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https://issues.apache.org/jira/browse/SPARK-27772?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16850264#comment-16850264
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Hyukjin Kwon commented on SPARK-27772:
--------------------------------------
k. please clarify the problem with before/after message to show that it's
useful for dev.
> SQLTestUtils Refactoring
> ------------------------
>
> Key: SPARK-27772
> URL: https://issues.apache.org/jira/browse/SPARK-27772
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.0.0
> Reporter: William Wong
> Priority: Minor
>
> The current `SQLTestUtils` created many `withXXX` utility functions to clean
> up tables/views/caches created for testing purpose. Some of those `withXXX`
> functions ignore certain exceptions, like `NoSuchTableException` in the clean
> up block (ie, the finally block).
>
> {code:java}
> /**
> * Drops temporary view `viewNames` after calling `f`.
> */
> protected def withTempView(viewNames: String*)(f: => Unit): Unit = {
> try f finally {
> // If the test failed part way, we don't want to mask the failure by
> failing to remove
> // temp views that never got created.
> try viewNames.foreach(spark.catalog.dropTempView) catch {
> case _: NoSuchTableException =>
> }
> }
> }
> {code}
> Maybe it is not the best approach. Because it is hard to anticipate what
> exception should or should not be ignored.
>
> We may hit similar scenario with Java's `try-with-resources` statement. Java
> does not mask exception throws in the try block with any exception caught in
> the 'close()' statement. Exception caught in the 'close()' statement would
> add as a suppressed exception instead. IMHO, it is a better approach.
>
> Therefore, I proposed to standardise those 'withXXX' function with following
> `withFinallyBlock` function, which does something similar to Java's
> try-with-resources statement.
> {code:java}
> /**
> * Drops temporary view `viewNames` after calling `f`.
> */
> protected def withTempView(viewNames: String*)(f: => Unit): Unit = {
> withFinallyBlock(f)(viewNames.foreach(spark.catalog.dropTempView))
> }
> /**
> * Executes the given tryBlock and then the given finallyBlock no matter
> whether tryBlock throws
> * an exception. If both tryBlock and finallyBlock throw exceptions, the
> exception thrown
> * from the finallyBlock with be added to the exception thrown from tryBlock
> as a
> * suppress exception. It helps to avoid masking the exception from tryBlock
> with exception
> * from finallyBlock
> */
> private def withFinallyBlock(tryBlock: => Unit)(finallyBlock: => Unit): Unit
> = {
> var fromTryBlock : Throwable = null
> try tryBlock catch {
> case cause : Throwable =>
> fromTryBlock = cause
> throw cause
> } finally {
> if (fromTryBlock != null) {
> try finallyBlock catch {
> case fromFinallyBlock : Throwable =>
> fromTryBlock.addSuppressed(fromFinallyBlock)
> throw fromTryBlock
> }
> } else {
> finallyBlock
> }
> }
> }
> {code}
>
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