docs/Phabricator.rst - llvm - Git at Google

 =============================
 Code Reviews with Phabricator
 =============================

 .. contents::
   :local:

 If you prefer to use a web user interface for code reviews, you can now submit
 your patches for Clang and LLVM at `LLVM's Phabricator`_ instance.

 While Phabricator is a useful tool for some, the relevant -commits mailing list
 is the system of record for all LLVM code review. The mailing list should be
 added as a subscriber on all reviews, and Phabricator users should be prepared
 to respond to free-form comments in mail sent to the commits list.

 Sign up
 -------

 To get started with Phabricator, navigate to `http://reviews.llvm.org`_ and
 click the power icon in the top right. You can register with a GitHub account,
 a Google account, or you can create your own profile.

 Make *sure* that the email address registered with Phabricator is subscribed
 to the relevant -commits mailing list. If your are not subscribed to the commit
 list, all mail sent by Phabricator on your behalf will be held for moderation.

 Note that if you use your Subversion user name as Phabricator user name,
 Phabricator will automatically connect your submits to your Phabricator user in
 the `Code Repository Browser`_.

 Requesting a review via the command line
 ----------------------------------------

 Phabricator has a tool called *Arcanist* to upload patches from
 the command line. To get you set up, follow the
 `Arcanist Quick Start`_ instructions.

 You can learn more about how to use arc to interact with
 Phabricator in the `Arcanist User Guide`_.

 Requesting a review via the web interface
 -----------------------------------------

 The tool to create and review patches in Phabricator is called
 *Differential*.

 Note that you can upload patches created through various diff tools,
 including git and svn. To make reviews easier, please always include
 **as much context as possible** with your diff! Don't worry, Phabricator
 will automatically send a diff with a smaller context in the review
 email, but having the full file in the web interface will help the
 reviewer understand your code.

 To get a full diff, use one of the following commands (or just use Arcanist
 to upload your patch):

 * ``git diff -U999999 other-branch``
 * ``svn diff --diff-cmd=diff -x -U999999``

 To upload a new patch:

 * Click *Differential*.
 * Click *+ Create Diff*.
 * Paste the text diff or browse to the patch file. Click *Create Diff*.
 * Leave the Repository field blank.
 * Leave the drop down on *Create a new Revision...* and click *Continue*.
 * Enter a descriptive title and summary.  The title and summary are usually
   in the form of a :ref:`commit message <commit messages>`.
 * Add reviewers and mailing
   lists that you want to be included in the review. If your patch is
   for LLVM, add llvm-commits as a Subscriber; if your patch is for Clang,
   add cfe-commits.
 * Leave the Repository and Project fields blank.
 * Click *Save*.

 To submit an updated patch:

 * Click *Differential*.
 * Click *+ Create Diff*.
 * Paste the updated diff or browse to the updated patch file. Click *Create Diff*.
 * Select the review you want to from the *Attach To* dropdown and click
   *Continue*.
 * Leave the Repository and Project fields blank.
 * Add comments about the changes in the new diff. Click *Save*.

 Reviewing code with Phabricator
 -------------------------------

 Phabricator allows you to add inline comments as well as overall comments
 to a revision. To add an inline comment, select the lines of code you want
 to comment on by clicking and dragging the line numbers in the diff pane.
 When you have added all your comments, scroll to the bottom of the page and
 click the Submit button.

 You can add overall comments in the text box at the bottom of the page.
 When you're done, click the Submit button.

 Phabricator has many useful features, for example allowing you to select
 diffs between different versions of the patch as it was reviewed in the
 *Revision Update History*. Most features are self descriptive - explore, and
 if you have a question, drop by on #llvm in IRC to get help.

 Note that as e-mail is the system of reference for code reviews, and some
 people prefer it over a web interface, we do not generate automated mail
 when a review changes state, for example by clicking "Accept Revision" in
 the web interface. Thus, please type LGTM into the comment box to accept
 a change from Phabricator.

 Committing a change
 -------------------

 Arcanist can manage the commit transparently. It will retrieve the description,
 reviewers, the ``Differential Revision``, etc from the review and commit it to the repository.

 ::

   arc patch D<Revision>
   arc commit --revision D<Revision>


 When committing an LLVM change that has been reviewed using
 Phabricator, the convention is for the commit message to end with the
 line:

 ::

   Differential Revision: <URL>

 where ``<URL>`` is the URL for the code review, starting with
 ``http://reviews.llvm.org/``.

 Note that Arcanist will add this automatically.

 This allows people reading the version history to see the review for
 context.  This also allows Phabricator to detect the commit, close the
 review, and add a link from the review to the commit.

 Abandoning a change
 -------------------

 If you decide you should not commit the patch, you should explicitly abandon
 the review so that reviewers don't think it is still open. In the web UI,
 scroll to the bottom of the page where normally you would enter an overall
 comment. In the drop-down Action list, which defaults to "Comment," you should
 select "Abandon Revision" and then enter a comment explaining why. Click the
 Submit button to finish closing the review.

 Status
 ------

 Please let us know whether you like it and what could be improved! We're still
 working on setting up a bug tracker, but you can email klimek-at-google-dot-com
 and chandlerc-at-gmail-dot-com and CC the llvm-dev mailing list with questions
 until then. We also could use help implementing improvements. This sadly is
 really painful and hard because the Phabricator codebase is in PHP and not as
 testable as you might like. However, we've put exactly what we're deploying up
 on an `llvm-reviews GitHub project`_ where folks can hack on it and post pull
 requests. We're looking into what the right long-term hosting for this is, but
 note that it is a derivative of an existing open source project, and so not
 trivially a good fit for an official LLVM project.

 .. _LLVM's Phabricator: http://reviews.llvm.org
 .. _`http://reviews.llvm.org`: http://reviews.llvm.org
 .. _Code Repository Browser: http://reviews.llvm.org/diffusion/
 .. _Arcanist Quick Start: http://www.phabricator.com/docs/phabricator/article/Arcanist_Quick_Start.html
 .. _Arcanist User Guide: http://www.phabricator.com/docs/phabricator/article/Arcanist_User_Guide.html
 .. _llvm-reviews GitHub project: https://github.com/r4nt/llvm-reviews/
	=============================
	Code Reviews with Phabricator
	=============================

	.. contents::
	:local:

	If you prefer to use a web user interface for code reviews, you can now submit
	your patches for Clang and LLVM at `LLVM's Phabricator`_ instance.

	While Phabricator is a useful tool for some, the relevant -commits mailing list
	is the system of record for all LLVM code review. The mailing list should be
	added as a subscriber on all reviews, and Phabricator users should be prepared
	to respond to free-form comments in mail sent to the commits list.

	Sign up
	-------

	To get started with Phabricator, navigate to `http://reviews.llvm.org`_ and
	click the power icon in the top right. You can register with a GitHub account,
	a Google account, or you can create your own profile.

	Make sure that the email address registered with Phabricator is subscribed
	to the relevant -commits mailing list. If your are not subscribed to the commit
	list, all mail sent by Phabricator on your behalf will be held for moderation.

	Note that if you use your Subversion user name as Phabricator user name,
	Phabricator will automatically connect your submits to your Phabricator user in
	the `Code Repository Browser`_.

	Requesting a review via the command line
	----------------------------------------

	Phabricator has a tool called Arcanist to upload patches from
	the command line. To get you set up, follow the
	`Arcanist Quick Start`_ instructions.

	You can learn more about how to use arc to interact with
	Phabricator in the `Arcanist User Guide`_.

	Requesting a review via the web interface
	-----------------------------------------

	The tool to create and review patches in Phabricator is called
	Differential.

	Note that you can upload patches created through various diff tools,
	including git and svn. To make reviews easier, please always include
	as much context as possible with your diff! Don't worry, Phabricator
	will automatically send a diff with a smaller context in the review
	email, but having the full file in the web interface will help the
	reviewer understand your code.

	To get a full diff, use one of the following commands (or just use Arcanist
	to upload your patch):

	* ``git diff -U999999 other-branch``
	* ``svn diff --diff-cmd=diff -x -U999999``

	To upload a new patch:

	* Click Differential.
	* Click + Create Diff.
	* Paste the text diff or browse to the patch file. Click Create Diff.
	* Leave the Repository field blank.
	* Leave the drop down on Create a new Revision... and click Continue.
	* Enter a descriptive title and summary. The title and summary are usually
	in the form of a :ref:`commit message <commit messages>`.
	* Add reviewers and mailing
	lists that you want to be included in the review. If your patch is
	for LLVM, add llvm-commits as a Subscriber; if your patch is for Clang,
	add cfe-commits.
	* Leave the Repository and Project fields blank.
	* Click Save.

	To submit an updated patch:

	* Click Differential.
	* Click + Create Diff.
	* Paste the updated diff or browse to the updated patch file. Click Create Diff.
	* Select the review you want to from the Attach To dropdown and click
	Continue.
	* Leave the Repository and Project fields blank.
	* Add comments about the changes in the new diff. Click Save.

	Reviewing code with Phabricator
	-------------------------------

	Phabricator allows you to add inline comments as well as overall comments
	to a revision. To add an inline comment, select the lines of code you want
	to comment on by clicking and dragging the line numbers in the diff pane.
	When you have added all your comments, scroll to the bottom of the page and
	click the Submit button.

	You can add overall comments in the text box at the bottom of the page.
	When you're done, click the Submit button.

	Phabricator has many useful features, for example allowing you to select
	diffs between different versions of the patch as it was reviewed in the
	Revision Update History. Most features are self descriptive - explore, and
	if you have a question, drop by on #llvm in IRC to get help.

	Note that as e-mail is the system of reference for code reviews, and some
	people prefer it over a web interface, we do not generate automated mail
	when a review changes state, for example by clicking "Accept Revision" in
	the web interface. Thus, please type LGTM into the comment box to accept
	a change from Phabricator.

	Committing a change
	-------------------

	Arcanist can manage the commit transparently. It will retrieve the description,
	reviewers, the ``Differential Revision``, etc from the review and commit it to the repository.

	::

	arc patch D<Revision>
	arc commit --revision D<Revision>


	When committing an LLVM change that has been reviewed using
	Phabricator, the convention is for the commit message to end with the
	line:

	::

	Differential Revision: <URL>

	where ``<URL>`` is the URL for the code review, starting with
	``http://reviews.llvm.org/``.

	Note that Arcanist will add this automatically.

	This allows people reading the version history to see the review for
	context. This also allows Phabricator to detect the commit, close the
	review, and add a link from the review to the commit.

	Abandoning a change
	-------------------

	If you decide you should not commit the patch, you should explicitly abandon
	the review so that reviewers don't think it is still open. In the web UI,
	scroll to the bottom of the page where normally you would enter an overall
	comment. In the drop-down Action list, which defaults to "Comment," you should
	select "Abandon Revision" and then enter a comment explaining why. Click the
	Submit button to finish closing the review.

	Status
	------

	Please let us know whether you like it and what could be improved! We're still
	working on setting up a bug tracker, but you can email klimek-at-google-dot-com
	and chandlerc-at-gmail-dot-com and CC the llvm-dev mailing list with questions
	until then. We also could use help implementing improvements. This sadly is
	really painful and hard because the Phabricator codebase is in PHP and not as
	testable as you might like. However, we've put exactly what we're deploying up
	on an `llvm-reviews GitHub project`_ where folks can hack on it and post pull
	requests. We're looking into what the right long-term hosting for this is, but
	note that it is a derivative of an existing open source project, and so not
	trivially a good fit for an official LLVM project.

	.. _LLVM's Phabricator: http://reviews.llvm.org
	.. _`http://reviews.llvm.org`: http://reviews.llvm.org
	.. _Code Repository Browser: http://reviews.llvm.org/diffusion/
	.. _Arcanist Quick Start: http://www.phabricator.com/docs/phabricator/article/Arcanist_Quick_Start.html
	.. _Arcanist User Guide: http://www.phabricator.com/docs/phabricator/article/Arcanist_User_Guide.html
	.. _llvm-reviews GitHub project: https://github.com/r4nt/llvm-reviews/