[
https://issues.apache.org/jira/browse/FLINK-1062?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14135341#comment-14135341
]
ASF GitHub Bot commented on FLINK-1062:
---------------------------------------
Github user StephanEwen commented on a diff in the pull request:
https://github.com/apache/incubator-flink/pull/113#discussion_r17596867
--- Diff:
flink-core/src/main/java/org/apache/flink/api/common/functions/util/FunctionUtils.java
---
@@ -57,31 +57,71 @@ public static RuntimeContext getFunctionRuntimeContext
(Function function, Runti
return defaultContext;
}
}
+
+ public static Method checkAndExtractLambdaMethod(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);
- public static boolean isLambdaFunction(Function function) {
- if (function == null) {
- throw new IllegalArgumentException();
- }
-
- for (Class<?> clazz = function.getClass(); clazz != null; clazz
= clazz.getSuperclass()) {
- try {
- Method replaceMethod =
clazz.getDeclaredMethod("writeReplace");
- replaceMethod.setAccessible(true);
- Object serialVersion =
replaceMethod.invoke(function);
-
- if
(serialVersion.getClass().getName().equals("java.lang.invoke.SerializedLambda"))
{
- return true;
+ // 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
}
}
- 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;
}
- catch (Throwable t) {
- // this should not happen, we are not executing
any method code.
- throw new RuntimeException("Error while
checking whether function is a lambda.", t);
+
+ // find lambda method
+ Method implClassMethod =
serializedLambda.getClass().getDeclaredMethod("getImplClass");
+ Method implMethodNameMethod =
serializedLambda.getClass().getDeclaredMethod("getImplMethodName");
+
+ String className = (String)
implClassMethod.invoke(serializedLambda);
+ String methodName = (String)
implMethodNameMethod.invoke(serializedLambda);
+
+ Class<?> implClass =
Class.forName(className.replace('/', '.'));
+
+ Method[] methods = implClass.getDeclaredMethods();
+ Method parameterizedMethod = null;
+ for(Method method : methods) {
+ if(method.getName().equals(methodName)) {
+ if(parameterizedMethod != null) {
+ // It is very unlikely that a
class contains multiple e.g. "lambda$2()" but its possible
+ // Actually, the signature need
to be checked, but this is very complex
+ throw new Exception("Lambda
method name is not unique.");
--- End diff --
Good catch!
> Type Extraction for Lambdas
> ---------------------------
>
> Key: FLINK-1062
> URL: https://issues.apache.org/jira/browse/FLINK-1062
> Project: Flink
> Issue Type: Improvement
> Components: Java API
> Affects Versions: 0.7-incubating
> Reporter: Stephan Ewen
> Assignee: Timo Walther
> Fix For: 0.7-incubating
>
>
> Lambdas currently work only for {{filter}} and {{reduce(a,b)}}, because
> Lambda type extraction is not in place right now.
> We need to extend the type extraction for lambdas to support the other
> functions.
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