Hey Matthias, Thanks for pointing that out. I agree that we only really need to change methods that are API-facing, and we probably want to avoid using Duration/Instant for Streams-facing members.
Like I said in my last email, I think the whole Windows interface is Streams-facing, and the builders we provide are otherwise API-facing. Likewise, `Window` is Streams-facing, so start and end should not use Duration. In SessionWindows, inactivityGap is Streams-facing. I actually think that ProcessorContext#schedule() is API-facing, so it should use Duration. The rationale is that streams processing doesn't call this method, only implementer of Processor do. Does that seem right? Also, it seems like ReadOnlyWindowStore#fetch() (2x) and #fetchAll() are API-facing (for IQ). When we call fetch() during processing, it's actually `WindowStore#fetch()`. Maybe we should move "WindowStoreIterator<V> fetch(K key, long timeFrom, long timeTo)" to the WindowStore interface and make all the ReadOnlyWindowStore methods take Durations. And likewise with the SessionStore interfaces. What do you think? Thanks, -John On Fri, Aug 24, 2018 at 10:51 AM John Roesler <j...@confluent.io> wrote: > Hi Nikolay, > > First: I wanted to let you know that we have dropped the `grace(long)` > method from the Windows interface, but we do still need to transition the > same method on TimeWindows and JoinWindows ( > https://github.com/apache/kafka/pull/5536) > > I have also been thinking it would be nice to replace `Windows` with an > interface, but for different reasons. I think we can even do it without > breaking source compatibility (but it would break binary compatibility): > create a new interface `WindowSpec`, deprecate `Windows` and make it > implement `WindowSpec`, add a new method: > `KGroupedStream#windowedBy(WindowSpec)`, and deprecate the old one. > > However, I don't think this would solve your problem, since the Windows > interface has two audiences: the DSL user and the implementer who wishes to > provide a new kind of windowing. I think we want to provide Duration to the > former, and long or Duration is fine for the latter. However, both of these > audiences are "external", so having an "internal" interface won't fit the > bill. > > I think my last PR #5536 actually helps the situation quite a bit. Let's > forget about the deprecated members. Now, all the public members of Windows > are abstract methods, so Windows is effectively an interface now. Here's > how it looks: > > public abstract class Windows<W extends Window> { > public abstract Map<Long, W> windowsFor(final long timestamp); > public abstract long size(); > public abstract long gracePeriodMs(); > } > > Notice that there is no part of this involved with the DSL. When you're > writing a topology, you don't call any of these methods. It's strictly an > interface that tells a Windows implementation what Streams expects from it. > A very simple implementation could have no builder methods at all and just > return fixed answers to these method calls (this is basically what > UnlimitedWindows does). It seems like, if we want to use long millis > internally, then we just need to leave Windows alone. > > What we do want to change is the builder methods in TimeWindows, > JoinWindows, and UnlimitedWindows. For example, `TimeWindows#of(long)` > would become `TimeWindows#of(Duration)`, etc. These are the DSL methods. > > Does that make sense? > -John > > > > On Thu, Aug 23, 2018 at 8:59 AM Nikolay Izhikov <nizhi...@apache.org> > wrote: > >> Hello, Mathias. >> >> Thanks for your feedback. >> >> > Thus, it might make sense to keep old and just add new ones? >> >> As far as I understand, we will keep old methods anyway to prevent public >> API backward compatibility. >> I agree with you, methods that used internally shouldn't be deprecated. >> >> > End users can use the "nicer" new ones, while we can still use the >> existing ones internally? >> > Not sure if it would be possible to keep the old ones without exposing >> them as public API? >> >> I think, when we decide to remove methods with `long` from public API, we >> can do the following: >> >> 1. Create an interface like `WindowsInternal`. >> 2. Change Windows to an interface. >> 3. Create package-private implementation `WindowsImpl`. >> >> ``` >> package org.apache.kafka.streams.kstream.internals; >> public interface WindowsInternal { >> public long start(); >> public long end(); >> //etc... >> } >> >> package org.apache.kafka.streams.kstream; >> public interface Windows<W extends Window> { >> public Instant start(); >> public Instant end(); >> //... >> } >> >> class WindowsImpl<W extends Window> implements Windows<W>, >> WindowsInternal { >> >> } >> ``` >> >> So, in public API we will expose only `Windows` interface and internally >> we can use `WindowsInternal` >> But, of course, this will be huge changes in public API. >> >> > Let me know what you think about this. >> >> I think in this KIP we shouldn't deprecate methods, that are used >> internally. >> I changed it, now my proposal is just add new methods. >> >> Please, let me know if anything more need to be done. >> >> В Ср, 22/08/2018 в 17:29 -0700, Matthias J. Sax пишет: >> > Thanks a lot for the KIP. >> > >> > From my understanding, the idea of the KIP is to improve the public API >> > at DSL level. However, not all public methods listed are part of DSL >> > level API, but part of runtime API. Those methods are called during >> > processing and are on the hot code path. I am not sure, if we want to >> > update those methods. We should carefully think about this, and consider >> > to keep Long/long type to keep runtime overhead small. Note, that the >> > methods I mention are not required to specify a program using the DSL >> > and thus is questionable if the DSL API would be improved if we change >> > the methods. >> > >> > It's unfortunate, that some part of the public API stretch the DSL >> > builder part as well as the runtime part... >> > >> > This affects the following methods (please double check if I missed >> any): >> > >> > - Windows#windowsFor() >> > - Window#start() >> > - Window#end() >> > - JoinWindows#windowFor() >> > - SessionWindows#inactivitiyGap() >> > - TimeWindows#windowFor() >> > - UnlimitedWindows#windowFor() >> > - ProcessorContext#schedule() >> > - ReadOnlyWindowStore#fetch() (2x) and #fetchAll() >> > - SessionStore#findSessions() (2x) >> > >> > maybe >> > - TimeWindowedDeserializer#getWindowSize() (it's unused atm, but I >> > could imagine that it might be use on the hot code path in the furture) >> > >> > So methods have "dual" use and might be called externally and >> internally: >> > >> > - Window#start() >> > - Window#end() >> > - ReadOnlyWindowStore#fetch() (2x) and #fetchAll() >> > - SessionStore#findSessions() (2x) >> > >> > Thus, it might make sense to keep old and just add new ones? End users >> > can use the "nicer" new ones, while we can still use the existing ones >> > internally? Not sure if it would be possible to keep the old ones >> > without exposing them as public API? >> > >> > Let me know what you think about this. >> > >> > >> > -Matthias >> > >> > >> > >> > On 8/21/18 11:41 PM, Nikolay Izhikov wrote: >> > > Dear, commiters. >> > > >> > > Please, pay attention to this KIP and share your opinion. >> > > >> > > В Вт, 21/08/2018 в 11:14 -0500, John Roesler пишет: >> > > > I'll solicit more reviews. Let's get at least one committer to >> chime in >> > > > before we start a vote (since we need their approval anyway). >> > > > -John >> > > > >> > > > On Mon, Aug 20, 2018 at 12:39 PM Nikolay Izhikov < >> nizhi...@apache.org> >> > > > wrote: >> > > > >> > > > > Hello, Ted. >> > > > > >> > > > > Thanks for the comment. >> > > > > >> > > > > I've edit KIP and change proposal to `windowSize`. >> > > > > >> > > > > Guys, any other comments? >> > > > > >> > > > > >> > > > > В Вс, 19/08/2018 в 14:57 -0700, Ted Yu пишет: >> > > > > > bq. // or just Duration windowSize(); >> > > > > > >> > > > > > +1 to the above choice. >> > > > > > The duration is obvious from the return type. For getter >> methods, we >> > > > > >> > > > > don't >> > > > > > use get as prefix (as least for new code). >> > > > > > >> > > > > > Cheers >> > > > > > >> > > > > > On Sun, Aug 19, 2018 at 8:03 AM Nikolay Izhikov < >> nizhi...@apache.org> >> > > > > >> > > > > wrote: >> > > > > > >> > > > > > > Hello, John. >> > > > > > > >> > > > > > > Thank you very much for your feedback! >> > > > > > > I've addressed all your comments. >> > > > > > > Please, see my answers and let my know is anything in KIP [1] >> needs to >> > > > > >> > > > > be >> > > > > > > improved. >> > > > > > > >> > > > > > > > The correct choice is actually "Instant", not> >> "LocalDateTime" >> > > > > > > >> > > > > > > I've changed the methods proposed in KIP [1] to use Instant. >> > > > > > > >> > > > > > > > I noticed some recent APIs are> missing (see KIP-328) >> > > > > > > > those APIs were just added and have never been released... >> you can >> > > > > >> > > > > just >> > > > > > > >> > > > > > > replace them. >> > > > > > > >> > > > > > > I've added new methods to KIP [1]. >> > > > > > > Not released methods marked for remove. >> > > > > > > >> > > > > > > > any existing method that's already deprecated, don't bother >> > > > > > > >> > > > > > > transitioning it to Duration. >> > > > > > > >> > > > > > > Fixed. >> > > > > > > >> > > > > > > > IllegalArgumentException... we should plan to mention this >> in the >> > > > > > > >> > > > > > > javadoc for those methods. >> > > > > > > >> > > > > > > Got it. >> > > > > > > >> > > > > > > > In Stores, windowSize and segmentInterval should also be >> durations. >> > > > > > > >> > > > > > > Fixed. >> > > > > > > >> > > > > > > > StreamsMetrics, recordLatency ... this one is better left >> alone. >> > > > > > > >> > > > > > > OK. I removed this method from KIP [1]. >> > > > > > > >> > > > > > > Two more questions question about implementation: >> > > > > > > >> > > > > > > 1. We have serveral methods without parameters. >> > > > > > > In java we can't have two methods with parameters with the >> same name. >> > > > > > > It wouldn't compile. >> > > > > > > So we have to rename new methods. Please, see suggested names >> and share >> > > > > > > your thoughts: >> > > > > > > >> > > > > > > Windows { >> > > > > > > long size() -> Duration windowSize(); >> > > > > > > } >> > > > > > > >> > > > > > > Window { >> > > > > > > long start() -> Instant startTime(); >> > > > > > > long end() -> Instant endTime(); >> > > > > > > } >> > > > > > > >> > > > > > > SessionWindows { >> > > > > > > long inactivityGap() -> Duration inactivityGapDuration(); >> > > > > > > } >> > > > > > > >> > > > > > > TimeWindowedDeserializer { >> > > > > > > Long getWindowSize() -> Duration getWindowSizeDuration(); >> // or >> > > > > >> > > > > just >> > > > > > > Duration windowSize(); >> > > > > > > } >> > > > > > > >> > > > > > > SessionBytesStoreSupplier { >> > > > > > > long retentionPeriod() -> Duration >> retentionPeriodDuration(); >> > > > > > > } >> > > > > > > >> > > > > > > WindowBytesStoreSupplier { >> > > > > > > long windowSize() -> Duration windowSizeDuration(); >> > > > > > > long retentionPeriod() -> Duration >> retentionPeriodDuration(); >> > > > > > > } >> > > > > > > >> > > > > > > 2. Do we want to use Duration and Instant inside API >> implementations? >> > > > > > > >> > > > > > > IGNITE-7277: "Durations potentially worsen memory pressure >> and gc >> > > > > > > performance, so internally, we will still use longMs as the >> > > > > >> > > > > representation." >> > > > > > > IGNITE-7222: Duration used to store retention. >> > > > > > > >> > > > > > > [1] >> > > > > > > >> > > > > >> > > > > >> https://cwiki.apache.org/confluence/display/KAFKA/KIP-358%3A+Migrate+Streams+API+to+Duration+instead+of+long+ms+times >> > > > > > > [2] >> > > > > > > >> > > > > >> > > > > >> https://github.com/apache/kafka/commit/b3771ba22acad7870e38ff7f58820c5b50946787#diff-47289575d3e3e2449f27b3a7b6788e1aR64 >> > > > > > > >> > > > > > > В Пт, 17/08/2018 в 14:46 -0500, John Roesler пишет: >> > > > > > > > Hi Nikolay, >> > > > > > > > >> > > > > > > > Thanks for this very nice KIP! >> > > > > > > > >> > > > > > > > To answer your questions: >> > > > > > > > 1. Correct, we should not delete existing methods that have >> been >> > > > > > > >> > > > > > > released, >> > > > > > > > but ... >> > > > > > > > >> > > > > > > > 2. Yes, we should deprecate the 'long' variants so that we >> can drop >> > > > > >> > > > > them >> > > > > > > > later on. Personally, I like to mention which version >> deprecated the >> > > > > > > >> > > > > > > method >> > > > > > > > so everyone can see later on how long it's been deprecated, >> but this >> > > > > >> > > > > may >> > > > > > > >> > > > > > > be >> > > > > > > > controversial, so let's let other weigh in. >> > > > > > > > >> > > > > > > > 3. I think you're asking whether it's appropriate to drop >> the "Ms" >> > > > > > > >> > > > > > > suffix, >> > > > > > > > and I think yes. So "long inactivityGapMs" would become >> "Duration >> > > > > > > > inactivityGap". >> > > > > > > > In the places where the parameter's name is just >> "duration", I think >> > > > > >> > > > > we >> > > > > > > >> > > > > > > can >> > > > > > > > pick something more descriptive (I realize it was already >> > > > > >> > > > > "durationMs"; >> > > > > > > > this is just a good time to improve it). >> > > > > > > > Also, you're correct that we shouldn't use a Duration to >> represent a >> > > > > > > >> > > > > > > moment >> > > > > > > > in time, like "startTime". The correct choice is actually >> "Instant", >> > > > > >> > > > > not >> > > > > > > > "LocalDateTime", though. >> > > > > > > > >> > > > > > > >> > > > > > > >> > > > > >> > > > > >> https://stackoverflow.com/questions/32437550/whats-the-difference-between-instant-and-localdatetime >> > > > > > > > explains why. >> > > > > > > > >> > > > > > > > I also had a few notes on the KIP itself: >> > > > > > > > 4. You might want to pull trunk again. I noticed some >> recent APIs are >> > > > > > > > missing (see KIP-328). >> > > > > > > > >> > > > > > > > 5. Speaking of KIP-328: those APIs were just added and have >> never >> > > > > >> > > > > been >> > > > > > > > released, so there's no need to deprecate the methods, you >> can just >> > > > > > > >> > > > > > > replace >> > > > > > > > them. >> > > > > > > > >> > > > > > > > 6. For any existing method that's already deprecated, don't >> bother >> > > > > > > > transitioning it to Duration. I think the examples I >> noticed were >> > > > > > > > deprecated in KIP-328, so you'll see what I'm talking about >> when you >> > > > > >> > > > > pull >> > > > > > > > trunk again. >> > > > > > > > >> > > > > > > > 7. Any method taking a Duration argument may throw an >> > > > > > > > IllegalArgumentException (we choose to convert >> ArithmeticException to >> > > > > > > > IllegalArgumentException, as I mentioned in the Jira >> ticket). We >> > > > > >> > > > > don't >> > > > > > > >> > > > > > > need >> > > > > > > > a "throws" declaration, but we should plan to mention this >> in the >> > > > > >> > > > > javadoc >> > > > > > > > for those methods. >> > > > > > > > >> > > > > > > > 8. In Stores, windowSize and segmentInterval should also be >> > > > > >> > > > > durations. >> > > > > > > > >> > > > > > > > 9. In StreamsMetrics, recordLatency could be just a >> Duration, but I >> > > > > > > > actually think this one is better left alone. IMO, it's >> more effort >> > > > > >> > > > > for >> > > > > > > > little gain to require users to construct a Duration before >> they >> > > > > >> > > > > call the >> > > > > > > > method, since they vary likely call System.currentTimeNanos >> before >> > > > > >> > > > > and >> > > > > > > > after the code in question. >> > > > > > > > >> > > > > > > > These are quite a few notes, but they're all minor. Overall >> the KIP >> > > > > >> > > > > looks >> > > > > > > > really good to me. Thanks for picking this up! >> > > > > > > > -John >> > > > > > > > >> > > > > > > > On Thu, Aug 16, 2018 at 9:55 AM Nikolay Izhikov < >> nizhi...@apache.org >> > > > > > > >> > > > > > > wrote: >> > > > > > > > >> > > > > > > > > Hello, Kafka developers. >> > > > > > > > > >> > > > > > > > > I would like to start a discussion of KIP-358 [1]. >> > > > > > > > > It based on a ticket KAFKA-7277 [2]. >> > > > > > > > > >> > > > > > > > > I crawled through Stream API and made my suggestions for >> API >> > > > > >> > > > > changes. >> > > > > > > > > >> > > > > > > > > I have several questions about changes. >> > > > > > > > > Please, share your comments: >> > > > > > > > > >> > > > > > > > > 1. I propose do not remove existing API methods with long >> ms >> > > > > > > >> > > > > > > parameters. >> > > > > > > > > Is it correct? >> > > > > > > > > >> > > > > > > > > 2. Should we mark existing methods as deprecated? >> > > > > > > > > >> > > > > > > > > 3. Suggested changes in ticket description are `long >> durationMs` to >> > > > > > > > > `Duration duration` and similar. >> > > > > > > > > I suggest to change 'long startTimeMs` to `LocalDateTime >> startTime` >> > > > > > > >> > > > > > > also. >> > > > > > > > > Should we do it? >> > > > > > > > > >> > > > > > > > > Please, note, it very first KIP for me, so tell me if I >> miss >> > > > > >> > > > > something >> > > > > > > > > obvious for experienced Kafka developers. >> > > > > > > > > >> > > > > > > > > [1] >> > > > > > > > > >> > > > > > > >> > > > > > > >> > > > > >> > > > > >> https://cwiki.apache.org/confluence/display/KAFKA/KIP-358%3A+Migrate+Streams+API+to+Duration+instead+of+long+ms+times >> > > > > > > > > [2] https://issues.apache.org/jira/browse/KAFKA-7277 >> > >> > > >
