'\" t
.\"     Title: depot_tools_tutorial
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: 04/10/2014
.\"    Manual: Chromium depot_tools Manual
.\"    Source: depot_tools bec7be9
.\"  Language: English
.\"
.TH "DEPOT_TOOLS_TUTORIAL" "7" "04/10/2014" "depot_tools bec7be9" "Chromium depot_tools Manual"
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
depot_tools_tutorial \- A tutorial introduction to the Chromium depot_tools git extensions\&.
.SH "DESCRIPTION"
.sp
The Chromium \fBdepot_tools\fR(7) suite contains many git workflow\-enhancing tools which are designed to work together to enable anyone to wrangle the Chromium codebase expertly\&. This tutorial explains how to do development on Chromium using these tools\&. This will cover:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Setting up
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Getting the code
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
TL;DR Walkthrough
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Creating / Uploading a CL
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Updating the code
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Managing multiple CLs
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Managing dependent CLs
.RE
.sp
Please refer to the manpages (or \-\-help output) for details about any of the commands mentioned in this tutorial\&.
.if n \{\
.sp
.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBNote\fR
.ps -1
.br
.sp
If your platform does not support manpages (or you prefer something a bit more expressive than plain text) you can find all documentation in \fIhtml\fR form in the [DEPOT_TOOLS]/docs/html folder\&.
.sp .5v
.RE
.SS "PREREQUISITES"
.sp
This tutorial assumes basic familiarity with git terminology and concepts\&. If you need to brush up on these, the following are very good resources:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\m[blue]\fBThink like (a) Git\fR\m[]\&\s-2\u[1]\d\s+2
\- A lighthearted overview of git\&. If you\(cqre sorta\-familiar with git, but not
\fIcomfortable\fR
with it, then give this a look\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\m[blue]\fBGit Immersion Tutorial\fR\m[]\&\s-2\u[2]\d\s+2
\- An in\-depth git tutorial\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\m[blue]\fBpcottle\(cqs Visual Git Branching\fR\m[]\&\s-2\u[3]\d\s+2
\- An excellent interactive/graphical demo on how git handles commits, branches, and shows the operations git performs on them\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\m[blue]\fBPro Git book\fR\m[]\&\s-2\u[4]\d\s+2
\- \(lqThe\(rq book for learning git from basics to advanced concepts\&. A bit dry, but very through\&.
.RE
.sp
If you\(cqve tried these out and are still having some trouble getting started, there are \fImany\fR other resources online which should help\&. If you\(cqre \fIreally\fR \fB\fIreally\fR\fR stuck, then chat up one of the Chromium infrastructure team members for some pointers\&.
.PP
Litmus Test
.RS 4
If you know what
git add,
git status,
git commit
do and you know
\fIessentially\fR
what
git rebase
does, then you should know enough to follow along\&.
.RE
.SH "SETTING UP"
.SS "GET DEPOT TOOLS"
.sp
Clone the \fIdepot_tools\fR repository:
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git clone https://chromium\&.googlesource\&.com/chromium/tools/depot_tools\fR
.fi
.if n \{\
.RE
.\}
.sp
.sp
Add \fIdepot_tools\fR to the \fIend\fR of your PATH and MANPATH (you will probably want to put this in your ~/\&.bashrc or ~/\&.zshrc)\&. Assuming you cloned \fIdepot_tools\fR to /path/to/depot_tools:
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ export PATH=$PATH:/path/to/depot_tools\fR
\fB$ export MANPATH=$MANPATH:/path/to/depot_tools/docs\fR  \fB(1)\fR
.fi
.if n \{\
.RE
.\}
.sp
.sp
\fB1. \fRObserve that this path is
depot_tools/\fBdocs\fR\&.
.br
.SS "BOOTSTRAPPING CONFIGURATION"
.sp
If you have never used git before, you\(cqll need to set some global git configurations; substitute your name and email address in the following commands:
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git config \-\-global user\&.name \(lqJohn Doe\(rq\fR
\fB$ git config \-\-global user\&.email \(lqjdoe@email\&.com\(rq\fR
\fB$ git config \-\-global core\&.autocrlf false\fR
\fB$ git config \-\-global core\&.filemode false\fR
\fB$\fR # and for fun!
\fB$ git config \-\-global color\&.ui true\fR
.fi
.if n \{\
.RE
.\}
.sp
.SH "GETTING THE CODE"
.sp
Pick an empty directory and run one of the following:
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ fetch chromium\fR  # Basic checkout for desktop Chromium
\fB$ fetch blink\fR     # Chromium code with Blink checked out to tip\-of\-tree
\fB$ fetch android\fR   # Chromium checkout for Android platform
\fB$ fetch ios\fR       # Chromium checkout for iOS platform
.fi
.if n \{\
.RE
.\}
.sp
.sp
When the fetch tool completes you should have the following in your working directory:
.sp
.if n \{\
.RS 4
.\}
.nf
\fB\&.gclient\fR   # A configuration file for you source checkout
\fBsrc/\fR       # Top\-level Chromium source checkout\&.
.fi
.if n \{\
.RE
.\}
.sp
.sp
If you are on linux, then you\(cqll need to run:
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ cd src && \&./build/install\-build\-deps\&.sh\fR
.fi
.if n \{\
.RE
.\}
.sp
.sp
And finally:
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ gclient sync\fR \fB(1)\fR
.fi
.if n \{\
.RE
.\}
.sp
.sp
\fB1. \fRThis will pull all dependencies of the Chromium src checkout\&. You will need to run this any time you update the main src checkout\&.
.br
.SH "TL;DR WALKTHROUGH"
.sp
This section will demo what a typical workflow looks like when writing, updating, and committing multiple CLs\&.
.sp

.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ fetch chromium\fR
\&.\&.\&. truncated output \&.\&.\&.
\fB$ cd src\fR
.fi
.if n \{\
.RE
.\}
.sp
(only on linux)
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ \&./build/install\-build\-deps\&.sh\fR
\&.\&.\&. truncated output \&.\&.\&.
.fi
.if n \{\
.RE
.\}
.sp
Pull in all dependencies for HEAD
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ gclient sync\fR
\&.\&.\&. truncated output \&.\&.\&.
.fi
.if n \{\
.RE
.\}
.sp
Let\*(Aqs fix something!
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git new\-branch fix_typo\fR
\fB$ echo \-e \*(Aq/Banana\ens/Banana/Kuun\enwq\*(Aq | ed build/whitespace_file\&.txt\fR
1503
It was a Domo\-Banana\&.
It was a Domo\-Kuun\&.
1501
\fB$ git commit \-am \*(AqFix terrible typo\&.\*(Aq\fR
[fix_typo 615ffa7] Fix terrible typo\&.
 1 file changed, 1 insertion(+), 1 deletion(\-)
\fB$ git map\fR
\fB* 615ffa7	\fR (\fBfix_typo\fR) 2014\-04\-10 ~ Fix terrible typo\&.
* \fBbeec6f4	\fR (origin/master, origin/HEAD) 2014\-04\-10 ~ Make ReflectorImpl use mailboxes\fB    <(fix_typo)\fR
* \fB41290e0	\fR 2014\-04\-10 ~ don\*(Aqt use glibc\-specific execinfo\&.h on uclibc builds
* \fBa76fde7	\fR 2014\-04\-10 ~ [fsp] Add requestUnmount() method together with the request manager\&.
* \fB9de7a71	\fR 2014\-04\-10 ~ linux_aura: Use system configuration for middle clicking the titlebar\&.
* \fB073b0c2	\fR 2014\-04\-10 ~ ContentView\->ContentViewCore in ContentViewRenderView
* \fB2250f53	\fR 2014\-04\-10 ~ ozone: evdev: Filter devices by path
* \fB33a7a74	\fR 2014\-04\-10 ~ Always output seccomp error messages to stderr
\fB$ git status\fR
# On branch fix_typo
# Your branch is ahead of \*(Aqorigin/master\*(Aq by 1 commit\&.
#   (use "git push" to publish your local commits)
#
nothing to commit, working directory clean
\fB$ git cl upload \-r domo@chromium\&.org \-\-send\-mail\fR
\&.\&.\&. truncated output \&.\&.\&.
.fi
.if n \{\
.RE
.\}
.sp
While we wait for feedback, let\*(Aqs do something else\&.
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git new\-branch chap2\fR
\fB$ git map\-branches\fR
\fBorigin/master
  chap2 *
\fR  fix_typo
\fB$ cat >> build/whitespace_file\&.txt <<EOF\fR

"You recall what happened on Mulholland drive?" The ceiling fan rotated slowly
overhead, barely disturbing the thick cigarette smoke\&. No doubt was left about
when the fan was last cleaned\&.
EOF
\fB$ git status\fR
# On branch chap2
# Your branch is up\-to\-date with \*(Aqorigin/master\*(Aq\&.
#
# Changes not staged for commit:
#   (use "git add <file>\&.\&.\&." to update what will be committed)
#   (use "git checkout \-\- <file>\&.\&.\&." to discard changes in working directory)
#
#	modified:   build/whitespace_file\&.txt
#
no changes added to commit (use "git add" and/or "git commit \-a")
.fi
.if n \{\
.RE
.\}
.sp
Someone on the code review pointed out that our typo\-fix has a typo :( We\*(Aqre still working on \*(Aqchap2\*(Aq but we really want to land \*(Aqfix_typo\*(Aq, so let\*(Aqs switch over and fix it\&.
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git freeze\fR
\fB$ git checkout fix_typo\fR
Switched to branch \*(Aqfix_typo\*(Aq
Your branch is ahead of \*(Aqorigin/master\*(Aq by 1 commit\&.
  (use "git push" to publish your local commits)
\fB$ echo \-e \*(Aq/Kuun\ens/Kuun/Kun\enwq\*(Aq | ed build/whitespace_file\&.txt\fR
1501
It was a Domo\-Kuun\&.
It was a Domo\-Kun\&.
1500
\fB$ git upstream\-diff \-\-wordwise\fR
\fBdiff \-\-git a/build/whitespace_file\&.txt b/build/whitespace_file\&.txt\fR
\fBindex 3eba355\&.\&.57cdcee 100644\fR
\fB\-\-\- a/build/whitespace_file\&.txt\fR
\fB+++ b/build/whitespace_file\&.txt\fR
@@ \-17,7 +17,7 @@ swept up the streets (for it is in London that our scene lies), rattling along
the housetops, and fiercely agitating the scanty flame of the lamps that
struggled against the elements\&. A hooded figure emerged\&.

It was a Domo\-BananaKun\&.

"What took you so long?", inquired his wife\&.

\fB$ git commit \-am \*(AqFix typo for good!\*(Aq\fR
[fix_typo 2c0ad9c] Fix typo for good!
 1 file changed, 1 insertion(+), 1 deletion(\-)
\fB$ git cl upload\fR
\&.\&.\&. truncated output \&.\&.\&.
.fi
.if n \{\
.RE
.\}
.sp
Since we got lgtm, let the CQ land it\&.
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git cl set_commit\fR
\fB$ git map\fR
* \fB0e2e52e	\fR (\fBchap2\fR) 2014\-04\-10 ~ FREEZE\&.unindexed
| \fB* 2c0ad9c	\fR (\fBfix_typo\fR) 2014\-04\-10 ~ Fix typo for good!
| * \fB615ffa7	\fR 2014\-04\-10 ~ Fix terrible typo\&.
|/
* \fBbeec6f4	\fR (origin/master, origin/HEAD) 2014\-04\-10 ~ Make ReflectorImpl use mailboxes\fB    <(chap2, fix_typo)\fR
* \fB41290e0	\fR 2014\-04\-10 ~ don\*(Aqt use glibc\-specific execinfo\&.h on uclibc builds
* \fBa76fde7	\fR 2014\-04\-10 ~ [fsp] Add requestUnmount() method together with the request manager\&.
* \fB9de7a71	\fR 2014\-04\-10 ~ linux_aura: Use system configuration for middle clicking the titlebar\&.
* \fB073b0c2	\fR 2014\-04\-10 ~ ContentView\->ContentViewCore in ContentViewRenderView
* \fB2250f53	\fR 2014\-04\-10 ~ ozone: evdev: Filter devices by path
* \fB33a7a74	\fR 2014\-04\-10 ~ Always output seccomp error messages to stderr
.fi
.if n \{\
.RE
.\}
.sp
Switch back to where we were using the nav* commands (for fun\&.\&.\&. git checkout would work here too)
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git map\-branches\fR
origin/master
  chap2
\fB  fix_typo *
$ git nav\-upstream\fR
Note: checking out \*(Aqorigin/master\*(Aq\&.

You are in \*(Aqdetached HEAD\*(Aq state\&. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout\&.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using \-b with the checkout command again\&. Example:

  git checkout \-b new_branch_name

HEAD is now at beec6f4\&.\&.\&. Make ReflectorImpl use mailboxes
\fB$ git nav\-downstream\fR
Please select a downstream branch
  0\&. chap2
  1\&. fix_typo
Selection (0\-1)[0]: 0
Previous HEAD position was beec6f4\&.\&.\&. Make ReflectorImpl use mailboxes
Switched to branch \*(Aqchap2\*(Aq
Your branch is ahead of \*(Aqorigin/master\*(Aq by 1 commit\&.
  (use "git push" to publish your local commits)
\fB$ git map\-branches\fR
origin/master
\fB  chap2 *
\fR  fix_typo
.fi
.if n \{\
.RE
.\}
.sp
Now we can pick up on chapter2 where we left off\&.
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git thaw\fR
\fB$ git diff\fR
\fBdiff \-\-git a/build/whitespace_file\&.txt b/build/whitespace_file\&.txt\fR
\fBindex 3eba355\&.\&.9d08d9d 100644\fR
\fB\-\-\- a/build/whitespace_file\&.txt\fR
\fB+++ b/build/whitespace_file\&.txt\fR
@@ \-34,3 +34,7 @@ with his fork, watching the runny jelly spread and pool across his plate,
 like the blood of a dying fawn\&. \e"It reminds me of that time \-\-\e" he started, as
 his wife cut in quickly: \e"\-\- please\&. I can\*(Aqt bear to hear it\&.\e"\&. A flury of
 images coming from the past flowed through his mind\&.
+
+"You recall what happened on Mulholland drive?" The ceiling fan rotated slowly
+overhead, barely disturbing the thick cigarette smoke\&. No doubt was left about
+when the fan was last cleaned\&.
\fB$ cat >> build/whitespace_file\&.txt <<EOF\fR

There was an poignant pause\&.
EOF
\fB$ git diff\fR
\fBdiff \-\-git a/build/whitespace_file\&.txt b/build/whitespace_file\&.txt\fR
\fBindex 3eba355\&.\&.e3a55de 100644\fR
\fB\-\-\- a/build/whitespace_file\&.txt\fR
\fB+++ b/build/whitespace_file\&.txt\fR
@@ \-34,3 +34,9 @@ with his fork, watching the runny jelly spread and pool across his plate,
 like the blood of a dying fawn\&. \e"It reminds me of that time \-\-\e" he started, as
 his wife cut in quickly: \e"\-\- please\&. I can\*(Aqt bear to hear it\&.\e"\&. A flury of
 images coming from the past flowed through his mind\&.
+
+"You recall what happened on Mulholland drive?" The ceiling fan rotated slowly
+overhead, barely disturbing the thick cigarette smoke\&. No doubt was left about
+when the fan was last cleaned\&.
+
+There was an poignant pause\&.
\fB$ git commit \-am \*(AqFinish chapter 2\*(Aq\fR
[chap2 ceef712] Finish chapter 2
 1 file changed, 6 insertions(+)
\fB$ git map\fR
\fB* ceef712	\fR (\fBchap2\fR) 2014\-04\-10 ~ Finish chapter 2
| * \fB2c0ad9c	\fR (\fBfix_typo\fR) 2014\-04\-10 ~ Fix typo for good!
| * \fB615ffa7	\fR 2014\-04\-10 ~ Fix terrible typo\&.
|/
* \fBbeec6f4	\fR (origin/master, origin/HEAD) 2014\-04\-10 ~ Make ReflectorImpl use mailboxes\fB    <(chap2, fix_typo)\fR
* \fB41290e0	\fR 2014\-04\-10 ~ don\*(Aqt use glibc\-specific execinfo\&.h on uclibc builds
* \fBa76fde7	\fR 2014\-04\-10 ~ [fsp] Add requestUnmount() method together with the request manager\&.
* \fB9de7a71	\fR 2014\-04\-10 ~ linux_aura: Use system configuration for middle clicking the titlebar\&.
* \fB073b0c2	\fR 2014\-04\-10 ~ ContentView\->ContentViewCore in ContentViewRenderView
* \fB2250f53	\fR 2014\-04\-10 ~ ozone: evdev: Filter devices by path
* \fB33a7a74	\fR 2014\-04\-10 ~ Always output seccomp error messages to stderr
\fB$ git cl upload \-r domo@chromium\&.org \-\-send\-mail\fR
\&.\&.\&. truncated output \&.\&.\&.
.fi
.if n \{\
.RE
.\}
.sp
We poke a committer until they lgtm :)
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git cl set_commit\fR
.fi
.if n \{\
.RE
.\}
.sp
While that runs through the CQ, let\*(Aqs get started on chapter 3\&. Since we know that chapter 3 depends on chapter 2, we\*(Aqll track the current chapter2 branch\&.
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git new\-branch \-\-upstream_current chap3\fR
\fB$ cat >> build/whitespace_file\&.txt <<EOF\fR

CHAPTER 3:
Mr\&. Usagi felt that something wasn\*(Aqt right\&. Shortly after the Domo\-Kun left he
began feeling sick\&.
EOF
\fB$ git commit \-am \*(Aqbeginning of chapter 3\*(Aq\fR
[chap3 7d4238a] beginning of chapter 3
 1 file changed, 4 insertions(+)
\fB$ git map\fR
\fB* 7d4238a	\fR (\fBchap3\fR) 2014\-04\-10 ~ beginning of chapter 3
* \fBceef712	\fR (\fBchap2\fR) 2014\-04\-10 ~ Finish chapter 2\fB    <(chap3)\fR
| * \fB2c0ad9c	\fR (\fBfix_typo\fR) 2014\-04\-10 ~ Fix typo for good!
| * \fB615ffa7	\fR 2014\-04\-10 ~ Fix terrible typo\&.
|/
* \fBbeec6f4	\fR (origin/master, origin/HEAD) 2014\-04\-10 ~ Make ReflectorImpl use mailboxes\fB    <(chap2, fix_typo)\fR
* \fB41290e0	\fR 2014\-04\-10 ~ don\*(Aqt use glibc\-specific execinfo\&.h on uclibc builds
* \fBa76fde7	\fR 2014\-04\-10 ~ [fsp] Add requestUnmount() method together with the request manager\&.
* \fB9de7a71	\fR 2014\-04\-10 ~ linux_aura: Use system configuration for middle clicking the titlebar\&.
* \fB073b0c2	\fR 2014\-04\-10 ~ ContentView\->ContentViewCore in ContentViewRenderView
* \fB2250f53	\fR 2014\-04\-10 ~ ozone: evdev: Filter devices by path
* \fB33a7a74	\fR 2014\-04\-10 ~ Always output seccomp error messages to stderr
.fi
.if n \{\
.RE
.\}
.sp
We haven\*(Aqt updated the code in a while, so let\*(Aqs do that now\&.
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git rebase\-update\fR
Fetching origin
From https://upstream
   beec6f4\&.\&.59cdb73  master     \-> origin/master
Rebasing: chap2
Rebasing: fix_typo
Failed! Attempting to squash fix_typo \&.\&.\&. Success!
Rebasing: chap3
Deleted branch fix_typo (was 5d26fec)\&.
Reparented chap3 to track origin/master (was tracking chap2)
Deleted branch chap2 (was 5d26fec)\&.
.fi
.if n \{\
.RE
.\}
.sp
Well look at that\&. The CQ landed our typo and chapter2 branches already and git rebase\-update cleaned them up for us\&.
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ gclient sync\fR
\&.\&.\&. truncated output \&.\&.\&.
\fB$ git map\fR
\fB* 93fe917	\fR (\fBchap3\fR) 2014\-04\-10 ~ beginning of chapter 3
* \fB5d26fec	\fR (origin/master, origin/HEAD) 2014\-04\-10 ~ Finish chapter 2\fB    <(chap3)\fR
* \fBdf7fefb	\fR 2014\-04\-10 ~ Revert 255617, due to it not tracking use of the link doctor page properly\&.
* \fB4b39cda	\fR 2014\-04\-10 ~ Fix terrible typo\&.
* \fB248c5b6	\fR 2014\-04\-10 ~ Temporarily CHECK(trial) in ChromeRenderProcessObserver::OnSetFieldTrialGroup\&.
* \fB8171df8	\fR 2014\-04\-10 ~ Remove AMD family check for the flapper crypto accelerator\&.
* \fBd6a30d2	\fR 2014\-04\-10 ~ Change the Pica load benchmark to listen for the polymer\-ready event
* \fBbeec6f4	\fR 2014\-04\-10 ~ Make ReflectorImpl use mailboxes
* \fB41290e0	\fR 2014\-04\-10 ~ don\*(Aqt use glibc\-specific execinfo\&.h on uclibc builds
* \fBa76fde7	\fR 2014\-04\-10 ~ [fsp] Add requestUnmount() method together with the request manager\&.
* \fB9de7a71	\fR 2014\-04\-10 ~ linux_aura: Use system configuration for middle clicking the titlebar\&.
* \fB073b0c2	\fR 2014\-04\-10 ~ ContentView\->ContentViewCore in ContentViewRenderView
* \fB2250f53	\fR 2014\-04\-10 ~ ozone: evdev: Filter devices by path
* \fB33a7a74	\fR 2014\-04\-10 ~ Always output seccomp error messages to stderr
.fi
.if n \{\
.RE
.\}
.sp
Someone on IRC mentions that they actually landed a chapter 3 already! We should pull their changes before continuing\&. Brace for a code conflict!
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git rebase\-update\fR
Fetching origin
From https://upstream
   5d26fec\&.\&.59cdb73  master     \-> origin/master
Rebasing: chap2
\&.\&.\&. lots of output, it\*(Aqs a conflict alright :(\&.\&.\&.
\fB$ git diff\fR
\fBdiff \-\-cc build/whitespace_file\&.txt\fR
\fBindex 1293282,f903ea2\&.\&.0000000\fR
\fB\-\-\- a/build/whitespace_file\&.txt\fR
\fB+++ b/build/whitespace_file\&.txt\fR
@@@ \-42,4 \-42,5 +42,9 @@@ when the fan was last cleaned
  There was an poignant pause\&.

  CHAPTER 3:
++<<<<<<< HEAD
 +Hilariousness! This chapter is awesome!
++=======
+ Mr\&. Usagi felt that something wasn\*(Aqt right\&. Shortly after the Domo\-Kun left he
+ began feeling sick\&.
++>>>>>>> beginning of chapter 3
.fi
.if n \{\
.RE
.\}
.sp
Oh, well, that\*(Aqs not too bad\&. In fact\&.\&.\&. that\*(Aqs a terrible chapter 3!
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ $EDITOR build/whitespace_file\&.txt\fR
\&.\&.\&. /me deletes bad chapter 3 \&.\&.\&.
\fB$ git add build/whitespace_file\&.txt\fR
\fB$ git diff \-\-cached\fR
\fBdiff \-\-git a/build/whitespace_file\&.txt b/build/whitespace_file\&.txt\fR
\fBindex 1293282\&.\&.f903ea2 100644\fR
\fB\-\-\- a/build/whitespace_file\&.txt\fR
\fB+++ b/build/whitespace_file\&.txt\fR
@@ \-42,4 +42,5 @@ when the fan was last cleaned\&.
 There was an poignant pause\&.

 CHAPTER 3:
\-Hilariousness! This chapter is awesome!
+Mr\&. Usagi felt that something wasn\*(Aqt right\&. Shortly after the Domo\-Kun left he
+began feeling sick\&.
.fi
.if n \{\
.RE
.\}
.sp
Much better
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git rebase \-\-continue\fR
Applying: beginning of chapter 3
\fB$ git rebase\-update\fR
Fetching origin
chap3 up\-to\-date
\fB$ gclient sync\fR
\&.\&.\&. truncated output \&.\&.\&.
\fB$ git map\fR
\fB* 1cb4f5b	\fR (\fBchap3\fR) 2014\-04\-10 ~ beginning of chapter 3
* \fB59cdb73	\fR (origin/master, origin/HEAD) 2014\-04\-10 ~ Refactor data interchange format\&.\fB    <(chap3)\fR
* \fB34676a3	\fR 2014\-04\-10 ~ Ensure FS is exited for all not\-in\-same\-page navigations\&.
* \fB7d4784e	\fR 2014\-04\-10 ~ Add best chapter2 ever!
* \fB5d26fec	\fR 2014\-04\-10 ~ Finish chapter 2
* \fBdf7fefb	\fR 2014\-04\-10 ~ Revert 255617, due to it not tracking use of the link doctor page properly\&.
* \fB4b39cda	\fR 2014\-04\-10 ~ Fix terrible typo\&.
* \fB248c5b6	\fR 2014\-04\-10 ~ Temporarily CHECK(trial) in ChromeRenderProcessObserver::OnSetFieldTrialGroup\&.
* \fB8171df8	\fR 2014\-04\-10 ~ Remove AMD family check for the flapper crypto accelerator\&.
* \fBd6a30d2	\fR 2014\-04\-10 ~ Change the Pica load benchmark to listen for the polymer\-ready event
* \fBbeec6f4	\fR 2014\-04\-10 ~ Make ReflectorImpl use mailboxes
* \fB41290e0	\fR 2014\-04\-10 ~ don\*(Aqt use glibc\-specific execinfo\&.h on uclibc builds
* \fBa76fde7	\fR 2014\-04\-10 ~ [fsp] Add requestUnmount() method together with the request manager\&.
* \fB9de7a71	\fR 2014\-04\-10 ~ linux_aura: Use system configuration for middle clicking the titlebar\&.
* \fB073b0c2	\fR 2014\-04\-10 ~ ContentView\->ContentViewCore in ContentViewRenderView
* \fB2250f53	\fR 2014\-04\-10 ~ ozone: evdev: Filter devices by path
* \fB33a7a74	\fR 2014\-04\-10 ~ Always output seccomp error messages to stderr
\fB$ git cl upload\fR
\&.\&.\&. truncated output \&.\&.\&.
.fi
.if n \{\
.RE
.\}
.sp
.sp
So there you have the basic flow\&. Note that you don\(cqt \fIhave\fR to do chromium development using these tools\&. Any git workflow is compatible, as long as git cl upload is able to upload good patches\&.
.SH "CREATING / UPLOADING A CL"
.if n \{\
.sp
.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBNote\fR
.ps -1
.br
.sp
The remainder of the tutorial assumes that your current working directory is the src/ folder mentioned in Getting the code\&.
.sp .5v
.RE
.sp
Each CL corresponds exactly with a single branch in git\&. Any time you want to begin a new CL, just:
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git new\-branch <branch_name>\fR
.fi
.if n \{\
.RE
.\}
.sp
.sp
This will create and checkout a new branch named branch_name which will track the default upstream (which is origin/master)\&. See \fBgit-new-branch\fR(1) for more features, such as the ability to track \fILKGR\fR\&.
.sp
Commit as many changes as you like to this branch\&. When you want to upload it for review, run:
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git cl upload\fR
.fi
.if n \{\
.RE
.\}
.sp
.sp
This will take the diff of your branch against its upstream (origin/master), and will post it to the \m[blue]\fBChromium code review site\fR\m[]\&\s-2\u[5]\d\s+2\&.
.SH "UPDATING THE CODE"
.sp
Inevitably, you\(cqll want to pull in changes from the main Chromium repo\&. This is pretty easy with \fIdepot_tools\fR:
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git rebase\-update\fR
.fi
.if n \{\
.RE
.\}
.sp
.sp
This command will update all of your CLs to contain the latest code from their upstreams\&. It will also automatically clean up CLs which have been committed and a couple other nice things\&. See \fBgit-rebase-update\fR(1) for the full scoop\&.
.sp
One thing to look out for are \fImerge conflicts\fR\&. These happen for exactly the same as they do with SVN, but the experience is a little more controllable with git\&. git rebase\-update will try to rebase all your branches for you, but if it encounters a merge conflict in one, it will halt and leave you in a rebase conflict state (see \fBgit-rebase\fR(1))\&. Resolving git rebase merge conflicts is beyond the scope of this tutorial, but there are many good sources online (see the Prerequisites for some)\&.
.sp
Sometimes you\(cqre pretty certain that you\(cqve committed a certain branch, but git rebase\-update isn\(cqt able to tell that for sure\&. This is usually because your branch doesn\(cqt rebase cleanly\&. You could just delete the branch with git branch \-D <branch>, but you\(cqd like to double check the diff of your branch against its upstream before deleting it\&. If this is the case you can abort the rebase started by git rebase\-update, and then run \fBgit-squash-branch\fR(1) to flatten your branch into a single commit\&. When you run git rebase\-update again, you\(cqll get a (hopefully) much smaller / saner diff\&. If it turns out you were wrong about your branch being fully committed, you can use \fBgit-reflog\fR(1) to reset your branch back to where it was before\&. If the diff looks inconsequential, you can use git rebase \-\-skip to ignore it, and then git rebase\-update will clean it up for you\&.
.sp
Once you\(cqre done resolving all of the merge conflict, just run git rebase\-update, and it will pick up where it left off\&. Once the command has finished updating all of your branches, it will return you back to the branch you started on\&.
.if n \{\
.sp
.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBNote\fR
.ps -1
.br
.sp
Running git rebase\-update will update all your branches, but it will not automatically run gclient sync to update your dependencies\&.
.sp .5v
.RE
.SH "MANAGING MULTIPLE CLS"
.sp
Sometimes you want to work on more than one CL at once (say, you have a CL posted for review and want to work on something else)\&. For each CL that you want to work on, just use git new\-branch <branchname>\&.
.sp
Once you start to have more than one CL at a time, it can be easy to lose your bearings\&. Fortunately, \fIdepot_tools\fR has two tools to help you out:
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git map\fR
*\:\fB 7dcfe47       \fR (\:\fBfrozen_changes\fR\:) 2014\-03\-12 ~ FREEZE\&.unindexed
* \fB4b0c180\fR        2014\-03\-12 ~ modfile
* \fB59a7cca\fR        2014\-03\-12 ~ a deleted file
* \fB6bec695\fR        (\:origin/master\:) 2014\-03\-11 ~ Add neat feature    \fB<(frozen_changes)\fR
* \fBd15a38a\fR        2014\-03\-11 ~ Epic README update
* \fBd559894\fR        (\:\fBmaster\fR\:) 2014\-03\-11 ~ Important upstream change
| * \fB9c311fd\fR      (\:\fBcool_feature\fR\:) 2014\-03\-11 ~ Respond to CL comments
| | * \fB2a1eeb2\fR    (\:\fBsubfeature\fR\:) 2014\-03\-11 ~ integrate with CoolService
| | * \fBd777af6\fR    2014\-03\-11 ~ slick commenting action
| |/
| * \fB265803a\fR      2014\-03\-11 ~ another improvement    \fB<(subfeature)\fR
| * \fB6d831ac\fR      (\:\fBspleen_tag\fR\:) 2014\-03\-11 ~ Refactor spleen
| * \fB82e74ab\fR      2014\-03\-11 ~ Add widget
|/
* \fBd08c5b3\fR        (\:\fBbogus_noparent\fR\:) 2014\-03\-11 ~ Wonderful beginnings    \fB<(cool_feature)\fR
.fi
.if n \{\
.RE
.\}
.sp
.sp
Note that this example repo is in dire need of a \fBgit-rebase-update\fR(1)!
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git map\-branches\fR
origin/master
  cool_feature
    subfeature
  frozen_changes *
  master
.fi
.if n \{\
.RE
.\}
.sp

.PP
\fBgit-map\fR(1)
.RS 4
This tool shows you the history of all of your branches in a pseudo\-graphical format\&. In particular, it will show you which commits all of your branches are on, which commit you currently have checked out, and more\&. Check out the doc for the full details\&.
.RE
.PP
\fBgit-map-branches\fR(1)
.RS 4
This tool just shows you which branches you have in your repo, and thier upstream relationship to each other (as well as which branch you have checked out at the moment)\&.
.RE
.sp
Additionally, sometimes you need to switch between branches, but you\(cqve got work in progress\&. You could use \fBgit-stash\fR(1), but that can be tricky to manage because you need to remember which branches you stashed what changes on\&. Helpfully \fIdepot_tools\fR includes two tools which can greatly assist in case:
.sp
\fBgit-freeze\fR(1) allows you to put the current branch in \*(Aqsuspended animation\*(Aq by committing your changes to a specially\-named commit on the top of your current branch\&. When you come back to your branch later, you can just run \fBgit-thaw\fR(1) to get your work\-in\-progress changes back to what they were\&.
.sp
Another useful tool is \fBgit-rename-branch\fR(1)\&. Unlike git branch \-m <old> <new>, this tool will correctly preserve the upstream relationships of your branch compared to its downstreams\&.
.sp
Finally, take a look at \fBgit-upstream-diff\fR(1)\&. This will show you the combined diff for all the commits on your branch against the upstream tracking branch\&. This is \fIexactly\fR what git cl upload will push up to code review\&. Additionally, consider trying the \-\-wordwise argument to get a colorized per\-word diff (instead of a per\-line diff)\&.
.SH "MANAGING DEPENDENT CLS"
.sp
Now that you know how to manage \fIindependent\fR CLs, we\(cqll see how to manage \fIdependent\fR CLs\&. Dependent CLs are useful when your second (or third or fourth or \&...) CL depends on the changes in one of your other CLs (such as: CL 2 won\(cqt compile without CL 1, but you want to submit them as two separate reviews)\&.
.sp
Like all of the other CLs we\(cqve created, we use \fBgit-new-branch\fR(1), but this time with an extra argument\&. First, git checkout the branch you want to base the new one on (i\&.e\&. CL 1), and then run:
.sp
.if n \{\
.RS 4
.\}
.nf
\fB$ git new\-branch \-\-upstream_current <branch_name>\fR
.fi
.if n \{\
.RE
.\}
.sp
.sp
This will make a new branch which tracks the \fIcurrent\fR branch as its upstream (as opposed to \fIorigin/master\fR)\&. All changes you commit to this branch will be in addition to the previous branch, but when you git cl upload, you will only upload the diff for the dependent (child) branch\&. You may have as many branches nested in this fashion as you like\&.
.sp
\fBgit-map\fR(1) and \fBgit-map-branches\fR(1) are particularly helpful when you have dependent branches\&. In addition, there are two helper commands which let you traverse your working copy up and down this tree of branches: \fBgit-nav-upstream\fR(1) and \fBgit-nav-downstream\fR(1)\&.
.sp
Sometimes when dealing with dependent CLs, it turns out that you accidentally based a branch on the wrong upstream, but since then you\(cqve committed changes to it, or even based \fIanother\fR branch off of that one\&. Or you discover that you have two independent CLs that would actually be much better off as dependent CLs\&. In instances like these, you can check out the offending branch and use \fBgit-reparent-branch\fR(1) to move it to track a different parent\&. Note that this can also be used to move a branch from tracking origin/master to lkgr or vice versa\&.
.SH "CONCLUSION"
.sp
Hopefully that gives you a good starting overview on Chromium development using \fIdepot_tools\fR\&. If you have questions which weren\(cqt answered by this tutorial or the man pages for the tools (see the index of all tools here: \fBdepot_tools\fR(7)), please feel free to ask\&.
.SH "GLOSSARY"
.PP
CL
.RS 4
A
\fIchange\-list\fR\&. This is a diff which you would like to commit to the codebase\&.
.RE
.PP
DEPS
.RS 4
A file in the chromium checkout which
gclient sync
uses to determine what dependencies to pull in\&. This file also contains
\fIhooks\fR\&.
.RE
.PP
LKGR
.RS 4
Last Known Good Revision\&. This is a
\fBgit-tag\fR(1)
which tracks the last version of
origin/master
which has passed the full set of testing on the
\m[blue]\fBmain Chromium waterfall\fR\m[]\&\s-2\u[6]\d\s+2\&.
.RE
.SH "CHROMIUM DEPOT_TOOLS"
.sp
Part of the chromium \fBdepot_tools\fR(7) suite\&. These tools are meant to assist with the development of chromium and related projects\&. Download the tools from \m[blue]\fBhere\fR\m[]\&\s-2\u[7]\d\s+2\&.
.SH "NOTES"
.IP " 1." 4
Think like (a) Git
.RS 4
\%http://think-like-a-git.net/
.RE
.IP " 2." 4
Git Immersion Tutorial
.RS 4
\%http://gitimmersion.com/
.RE
.IP " 3." 4
pcottle\(cqs Visual Git Branching
.RS 4
\%http://pcottle.github.io/learnGitBranching
.RE
.IP " 4." 4
Pro Git book
.RS 4
\%http://git-scm.com/book
.RE
.IP " 5." 4
Chromium code review site
.RS 4
\%https://codereview.chromium.org
.RE
.IP " 6." 4
main Chromium waterfall
.RS 4
\%http://build.chromium.org
.RE
.IP " 7." 4
here
.RS 4
\%https://chromium.googlesource.com/chromium/tools/depot_tools.git
.RE