Merge git://repo.or.cz/git-gui

[git.git] / contrib / fast-import / git-p4.txt

diff --git a/contrib/fast-import/git-p4.txt b/contrib/fast-import/git-p4.txt
index 5f7251c2d6d626da9d2e16771df5ab6f486895d9..b16a8384bcfbfe33dc33e1076c64f5d36e75e803 100644 (file)
--- a/contrib/fast-import/git-p4.txt
+++ b/contrib/fast-import/git-p4.txt
@@ -4,13 +4,31 @@ 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".
+done using "git-p4 sync" or "git-p4 rebase". Submitting changes from Git back
+to Perforce is done using "git-p4 submit".
 
 Importing
 =========
 
-The procedure is simple:
+You can simply start with
+
+  git-p4 clone //depot/path/project
+
+or
+
+  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 (remotes/p4 actually), 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:
+
+  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
@@ -18,8 +36,8 @@ The procedure is simple:
   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 use a different branch.
 
 If you want to import the entire history of a given depot path just use
 
@@ -31,7 +49,6 @@ 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 :)
 
-
 Incremental Imports
 ===================
 
@@ -40,12 +57,24 @@ 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.
 
 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.
 
+
+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 git-p4.syncFromOrigin false
+
 Updating
 ========
 
@@ -82,3 +111,49 @@ continue importing the remaining changes with
 
 After submitting you should sync your perforce import branch ("p4" or "origin")
 from Perforce using git-p4's sync command.
+
+If you have changes in your working directory that you haven't committed into
+git yet but that you want to commit to Perforce directly ("quick fixes") then
+you do not have to go through the intermediate step of creating a git commit
+first but you can just call
+
+  git-p4 submit --direct
+
+
+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
+
+
+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
+