slinkydeveloper commented on a change in pull request #18352:
URL: https://github.com/apache/flink/pull/18352#discussion_r784104335
##
File path:
flink-table/flink-table-common/src/main/java/org/apache/flink/table/functions/UserDefinedFunctionHelper.java
##
@@ -243,6 +244,36 @@ public static void prepareInstance(ReadableConfig config,
UserDefinedFunction fu
cleanFunction(config, function);
}
+/**
+ * Returns whether a {@link UserDefinedFunction} can be easily serialized
and identified by only
+ * a fully qualified class name. It must have a default constructor and no
serializable fields.
+ */
+public static boolean isClassNameSerializable(UserDefinedFunction
function) {
+final Class functionClass = function.getClass();
+if (!InstantiationUtil.hasPublicNullaryConstructor(functionClass)) {
+// function must be parameterized
+return false;
+}
+Class currentClass = functionClass;
+while (!currentClass.equals(UserDefinedFunction.class)) {
+for (Field field : currentClass.getDeclaredFields()) {
+if (!Modifier.isTransient(field.getModifiers())
+&& !Modifier.isStatic(field.getModifiers())) {
+// function seems to be stateful
+return false;
+}
+}
+currentClass = currentClass.getSuperclass();
+}
Review comment:
That sounds like a very magic way to find out whether a function is
stateful or not. Don't we have a marker interface for that?
##
File path:
flink-table/flink-table-common/src/test/java/org/apache/flink/table/functions/UserDefinedFunctionHelperTest.java
##
@@ -143,34 +162,27 @@ private void testErrorMessage() {
@Nullable String expectedErrorMessage;
-TestSpec(Class functionClass) {
+TestSpec(
+@Nullable Class functionClass,
+@Nullable UserDefinedFunction functionInstance,
+@Nullable CatalogFunction catalogFunction) {
this.functionClass = functionClass;
-this.functionInstance = null;
-this.catalogFunction = null;
-}
-
-TestSpec(UserDefinedFunction functionInstance) {
-this.functionClass = null;
this.functionInstance = functionInstance;
-this.catalogFunction = null;
-}
-
-TestSpec(CatalogFunction catalogFunction) {
-this.functionClass = null;
-this.functionInstance = null;
this.catalogFunction = catalogFunction;
}
static TestSpec forClass(Class
function) {
-return new TestSpec(function);
+return new TestSpec(function, null, null);
}
static TestSpec forInstance(UserDefinedFunction function) {
-return new TestSpec(function);
+return new TestSpec(null, function, null);
}
-static TestSpec forCatalogFunction(String className, FunctionLanguage
language) {
-return new TestSpec(new CatalogFunctionMock(className, language));
+static TestSpec forCatalogFunction(
+String className,
+@SuppressWarnings("SameParameterValue") FunctionLanguage
language) {
Review comment:
What warning is this one?
##
File path:
flink-table/flink-table-common/src/main/java/org/apache/flink/table/functions/UserDefinedFunction.java
##
@@ -58,9 +60,13 @@
/** Returns a unique, serialized representation for this function. */
public final String functionIdentifier() {
+final String className = getClass().getName();
+if (isClassNameSerializable(this)) {
+return className;
+}
final String md5 =
EncodingUtils.hex(EncodingUtils.md5(EncodingUtils.encodeObjectToString(this)));
-return getClass().getName().replace('.', '$').concat("$").concat(md5);
+return className.concat("$").concat(md5);
Review comment:
Does this logic works when the function is implemented as a scala
`object`?
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