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git-p4: introduce asciidoc documentation

Add proper documentation for git-p4.  Delete the old .txt
documentation from contrib/fast-import.

Cc: Frans Klaver <fransklaver@gmail.com>
Cc: Luke Diamand <luke@diamand.org>
Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Pete Wyckoff 2011-12-24 21:07:31 -05:00 committed by Junio C Hamano
parent 9e602b24fb
commit 6679c34c47
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git-p4(1)
=========
NAME
----
git-p4 - Import from and submit to Perforce repositories
SYNOPSIS
--------
[verse]
'git p4 clone' [<sync options>] [<clone options>] <p4 depot path>...
'git p4 sync' [<sync options>] [<p4 depot path>...]
'git p4 rebase'
'git p4 submit' [<submit options>] [<master branch name>]
DESCRIPTION
-----------
This command provides a way to interact with p4 repositories
using git.
Create a new git repository from an existing p4 repository using
'git p4 clone', giving it one or more p4 depot paths. Incorporate
new commits from p4 changes with 'git p4 sync'. The 'sync' command
is also used to include new branches from other p4 depot paths.
Submit git changes back to p4 using 'git p4 submit'. The command
'git p4 rebase' does a sync plus rebases the current branch onto
the updated p4 remote branch.
EXAMPLE
-------
* Create an alias for 'git p4', using the full path to the 'git-p4'
script if needed:
+
------------
$ git config --global alias.p4 '!git-p4'
------------
* Clone a repository:
+
------------
$ git p4 clone //depot/path/project
------------
* Do some work in the newly created git repository:
+
------------
$ cd project
$ vi foo.h
$ git commit -a -m "edited foo.h"
------------
* Update the git repository with recent changes from p4, rebasing your
work on top:
+
------------
$ git p4 rebase
------------
* Submit your commits back to p4:
+
------------
$ git p4 submit
------------
COMMANDS
--------
Clone
~~~~~
Generally, 'git p4 clone' is used to create a new git directory
from an existing p4 repository:
------------
$ git p4 clone //depot/path/project
------------
This:
1. Creates an empty git repository in a subdirectory called 'project'.
+
2. Imports the full contents of the head revision from the given p4
depot path into a single commit in the git branch 'refs/remotes/p4/master'.
+
3. Creates a local branch, 'master' from this remote and checks it out.
To reproduce the entire p4 history in git, use the '@all' modifier on
the depot path:
------------
$ git p4 clone //depot/path/project@all
------------
Sync
~~~~
As development continues in the p4 repository, those changes can
be included in the git repository using:
------------
$ git p4 sync
------------
This command finds new changes in p4 and imports them as git commits.
P4 repositories can be added to an existing git repository using
'git p4 sync' too:
------------
$ mkdir repo-git
$ cd repo-git
$ git init
$ git p4 sync //path/in/your/perforce/depot
------------
This imports the specified depot into
'refs/remotes/p4/master' in an existing git repository. The
'--branch' option can be used to specify a different branch to
be used for the p4 content.
If a git repository includes branches 'refs/remotes/origin/p4', these
will be fetched and consulted first during a 'git p4 sync'. Since
importing directly from p4 is considerably slower than pulling changes
from a git remote, this can be useful in a multi-developer environment.
Rebase
~~~~~~
A common working pattern is to fetch the latest changes from the p4 depot
and merge them with local uncommitted changes. Often, the p4 repository
is the ultimate location for all code, thus a rebase workflow makes
sense. This command does 'git p4 sync' followed by 'git rebase' to move
local commits on top of updated p4 changes.
------------
$ git p4 rebase
------------
Submit
~~~~~~
Submitting changes from a git repository back to the p4 repository
requires a separate p4 client workspace. This should be specified
using the 'P4CLIENT' environment variable or the git configuration
variable 'git-p4.client'. The p4 client must exist, but the client root
will be created and populated if it does not already exist.
To submit all changes that are in the current git branch but not in
the 'p4/master' branch, use:
------------
$ git p4 submit
------------
To specify a branch other than the current one, use:
------------
$ git p4 submit topicbranch
------------
The upstream reference is generally 'refs/remotes/p4/master', but can
be overridden using the '--origin=' command-line option.
The p4 changes will be created as the user invoking 'git p4 submit'. The
'--preserve-user' option will cause ownership to be modified
according to the author of the git commit. This option requires admin
privileges in p4, which can be granted using 'p4 protect'.
OPTIONS
-------
General options
~~~~~~~~~~~~~~~
All commands except clone accept this option.
--git-dir <dir>::
Set the 'GIT_DIR' environment variable. See linkgit:git[1].
Sync options
~~~~~~~~~~~~
These options can be used in the initial 'clone' as well as in
subsequent 'sync' operations.
--branch <branch>::
Import changes into given branch. If the branch starts with
'refs/', it will be used as is, otherwise the path 'refs/heads/'
will be prepended. The default branch is 'master'.
--detect-branches::
Use the branch detection algorithm to find new paths in p4. It is
documented below in "BRANCH DETECTION".
--changesfile <file>::
Import exactly the p4 change numbers listed in 'file', one per
line. Normally, 'git p4' inspects the current p4 repository
state and detects the changes it should import.
--silent::
Do not print any progress information.
--verbose::
Provide more progress information.
--detect-labels::
Query p4 for labels associated with the depot paths, and add
them as tags in git.
--import-local::
By default, p4 branches are stored in 'refs/remotes/p4/',
where they will be treated as remote-tracking branches by
linkgit:git-branch[1] and other commands. This option instead
puts p4 branches in 'refs/heads/p4/'.
--max-changes <n>::
Limit the number of imported changes to 'n'. Useful to
limit the amount of history when using the '@all' p4 revision
specifier.
--keep-path::
The mapping of file names from the p4 depot path to git, by
default, involves removing the entire depot path. With this
option, the full p4 depot path is retained in git. For example,
path '//depot/main/foo/bar.c', when imported from
'//depot/main/', becomes 'foo/bar.c'. With '--keep-path', the
git path is instead 'depot/main/foo/bar.c'.
--use-client-spec::
Use a client spec to find the list of interesting files in p4.
The client spec is discovered using 'p4 client -o' which checks
the 'P4CLIENT' environment variable and returns a mapping of
depot files to workspace files.
Clone options
~~~~~~~~~~~~~
These options can be used in an initial 'clone', along with the 'sync'
options described above.
--destination <directory>::
Where to create the git repository. If not provided, the last
component in the p4 depot path is used to create a new
directory.
--bare::
Perform a bare clone. See linkgit:git-clone[1].
-/ <path>::
Exclude selected depot paths when cloning.
Submit options
~~~~~~~~~~~~~~
These options can be used to modify 'git p4 submit' behavior.
--verbose::
Provide more progress information.
--origin <commit>::
Upstream location from which commits are identified to submit to
p4. By default, this is the most recent p4 commit reachable
from 'HEAD'.
-M[<n>]::
Detect renames. See linkgit:git-diff[1]. Renames will be
represented in p4 using explicit 'move' operations.
--preserve-user::
Re-author p4 changes before submitting to p4. This option
requires p4 admin privileges.
DEPOT PATH SYNTAX
-----------------
The p4 depot path argument to 'git p4 sync' and 'git p4 clone' can
be one or more space-separated p4 depot paths, with an optional
p4 revision specifier on the end:
"//depot/my/project"::
Import one commit with all files in the '#head' change under that tree.
"//depot/my/project@all"::
Import one commit for each change in the history of that depot path.
"//depot/my/project@1,6"::
Import only changes 1 through 6.
"//depot/proj1 //depot/proj2@all"::
Import all changes from both named depot paths.
See 'p4 help revisions' for the full syntax of p4 revision specifiers.
BRANCH DETECTION
----------------
P4 does not have the same concept of a branch as git. Instead,
p4 organizes its content as a directory tree, where by convention
different logical branches are in different locations in the tree.
The 'p4 branch' command is used to maintain mappings between
different areas in the tree, and indicate related content. 'git p4'
can use these mappings to determine branch relationships.
If you have a repository where all the branches of interest exist as
subdirectories of a single depot path, you can use '--detect-branches'
when cloning or syncing to have 'git p4' automatically find
subdirectories in p4, and to generate these as branches in git.
For example, if the P4 repository structure is:
----
//depot/main/...
//depot/branch1/...
----
And "p4 branch -o branch1" shows a View line that looks like:
----
//depot/main/... //depot/branch1/...
----
Then this 'git p4 clone' command:
----
git p4 clone --detect-branches //depot@all
----
produces a separate branch in 'refs/remotes/p4/' for //depot/main,
called 'master', and one for //depot/branch1 called 'depot/branch1'.
However, it is not necessary to create branches in p4 to be able to use
them like branches. Because it is difficult to infer branch
relationships automatically, a git configuration setting
'git-p4.branchList' can be used to explicitly identify branch
relationships. It is a list of "source:destination" pairs, like a
simple p4 branch specification, where the "source" and "destination" are
the path elements in the p4 repository. The example above relied on the
presence of the p4 branch. Without p4 branches, the same result will
occur with:
----
git config git-p4.branchList main:branch1
git p4 clone --detect-branches //depot@all
----
PERFORMANCE
-----------
The fast-import mechanism used by 'git p4' creates one pack file for
each invocation of 'git p4 sync'. Normally, git garbage compression
(linkgit:git-gc[1]) automatically compresses these to fewer pack files,
but explicit invocation of 'git repack -adf' may improve performance.
CONFIGURATION VARIABLES
-----------------------
The following config settings can be used to modify 'git p4' behavior.
They all are in the 'git-p4' section.
General variables
~~~~~~~~~~~~~~~~~
git-p4.user::
User specified as an option to all p4 commands, with '-u <user>'.
The environment variable 'P4USER' can be used instead.
git-p4.password::
Password specified as an option to all p4 commands, with
'-P <password>'.
The environment variable 'P4PASS' can be used instead.
git-p4.port::
Port specified as an option to all p4 commands, with
'-p <port>'.
The environment variable 'P4PORT' can be used instead.
git-p4.host::
Host specified as an option to all p4 commands, with
'-h <host>'.
The environment variable 'P4HOST' can be used instead.
git-p4.client::
Client specified as an option to all p4 commands, with
'-c <client>'. This can also be used as a way to find
the client spec for the 'useClientSpec' option.
The environment variable 'P4CLIENT' can be used instead.
Clone and sync variables
~~~~~~~~~~~~~~~~~~~~~~~~
git-p4.syncFromOrigin::
Because importing commits from other git repositories is much faster
than importing them from p4, a mechanism exists to find p4 changes
first in git remotes. If branches exist under 'refs/remote/origin/p4',
those will be fetched and used when syncing from p4. This
variable can be set to 'false' to disable this behavior.
git-p4.branchUser::
One phase in branch detection involves looking at p4 branches
to find new ones to import. By default, all branches are
inspected. This option limits the search to just those owned
by the single user named in the variable.
git-p4.branchList::
List of branches to be imported when branch detection is
enabled. Each entry should be a pair of branch names separated
by a colon (:). This example declares that both branchA and
branchB were created from main:
-------------
git config git-p4.branchList main:branchA
git config --add git-p4.branchList main:branchB
-------------
git-p4.useClientSpec::
Specify that the p4 client spec to be used to identify p4 depot
paths of interest. This is equivalent to specifying the option
'--use-client-spec'. The variable 'git-p4.client' can be used
to specify the name of the client.
Submit variables
~~~~~~~~~~~~~~~~
git-p4.detectRenames::
Detect renames. See linkgit:git-diff[1].
git-p4.detectCopies::
Detect copies. See linkgit:git-diff[1].
git-p4.detectCopiesHarder::
Detect copies harder. See linkgit:git-diff[1].
git-p4.preserveUser::
On submit, re-author changes to reflect the git author,
regardless of who invokes 'git p4 submit'.
git-p4.allowMissingP4Users::
When 'preserveUser' is true, 'git p4' normally dies if it
cannot find an author in the p4 user map. This setting
submits the change regardless.
git-p4.skipSubmitEdit::
The submit process invokes the editor before each p4 change
is submitted. If this setting is true, though, the editing
step is skipped.
git-p4.skipSubmitEditCheck::
After editing the p4 change message, 'git p4' makes sure that
the description really was changed by looking at the file
modification time. This option disables that test.
git-p4.allowSubmit::
By default, any branch can be used as the source for a 'git p4
submit' operation. This configuration variable, if set, permits only
the named branches to be used as submit sources.
git-p4.skipUserNameCheck::
If the user running 'git p4 submit' does not exist in the p4
user map, 'git p4' exits. This option can be used to force
submission regardless.
IMPLEMENTATION DETAILS
----------------------
* Changesets from p4 are imported using git fast-import.
* Cloning or syncing does not require a p4 client; file contents are
collected using 'p4 print'.
* Submitting requires a p4 client, which is not in the same location
as the git repository. Patches are applied, one at a time, to
this p4 client and submitted from there.
* Each commit imported by 'git p4' has a line at the end of the log
message indicating the p4 depot location and change number. This
line is used by later 'git p4 sync' operations to know which p4
changes are new.

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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.skipSubmitEdit
git config [--global] git-p4.skipSubmitEdit false
Normally, git-p4 invokes an editor after each commit is applied so
that you can make changes to the submit message. Setting this
variable to true will skip the editing step, submitting the change as is.
git-p4.skipSubmitEditCheck
git config [--global] git-p4.skipSubmitEditCheck false
After the editor is invoked, git-p4 normally makes sure you saved the
change description, as an indication that you did indeed read it over
and edit it. You can quit without saving to abort the submit (or skip
this change and continue). Setting this variable to true will cause
git-p4 not to check if you saved the change description. This variable
only matters if git-p4.skipSubmitEdit has not been set to true.
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