kafka CompositeKeyValueIterator 源码
kafka CompositeKeyValueIterator 代码
文件路径：/streams/src/main/java/org/apache/kafka/streams/state/internals/CompositeKeyValueIterator.java
/*
* 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.state.internals;
import org.apache.kafka.streams.KeyValue;
import org.apache.kafka.streams.state.KeyValueIterator;
import java.util.Iterator;
import java.util.NoSuchElementException;
class CompositeKeyValueIterator<K, V, StoreType> implements KeyValueIterator<K, V> {
private final Iterator<StoreType> storeIterator;
private final NextIteratorFunction<K, V, StoreType> nextIteratorFunction;
private KeyValueIterator<K, V> current;
CompositeKeyValueIterator(final Iterator<StoreType> underlying,
final NextIteratorFunction<K, V, StoreType> nextIteratorFunction) {
this.storeIterator = underlying;
this.nextIteratorFunction = nextIteratorFunction;
}
@Override
public void close() {
if (current != null) {
current.close();
current = null;
}
}
@Override
public K peekNextKey() {
throw new UnsupportedOperationException("peekNextKey not supported");
}
@Override
public boolean hasNext() {
while ((current == null || !current.hasNext()) && storeIterator.hasNext()) {
close();
current = nextIteratorFunction.apply(storeIterator.next());
}
return current != null && current.hasNext();
}
@Override
public KeyValue<K, V> next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
return current.next();
}
}
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