/*
* 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.kafka.streams.kstream.internals;
import org.apache.kafka.streams.kstream.Aggregator;
import org.apache.kafka.streams.kstream.Initializer;
import org.apache.kafka.streams.processor.AbstractProcessor;
import org.apache.kafka.streams.processor.Processor;
import org.apache.kafka.streams.processor.ProcessorContext;
import org.apache.kafka.streams.state.KeyValueStore;
public class KStreamAggregate<K, V, T> implements KStreamAggProcessorSupplier<K, K, V, T> {
private final String storeName;
private final Initializer<T> initializer;
private final Aggregator<? super K, ? super V, T> aggregator;
private boolean sendOldValues = false;
public KStreamAggregate(String storeName, Initializer<T> initializer, Aggregator<? super K, ? super V, T> aggregator) {
this.storeName = storeName;
this.initializer = initializer;
this.aggregator = aggregator;
}
@Override
public Processor<K, V> get() {
return new KStreamAggregateProcessor();
}
@Override
public void enableSendingOldValues() {
sendOldValues = true;
}
private class KStreamAggregateProcessor extends AbstractProcessor<K, V> {
private KeyValueStore<K, T> store;
private TupleForwarder<K, T> tupleForwarder;
@SuppressWarnings("unchecked")
@Override
public void init(ProcessorContext context) {
super.init(context);
store = (KeyValueStore<K, T>) context.getStateStore(storeName);
tupleForwarder = new TupleForwarder<>(store, context, new ForwardingCacheFlushListener<K, V>(context, sendOldValues), sendOldValues);
}
@Override
public void process(K key, V value) {
if (key == null)
return;
T oldAgg = store.get(key);
if (oldAgg == null)
oldAgg = initializer.apply();
T newAgg = oldAgg;
// try to add the new new value
if (value != null) {
newAgg = aggregator.apply(key, value, newAgg);
}
// update the store with the new value
store.put(key, newAgg);
tupleForwarder.maybeForward(key, newAgg, oldAgg);
}
}
@Override
public KTableValueGetterSupplier<K, T> view() {
return new KTableValueGetterSupplier<K, T>() {
public KTableValueGetter<K, T> get() {
return new KStreamAggregateValueGetter();
}
@Override
public String[] storeNames() {
return new String[]{storeName};
}
};
}
private class KStreamAggregateValueGetter implements KTableValueGetter<K, T> {
private KeyValueStore<K, T> store;
@SuppressWarnings("unchecked")
@Override
public void init(ProcessorContext context) {
store = (KeyValueStore<K, T>) context.getStateStore(storeName);
}
@Override
public T get(K key) {
return store.get(key);
}
}
}