目录
什么是特性分支？
特性分支是从开发分支迁出的副本分支，专门用于开发新特性，当特性开发完成后，特性分支中的内容会被合回开发分支。特性在这里指能够完成部分业务功能的代码集合，在SCRUM中，对应一个由多个任务组成的用户故事场景。
在任何情况下，特性分支存活时间都应该尽可能短，比如，一个人或者一个团队能够在一天时间内结束在特性分支上的开发。如果使用SCRUM开发，迭代长度是故事的最大长度，也是特性分支的最大存活上限。缩短特性分支存活时间有利于特性合回开发分支，也有利于更好的持续集成。
一旦特性开发完成并合回开发分支后，特性分支被删掉，防止有人继续向特性分支合入代码。
特性分支工作流程
特性分支是nvie‘s branching model的一部分：
创建特性分支
当在特性分支上开发新特性时，首先需要从开发分支迁出特性分支：
$ git checkout -b myfeature develop
Switched to a new branch "myfeature"
特性分支合入开发分支
特性开发完成后，特性分支需要合入开发分支，以便在下一个release交付：
$ git checkout develop
Switched to branch 'develop'
$ git merge --no-ff myfeature
Updating ea1b82a..05e9557
(Summary of changes)
$ git branch -d myfeature
Deleted branch myfeature (was 05e9557).
$ git push origin develop
--no-ff选项会使git在develop分支上创建一个独立的提交对象，即使这次合并可以“快进”合入。这样做的好处是，1）可以通过这个提交对象判断特性分支曾经存在过，2）把这个特性的所有提交合并成一个提交合入develop分支。
比较：
在后一个图中，你无法明显看出哪些提交属于一个特性，除非阅读每一个提交信息。同样，回退一个特性也很困难。但如果你使用--no-ff选项，上面的问题就不存在了。
尽管--no-ff选项会创建一些多余的空提交对象，但相比于上面存在的问题，这样做是值得的。
为什么要用特性分支
- 与开发分支隔绝，避免同时开发的多个特性因过早合入开发分支，而相互影响（我不受别人影响）
- 保证开发中的特性能够从容不迫的验证完成后再提交开发分支，即能够最大可能的保障合入特性的正确性、完整性（我不影响别人）
- 方便在多个分支间并行切换开发
Git Flow工具介绍
gitflow是工具，更是一种流程（workflow）。
nvie‘s branching model的各种分支操作相对复杂，使用git自带的命令操作十分不便，于是nvie又配套提供了一个更高层次的git命令封装，叫gitflow。
$ git flow help
usage: git flow <subcommand>
Available subcommands are:
init Initialize a new git repo with support for the branching model.
feature Manage your feature branches.
release Manage your release branches.
hotfix Manage your hotfix branches.
support Manage your support branches.
version Shows version information.
Try 'git flow <subcommand> help' for details.
具体参考Using git-flow to automate your git branching workflow
但nvie‘s gitflow并未考虑如何与Gerrit结合：一旦特性分支结束，新特性会直接合入本地develop分支，无法经过Gerrit评审。因此，RasmusVoss基于nvie‘s gitflow又扩展出了Gerrit-friendly gitlfow，主要增强了git feature命令，使其支持提交Gerrit评审，使用起来方便很多。
Gerrit-friendly gitlfow的设计基于以下认识：
- 当特性开发完成，特性分支全部内容作为一次评审进行提交
- 如果特性分支合入
develop分支发生冲突，冲突需要在特性提交Gerrit之前解决 - 评审导致的修改变更仍提交在特性分支
- 一旦评审结束，代码合入
develop分支，特性分支被删除
使用Git Flow进行特性开发
下面以一个实例详细描述如何使用gitflow进行特性开发。
假设我们要开发的故事名称为“DAP-2715 HDFS支持故障域”，它需要持续开发3～5天或更多（最多不超过一个迭代）。
初始化代码库
gitflow初次使用需要对代码库进行初始化：设置develop分支、master分支。
如果代码库还没有初始化，使用如下方式初始化:
$ git flow init
Which branch should be used for bringing forth production releases?
- develop-2.7.3
- master-2.7.3
Branch name for production releases: [master-2.7.3]
Which branch should be used for integration of the "next release"?
- develop-2.7.3
Branch name for "next release" development: [develop-2.7.3]
How to name your supporting branch prefixes?
Feature branches? [feature/]
Release branches? [release/]
Hotfix branches? [hotfix/]
Support branches? [support/]
Version tag prefix? []
创建特性分支
现在可以使用git flow feature start <feature-name>创建特性分支了，建议使用jira号作为特性分支名称（为了助记还可以在名称中增加一些描述性文字）：
$ git flow feature start DAP-2715
git checkout -b feature/DAP-2715 develop-2.7.3
Switched to a new branch 'feature/DAP-2715'
Summary of actions:
- A new branch 'feature/DAP-2715' was created, based on 'develop-2.7.3'
- You are now on branch 'feature/DAP-2715'
Now, start committing on your feature. When done, use:
git flow feature submit DAP-2715
If you want to colaborate on the feature, use:
git flow feature publish DAP-2715
If you want to abandon the feature, or if it has been merged into develop, use:
git flow feature delete DAP-2715
共享特性分支（可选）
如果特性需要多人协作，可以使用如下命令将创建在本地的特性分支推送到远端供他人协作开发：
$ git flow feature publish DAP-2715
Total 0 (delta 0), reused 0 (delta 0)
remote: Processing changes: refs: 1, done
To http://127.0.0.1/gerrit/Hadoop
* [new branch] feature/DAP-2715 -> feature/DAP-2715
Already on 'feature/DAP-2715'
Your branch is up to date with 'gerrit/feature/DAP-2715'.
Summary of actions:
- A new remote branch 'feature/DAP-2715' was created
- The local branch 'feature/DAP-2715' was configured to track the remote branch
- You are now on branch 'feature/DAP-2715'
推送完成后，Gerrit可以看到共享中的特性分支：
下载远端特性分支（可选）
共享完特性分支后，其他人可以通过git flow feature track <feature-name>在本地仓库跟踪这个远端特性分支：
$ git flow feature track DAP-2715
Branch 'feature/DAP-2715' set up to track remote branch 'feature/DAP-2715' from 'origin'.
Switched to a new branch 'feature/DAP-2715'
Summary of actions:
- A new remote tracking branch 'feature/DAP-2715' was created
- You are now on branch 'feature/DAP-2715'
在特性分支上开发
有了特性分支后，就可以在特性分支上进行一些本地变更提交。如果是多人协作，还可以把变更推送到远端，或者从远端拉取一些其他人的变更：
$ git commit -m "add some function 1"
...
$ git commit -m "add some function 2"
...
$ git commit -m "add some tests"
...
$ git pull --rebase # 拉取远端变更，--rebase可选，默认行为是merge
...
$ git push # 将本地变更推送到远端
...
在特性分支上阶段性评审（可选/不推荐）
特性分支允许开发者不经过评审直接将变更推送到远端特性分支。但如果想进行评审，仍可按照原有方式进行评审（注意：评审通过，代码只会合入特性分支，不会合入develop分支，也不应该合入develop分支，因为特性此时只是半成品，所以此时进行评审意义不大，不推荐如此）：
$ git push origin HEAD:refs/for/feature/DAP-2715 # 或者使用git review（此时需保证.gitreview中的defaultBranch=feature/DAP-2715）
Counting objects: 2, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (2/2), 276 bytes | 276.00 KiB/s, done.
Total 2 (delta 1), reused 0 (delta 0)
remote: Resolving deltas: 100% (1/1)
remote: Processing changes: new: 1, refs: 1, done
remote:
remote: New Changes:
remote: http://127.0.0.1/gerrit/2 fix some bugs
remote:
To http://127.0.0.1/gerrit/Hadoop
* [new branch] HEAD -> refs/for/feature/DAP-2715
申请合入开发分支
当特性开发验证完成，使用下述命令发起评审，评审一旦通过会被合入develop分支：
$ git flow feature submit DAP-2715
Summary of actions:
- All commits on you feature branch were squashed into one,
and the resulting commit was pushed to Gerrit for review:
Commit: (9f61738a7..) jira: DAP-2715 HDFS支持故障域
Change-Id: Ic7679118a288b1b189f082496d654a8b63d2b90f
Review:
评审发起时，gitflow会把特性分支上所有新增变更合并成一次提交，你可以在此时将故事jira标题作为整个特性的提交记录：
# This is the commit message for the entire feature branch you are submitting to Gerrit.
# Changes made to this message will be recorded as a new commit in your feature branch.
jira: DAP-2715 HDFS支持故障域 # 将故事jira标题作为特性的提交记录
# This is a combination of 4 commits.
# The 1st commit's message is:
add some function 1
# The 2nd commit's message is:
add some function 2
# The 3rd commit's message is:
add some tests
# The 4th commit's message is:
fix some bugs
# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
Gerrit上会看到这次评审：
评审反馈修改
当评审-1时，根据评审意见进行修改，修改后会新增一个/多个变更记录（e64a27d06f47f134575f43a3410e13cec4901a63）：
commit e64a27d06f47f134575f43a3410e13cec4901a63 (HEAD -> feature/DAP-2715)
Author: wenxinhe <[email protected]>
Date: Sat Jan 6 20:41:53 2018 +0800
gerrit review changes
Change-Id: I405d9455eb1fafedd5270bddc40ac9e8cd727055
commit c0dd592e779680d33457cb1f3e4009eff9c32c65
Author: wenxinhe <[email protected]>
Date: Sat Jan 6 19:58:58 2018 +0800
DAP-2715 HDFS支持故障域
add some function 1
add some function 2
add some tests
fix some bugs
Change-Id: If454a22b91bb8282bac3b17a5e5679b850e18a3c
commit 70b5cd82c94624b47e73a0223346eefe23ed5dbc
...
可以再次使用git flow feature submit DAP-2715提交评审，此时提交信息因为gitflow考虑不完善，会缺失掉最近一次的修改信息（在本例中是“gerrit review changes”），如果修改信息比较有用，我们可以手工添加上：
# This is the commit message for the entire feature branch you are submitting to Gerrit.
# Changes made to this message will be recorded as a new commit in your feature branch.
DAP-2715 HDFS支持故障域
add some function 1
add some function 2
add some tests
fix some bugs
gerrit review changes # 此修改信息可以手工添加
# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# On branch feature/DAP-2715
# Your branch is ahead of 'origin/feature/DAP-2715' by 2 commits.
# (use "git push" to publish your local commits)
#
从评审单中拉取代码（可选）
使用git flow feature fromreview可以将Gerrit上的评审单拉取到本地进行代码评审或变更：
// TODO Gerrit被UAC屏蔽，该功能无法使用
删除特性分支
一旦特性分支通过评审合入develop分支，特性分支就完成了历史使命，需要被删除，同时远端仓库上的特性分支也要被删除：
$ git flow feature delete DAP-2715
This feature branch also seems to exist on Gerrit.
Also delete branch from Gerrit? [y/N] y
Summary of actions:
- The remote branch 'feature/DAP-2715' was deleted
- The local branch 'feature/DAP-2715' was deleted
- You are now on branch 'develop-2.7.3'
此时，Gerrit上只剩develop分支和master分支：
develop分支上可以看到特性分支合入的提交记录：