[SPARK-3266] [Java] Change JavaRDDLike trait to abstract class.#2186
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JoshRosen wants to merge 1 commit intoapache:masterfrom
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[SPARK-3266] [Java] Change JavaRDDLike trait to abstract class.#2186JoshRosen wants to merge 1 commit intoapache:masterfrom
JoshRosen wants to merge 1 commit intoapache:masterfrom
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JavaRDDLike's current design is a holdover from an earlier prototype that tried to achieve code-reuse for methods like map(), filter(), etc. using the same builder-trait pattern that the Scala collections library uses. This approach didn't work due to some compiler issues, but unfortunately we never removed the confusing trait implementation. This patch changes JavaRDDLike from a trait to an abstract base class. This should be source-compatible with earlier versions. This change resolves some problems with certain inherited methods having the wrong signatures in the bytecode (such as max(); see SPARK-3266).
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QA tests have started for PR 2186 at commit
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QA tests have finished for PR 2186 at commit
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QA tests have started for PR 2186 at commit
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QA tests have finished for PR 2186 at commit
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Contributor
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test this please |
Contributor
Author
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This almost certainly breaks binary compatibility; sorry for letting this PR sit for so long. I'll try to update it today or tomorrow. |
JoshRosen
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Oct 26, 2014
This PR addresses a Scala compiler bug ([SI-8905](https://issues.scala-lang.org/browse/SI-8905)) that was breaking some of the Spark Java APIs. In a nutshell, it seems that methods whose implementations are inherited from generic traits sometimes have their type parameters erased to Object. This was causing methods like `DoubleRDD.min()` to throw confusing NoSuchMethodErrors at runtime. The workaround is to move the implementations of these methods out of the trait. Ideally, I'd like to just delete the trait and convert it into an abstract class, but this technically breaks binary compatibility because it removes an interface (see apache#2186). Instead, I remove the method implementations from the traits and put them in AbstractJavaDStream and AbstractJavaRDD classes that inherit from their respective traits. This leads to a bit of redundancy, but I think it's the cleanest general solution that maintains binary compatibility. I also improved the test coverage of the Java API.
Contributor
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ping @JoshRosen, trying to decrease the number of open SQL PRs ;) |
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JavaRDDLike's current design is a holdover from an earlier prototype that tried
to achieve code-reuse for methods like map(), filter(), etc. using the same
builder-trait pattern that the Scala collections library uses. This approach
didn't work due to some compiler issues, but unfortunately we never removed
the confusing trait implementation.
This patch changes JavaRDDLike from a trait to an abstract base class.
This should be source-compatible with earlier versions.
This change resolves some problems with certain inherited methods having the
wrong signatures in the bytecode (such as max(); see SPARK-3266).