Hi Tagir,
Interesting issues.
Regarding Stream.concat, it may be that, today, changes to the
sequential/parallel execution mode aren't propagated to the streams being
concatenated. But is that something inherent to the specification of
concatenation, or is it something that might change in the future? It's
currently unspecified, so adding a clarification really sounds more like
changing the specification to reflect the current implementation, which I'd
prefer not to do.
Regarding the default implementations of takeWhile/dropWhile, again, today, they
don't propagate the execution mode upstream. But is this just a bug? Granted the
API for doing so isn't obvious, but isn't this something that could just be fixed?
s'marks
On 7/31/15 9:36 PM, Tagir Valeev wrote:
Hello!
Probably additional clarifications should be added about Stream.concat method
(and primitive analogs). Currently it's unclear that the resulting stream is
actually the new pipeline, which do not propagate parallel status to the
concatenated streams. See also my StackOverflow question:
http://stackoverflow.com/q/30464397/4856258
Also things become more complex in JDK9 with the introduction of
takeWhile/dropWhile. For JDK Stream implementation these two are normal
intermediate operations, but if it happens that user has his own stream
implementation or delegate to JDK stream, then the default takeWhile/dropWhile
implementation is used which is actually starts new pipeline at given point,
so further changes of parallel/sequential mode are not propagated to the
initial pipeline. In my StreamEx library I call such operations as
"quasi-intermediate", and explicitly clarify this point. See the JavaDoc:
http://amaembo.github.io/streamex/javadoc/javax/util/streamex/package-summary.html#StreamOps
Probably some clarification should be added to @implSpec section of
takeWhile/dropWhile.
With best regards,
Tagir Valeev.
On Sat, Aug 1, 2015 at 3:19 AM, Stuart Marks <stuart.ma...@oracle.com
<mailto:stuart.ma...@oracle.com>> wrote:
Hi all,
The sequential() and parallel() methods on a stream set the execution mode
for the entire pipeline. Unfortunately this isn't particularly clear from
the documentation. This has been a recurring question. Please review this
change to the java.util.stream package documentation to help clarify this
point.
I've also added a couple anchor tags that were missing from various
sections.
This is intended to be a purely editorial change, not a specification
change.
Bug:
https://bugs.openjdk.java.net/browse/JDK-8132800
Webrev:
http://cr.openjdk.java.net/~smarks/reviews/8132800/webrev.0/
<http://cr.openjdk.java.net/%7Esmarks/reviews/8132800/webrev.0/>
Thanks,
s'marks
