and warns if they are not. This disables the check. + +git-p4.detectRenames + +Detect renames when submitting changes to Perforce server. Will enable -M git +argument. Can be optionally set to a number representing the threshold +percentage value of the rename detection. + + git config [--global] git-p4.detectRenames true + git config [--global] git-p4.detectRenames 50 + +git-p4.detectCopies + +Detect copies when submitting changes to Perforce server. Will enable -C git +argument. Can be optionally set to a number representing the threshold +percentage value of the copy detection. + + git config [--global] git-p4.detectCopies true + git config [--global] git-p4.detectCopies 80 + +git-p4.detectCopiesHarder + +Detect copies even between files that did not change when submitting changes to +Perforce server. Will enable --find-copies-harder git argument. + + git config [--global] git-p4.detectCopies true + +git-p4.branchUser + +Only use branch specifications defined by the selected username. + + git config [--global] git-p4.branchUser username + +git-p4.branchList + +List of branches to be imported when branch detection is enabled. + + git config [--global] git-p4.branchList main:branchA + git config [--global] --add git-p4.branchList main:branchB + +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 + |