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/*
* 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.runtime.state;
import org.apache.flink.types.Pair;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Queue;
/**
* A key-value iterator over all possible groups within the same state storage (the same stat name).
*/
public class GroupIterator implements Iterator> {
private final Queue>> groupIterators;
/** The node for the current head group. */
private volatile Iterator> headIterator;
public GroupIterator(Collection>> iteratorCollection) {
this.groupIterators = new LinkedList<>();
for (Iterator> iterator : iteratorCollection) {
if (iterator.hasNext()) {
groupIterators.add(iterator);
}
}
this.headIterator = this.groupIterators.poll();
}
@Override
public boolean hasNext() {
return !groupIterators.isEmpty() || (headIterator != null && headIterator.hasNext());
}
@Override
public Pair next() {
if (!headIterator.hasNext()) {
if (!groupIterators.isEmpty()) {
headIterator = groupIterators.poll();
}
}
return headIterator.next();
}
@Override
public void remove() {
headIterator.remove();
}
}
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