git4p4

git4p4 is a command line utility that helps with using Git from inside a Perforce workspace.

Motivation

One of Perforce's problems is that it's not practical to work on a series of commits locally before submitting them to the server. Files being worked on can be opened for edit in different pending changelists, but it breaks down when the different changes affect the same files. Shelving changelists only partially addresses the problem, and it gets quickly inconvenient to use since subsequent shelves would contain previous changes anyway.

On the other hand, one of Git's strengths is that it can store a series of changes as local commits, and makes it easy to checkout those changes, amend them, split them, squash them, and more.

So git4p4 effectively lets you use a local Git repository as a super-charged Perforce shelf.

Quickstart

Set things up:

1. Create a Git repository inside your Perforce workspace.
2. Add all the files to Git as the initial repository commit.
3. Create a p4 branch at that commit, then switch back to master or whatever your default branch name is.

Work in Git:

1. Write some code, delete some code, etc.
2. Submit these changes in Git. Do more changes, and commit those too.
3. Eventually you have one or more commits that you are ready to submit via P4.

Convert your Git changes to P4:

This is where git4p4 comes in. By default, running it will:

1. Grab all the commits between p4 and your current branch head.
2. Try to convert each commit into a P4 changelist.
3. The script stops converting when it detects that a commit contains a file that's already in a pending changelist. For instance, commit A contains foo.cpp, commit B and C contains other files, and commit D also contains foo.cpp. In this case, git4p4 will convert commits A, B, and C to P4 changelists, and stop there, since foo.cpp is already open for edit in the first changelist.
4. Once the script is done, it shelves and reverts all convert P4 changelists, moves the p4 head to the last converted Git commit, and checks out whatever commit the Git repository was checked out to before running the script. You can pass -p (--p4-work) to instead stay on the last converted commit, with non-reverted pending changelists (i.e. staying "in the P4 world").
5. Check out the other git4p4 options!

Continue working by submitting your P4 changelists, doing more work, etc. Rinse and repeat.

Gotchas

Watch out for a few things:

• Add a .gitignore to your Git repository that matches your p4ignore.
• When you sync your workspace in P4, go back to the p4 branch in the Git repository, commit all the new files in Git, and rebase your changes on top of that. Generally, watch out about not introducing discrepancies between Git and P4.