JoshRosen commented on code in PR #49212: URL: https://github.com/apache/spark/pull/49212#discussion_r1908033776
########## core/src/test/scala/org/apache/spark/util/BestEffortLazyValSuite.scala: ########## @@ -0,0 +1,99 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.spark.util + +import java.io.NotSerializableException + +import org.apache.spark.{SerializerHelper, SparkFunSuite} + +class BestEffortLazyValSuite extends SparkFunSuite with SerializerHelper { + + test("BestEffortLazy works") { + var test: Option[Object] = None + + val lazyval = new BestEffortLazyVal(() => { + test = Some(new Object()) + test + }) + + // Ensure no initialization happened before the lazy value was invoked + assert(test.isEmpty) + + // Ensure the first invocation creates a new object + assert(lazyval() == test && test.isDefined) + + // Ensure the subsequent invocation serves the same object + assert(lazyval() == test && test.isDefined) Review Comment: I should clarify that my proposed test is not necessarily guaranteed to _always_ fail for all mutations of this form because we do a `cached.get()` after the write and it's therefore possible to pick an interleaving like ```scala cached.set(newValue) Thread.sleep(Thread.currentThread().getId % 10) cached.get() ``` where most likely the race on `get()` will be consistently resolved in favor of reading one writer vs. another. But at least the new test is capable of sometimes failing, whereas the old one was not because its assertions were not strong enough. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
