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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 java.io.IOException;
import java.util.Collections;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.MemorySegment;
import org.apache.flink.runtime.io.disk.SpillingBuffer;
import org.apache.flink.runtime.io.disk.iomanager.IOManager;
import org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable;
import org.apache.flink.runtime.memory.ListMemorySegmentSource;
import org.apache.flink.runtime.memory.MemoryAllocationException;
import org.apache.flink.runtime.memory.MemoryManager;
import org.apache.flink.runtime.util.ResettableMutableObjectIterator;
import org.apache.flink.util.MutableObjectIterator;
/**
* Implementation of a resettable iterator. While iterating the first time over the data, the iterator writes the
* records to a spillable buffer. Any subsequent iteration re-reads the data from that buffer.
*
* @param The type of record that the iterator handles.
*/
public class SpillingResettableMutableObjectIterator implements ResettableMutableObjectIterator {
private static final Logger LOG = LoggerFactory.getLogger(SpillingResettableMutableObjectIterator.class);
// ------------------------------------------------------------------------
protected DataInputView inView;
protected final TypeSerializer serializer;
private long elementCount;
private long currentElementNum;
protected final SpillingBuffer buffer;
protected final MutableObjectIterator input;
protected final MemoryManager memoryManager;
private final List memorySegments;
private final boolean releaseMemoryOnClose;
// ------------------------------------------------------------------------
public SpillingResettableMutableObjectIterator(MutableObjectIterator input, TypeSerializer serializer,
MemoryManager memoryManager, IOManager ioManager,
int numPages, AbstractInvokable parentTask)
throws MemoryAllocationException
{
this(input, serializer, memoryManager, ioManager, memoryManager.allocatePages(parentTask, numPages), true);
}
public SpillingResettableMutableObjectIterator(MutableObjectIterator input, TypeSerializer serializer,
MemoryManager memoryManager, IOManager ioManager,
List memory)
{
this(input, serializer, memoryManager, ioManager, memory, false);
}
private SpillingResettableMutableObjectIterator(MutableObjectIterator input, TypeSerializer serializer,
MemoryManager memoryManager, IOManager ioManager,
List memory, boolean releaseMemOnClose)
{
this.memoryManager = memoryManager;
this.input = input;
this.serializer = serializer;
this.memorySegments = memory;
this.releaseMemoryOnClose = releaseMemOnClose;
if (LOG.isDebugEnabled()) {
LOG.debug("Creating spilling resettable iterator with " + memory.size() + " pages of memory.");
}
this.buffer = new SpillingBuffer(ioManager, new ListMemorySegmentSource(memory), memoryManager.getPageSize());
}
public void open() {}
@Override
public void reset() throws IOException {
this.inView = this.buffer.flip();
this.currentElementNum = 0;
}
public List close() throws IOException {
if (LOG.isDebugEnabled()) {
LOG.debug("Spilling Resettable Iterator closing. Stored " + this.elementCount + " records.");
}
this.inView = null;
final List memory = this.buffer.close();
memory.addAll(this.memorySegments);
this.memorySegments.clear();
if (this.releaseMemoryOnClose) {
this.memoryManager.release(memory);
return Collections.emptyList();
} else {
return memory;
}
}
@Override
public T next(T reuse) throws IOException {
if (this.inView != null) {
// reading, any subsequent pass
if (this.currentElementNum < this.elementCount) {
try {
reuse = this.serializer.deserialize(reuse, this.inView);
} catch (IOException e) {
throw new RuntimeException("SpillingIterator: Error reading element from buffer.", e);
}
this.currentElementNum++;
return reuse;
} else {
return null;
}
} else {
// writing pass (first)
if ((reuse = this.input.next(reuse)) != null) {
try {
this.serializer.serialize(reuse, this.buffer);
} catch (IOException e) {
throw new RuntimeException("SpillingIterator: Error writing element to buffer.", e);
}
this.elementCount++;
return reuse;
} else {
return null;
}
}
}
@Override
public T next() throws IOException {
T result = null;
if (this.inView != null) {
// reading, any subsequent pass
if (this.currentElementNum < this.elementCount) {
try {
result = this.serializer.deserialize(this.inView);
} catch (IOException e) {
throw new RuntimeException("SpillingIterator: Error reading element from buffer.", e);
}
this.currentElementNum++;
return result;
} else {
return null;
}
} else {
// writing pass (first)
if ((result = this.input.next()) != null) {
try {
this.serializer.serialize(result, this.buffer);
} catch (IOException e) {
throw new RuntimeException("SpillingIterator: Error writing element to buffer.", e);
}
this.elementCount++;
return result;
} else {
return null;
}
}
}
public void consumeAndCacheRemainingData() throws IOException {
// check that we are in the first pass and that more input data is left
if (this.inView == null) {
T holder = this.serializer.createInstance();
while ((holder = this.input.next(holder)) != null) {
try {
this.serializer.serialize(holder, this.buffer);
} catch (IOException e) {
throw new RuntimeException("SpillingIterator: Error writing element to buffer.", e);
}
this.elementCount++;
}
}
}
}
