记一次git reset事故

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因为一次 git reset 操作回滚提交差点丢掉近一周的代码，而且还是明天就要提测的紧急项目，慌得一匹。。。

事故过程：

1、从 branchA 分支的 commitA1 节点牵出一个 branchB 分支
2、branchA 分支的 commitA1、commitA2 … commitAn 提交记录
3、branchB 分支的 commitB1、commitB2 … commitBn 提交记录
4、branchB 分支开发完成后，打算将 branchA 分支合并到 branchB 分支上
5、合并之后发现有冲突，并且解决起来太麻烦，所以打算取消合并，暂时只提测 branchB 分支的代码，然后执行了回滚操作

因为 branchB 分支只有我一个人在工作，且合并代码的那次提交记录是无用的，所以执行了 git reset 操作，且加了 --hard（抛弃合并那次的提交） ，并强推到了远程：

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yujiaqideMacBook-Pro:TDFMemberPod gonghonglou$ git reset --hard 1f88a09e3d359aa2213a0750e32d08f2ff4086e0
HEAD is now at 1f88a09e update

yujiaqideMacBook-Pro:TDFMemberPod gonghonglou$ git push -f
Total 0 (delta 0), reused 0 (delta 0)
remote: 
remote: To create a merge request for feature/917, visit:
remote:   http://git.xxxxxxxx.com/ios/TDFMemberPod/merge_requests/new?merge_request%5Bsource_branch%5D=feature%2F917
remote: 
To git.xxxxxxxx.com:ios/TDFMemberPod.git
 + 7ff865d7...1f88a09e feature/917 -> feature/917 (forced update)

理想其况下执行上述操作是没问题的，但当时因为 commitAn 的提交信息和 commitBn 的提交信息是一样的，没有仔细查看节点信息，commit 的 hash 值写错了，实际执行的操作是：

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git reset --hard commitAn
git push -f

但正确的执行的操作应该是：

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git reset --hard commitBn
git push -f

然后发现 branchB 分支上的代码只有 branchA 分支的代码，而原来 branchB 分支的代码被删除了，而且已经推送到了远程，前边说过了 branchB 分支只有我一个人在工作，这下本地和远程都丢失了代码。。。慌得一匹。。。

解决过程：

虽然慌得一匹，但总感觉 git 应该有应对这样操作失误的方法，打电话给师兄求助，解决流程如下。

执行 git reset 操作后，再执行 git log 是看不到回滚的那部分提交的，能看到只是现在分支上存在的提交，只剩下 branchA 分支上的提交：

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yujiaqideMacBook-Pro:TDFMemberPod gonghonglou$ git log
commit 1f88a09e3d359aa2213a0750e32d08f2ff4086e0 (HEAD -> feature/917, origin/release/0.7.20, origin/feature/917, release/0.7.20)
Author: xxxxxxxx <xxxxxxxx@xxxx.com>
Date:   Tue Aug 21 18:36:14 2018 +0800

    update

commit 4ae03f23a72955290f0daffa2ae3696c69067776
Author: xxxxxxxx <xxxxxxxx@xxxx.com>
Date:   Tue Aug 21 15:56:46 2018 +0800

    update:账单页面 ui修改

commit ef7140f36c99ca3940b95a51a7cda3a88c8efca2
Author: xxxxxxxx <xxxxxxxx@xxxx.com>
Date:   Tue Aug 21 14:08:59 2018 +0800

    服务端下发

commit 38c67dcf627a3e2c7342dc5ca12c68b2b71a6c7e
Author: xxxxxxxx <xxxxxxxx@xxxx.com>
Date:   Tue Aug 21 14:07:03 2018 +0800

......

这时候只有执行 git reflog 命令，可以看到 git reset 回滚的提交：

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yujiaqideMacBook-Pro:TDFMemberPod gonghonglou$ git reflog
1f88a09e (HEAD -> feature/917, origin/release/0.7.20, origin/feature/917, release/0.7.20) HEAD@{0}: reset: moving to HEAD
1f88a09e (HEAD -> feature/917, origin/release/0.7.20, origin/feature/917, release/0.7.20) HEAD@{1}: reset: moving to 1f88a09e3d359aa2213a0750e32d08f2ff4086e0
7ff865d7 HEAD@{2}: checkout: moving from release/0.7.20 to feature/917
1f88a09e (HEAD -> feature/917, origin/release/0.7.20, origin/feature/917, release/0.7.20) HEAD@{3}: reset: moving to HEAD
1f88a09e (HEAD -> feature/917, origin/release/0.7.20, origin/feature/917, release/0.7.20) HEAD@{4}: checkout: moving from feature/917 to release/0.7.20
7ff865d7 HEAD@{5}: commit (merge): Merge branch 'release/0.7.20' into feature/917
7d5f5fc3 HEAD@{6}: reset: moving to HEAD
7d5f5fc3 HEAD@{7}: checkout: moving from release/0.7.20 to feature/917
1f88a09e (HEAD -> feature/917, origin/release/0.7.20, origin/feature/917, release/0.7.20) HEAD@{8}: pull origin release/0.7.20: Fast-forward
555bc18b HEAD@{9}: checkout: moving from feature/917 to release/0.7.20
7d5f5fc3 HEAD@{10}: commit: update
65ed2c95 HEAD@{11}: commit: 跳转url
5bcc6ce4 HEAD@{12}: commit: update json/js from setting_model
a519a43a HEAD@{13}: commit: update json/js from setting_model
5562d3a3 HEAD@{14}: commit: 修改报名及预览
52915778 HEAD@{15}: commit: update json/js from setting_model
53f49fe1 HEAD@{16}: commit: 917json拷贝

......

找到 branchB 分支上的 commitBn 提交的 hash 值，再执行 git reset commitBn，回到合并前的正确的提交节点上：

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yujiaqideMacBook-Pro:TDFMemberPod gonghonglou$ git reset 7d5f5fc3
Unstaged changes after reset:
M	Classes/AccurateMarking/Assets/directPreview.js
D	Classes/Assets/917_coupons.js
D	Classes/Assets/917_coupons.json
D	Classes/Assets/917_register.js
D	Classes/Assets/917_register.json
M	Classes/Assets/member_base_info.js
M	Classes/Assets/member_base_info.json
M	Classes/Assets/member_card_detail.js

......

此时查看 git ststus：

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yujiaqideMacBook-Pro:TDFMemberPod gonghonglou$ git status
On branch feature/917
Your branch and 'origin/feature/917' have diverged,
and have 19 and 68 different commits each, respectively.
  (use "git pull" to merge the remote branch into yours)

Changes not staged for commit:
  (use "git add/rm <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

	modified:   Classes/AccurateMarking/Assets/directPreview.js
	deleted:    Classes/Assets/917_coupons.js
	deleted:    Classes/Assets/917_coupons.json
	deleted:    Classes/Assets/917_register.js
	deleted:    Classes/Assets/917_register.json
	modified:   Classes/Assets/member_base_info.js
	modified:   Classes/Assets/member_base_info.json

......

modified:   TDFMemberPod/Info.plist
	modified:   TDFMemberPod/ViewController.m
	modified:   fileCopy/config

Untracked files:
  (use "git add <file>..." to include in what will be committed)

	Classes/MarketingPlan/

no changes added to commit (use "git add" and/or "git commit -a")

此时虽然节点回到了正确的地方，但是代码还是包含了 branchA 分支上合过来的代码，而这些代码应该是存在了工作区，所以执行 git log 能看到到提交记录只有 branchA 分支的：

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yujiaqideMacBook-Pro:TDFMemberPod gonghonglou$ git log
commit 7d5f5fc36a4874200dea0b7e255e654c474eaf0e (HEAD -> feature/917)
Author: xxxxxxxx <xxxxxxxx@xxxx.com>
Date:   Tue Aug 21 21:31:23 2018 +0800

    update

commit 65ed2c955a53d0864403ac08609a9367cae6d650
Author: xxxxxxxx <xxxxxxxx@xxxx.com>
Date:   Tue Aug 21 21:17:59 2018 +0800

    跳转url

commit 5bcc6ce453bdfe94dc5efac39b46d2123caf5de1
Author: xxxxxxxx <xxxxxxxx@xxxx.com>
Date:   Tue Aug 21 21:17:28 2018 +0800

    update json/js from setting_model

......

执行 git reset --hard 命令抛弃 branchA 分支合过来的代码，并回到合并前的正确的提交节点上：

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yujiaqideMacBook-Pro:TDFMemberPod gonghonglou$ git reset --hard 7d5f5fc3
HEAD is now at 7d5f5fc3 update

执行 git log 能看到现在的提交只包含了 branchB 分支上的提交记录，代码也是正确的：

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yujiaqideMacBook-Pro:TDFMemberPod gonghonglou$ git log
commit 7d5f5fc36a4874200dea0b7e255e654c474eaf0e (HEAD -> feature/917)
Author: xxxxxxxx <xxxxxxxx@xxxx.com>
Date:   Tue Aug 21 21:31:23 2018 +0800

    update

commit 65ed2c955a53d0864403ac08609a9367cae6d650
Author: xxxxxxxx <xxxxxxxx@xxxx.com>
Date:   Tue Aug 21 21:17:59 2018 +0800

    跳转url

commit 5bcc6ce453bdfe94dc5efac39b46d2123caf5de1
Author: xxxxxxxx <xxxxxxxx@xxxx.com>
Date:   Tue Aug 21 21:17:28 2018 +0800

    update json/js from setting_model

......

这时执行 git push -f 强制覆盖远程代码：

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yujiaqideMacBook-Pro:TDFMemberPod gonghonglou$ git push -f
Counting objects: 176, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (171/171), done.
Writing objects: 100% (176/176), 35.19 KiB | 2.35 MiB/s, done.
Total 176 (delta 122), reused 5 (delta 5)
remote: Resolving deltas: 100% (122/122), completed with 22 local objects.
remote: 
remote: To create a merge request for feature/917, visit:
remote:   http://git.xxxxxxxx.com/ios/TDFMemberPod/merge_requests/new?merge_request%5Bsource_branch%5D=feature%2F917
remote: 
To git.xxxxxxxx:ios/TDFMemberPod.git
 + 1f88a09e...7d5f5fc3 feature/917 -> feature/917 (forced update)

经验教训

1、git reset --hard 会清除当前节点到回滚节点之间的所有提交，直接回退节点，不留痕迹。

2、执行了 git reset --hard 操作后，是不能直接执行 git push 来推送了，需要加强制命令 git push -f 来覆盖远程代码。

2、即使分支只有一个人在工作，但执行回滚操作是还是应当慎用 git reset，或者可以使用 git revet 来执行回滚。两者比较直观的区别是 git reset 会抛弃当前节点到将要回滚节点之间的提交，直接回退节点，而 git revet 是将之前的提交操作逆向执行一遍，回到将要回滚的节点的状态，并生成一个新的提交，这样所有的操作都在 git 上有记录。

3、即使错误的执行了 git reset 操作，并强推到了远程，要保护好自己本地的工作目录，通过 git reflog 命令查看 git reset 操作，找到之前的节点重新 git reset 一次。

4、如果本地工作目录缺失，只能通过共同工作于该分支的同事的本地记录来尽量挽回损失了，如果有共同工作于该分支的同事的话。

5、git：https://git-scm.com/book/zh/v2