/*
* 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.streaming.runtime.operators.windowing.functions;
import org.apache.flink.api.common.functions.Function;
import org.apache.flink.api.common.state.KeyedStateStore;
import org.apache.flink.streaming.api.windowing.windows.Window;
import org.apache.flink.util.Collector;
/**
* Internal interface for functions that are evaluated over keyed (grouped) windows.
*
* @param <IN> The type of the input value.
* @param <OUT> The type of the output value.
* @param <KEY> The type of the key.
*/
public interface InternalWindowFunction<IN, OUT, KEY, W extends Window> extends Function {
/**
* Evaluates the window and outputs none or several elements.
*
* @param context The context in which the window is being evaluated.
* @param input The elements in the window being evaluated.
* @param out A collector for emitting elements.
*
* @throws Exception The function may throw exceptions to fail the program and trigger recovery.
*/
void process(KEY key, W window, InternalWindowContext context, IN input, Collector<OUT> out) throws Exception;
/**
* Deletes any state in the {@code Context} when the Window is purged.
*
* @param context The context to which the window is being evaluated
* @throws Exception The function may throw exceptions to fail the program and trigger recovery.
*/
void clear(W window, InternalWindowContext context) throws Exception;
/**
* A context for {@link InternalWindowFunction}, similar to
* {@link org.apache.flink.streaming.api.functions.windowing.ProcessWindowFunction.Context} but
* for internal use.
*/
interface InternalWindowContext extends java.io.Serializable {
long currentProcessingTime();
long currentWatermark();
KeyedStateStore windowState();
KeyedStateStore globalState();
}
}