我可以配置 git blame 以始终忽略某些提交吗?想要一劳永逸地修复 git blame [英] Can I configure git blame to always ignore certain commits? Want to fix git blame once and for all

问题描述

我在一个 git blame 已被有效破坏的存储库中.

我想在 git blame 中忽略两个提交.

• Commit 1 破坏了很多的文件.
• 提交 2 立即还原了提交 1.

现在每次我 git blame 一行时，我都会看到 [commit 2] 的作者，而不是真正的逻辑作者.

我最终不得不做一个 git log [有问题的文件]，或者在 这个问题.

每当我在 Intellij 中使用 Annotate 功能时，这两次提交让我感到难过(这基本上是 git 责备).

有没有人在不重写历史记录的情况下解决了这个问题?

解决方案

每当我在 Intellij 中使用 Annotate 功能时，这两次提交让我感到难过(这基本上是 git 责备).
有没有人在不重写历史记录的情况下解决了这个问题?

在 2019 年第三季度之前，没有
但是在 Git 2.23 中，您将能够指示 git blame 忽略这两个有问题的提交.(IntelliJ注释"功能可能需要一段时间才能赶上)

迈克尔电镀 评论:

<块引用>

git blame --ignore-rev 假设指定的提交进行了无趣的更改(例如重新格式化).
不幸的是，删除和添加文件都是相当剧烈的变化，所以 --ignore-rev 在这里无济于事.

话虽如此，git blame 现在可以忽略提交(甚至在这种特殊情况下可能不会).

总的来说，从 Git 2.23 开始:

"git blame" 学会了 "ignore" 在历史中提交，其影响(以及它们的存在)被忽略.

你可以在你的 git config 中注册它！您甚至不需要在每个 git blame 调用的参数中传递这些提交.

参见 commit 78fafbb(2019 年 6 月 30 日)和 commit 1d028dc(2019 年 6 月 20 日)来自 迈克尔电镀 (``).
请参阅 commit 07a54dc(2019 年 6 月 28 日)，作者 杰夫·金 (peff).
参见 commit f0cbe74、commit a07a977(2019 年 6 月 20 日)，以及 提交 1fc7338、提交 8934ac8、commit ae3f36d, 提交ae3f36d"noreferrer">提交 55f808f、提交 f93895f href="、https://github.com/git/git/commit/24eb33ebc515fe0f459a3fed6b16614a0312037f" rel="noreferrer">commit 24eb33e (152019 年 5 月)由 Barret Rhoden (brho) 提供.
^{(由 Junio C Hamano 合并 -- gitster -- 在 commit 209f075，2019 年 7 月 19 日)}

<块引用>

blame:添加忽略提交及其更改的能力

在指责文件时，进行格式更改或函数重命名的提交通常并不有趣.
用户可能认为这样的提交不感兴趣"，并希望在分配责任时忽略它并对其进行更改.

例如，假设一个文件具有以下 git history/rev-list:

---O---A---X---B---C---D---Y---E---F

提交 X 和 Y 都触及特定的行，而其他提交则这样做不是:

X:取第三个参数"-MyFunc(1, 2);+MyFunc(1, 2, 3);Y:删除驼峰"-MyFunc(1, 2, 3);+my_func(1, 2, 3);

git-blame 会将更改归咎于 Y.
我希望能够忽略 Y:提交的存在以及它所做的任何更改.
这与 -S rev-list 不同，后者指定了要处理的提交列表以供处理.
我们仍然会处理 Y，但不要让责任坚持".

此补丁增加了用户使用 --ignore-rev=rev 忽略修订的能力，该修订可能会重复.
他们可以指定一组包含 revs 完整对象名称的文件，例如SHA-1 哈希值，每行一个.
可以使用 blame.ignoreRevFile 配置选项指定单个文件或使用 --ignore-rev-file=file.
config 选项和命令行选项都可以重复多次.

空文件名 "" 将清除以前处理过的文件中的 rev 列表.
配置选项在命令行选项之前处理.

对于典型的用例，项目将维护包含执行大规模重新格式化的提交的修订的文件，并且他们的用户可以选择忽略该文件中的所有提交.

此外，用户可以使用 --ignore-rev 选项进行一次性调查.
回到上面的例子，X 是对功能的实质性改变，而不是用户感兴趣的改变.
用户检查了 X，但想要找到该行的先前更改 - 可能是引入该函数调用的提交.

为了实现这一点，我们不能简单地从 rev-list 中删除所有被忽略的提交.
我们需要区分 Y 引入的更改，以便我们可以忽略它们.
我们让指责传递给 Y，就像正常处理时一样.
当 Y 是目标时，我们确保 Y 不会保留任何责任.
Y 负责的任何更改都会传递给其父级.请注意，我们对所有替罪羊(父母)进行了一次检查以尝试正常地推卸责任；我们不知道是否需要忽略提交，直到我们检查了所有的父项.

blame_entry 将向上传递，直到我们找到一个提交，该提交具有影响这些行的差异块.

一个问题是被忽略的提交确实做了一些改变，并且没有通用的解决方案来在父提交中找到对应于被忽略提交中给定行的行.
这使得很难在被忽略的提交的差异中归因于特定的行正确.

例如，被忽略提交的父级有这个，比如在第 11 行:

commit-a 11) #include "a.h"commit-b 12) #include "b.h"

提交 X，我们将忽略它，交换这些行:

commit-X 11) #include "b.h"commit-X 12) #include "a.h"

我们可以将这个blame 条目传递给父项，但是第 11 行将归因于提交 A，即使include b.h"来自提交 B.
责备机制将在第 11 行查看文件的父视图.

ignore_blame_entry() 设置为允许使用替代算法来猜测每行责任.
任何不属于父级的行都将继续归咎于被忽略的提交，就好像该提交没有被忽略一样.
即将发布的补丁能够检测到这些行并在错误输出中标记它们.

现有算法很简单:将每一行归咎于父级差异块中相应行.
超出此范围的任何线条都与目标保持一致.

例如，被忽略提交的父级有这个，比如在第 11 行:

commit-a 11) void new_func_1(void *x, void *y);commit-b 12) void new_func_2(void *x, void *y);提交-c 13) some_line_c提交-d 14) some_line_d

在提交X"之后，我们有:

commit-X 11) void new_func_1(void *x,commit-X 12) 无效 *y);commit-X 13) void new_func_2(void *x,commit-X 14) 无效 *y);提交-c 15) some_line_c提交-d 16) some_line_d

提交 X 额外生成两行:13 和 14.
当前的 guess_line_blames() 算法不会将这些归因于父级，其差异块只有两行 - 而不是四行.

当我们用当前算法忽略时，我们得到:

commit-a 11) void new_func_1(void *x,commit-b 12) 无效 *y);commit-X 13) void new_func_2(void *x,commit-X 14) 无效 *y);提交-c 15) some_line_c提交-d 16) some_line_d

请注意，第 12 行被归咎于 B，尽管 B 是 new_func_2() 的提交，而不是 new_func_1().
即使 guess_line_blames() 在父级中找到一行，它仍然可能不正确.

<小时>

git blame 新文档:

<块引用>

--ignore-rev ::在分配责任时忽略修订所做的更改，就好像改变从未发生.被忽略的人更改或添加的行提交将归咎于更改该行的先前提交或附近的线路.可以多次指定此选项以忽略不止一次修订.--ignore-revs-file <文件>:

忽略 file 中列出的修订，这些修订必须在 与 fsck.skipList 格式相同.
此选项可能会重复，并且这些文件将在使用 blame.ignoreRevsFile 配置选项指定的任何文件之后进行处理.
空文件名 "" 将清除以前处理过的文件中的 rev 列表.

git 配置 新文档:

<块引用>

blame.ignoreRevsFile:

忽略文件中列出的修订，每行一个未缩写的对象名称，在 git blame 中.
以 # 开头的空格和注释将被忽略.
此选项可能会重复多次.
空文件名将重置被忽略的修订列表.
此选项将在命令行选项 --ignore-revs-file 之前处理.

<小时>

由于线检测并不总是完美的:

<块引用>

blame:为忽略或不可责备的行的输出添加配置选项

当忽略提交时，由于我们的启发式方法的不准确，被指责的提交可能不对更改负责.
用户可能想知道特定线路何时存在潜在的不准确责任.

此外，guess_line_blames() 可能无法找到任何父提交被忽略的提交触及的给定行.
那些无可指责"的行仍然归咎于被忽略的提交.
用户可能想知道某行是否无可指责，这样他们就不会花时间调查他们认为无趣的提交.

这个补丁增加了两个配置选项来标记这两种类型的行责备的输出.

第一个选项可以通过指定blame.markIgnoredLines来识别被忽略的行.
设置此选项后，每个被归咎于被忽略提交以外的提交的blame行都标有?".

例如:

278b6158d6fdb (Barret Rhoden 2016-04-11 13:57:54 -0400 26)

显示为:

?278b6158d6fd (Barret Rhoden 2016-04-11 13:57:54 -0400 26)

'?' 放在提交之前的位置，并且哈希少了一个字符.

有时我们甚至无法猜测祖先提交触及了什么线.
这些台词无可指责".
第二个选项 blame.markUnblamableLines 将用*"标记该行.

比如说我们忽略了e5e8d36d04cbe，但是我们不能责怪另一次提交的这一行:

e5e8d36d04cbe (Barret Rhoden 2016-04-11 13:57:54 -0400 26)

显示为:

*e5e8d36d04cb (Barret Rhoden 2016-04-11 13:57:54 -0400 26)

当这些配置选项一起使用时，被忽略提交触及的每一​​行都将被标记为?"或*".

这意味着 git 配置 手册页 现在有:

<块引用>

blame.markUnblamables:

在git blame的输出中用'*'标记被忽略的修订更改的行，我们无法将其归因于另一个提交.

blame.markIgnoredLines:

在 git blame 的输出中用 '?' 标记由我们归因于另一个提交的忽略修订更改的行.

<小时>

最后，改进git blame行检测:

<块引用>

blame:添加指纹启发式以匹配被忽略的行

此算法将用于从忽略的提交中识别行的启发式算法替换为在父文件版本中查找可能的候选行的启发式算法.
实际替换发生在即将到来的提交中.

旧的启发式方法只是将目标中的行分配给父级中相同的行号(加上偏移量).新函数使用指纹算法来检测行之间的相似性.

新的启发式方法旨在准确匹配由 clang-format 和 clang-tidy 等格式化工具机械地进行的更改.
这些工具进行更改，例如拆分行以适应字符限制或更改标识符以符合命名约定.
启发式不是为了匹配更广泛的重构更改，在这种情况下可能会产生误导性的结果.

在大多数情况下，格式化工具会保留行顺序，因此针对此类情况优化了启发式方法.(某些类型的更改会重新排列行，例如排序保持行内容相同，git blame -M 选项已可用于解决此问题.
依赖排序的好处是因为源代码经常重复相同的字符序列，例如在一行上声明一个标识符并在随后的几行中使用该标识符.
这意味着线条可能看起来非常相似，这在进行模糊匹配时会出现问题.依赖排序为我们提供了额外的线索来指向真正的匹配.

启发式每次对单个差异块更改进行操作.
它为更改的每一侧的每一行创建一个指纹".

指纹在t/t8014-blame-ignore-fuzzy.sh 其中包含示例父文件和目标文件以及父文件中的行号必须匹配.

I am in a repository where git blame has effectively been broken.

There are two commits I want to ignore in git blame.

• Commit 1 destroyed a lot of files.
• Commit 2 immediately reverted commit 1.

Every time I git blame a line now I see the author of [commit 2] instead of the true logical author.

I end up having to do a git log [file in question] instead, or another one of the solutions listed in this question.

These two commits make me sad whenever I use the Annotate feature in Intellij (which is basically git blame).

Has anybody ever fixed this problem before without rewriting history?

解决方案

These two commits make me sad whenever I use the Annotate feature in Intellij (which is basically git blame).
Has anybody ever fixed this problem before without rewriting history?

Before Q3 2019, no.
But with Git 2.23, you will be able to instruct git blame to ignore those two problematic commits. (IntelliJ "annotate" feature might take a while before catching up)

Michael Platings comments though:

git blame --ignore-rev works on the assumption that the specified commit made an uninteresting change (e.g. reformatting).
Unfortunately both removing and adding a file are quite drastic changes so --ignore-rev won't help here.

That being said, git blame can now ignore commits (even maybe not in this particular case).

In general, since Git 2.23:

"git blame" learned to "ignore" commits in the history, whose effects (as well as their presence) get ignored.

And you can register that in your git config! You don't even need to pass those commits in parameters on every git blame call.

See commit 78fafbb (30 Jun 2019), and commit 1d028dc (20 Jun 2019) by Michael Platings (``).
See commit 07a54dc (28 Jun 2019) by Jeff King (peff).
See commit f0cbe74, commit a07a977 (20 Jun 2019), and commit 1fc7338, commit 8934ac8, commit ae3f36d, commit 55f808f, commit f93895f, commit 24eb33e (15 May 2019) by Barret Rhoden (brho).
^{(Merged by Junio C Hamano -- gitster -- in commit 209f075, 19 Jul 2019)}

blame: add the ability to ignore commits and their changes

Commits that make formatting changes or function renames are often not interesting when blaming a file.
A user may deem such a commit as 'not interesting' and want to ignore and its changes it when assigning blame.

For example, say a file has the following git history / rev-list:

---O---A---X---B---C---D---Y---E---F

Commits X and Y both touch a particular line, and the other commits do not:

X: "Take a third parameter"
-MyFunc(1, 2);
+MyFunc(1, 2, 3);

Y: "Remove camelcase"
-MyFunc(1, 2, 3);
+my_func(1, 2, 3);

git-blame will blame Y for the change.
I'd like to be able to ignore Y: both the existence of the commit as well as any changes it made.
This differs from -S rev-list, which specifies the list of commits to process for the blame.
We would still process Y, but just don't let the blame 'stick.'

This patch adds the ability for users to ignore a revision with --ignore-rev=rev, which may be repeated.
They can specify a set of files of full object names of revs, e.g. SHA-1 hashes, one per line.
A single file may be specified with the blame.ignoreRevFile config option or with --ignore-rev-file=file.
Both the config option and the command line option may be repeated multiple times.

An empty file name "" will clear the list of revs from previously processed files.
Config options are processed before command line options.

For a typical use case, projects will maintain the file containing revisions for commits that perform mass reformatting, and their users have the option to ignore all of the commits in that file.

Additionally, a user can use the --ignore-rev option for one-off investigation.
To go back to the example above, X was a substantive change to the function, but not the change the user is interested in.
The user inspected X, but wanted to find the previous change to that line - perhaps a commit that introduced that function call.

To make this work, we can't simply remove all ignored commits from the rev-list.
We need to diff the changes introduced by Y so that we can ignore them.
We let the blames get passed to Y, just like when processing normally.
When Y is the target, we make sure that Y does not keep any blames.
Any changes that Y is responsible for get passed to its parent. Note we make one pass through all of the scapegoats (parents) to attempt to pass blame normally; we don't know if we need to ignore the commit until we've checked all of the parents.

The blame_entry will get passed up the tree until we find a commit that has a diff chunk that affects those lines.

One issue is that the ignored commit did make some change, and there is no general solution to finding the line in the parent commit that corresponds to a given line in the ignored commit.
That makes it hard to attribute a particular line within an ignored commit's diff correctly.

For example, the parent of an ignored commit has this, say at line 11:

commit-a 11) #include "a.h"
commit-b 12) #include "b.h"

Commit X, which we will ignore, swaps these lines:

commit-X 11) #include "b.h"
commit-X 12) #include "a.h"

We can pass that blame entry to the parent, but line 11 will be attributed to commit A, even though "include b.h" came from commit B.
The blame mechanism will be looking at the parent's view of the file at line number 11.

ignore_blame_entry() is set up to allow alternative algorithms for guessing per-line blames.
Any line that is not attributed to the parent will continue to be blamed on the ignored commit as if that commit was not ignored.
Upcoming patches have the ability to detect these lines and mark them in the blame output.

The existing algorithm is simple: blame each line on the corresponding line in the parent's diff chunk.
Any lines beyond that stay with the target.

For example, the parent of an ignored commit has this, say at line 11:

commit-a 11) void new_func_1(void *x, void *y);
commit-b 12) void new_func_2(void *x, void *y);
commit-c 13) some_line_c
commit-d 14) some_line_d

After a commit 'X', we have:

commit-X 11) void new_func_1(void *x,
commit-X 12)                 void *y);
commit-X 13) void new_func_2(void *x,
commit-X 14)                 void *y);
commit-c 15) some_line_c
commit-d 16) some_line_d

Commit X nets two additionally lines: 13 and 14.
The current guess_line_blames() algorithm will not attribute these to the parent, whose diff chunk is only two lines - not four.

When we ignore with the current algorithm, we get:

commit-a 11) void new_func_1(void *x,
commit-b 12)                 void *y);
commit-X 13) void new_func_2(void *x,
commit-X 14)                 void *y);
commit-c 15) some_line_c
commit-d 16) some_line_d

Note that line 12 was blamed on B, though B was the commit for new_func_2(), not new_func_1().
Even when guess_line_blames() finds a line in the parent, it may still be incorrect.

---

git blame new documentation:

--ignore-rev <rev>::
Ignore changes made by the revision when assigning blame, as if the
change never happened.  Lines that were changed or added by an ignored
commit will be blamed on the previous commit that changed that line or
nearby lines.  This option may be specified multiple times to ignore
more than one revision.

--ignore-revs-file <file>:

Ignore revisions listed in file, which must be in the same format as an fsck.skipList.
This option may be repeated, and these files will be processed after any files specified with the blame.ignoreRevsFile config option.
An empty file name, "", will clear the list of revs from previously processed files.

git config new documentation:

blame.ignoreRevsFile:

Ignore revisions listed in the file, one unabbreviated object name per line, in git blame.
Whitespace and comments beginning with # are ignored.
This option may be repeated multiple times.
Empty file names will reset the list of ignored revisions.
This option will be handled before the command line option --ignore-revs-file.

---

Since the line detection is not always perfect:

blame: add config options for the output of ignored or unblamable lines

When ignoring commits, the commit that is blamed might not be responsible for the change, due to the inaccuracy of our heuristic.
Users might want to know when a particular line has a potentially inaccurate blame.

Furthermore, guess_line_blames() may fail to find any parent commit for a given line touched by an ignored commit.
Those 'unblamable' lines remain blamed on an ignored commit.
Users might want to know if a line is unblamable so that they do not spend time investigating a commit they know is uninteresting.

This patch adds two config options to mark these two types of lines in the output of blame.

The first option can identify ignored lines by specifying blame.markIgnoredLines.
When this option is set, each blame line that was blamed on a commit other than the ignored commit is marked with a '?'.

For example:

278b6158d6fdb (Barret Rhoden  2016-04-11 13:57:54 -0400 26)

appears as:

?278b6158d6fd (Barret Rhoden  2016-04-11 13:57:54 -0400 26)

where the '?' is placed before the commit, and the hash has one fewer characters.

Sometimes we are unable to even guess at what ancestor commit touched a line.
These lines are 'unblamable.'
The second option, blame.markUnblamableLines, will mark the line with '*'.

For example, say we ignore e5e8d36d04cbe, yet we are unable to blame this line on another commit:

e5e8d36d04cbe (Barret Rhoden  2016-04-11 13:57:54 -0400 26)

appears as:

*e5e8d36d04cb (Barret Rhoden  2016-04-11 13:57:54 -0400 26)

When these config options are used together, every line touched by an ignored commit will be marked with either a '?' or a '*'.

That means the git config man page now has:

blame.markUnblamables: 

Mark lines that were changed by an ignored revision that we could not attribute to another commit with a '*' in the output of git blame.

blame.markIgnoredLines:

Mark lines that were changed by an ignored revision that we attributed to another commit with a '?' in the output of git blame.

---

Finally, to improve the git blame line detection:

blame: add a fingerprint heuristic to match ignored lines

This algorithm will replace the heuristic used to identify lines from ignored commits with one that finds likely candidate lines in the parent's version of the file.
The actual replacement occurs in an upcoming commit.

The old heuristic simply assigned lines in the target to the same line number (plus offset) in the parent. The new function uses a fingerprinting algorithm to detect similarity between lines.

The new heuristic is designed to accurately match changes made mechanically by formatting tools such as clang-format and clang-tidy.
These tools make changes such as breaking up lines to fit within a character limit or changing identifiers to fit with a naming convention.
The heuristic is not intended to match more extensive refactoring changes and may give misleading results in such cases.

In most cases formatting tools preserve line ordering, so the heuristic is optimized for such cases. (Some types of changes do reorder lines e.g. sorting keep the line content identical, the git blame -M option can already be used to address this).
The reason that it is advantageous to rely on ordering is due to source code repeating the same character sequences often e.g. declaring an identifier on one line and using that identifier on several subsequent lines.
This means that lines can look very similar to each other which presents a problem when doing fuzzy matching. Relying on ordering gives us extra clues to point towards the true match.

The heuristic operates on a single diff chunk change at a time.
It creates a "fingerprint" for each line on each side of the change.

Fingerprints are described in detail in the comment for struct fingerprint, but essentially are a multiset of the character pairs in a line.

• The heuristic first identifies the line in the target entry whose fingerprint is most clearly matched to a line fingerprint in the parent entry.
  Where fingerprints match identically, the position of the lines is used as a tie-break. - The heuristic locks in the best match, and subtracts the fingerprint of the line in the target entry from the fingerprint of the line in the parent entry to prevent other lines being matched on the same parts of that line.
• It then repeats the process recursively on the section of the chunk before the match, and then the section of the chunk after the match.

Here's an example of the difference the fingerprinting makes.
Consider a file with two commits:

    commit-a 1) void func_1(void *x, void *y);
    commit-b 2) void func_2(void *x, void *y);

After a commit 'X', we have:

    commit-X 1) void func_1(void *x,
    commit-X 2)             void *y);
    commit-X 3) void func_2(void *x,
    commit-X 4)             void *y);

When we blame-ignored with the old algorithm, we get:

    commit-a 1) void func_1(void *x,
    commit-b 2)             void *y);
    commit-X 3) void func_2(void *x,
    commit-X 4)             void *y);

Where commit-b is blamed for 2 instead of 3.

With the fingerprint algorithm, we get:

    commit-a 1) void func_1(void *x,
    commit-a 2)             void *y);
    commit-b 3) void func_2(void *x,
    commit-b 4)             void *y);

Note line 2 could be matched with either commit-a or commit-b as it is equally similar to both lines, but is matched with commit-a because its position as a fraction of the new line range is more similar to commit-a as a fraction of the old line range.
Line 4 is also equally similar to both lines, but as it appears after line 3 which will be matched first it cannot be matched with an earlier line.

For many more examples, see t/t8014-blame-ignore-fuzzy.sh which contains example parent and target files and the line numbers in the parent that must be matched.

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