org.apache.flink.runtime.operators.resettable.ReusingBlockResettableIterator 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.resettable;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable;
import org.apache.flink.runtime.memory.MemoryAllocationException;
import org.apache.flink.runtime.memory.MemoryManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.Iterator;
/**
* Implementation of an iterator that fetches a block of data into main memory and offers resettable
* access to the data in that block.
*
*/
public class ReusingBlockResettableIterator extends NonReusingBlockResettableIterator {
public static final Logger LOG = LoggerFactory.getLogger(ReusingBlockResettableIterator.class);
private final T reuseElement;
// ------------------------------------------------------------------------
public ReusingBlockResettableIterator(MemoryManager memoryManager, Iterator input,
TypeSerializer serializer, int numPages,
AbstractInvokable ownerTask)
throws MemoryAllocationException
{
this(memoryManager, serializer, numPages, ownerTask);
this.input = input;
}
public ReusingBlockResettableIterator(MemoryManager memoryManager, TypeSerializer
serializer, int numPages, AbstractInvokable ownerTask)
throws MemoryAllocationException
{
super(memoryManager, serializer, numPages, ownerTask);
this.reuseElement = serializer.createInstance();
}
// ------------------------------------------------------------------------
@Override
public boolean hasNext() {
try {
if (this.nextElement == null) {
if (this.readPhase) {
// read phase, get next element from buffer
T tmp = getNextRecord(this.reuseElement);
if (tmp != null) {
this.nextElement = tmp;
return true;
} else {
return false;
}
} else {
if (this.input.hasNext()) {
final T next = this.input.next();
if (writeNextRecord(next)) {
this.nextElement = next;
return true;
} else {
this.leftOverElement = next;
return false;
}
} else {
this.noMoreBlocks = true;
return false;
}
}
} else {
return true;
}
} catch (IOException ioex) {
throw new RuntimeException("Error (de)serializing record in block resettable iterator.", ioex);
}
}
}