Re: Git doesn't detect change, if file modification time is restored to original one

2015-07-23 Thread Konstantin Khomoutov
On Thu, 23 Jul 2015 11:14:11 +0200
Konrád Lőrinczi klorin...@gmail.com wrote:

[...]
 I accept these solutions as workarounds, but the real solution would
 be: Dev suggestions:
 1) Add a --force-reread option to git status, so user can force
 reread tree. git status --force-reread
 
 2) Add status.force-reread (true or false) option to .git/config so
 user can set this variable permanently for a repo.
 status.force-reread = false (should be default)
 
 Could be possible to implement 1) and 2) features to next git release?

Could you explain what's your real use case with preserving mtimes
while changing the files?  I mean, implementing mtime-stability
in your tools appears to be a good excersize in programming but what
real-world problem does it solve?

I'm asking because if you are not going to implement the changes to
Git you suggested yourself, then someone else should be *convinced* to
do so.  So far, your trouble appears to be too artifical to bother.
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Re: Git doesn't detect change, if file modification time is restored to original one

2015-07-23 Thread Johannes Schindelin
Hi,

On 2015-07-23 09:29, Konrád Lőrinczi wrote:
 I wrote a search  replace perl script, which recursively searches
 files and replaces text in them. After replace, it restores original
 modification time (mtime) of file.

Since this is almost identical to 
https://github.com/msysgit/git/issues/312#issuecomment-124030520 I assume that 
you wrote that.

In my answer on the (already closed) GitHub ticket, I wrote this:

-- snipsnap --


I wrote a search  replace perl script, which recursively searches
files and replaces text in them. After replace, it restores original
modification time (mtime) of file.

By this restoring of the original modification time you broke the contract: 
the mtime should reflect the time of the latest change. You replaced something, 
i.e. changed the file contents. Git expects the mtime to be adjusted in that 
case. By painstakingly faking it back to its original value you essentially 
told Git: don't worry, this file has not changed since you last saw it.

There is nothing Git can do to outguess you when you go out of your way to 
break the most fundamental promise of the mtime value.

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Re: Git doesn't detect change, if file modification time is restored to original one

2015-07-23 Thread Karsten Blees
Am 23.07.2015 um 16:53 schrieb Konstantin Khomoutov:
 On Thu, 23 Jul 2015 11:14:11 +0200
 Konrád Lőrinczi klorin...@gmail.com wrote:
 
 [...]
 I accept these solutions as workarounds, but the real solution would
 be: Dev suggestions:
 1) Add a --force-reread option to git status, so user can force
 reread tree. git status --force-reread

 2) Add status.force-reread (true or false) option to .git/config so
 user can set this variable permanently for a repo.
 status.force-reread = false (should be default)

 Could be possible to implement 1) and 2) features to next git release?
 
 Could you explain what's your real use case with preserving mtimes
 while changing the files?  I mean, implementing mtime-stability
 in your tools appears to be a good excersize in programming but what
 real-world problem does it solve?
 

I'd like to add that this is not a git-specific problem: resetting mtime
on purpose will fool lots of programs, including backup software, file
synchronization tools (rsync, xcopy /D), build systems (make), and web
servers / proxies (If-Modified-Since requests).

So you would typically reset mtime if you *want* programs to ignore the
changes.


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Re: Git doesn't detect change, if file modification time is restored to original one

2015-07-23 Thread Junio C Hamano
Karsten Blees karsten.bl...@gmail.com writes:

 I'd like to add that this is not a git-specific problem: resetting mtime
 on purpose will fool lots of programs, including backup software, file
 synchronization tools (rsync, xcopy /D), build systems (make), and web
 servers / proxies (If-Modified-Since requests).

 So you would typically reset mtime if you *want* programs to ignore the
 changes.

Yup.  Nicely phrased.

When you run a wholesale rewrite of many files, often you find that
some (or many) of the files did not have to be modified.  E.g.
perl -i -e 's/old/new/' * may want to touch all files, but the
files that did not have string 'old' in them would have the same
contents as before.  In such a case, you can avoid unnecessary
reinspection of contents (e.g. recompilation) by many tools that pay
attention to mtime to see if contents changed by reverting mtime to
the original for files that did not change.

Git also pays attention to fields other than mtime, so after

perl -i -e 's/old/ancient/' *

and reverting mtime even for ones that got changed, we should notice
the changes.  But you are correct that such an abuse of touch will
break many other tools.

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Git doesn't detect change, if file modification time is restored to original one

2015-07-23 Thread Konrád Lőrinczi
I wrote a search  replace perl script, which recursively searches
files and replaces text in them. After replace, it restores original
modification time (mtime) of file.

Interesting, that git status doesn't show replaced changes, if the
mtime is same as original.

Is there a way to force git status to show changes, even if the file
dates are the same?


I tried to set core to:
trustctime = false
checkStat = minimal
Unfortunately the change is still not detected :(
It seems isn't a way to force fallback to file checking and completely
ignore file modification date :(


Any idea?


Thanks,
Konrad Lorinczi
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Re: Git doesn't detect change, if file modification time is restored to original one

2015-07-23 Thread Konrád Lőrinczi
Based on [1] I found some solutions which makes the changed files
appear again as changed:
a) touch -m --date=01/01/1980 .git/index
So it is a touch, but only a single one, instead of touching all the
files in the work dir.

b) git read-tree HEAD
Also working well.


I accept these solutions as workarounds, but the real solution would be:
Dev suggestions:
1) Add a --force-reread option to git status, so user can force reread tree.
git status --force-reread

2) Add status.force-reread (true or false) option to .git/config so
user can set this variable permanently for a repo.
status.force-reread = false (should be default)


Could be possible to implement 1) and 2) features to next git release?


Thanks,
Konrad Lorinczi


[1] https://github.com/msysgit/git/issues/312

2015-07-23 9:58 GMT+02:00 Sebastian Schuberth sschube...@gmail.com:
 On 7/23/2015 9:29, Konrád Lőrinczi wrote:

 Interesting, that git status doesn't show replaced changes, if the
 mtime is same as original.

 See the somewhat related FAQ entry at [1] and also the lengthy discussion at 
 [2] about a similar issue. That said, deleting the .git/index file should 
 make these files appear as modified.

 [1] 
 https://git.wiki.kernel.org/index.php/Git_FAQ#Why_isn.27t_Git_preserving_modification_time_on_files.3F
 [2] https://github.com/msysgit/git/issues/312

 Regards,
 Sebastian

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