Add a basic tutorial for the tools in depot_tools.

docs/man7/depot_tools_tutorial.7

+'\" 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: 04/04/2014
+.\"    Manual: Chromium depot_tools Manual
+.\"    Source: depot_tools b4ee6b0
+.\"  Language: English
+.\"
+.TH "DEPOT_TOOLS_TUTORIAL" "7" "04/04/2014" "depot_tools b4ee6b0" "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
+.\}
+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 will assume some basic familarity with git terminology and basic premises\&. 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]\fBPro Git book\fR\m[]\&\s-2\u[1]\d\s+2
+\- Pretty good overview of git to bootstrap a working knowledge\&.
+.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
+.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 "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 it\(cqs upstream (origin/master), and will post it to the \m[blue]\fBChromium code review site\fR\m[]\&\s-2\u[4]\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 because your branch doesn\(cqt rebase cleanly, and 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, 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, you can use \fBgit-reflog\fR(1) to reset your branch back to where it was\&.
+.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)\&. No, I\(cqm not going to explain what it does\&.
+.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 a (not very surprising) twist\&. 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 say that you have two independent CLs that would actually be much better off as dependent CLs\&. Not to worry, because you can just check out the offending branch and use \fBgit-reparent-branch\fR(1) to move it around the tree\&.
+.SH "CONCLUSION"
+.sp
+Well that wraps up the whirlwind tour of the \fIdepot_tools\fR helper tools\&. 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 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[5]\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[6]\d\s+2\&.
+.SH "NOTES"
+.IP " 1." 4
+Pro Git book
+.RS 4
+\%http://git-scm.com/book
+.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
+Chromium code review site
+.RS 4
+\%https://codereview.chromium.org
+.RE
+.IP " 5." 4
+main Chromium waterfall
+.RS 4
+\%http://build.chromium.org
+.RE
+.IP " 6." 4
+here
+.RS 4
+\%https://chromium.googlesource.com/chromium/tools/depot_tools.git
+.RE