Emacs使用Git-Rebase将缓冲区恢复为奇怪的以前的状态 [英] Emacs Reverts Buffer to Weird Previous State with Git-Rebase

问题描述

我在OS X上使用Emacs（23.3.1）。我从终端发出git命令，而不是使用任何Emacs的VC功能。

 （自定义）我的Emacs设置为在修改文件时进行刷新，这是通过我的.emacs文件的这些行启用的。 - 设置变量
 ... 
'（自动恢复间隔1）
 ... 
）
（全局自动恢复模式1） 
  

这一直符合我的预期;如果我拉，我的Emacs缓冲区将更新与合并或冲突，就好像我已经退出缓冲区，并新加载每一个。

最近，我开始rebasing（调用git-取，然后git-rebase），而不是简单地拉（用git-pull），我不知道这个问题是否真的与git-rebase有关，但我当然没有注意到这个问题，现在就做。

所以问题在于：我更新了一个文件，使用 git commit -am... git fetch origin ，然后运行 git rebase origin / master （有时压扁在交互模式下一起提交） 。现在我已经引入了远程更新，我继续编辑文件，发现它看起来像我失去了所有最近的更改。第一次发生时，我非常生气，并且诅咒了rebase算法，以某种方式失去了我的修改，直到我意识到该文件完全完好无损，这只是Emacs在修改之前以某种方式恢复了文件的版本我刚刚承诺。我总是可以通过关闭缓冲区并重新加载文件来解决问题，但每次都会很痛苦。

有没有人知道问题是什么是

解决方案

我是 autorevert 的原作者，但是，我不得不深入到我的记忆中，因为我还没有使用过它一段时间。

我相信这可以归结为Emacs核心的一个问题函数 verify-visited-file-modtime ，它自动恢复用来检查是否需要刷新缓冲区。

<这可能是由于以下原因造成的：

• 这可能是一种竞争条件，Emacs在此之前读取文件它被完全写入，但将缓冲区modtime设置为结束时间。 （当发生这种情况时，Emacs会自动恢复缓冲区的一半，但新的自动恢复不会触发恢复文件的最终版本。）

如果文件的两个变体具有相同的时间戳，那么Emacs将不会看到区别。 >我不认为你可以在Lisp方面做很少的事情来正确地工作（不用解决暴力解决方案）。 Emacs确实需要原子地获取已打开并读入缓冲区的文件的指纹，并且这只能从内核（这是我的区域外）完成。此外，某些文件系统的时间戳分辨率不会超过一秒，因此很难使用时间戳来检测文件是否已更改。




I'm using Emacs (23.3.1) on OS X. I'm issuing git commands from a terminal, not using any of Emacs' VC functionality. I have Emacs set up to refresh when files are modified, which is enabled by these lines of my .emacs file:

(custom-set-variables
 ...
 '(auto-revert-interval 1)
 ... 
)
(global-auto-revert-mode 1)

This has always worked as I expected; if I pulled, my Emacs buffers would update with the merges or conflicts as if I had quit the buffers and freshly loaded each one.

Recently I started rebasing (calling git-fetch and then git-rebase) instead of simply pulling (with git-pull), and I don't know if the issue actually has to do with git-rebase, but I certainly didn't notice the problem before then and do now.

So here's the problem: I update a file, commit the changes with git commit -am "...", run git fetch origin, then run git rebase origin/master (sometimes squashing commits together in interactive mode). Now that I've pulled in the remote updates, I go to edit the file some more, and find that it looks like I've lost all my recent changes. The first time it happened, I got very mad and cursed the rebase algorithm for somehow losing my changes, until I realized that the file was completely intact and it was just that Emacs had somehow reverted to the version of the file prior to the changes I'd just committed. I can always solve the problem by closing the buffer and loading the file again, but this is quite a pain to do every time.

Does anyone have any idea what the problem is?

解决方案

I'm the original author of autorevert, however, I have to dig quite deep into my memory as I haven't worked with it for quite some time.

I believe this boils down to a problem with the Emacs core function verify-visited-file-modtime, which auto-revert use to check if a buffers needs to be refreshed.

This could be caused by a number of reasons:

• This could be a race condition, where Emacs reads a file before it was completely written, but sets the buffer modtime to the end time. (When this occurs, Emacs has auto-reverted the buffer half-way, but a new auto-revert does not trigger to revert the final version of the file.)

• If the two variants of the file have the same time stamp, then Emacs will not see the difference.

I don't think that there is little you can do on the lisp side to get this working properly (without resolving to brute-force solutions). Emacs really need to atomically get a fingerprint of the file that has been opened and read into a buffer, and this can only be done from the core (which is something outside my area). Also, some file systems don't have a higher timestap resolution than one second, making it inherently difficult to use the timestamp to detect if a file has been changed.

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