Josh Bloch is a long-time software rock star who originated as a PhD
alumnus of the transactions group at CMU back when they were really
strong in that area. (Not that that helps answer any of the legal
questions. :-))
On 10/28/17 4:30 PM, Till Westmann wrote:
I largely agree with Xikui.
This one [2] seems to clearly state in its header that it’s published
by Oracle under the GPL (which is category X [3] and cannot be included
in Apache products).
It would be interesting to understand the provenance of the Spark
version to understand if/why it is not derived from the Oracle
implementation. If they are essentially all the same implementation,
I’d like to understand who the original copyright owner is (Josh
Bloch?) and when the decision was taken to license the same
implementation under both Apache and GPL licenses before we add it to
the Hyracks code base.
Alternatively, if the Android/Spark implementation is independent of
the Oracle implementation, we should be able to base our implementaion
on that.
Cheers,
Till
[2]
https://github.com/retrostreams/android-retrostreams/blob/master/src/main/java/java9/util/TimSort.java
[3] https://www.apache.org/legal/resolved.html#category-x
On 28 Oct 2017, at 10:54, Chen Luo wrote:
Thanks guys! I think the one I'm using is identical to the one
pointed by
Wail
(https://github.com/retrostreams/android-retrostreams/blob/master/src/
main/java/java9/util/TimSort.java), and also identical to the one
used by
Spark. All these three implementations are credit to the same person
Josh
Bloch.
Then we're good!
Best regards,
Chen Luo
On Sat, Oct 28, 2017 at 9:52 AM, Xikui Wang <[email protected]> wrote:
I think probably it's not okay to use JDK's implementation due to the
license issue [1]. (Search for BCL)
Alternatively, you could use the one that Spark used from the Android
Opensource Project, as Wail pointed out. That one is under Apache
License.
[1] https://www.apache.org/legal/resolved.html
On Sat, Oct 28, 2017 at 9:44 AM, Wail Alkowaileet <[email protected]>
wrote:
P.S Spark implementation is under Apache.
On Sat, Oct 28, 2017 at 9:41 AM, Wail Alkowaileet <[email protected]>
wrote:
Android has an implementation:
https://github.com/retrostreams/android-retrostreams/blob/master/src/
main/java/java9/util/TimSort.java
Spark has ported it
https://github.com/apache/spark/blob/master/core/src/
main/java/org/apache/spark/util/collection/TimSort.java
We can customize it for AsterixDB comparators.
On Sat, Oct 28, 2017 at 9:28 AM, Chen Luo <[email protected]> wrote:
I don't know whether there is an easy way for us to directly reuse
TimSort
in JDK since it's design for sorting objects in an Array, while in
Hyracks
we don't have explicit object creation and sort everything in main
memory.
So what I did is that I copied it's source code, and replaced all
object
assignments/swaps/comparisons using Hyracks in-memory operations.
Best regards,
Chen Luo
On Sat, Oct 28, 2017 at 12:07 AM, 李文海 <[email protected]>
wrote:
I believe reusing jdk afap could be better. btw, timsort is better
than
others by 1x when records are locally ordered .
best
在 2017-10-28 14:38:21，"abdullah alamoudi" <[email protected]>
写道：
While I have no answer to the question of legality, this sounds
great.
~Abdullah.
On Oct 27, 2017, at 9:20 PM, Chen Luo <[email protected]> wrote:
Hi devs,
I have adapted the TimSort algorithm used in JDK
(java.util.TimSort)
into
Hyracks, which gives 10-20% performance improvements on random
data.
It
will be more useful if the input data is partially sorted, e.g.,
primary
keys fetched from secondary index scan, which I haven't got time
to
experiment with.
*Before going any further, is it legal to adapt some algorithm
implementation from JDK into our codebase? *I saw the JDK
implementation
itself is adopted from
http://svn.python.org/projects/python/trunk/Objects/listsort.txt
as
well.
Best regards,
Chen Luo
--
*Regards,*
Wail Alkowaileet
--
*Regards,*
Wail Alkowaileet
