[RFC] [openjdk] provide milisecond modification timestamps

[Andrew Hughes]

----- Original Message -----
> Am Montag, den 23.04.2012, 12:41 -0400 schrieb Andrew Hughes:
> > ----- Original Message -----
> > > diff -r 8ac52c85f9e9
> > > src/solaris/native/java/io/UnixFileSystem_md.c
> > > --- a/src/solaris/native/java/io/UnixFileSystem_md.c	Wed Feb 23
> > > 15:49:19
> > > 2011 -0800
> > > +++ b/src/solaris/native/java/io/UnixFileSystem_md.c	Sat Apr 21
> > > 10:11:26
> > > 2012 +0200
> > > @@ -197,7 +197,10 @@
> > >      WITH_FIELD_PLATFORM_STRING(env, file, ids.path, path) {
> > >          struct stat64 sb;
> > >          if (stat64(path, &sb) == 0) {
> > > -            rv = 1000 * (jlong)sb.st_mtime;
> > > +            if(sb.st_mtimensec != 0)
> > > +            	rv = (jlong)sb.st_mtimensec / 1000000;
> > > +            else
> > > +                rv = 1000 * (jlong)sb.st_mtime;
> > >          }
> > >      } END_PLATFORM_STRING(env, path);
> > >      return rv;
> > > 
> > > 
> > > 
> > 
> 
> Hi Andrew,
> 
> > This looks a sensible improvement to me.  I can add it to the
> > IcedTea
> > repository.
> 
> But it only looks sensible :-) The correct patch against jdk7 is
> attached!
> 
> I looks like the field st_mtim.tv_nsec is just an extension to the
> second accuracy provided by st_mtim.tv_sec.
> 

Ah right, yes this is the same way clock_gettime works, which we use
to implement System.nanoTime in GNU Classpath:

  result = (jlong) tp.tv_sec;
  result *= (jlong)1000000000L;
  result += (jlong)tp.tv_nsec;

The difference here is that the Java API means that most of the accuracy
gain is lost in the division.  I wonder if there is a case for a deeper
patch that allows nanosecond accuracy to be fully exposed?

> But I don't know if this compiles on Solaris, etc... But according to
> the man page of stat() it should compile if compatible to
> POSIX.1-2008.
> 
> > 
> > Have you signed the Oracle Contributor Agreement (OCA) so it can
> > also
> > be upstreamed to OpenJDK?
> 
> Not yet...
> 
> thomas
> 
> 
> 

-- 
Andrew :)

Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

PGP Key: 248BDC07 (https://keys.indymedia.org/)
Fingerprint = EC5A 1F5E C0AD 1D15 8F1F  8F91 3B96 A578 248B DC07