[JSR310 M7 Review request] 8007572: Replace existing jdk timezone data at <java.home>/lib/zi with JSR310's tzdb.

[Andrew Hughes]

----- Original Message -----
> The build part of this review looks good to me.
> 

Judging by this changeset, I gather javazic is no longer being run.
If so, why is the source code being retained in the tree?  It means
that a build of OpenJDK against itself now fails.  The new
build system currently finds the javazic source code and tries to compile it,
but fails because ZoneInfoFile.java has changed and Gen.java can no longer
compile against it.  Deleting the javazic source code fixes the
build.

Any reason not to commit this?

http://cr.openjdk.java.net/~andrew/build/javazic/webrev.01/

> /Erik
> 
> On 2013-02-07 19:31, Xueming Shen wrote:
> > Hi,
> >
> > 8007572: Replace existing jdk timezone data at <java.home>/lib/zi
> > with
> > JSR310's tzdb.
> >
> > Webrev:
> > http://cr.openjdk.java.net/~sherman/8007572/
> >
> > Note:
> > JDK/JRE has been using the time zone data at <java.home>/lib/zi for
> > j.u.TimeZone since JDK 1.4.0 [1]. JSR310 has introduced in its own
> > time zone data file/format <java.home>lib/tzdb.jar to provide the
> > time
> > zone data support for its new java.time date-time classes.
> >
> > So we now have two different time zone data files in different
> > formats
> > (though from the same time zone data source, Olson tz data, now the
> > IANA
> > Time Zone Datebase) to support two sets of date-time APIs
> > (java.util
> > date-time classes and java.time date-time classes) in one JDK/JRE,
> > which
> > definitely will add the maintenance burden going forward, given the
> > fact
> > that we will have to update/distribute the latest tzdb data in
> > JDK/JRE
> > periodically [2].
> >
> > Also the current way the time-zone data is being
> > distributed/installed
> > (at <java.home>/lib.zi, as individual file for each time zone) has
> > been
> > a footprint concern for some configurations, especially the small
> > embedded
> > environment. The JEP151 [3] was originally submitted to propose to
> > store
> > the time-zone data more efficiently into a single compressed file.
> > The
> > JEP 151 has been withdrawn since, with the assumption that JDK 8
> > may
> > replace the "zi" data with the much smaller JSR310 tzdb data file.
> >
> > As indicated in JEP151, current installed "zi" directory probably
> > takes
> > up 1M of disk-space with the 0.5k default file-system-block-size.
> > Even
> > with the proposed "store in one single compressed file" approach,
> > it will
> > still take about 250K space for all tzdb data in "zi" directory.
> > JSR310
> > tzdb data file however is much smaller. It is around 40K for
> > compressed
> > and 100k uncompressed, for the same tz data.
> >
> > The proposed change is to share the JSR310 time zone data tzdb.jar
> > with j.u.TimeZone by converting the JSR310 tzdb data completely
> > (bits
> > to bits compatible) at runtime into the internal data structure
> > that
> > j.u.TimeZone needs for its time zone data functionality/needs.
> >
> > Thanks!
> > -Sherman
> >
> > [1] https://jbs.oracle.com/bugs/browse/JDK-4230123
> > [2]
> > http://www.oracle.com/technetwork/java/javase/tzupdater-readme-136440.html
> > [3] http://openjdk.java.net/jeps/151
> 

-- 
Andrew :)

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

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