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ASF GitHub Bot commented on FLINK-4793: --------------------------------------- Github user twalthr commented on a diff in the pull request: https://github.com/apache/flink/pull/2621#discussion_r82812545 --- Diff: flink-core/src/main/java/org/apache/flink/api/java/typeutils/TypeExtractionUtils.java --- @@ -0,0 +1,167 @@ +/* + * 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.flink.api.java.typeutils; + +import java.lang.reflect.Constructor; +import java.lang.reflect.Method; +import java.lang.reflect.Type; +import java.util.ArrayList; +import java.util.List; +import org.apache.flink.annotation.Internal; +import org.apache.flink.api.common.functions.Function; +import static org.objectweb.asm.Type.getConstructorDescriptor; +import static org.objectweb.asm.Type.getMethodDescriptor; + +@Internal +public class TypeExtractionUtils { + + private TypeExtractionUtils() { + // do not allow instantiation + } + + /** + * Similar to a Java 8 Executable but with a return type. + */ + public static class LambdaExecutable { + + private Type[] parameterTypes; + private Type returnType; + private String name; + private Object executable; + + public LambdaExecutable(Constructor<?> constructor) { + this.parameterTypes = constructor.getGenericParameterTypes(); + this.returnType = constructor.getDeclaringClass(); + this.name = constructor.getName(); + this.executable = constructor; + } + + public LambdaExecutable(Method method) { + this.parameterTypes = method.getGenericParameterTypes(); + this.returnType = method.getGenericReturnType(); + this.name = method.getName(); + this.executable = method; + } + + public Type[] getParameterTypes() { + return parameterTypes; + } + + public Type getReturnType() { + return returnType; + } + + public String getName() { + return name; + } + + public boolean executablesEquals(Method m) { + return executable.equals(m); + } + + public boolean executablesEquals(Constructor<?> c) { + return executable.equals(c); + } + } + + public static LambdaExecutable checkAndExtractLambda(Function function) { + try { + // get serialized lambda + Object serializedLambda = null; + for (Class<?> clazz = function.getClass(); clazz != null; clazz = clazz.getSuperclass()) { + try { + Method replaceMethod = clazz.getDeclaredMethod("writeReplace"); + replaceMethod.setAccessible(true); + Object serialVersion = replaceMethod.invoke(function); + + // check if class is a lambda function + if (serialVersion.getClass().getName().equals("java.lang.invoke.SerializedLambda")) { + + // check if SerializedLambda class is present + try { + Class.forName("java.lang.invoke.SerializedLambda"); + } + catch (Exception e) { + throw new UnsupportedOperationException("User code tries to use lambdas, but framework is running with a Java version < 8"); + } + serializedLambda = serialVersion; + break; + } + } + catch (NoSuchMethodException e) { + // thrown if the method is not there. fall through the loop + } + } + + // not a lambda method -> return null + if (serializedLambda == null) { + return null; + } + + // find lambda method + Method implClassMethod = serializedLambda.getClass().getDeclaredMethod("getImplClass"); + Method implMethodNameMethod = serializedLambda.getClass().getDeclaredMethod("getImplMethodName"); + Method implMethodSig = serializedLambda.getClass().getDeclaredMethod("getImplMethodSignature"); + + String className = (String) implClassMethod.invoke(serializedLambda); + String methodName = (String) implMethodNameMethod.invoke(serializedLambda); + String methodSig = (String) implMethodSig.invoke(serializedLambda); + + Class<?> implClass = Class.forName(className.replace('/', '.'), true, Thread.currentThread().getContextClassLoader()); + + // find constructor + if (methodName.equals("<init>")) { + Constructor<?>[] constructors = implClass.getDeclaredConstructors(); + for (Constructor<?> constructor : constructors) { + if(getConstructorDescriptor(constructor).equals(methodSig)) { + return new LambdaExecutable(constructor); + } + } + } + // find method + else { + List<Method> methods = getAllDeclaredMethods(implClass); + for (Method method : methods) { + if(method.getName().equals(methodName) && getMethodDescriptor(method).equals(methodSig)) { + return new LambdaExecutable(method); + } + } + } + throw new Exception("No lambda method found."); + } + catch (Exception e) { + throw new RuntimeException("Could not extract lambda method out of function: " + e.getClass().getSimpleName() + " - " + e.getMessage(), e); --- End diff -- I will use an `IllegalStateException`. > Using a local method with :: notation in Java 8 causes index out of bounds > -------------------------------------------------------------------------- > > Key: FLINK-4793 > URL: https://issues.apache.org/jira/browse/FLINK-4793 > Project: Flink > Issue Type: Bug > Reporter: Ted Dunning > Assignee: Timo Walther > > I tried to use the toString method on an object as a map function: > {code} > .<String>map(Trade::toString) > {code} > This caused an index out of bounds error: > {code} > java.lang.ArrayIndexOutOfBoundsException: -1 > at > org.apache.flink.api.java.typeutils.TypeExtractor.getUnaryOperatorReturnType(TypeExtractor.java:351) > at > org.apache.flink.api.java.typeutils.TypeExtractor.getUnaryOperatorReturnType(TypeExtractor.java:305) > at > org.apache.flink.api.java.typeutils.TypeExtractor.getMapReturnTypes(TypeExtractor.java:120) > at > org.apache.flink.streaming.api.datastream.DataStream.map(DataStream.java:506) > at > com.mapr.aggregate.AggregateTest.testAggregateTrades(AggregateTest.java:81) > at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) > at > sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) > at > sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) > at > org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) > at > org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) > at > org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) > at > org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) > at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) > at > org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) > at > org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) > at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) > at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) > at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) > at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) > at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) > at org.junit.runners.ParentRunner.run(ParentRunner.java:363) > at org.junit.runner.JUnitCore.run(JUnitCore.java:137) > at > com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:68) > {code} > On the other hand, if I use a public static method, like this: > {code} > .<Trade>map(Trade::fromString) > {code} > All is good. fromString and toString are defined like this: > {code} > public static Trade fromString(String s) throws IOException { > return mapper.readValue(s, Trade.class); > } > @Override > public String toString() { > return String.format("{\"%s\", %d, %d, %.2f}", symbol, time, volume, > price); > } > {code} > This might be a viable restriction on what functions I can use, but there > certainly should be a better error message, if so. -- This message was sent by Atlassian JIRA (v6.3.4#6332)