bug#12802: 23.4; feature wish: file-attributes in microsecond precision

bug#12802: 23.4; feature wish: file-attributes in microsecond precision

[Hendrik Tews]

Hi,

please make file access/modification/status change times
available in microsecond precision on those systems that support
that. 

Motivation: I am maintaining an extension of Proof General that
compiles Coq source files to Coq object files on the fly when
needed. For that I have to compare file modification times in a
way similar to make. I would really like to do this with a
precision better than 1 second.

Thanks in advance,

Hendrik Tews

bug#12802: 23.4; feature wish: file-attributes in microsecond precision

[Glenn Morris]

Version: 24.3

Hendrik Tews wrote:

> please make file access/modification/status change times
> available in microsecond precision on those systems that support
> that. 

I believe this is already (more than) implemented and should appear in
24.3. From the NEWS file:

     *** `current-time' now returns extended-format time stamps (HIGH
     LOW USEC PSEC), where the new PSEC slot specifies picoseconds. PSEC
     is typically a multiple of 1000 on current machines. Other
     functions that use this format, such as file-attributes and
     format-time-string, have been changed accordingly.

bug#12802: 23.4; feature wish: file-attributes in microsecond precision

[Stefan Monnier]

> please make file access/modification/status change times available in
> microsecond precision on those systems that support that. 

Your wish has been granted.

> Motivation: I am maintaining an extension of Proof General that
> compiles Coq source files to Coq object files on the fly when
> needed. For that I have to compare file modification times in a
> way similar to make.

AFAIK `make' does not require such fine-precision.   Basically if the
time-stamp on the generated file is equal to the source, then it's
considered as new enough (IOW in the absence of a proof that the
generated file is older, it is assumed to be newer).


        Stefan

bug#12802: 23.4; feature wish: file-attributes in microsecond precision

[Eli Zaretskii]

> From: Stefan Monnier <monnier@IRO.UMontreal.CA>
> Date: Sun, 04 Nov 2012 22:40:52 -0500
> Cc: 12802@debbugs.gnu.org
> 
> > Motivation: I am maintaining an extension of Proof General that
> > compiles Coq source files to Coq object files on the fly when
> > needed. For that I have to compare file modification times in a
> > way similar to make.
> 
> AFAIK `make' does not require such fine-precision.

GNU Make supports nanosecond time resolution when the underlying
library provides that.

bug#12802: 23.4; feature wish: file-attributes in microsecond precision

[Stefan Monnier]

>> AFAIK `make' does not require such fine-precision.
> GNU Make supports nanosecond time resolution when the underlying
> library provides that.

Yes, it supports it when it's available (which doesn't just depend
on the library but also the filesystem).  But that still a far cry from
requiring it ;-)


        Stefan