org.apache.flink.runtime.operators.util.ReaderIterator Maven / Gradle / Ivy
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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.operators.util;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.runtime.io.network.api.reader.MutableReader;
import org.apache.flink.runtime.plugable.DeserializationDelegate;
import org.apache.flink.runtime.plugable.NonReusingDeserializationDelegate;
import org.apache.flink.runtime.plugable.ReusingDeserializationDelegate;
import org.apache.flink.util.MutableObjectIterator;
import java.io.IOException;
/**
* A {@link MutableObjectIterator} that wraps a reader from an input channel and
* produces the reader's records.
*
* The reader supports reading objects with possible reuse of mutable types, and
* without reuse of mutable types.
*/
public class ReaderIterator implements MutableObjectIterator {
private final MutableReader> reader; // the source
private final ReusingDeserializationDelegate reusingDelegate;
private final NonReusingDeserializationDelegate nonReusingDelegate;
/**
* Creates a new iterator, wrapping the given reader.
*
* @param reader The reader to wrap.
*/
public ReaderIterator(MutableReader> reader, TypeSerializer serializer) {
this.reader = reader;
this.reusingDelegate = new ReusingDeserializationDelegate(serializer);
this.nonReusingDelegate = new NonReusingDeserializationDelegate(serializer);
}
@Override
public T next(T target) throws IOException {
this.reusingDelegate.setInstance(target);
try {
if (this.reader.next(this.reusingDelegate)) {
return this.reusingDelegate.getInstance();
} else {
return null;
}
}
catch (InterruptedException e) {
throw new IOException("Reader interrupted.", e);
}
}
@Override
public T next() throws IOException {
try {
if (this.reader.next(this.nonReusingDelegate)) {
return this.nonReusingDelegate.getInstance();
} else {
return null;
}
}
catch (InterruptedException e) {
throw new IOException("Reader interrupted.", e);
}
}
}