org.apache.flink.runtime.util.NonReusingMutableToRegularIteratorWrapper Maven / Gradle / Ivy
/*
* 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.util;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.util.MutableObjectIterator;
import org.apache.flink.util.TraversableOnceException;
import java.io.IOException;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* This class wraps a {@link org.apache.flink.util.MutableObjectIterator} into a regular
* {@link java.util.Iterator}. It will always create new instances and not reuse objects.
*/
public class NonReusingMutableToRegularIteratorWrapper implements Iterator, Iterable {
private final MutableObjectIterator source;
private T current;
private boolean currentIsAvailable;
private boolean iteratorAvailable = true;
public NonReusingMutableToRegularIteratorWrapper(MutableObjectIterator source, TypeSerializer serializer) {
this.source = source;
this.current = null;
}
@Override
public boolean hasNext() {
if (currentIsAvailable) {
return true;
} else {
try {
if ((current = source.next()) != null) {
currentIsAvailable = true;
return true;
} else {
return false;
}
} catch (IOException ioex) {
throw new RuntimeException("Error reading next record: " + ioex.getMessage(), ioex);
}
}
}
@Override
public T next() {
if (currentIsAvailable || hasNext()) {
currentIsAvailable = false;
return current;
} else {
throw new NoSuchElementException();
}
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
@Override
public Iterator iterator() {
if (iteratorAvailable) {
iteratorAvailable = false;
return this;
}
else {
throw new TraversableOnceException();
}
}
}