[SPARK-32624][SQL][FOLLOWUP] Fix regression in CodegenContext.addReferenceObj on nested Scala types #29602
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…624: it'll get a "null" for class name of some nested Scala types
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cc original author and potential reviewers: @wangyum @cloud-fan @maropu @kiszk @viirya |
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Test build #128114 has finished for PR 29602 at commit
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viirya
approved these changes
Sep 1, 2020
HyukjinKwon
approved these changes
Sep 1, 2020
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Merged to master and branch-3.0. |
HyukjinKwon
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Sep 1, 2020
…renceObj on nested Scala types ### What changes were proposed in this pull request? Use `CodeGenerator.typeName()` instead of `Class.getCanonicalName()` in `CodegenContext.addReferenceObj()` for getting the runtime class name for an object. ### Why are the changes needed? #29439 fixed a bug in `CodegenContext.addReferenceObj()` for `Array[Byte]` (i.e. Spark SQL's `BinaryType`) objects, but unfortunately it introduced a regression for some nested Scala types. For example, for `implicitly[Ordering[UTF8String]]`, after that PR `CodegenContext.addReferenceObj()` would return `((null) references[0] /* ... */)`. The actual type for `implicitly[Ordering[UTF8String]]` is `scala.math.LowPriorityOrderingImplicits$$anon$3` in Scala 2.12.10, and `Class.getCanonicalName()` returns `null` for that class. On the other hand, `Class.getName()` is safe to use for all non-array types, and Janino will happily accept the type name returned from `Class.getName()` for nested types. `CodeGenerator.typeName()` happens to do the right thing by correctly handling arrays and otherwise use `Class.getName()`. So it's a better alternative than `Class.getCanonicalName()`. Side note: rule of thumb for using Java reflection in Spark: it may be tempting to use `Class.getCanonicalName()`, but for functions that may need to handle Scala types, please avoid it due to potential issues with nested Scala types. Instead, use `Class.getName()` or utility functions in `org.apache.spark.util.Utils` (e.g. `Utils.getSimpleName()` or `Utils.getFormattedClassName()` etc). ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? Added new unit test case for the regression case in `CodeGenerationSuite`. Closes #29602 from rednaxelafx/spark-32624-followup. Authored-by: Kris Mok <kris.mok@databricks.com> Signed-off-by: HyukjinKwon <gurwls223@apache.org> (cherry picked from commit 6e5bc39) Signed-off-by: HyukjinKwon <gurwls223@apache.org>
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Good catch, late LGTM |
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What changes were proposed in this pull request?
Use
CodeGenerator.typeName()instead ofClass.getCanonicalName()inCodegenContext.addReferenceObj()for getting the runtime class name for an object.Why are the changes needed?
#29439 fixed a bug in
CodegenContext.addReferenceObj()forArray[Byte](i.e. Spark SQL'sBinaryType) objects, but unfortunately it introduced a regression for some nested Scala types.For example, for
implicitly[Ordering[UTF8String]], after that PRCodegenContext.addReferenceObj()would return((null) references[0] /* ... */). The actual type forimplicitly[Ordering[UTF8String]]isscala.math.LowPriorityOrderingImplicits$$anon$3in Scala 2.12.10, andClass.getCanonicalName()returnsnullfor that class.On the other hand,
Class.getName()is safe to use for all non-array types, and Janino will happily accept the type name returned fromClass.getName()for nested types.CodeGenerator.typeName()happens to do the right thing by correctly handling arrays and otherwise useClass.getName(). So it's a better alternative thanClass.getCanonicalName().Side note: rule of thumb for using Java reflection in Spark: it may be tempting to use
Class.getCanonicalName(), but for functions that may need to handle Scala types, please avoid it due to potential issues with nested Scala types.Instead, use
Class.getName()or utility functions inorg.apache.spark.util.Utils(e.g.Utils.getSimpleName()orUtils.getFormattedClassName()etc).Does this PR introduce any user-facing change?
No.
How was this patch tested?
Added new unit test case for the regression case in
CodeGenerationSuite.