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<? extends UserDefinedFunction> functionClass) {
+ TestSpec(
+ @Nullable Class<? extends UserDefinedFunction> 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<? extends UserDefinedFunction>
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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