1 ============================= 2 Code Reviews with Phabricator 3 ============================= 4 5 .. contents:: 6 :local: 7 8 If you prefer to use a web user interface for code reviews, you can now submit 9 your patches for Clang and LLVM at `LLVM's Phabricator`_ instance. 10 11 While Phabricator is a useful tool for some, the relevant -commits mailing list 12 is the system of record for all LLVM code review. The mailing list should be 13 added as a subscriber on all reviews, and Phabricator users should be prepared 14 to respond to free-form comments in mail sent to the commits list. 15 16 Sign up 17 ------- 18 19 To get started with Phabricator, navigate to `http://reviews.llvm.org`_ and 20 click the power icon in the top right. You can register with a GitHub account, 21 a Google account, or you can create your own profile. 22 23 Make *sure* that the email address registered with Phabricator is subscribed 24 to the relevant -commits mailing list. If you are not subscribed to the commit 25 list, all mail sent by Phabricator on your behalf will be held for moderation. 26 27 Note that if you use your Subversion user name as Phabricator user name, 28 Phabricator will automatically connect your submits to your Phabricator user in 29 the `Code Repository Browser`_. 30 31 Requesting a review via the command line 32 ---------------------------------------- 33 34 Phabricator has a tool called *Arcanist* to upload patches from 35 the command line. To get you set up, follow the 36 `Arcanist Quick Start`_ instructions. 37 38 You can learn more about how to use arc to interact with 39 Phabricator in the `Arcanist User Guide`_. 40 41 Requesting a review via the web interface 42 ----------------------------------------- 43 44 The tool to create and review patches in Phabricator is called 45 *Differential*. 46 47 Note that you can upload patches created through various diff tools, 48 including git and svn. To make reviews easier, please always include 49 **as much context as possible** with your diff! Don't worry, Phabricator 50 will automatically send a diff with a smaller context in the review 51 email, but having the full file in the web interface will help the 52 reviewer understand your code. 53 54 To get a full diff, use one of the following commands (or just use Arcanist 55 to upload your patch): 56 57 * ``git diff -U999999 other-branch`` 58 * ``svn diff --diff-cmd=diff -x -U999999`` 59 60 To upload a new patch: 61 62 * Click *Differential*. 63 * Click *+ Create Diff*. 64 * Paste the text diff or browse to the patch file. Click *Create Diff*. 65 * Leave the Repository field blank. 66 * Leave the drop down on *Create a new Revision...* and click *Continue*. 67 * Enter a descriptive title and summary. The title and summary are usually 68 in the form of a :ref:`commit message <commit messages>`. 69 * Add reviewers (see below for advice) and subscribe mailing 70 lists that you want to be included in the review. If your patch is 71 for LLVM, add llvm-commits as a Subscriber; if your patch is for Clang, 72 add cfe-commits. 73 * Leave the Repository and Project fields blank. 74 * Click *Save*. 75 76 To submit an updated patch: 77 78 * Click *Differential*. 79 * Click *+ Create Diff*. 80 * Paste the updated diff or browse to the updated patch file. Click *Create Diff*. 81 * Select the review you want to from the *Attach To* dropdown and click 82 *Continue*. 83 * Leave the Repository and Project fields blank. 84 * Add comments about the changes in the new diff. Click *Save*. 85 86 Choosing reviewers: You typically pick one or two people as initial reviewers. 87 This choice is not crucial, because you are merely suggesting and not requiring 88 them to participate. Many people will see the email notification on cfe-commits 89 or llvm-commits, and if the subject line suggests the patch is something they 90 should look at, they will. 91 92 Here are a couple of ways to pick the initial reviewer(s): 93 94 * Use ``svn blame`` and the commit log to find names of people who have 95 recently modified the same area of code that you are modifying. 96 * Look in CODE_OWNERS.TXT to see who might be responsible for that area. 97 * If you've discussed the change on a dev list, the people who participated 98 might be appropriate reviewers. 99 100 Even if you think the code owner is the busiest person in the world, it's still 101 okay to put them as a reviewer. Being the code owner means they have accepted 102 responsibility for making sure the review happens. 103 104 Reviewing code with Phabricator 105 ------------------------------- 106 107 Phabricator allows you to add inline comments as well as overall comments 108 to a revision. To add an inline comment, select the lines of code you want 109 to comment on by clicking and dragging the line numbers in the diff pane. 110 When you have added all your comments, scroll to the bottom of the page and 111 click the Submit button. 112 113 You can add overall comments in the text box at the bottom of the page. 114 When you're done, click the Submit button. 115 116 Phabricator has many useful features, for example allowing you to select 117 diffs between different versions of the patch as it was reviewed in the 118 *Revision Update History*. Most features are self descriptive - explore, and 119 if you have a question, drop by on #llvm in IRC to get help. 120 121 Note that as e-mail is the system of reference for code reviews, and some 122 people prefer it over a web interface, we do not generate automated mail 123 when a review changes state, for example by clicking "Accept Revision" in 124 the web interface. Thus, please type LGTM into the comment box to accept 125 a change from Phabricator. 126 127 Committing a change 128 ------------------- 129 130 Once a patch has been reviewed and approved on Phabricator it can then be 131 committed to trunk. There are multiple workflows to achieve this. Whichever 132 method you follow it is recommend that your commit message ends with the line: 133 134 :: 135 136 Differential Revision: <URL> 137 138 where ``<URL>`` is the URL for the code review, starting with 139 ``http://reviews.llvm.org/``. 140 141 This allows people reading the version history to see the review for 142 context. This also allows Phabricator to detect the commit, close the 143 review, and add a link from the review to the commit. 144 145 Note that if you use the Arcanist tool the ``Differential Revision`` line will 146 be added automatically. If you don't want to use Arcanist, you can add the 147 ``Differential Revision`` line (as the last line) to the commit message 148 yourself. 149 150 Using the Arcanist tool can simplify the process of committing reviewed code 151 as it will retrieve reviewers, the ``Differential Revision``, etc from the review 152 and place it in the commit message. Several methods of using Arcanist to commit 153 code are given below. If you do not wish to use Arcanist then simply commit 154 the reviewed patch as you would normally. 155 156 Note that if you commit the change without using Arcanist and forget to add the 157 ``Differential Revision`` line to your commit message then it is recommended 158 that you close the review manually. In the web UI, under "Leap Into Action" put 159 the SVN revision number in the Comment, set the Action to "Close Revision" and 160 click Submit. Note the review must have been Accepted first. 161 162 Subversion and Arcanist 163 ^^^^^^^^^^^^^^^^^^^^^^^ 164 165 On a clean Subversion working copy run the following (where ``<Revision>`` is 166 the Phabricator review number): 167 168 :: 169 170 arc patch D<Revision> 171 arc commit --revision D<Revision> 172 173 The first command will take the latest version of the reviewed patch and apply it to the working 174 copy. The second command will commit this revision to trunk. 175 176 git-svn and Arcanist 177 ^^^^^^^^^^^^^^^^^^^^ 178 179 This presumes that the git repository has been configured as described in :ref:`developers-work-with-git-svn`. 180 181 On a clean Git repository on an up to date ``master`` branch run the 182 following (where ``<Revision>`` is the Phabricator review number): 183 184 :: 185 186 arc patch D<Revision> 187 188 189 This will create a new branch called ``arcpatch-D<Revision>`` based on the 190 current ``master`` and will create a commit corresponding to ``D<Revision>`` with a 191 commit message derived from information in the Phabricator review. 192 193 Check you are happy with the commit message and amend it if necessary. Now switch to 194 the ``master`` branch and add the new commit to it and commit it to trunk. This 195 can be done by running the following: 196 197 :: 198 199 git checkout master 200 git merge --ff-only arcpatch-D<Revision> 201 git svn dcommit 202 203 204 205 Abandoning a change 206 ------------------- 207 208 If you decide you should not commit the patch, you should explicitly abandon 209 the review so that reviewers don't think it is still open. In the web UI, 210 scroll to the bottom of the page where normally you would enter an overall 211 comment. In the drop-down Action list, which defaults to "Comment," you should 212 select "Abandon Revision" and then enter a comment explaining why. Click the 213 Submit button to finish closing the review. 214 215 Status 216 ------ 217 218 Please let us know whether you like it and what could be improved! We're still 219 working on setting up a bug tracker, but you can email klimek-at-google-dot-com 220 and chandlerc-at-gmail-dot-com and CC the llvm-dev mailing list with questions 221 until then. We also could use help implementing improvements. This sadly is 222 really painful and hard because the Phabricator codebase is in PHP and not as 223 testable as you might like. However, we've put exactly what we're deploying up 224 on an `llvm-reviews GitHub project`_ where folks can hack on it and post pull 225 requests. We're looking into what the right long-term hosting for this is, but 226 note that it is a derivative of an existing open source project, and so not 227 trivially a good fit for an official LLVM project. 228 229 .. _LLVM's Phabricator: http://reviews.llvm.org 230 .. _`http://reviews.llvm.org`: http://reviews.llvm.org 231 .. _Code Repository Browser: http://reviews.llvm.org/diffusion/ 232 .. _Arcanist Quick Start: https://secure.phabricator.com/book/phabricator/article/arcanist_quick_start/ 233 .. _Arcanist User Guide: https://secure.phabricator.com/book/phabricator/article/arcanist/ 234 .. _llvm-reviews GitHub project: https://github.com/r4nt/llvm-reviews/ 235
