rednaxelafx commented on a change in pull request #28463:
URL: https://github.com/apache/spark/pull/28463#discussion_r421315768
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File path: core/src/main/scala/org/apache/spark/util/ClosureCleaner.scala
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@@ -414,6 +433,142 @@ private[spark] object ClosureCleaner extends Logging {
}
}
+private[spark] object IndylambdaScalaClosures extends Logging {
+ // internal name of java.lang.invoke.LambdaMetafactory
+ val LambdaMetafactoryClassName = "java/lang/invoke/LambdaMetafactory"
+ // the method that Scala indylambda use for bootstrap method
+ val LambdaMetafactoryMethodName = "altMetafactory"
+ val LambdaMetafactoryMethodDesc = "(Ljava/lang/invoke/MethodHandles$Lookup;"
+
+ "Ljava/lang/String;Ljava/lang/invoke/MethodType;[Ljava/lang/Object;)" +
+ "Ljava/lang/invoke/CallSite;"
+
+ /**
+ * Check if the given reference is a indylambda style Scala closure.
+ * If so, return a non-empty serialization proxy (SerializedLambda) of the
closure;
+ * otherwise return None.
+ *
+ * @param maybeClosure the closure to check.
+ */
+ def getSerializationProxy(maybeClosure: AnyRef): Option[SerializedLambda] = {
+ val maybeClosureClass = maybeClosure.getClass
+
+ // shortcut the fast check:
+ // indylambda closure classes are generated by Java's LambdaMetafactory,
and they're always
+ // synthetic.
+ if (!maybeClosureClass.isSynthetic) return None
+
+ val implementedInterfaces =
ClassUtils.getAllInterfaces(maybeClosureClass).asScala
+ val isClosureCandidate = implementedInterfaces.exists(_.getName ==
"scala.Serializable") &&
Review comment:
Thank you very much! This is very useful information. Does that mean I
should check for `maybeClosure.isInstanceOf[Serializable]` here instead of
bothering with explicitly checking the name `scala.Serializable`? Assuming
we're running on a JVM instead of running in a no-Java environment, this
instanceof check should always be true for Scala closures, right?
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