eu.stratosphere.pact.runtime.hash.HashPartition Maven / Gradle / Ivy
/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* Licensed 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 eu.stratosphere.pact.runtime.hash;
import java.io.EOFException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.LinkedBlockingQueue;
import eu.stratosphere.api.common.typeutils.TypeComparator;
import eu.stratosphere.api.common.typeutils.TypeSerializer;
import eu.stratosphere.core.memory.MemorySegment;
import eu.stratosphere.core.memory.MemorySegmentSource;
import eu.stratosphere.core.memory.SeekableDataInputView;
import eu.stratosphere.core.memory.SeekableDataOutputView;
import eu.stratosphere.nephele.services.iomanager.BlockChannelWriter;
import eu.stratosphere.nephele.services.iomanager.Channel;
import eu.stratosphere.nephele.services.iomanager.ChannelWriterOutputView;
import eu.stratosphere.nephele.services.iomanager.IOManager;
import eu.stratosphere.nephele.services.memorymanager.AbstractPagedInputView;
import eu.stratosphere.nephele.services.memorymanager.AbstractPagedOutputView;
import eu.stratosphere.pact.runtime.io.RandomAccessOutputView;
import eu.stratosphere.pact.runtime.util.MathUtils;
import eu.stratosphere.util.MutableObjectIterator;
/**
*
* @param BT The type of the build side records.
* @param PT The type of the probe side records.
*/
public class HashPartition extends AbstractPagedInputView implements SeekableDataInputView
{
// --------------------------------- Table Structure Auxiliaries ------------------------------------
protected MemorySegment[] overflowSegments; // segments in which overflow buckets from the table structure are stored
protected int numOverflowSegments; // the number of actual segments in the overflowSegments array
protected int nextOverflowBucket; // the next free bucket in the current overflow segment
// ------------------------------------- Type Accessors --------------------------------------------
private final TypeSerializer buildSideSerializer;
private final TypeSerializer probeSideSerializer;
// -------------------------------------- Record Buffers --------------------------------------------
protected MemorySegment[] partitionBuffers;
private int currentBufferNum;
private int finalBufferLimit;
private BuildSideBuffer buildSideWriteBuffer;
protected ChannelWriterOutputView probeSideBuffer;
private RandomAccessOutputView overwriteBuffer;
private long buildSideRecordCounter; // number of build-side records in this partition
protected long probeSideRecordCounter; // number of probe-side records in this partition
// ----------------------------------------- General ------------------------------------------------
private final int segmentSizeBits; // the number of bits in the mem segment size;
private final int memorySegmentSize; // the size of the memory segments being used
private final int partitionNumber; // the number of the partition
protected int recursionLevel; // the recursion level on which this partition lives
// ------------------------------------------ Spilling ----------------------------------------------
private BlockChannelWriter buildSideChannel; // the channel writer for the build side, if partition is spilled
protected BlockChannelWriter probeSideChannel; // the channel writer from the probe side, if partition is spilled
// ------------------------------------------ Restoring ----------------------------------------------
protected boolean furtherPartitioning = false;
protected void setFurtherPatitioning(boolean v) {
furtherPartitioning = v;
}
// --------------------------------------------------------------------------------------------------
/**
* Creates a new partition, initially in memory, with one buffer for the build side. The partition is
* initialized to expect record insertions for the build side.
*
* @param partitionNumber The number of the partition.
* @param recursionLevel The recursion level - zero for partitions from the initial build, n + 1 for
* partitions that are created from spilled partition with recursion level n.
* @param initialBuffer The initial buffer for this partition.
* @param writeBehindBuffers The queue from which to pop buffers for writing, once the partition is spilled.
*/
HashPartition(TypeSerializer buildSideAccessors, TypeSerializer probeSideAccessors,
int partitionNumber, int recursionLevel, MemorySegment initialBuffer, MemorySegmentSource memSource,
int segmentSize)
{
super(0);
this.buildSideSerializer = buildSideAccessors;
this.probeSideSerializer = probeSideAccessors;
this.partitionNumber = partitionNumber;
this.recursionLevel = recursionLevel;
this.memorySegmentSize = segmentSize;
this.segmentSizeBits = MathUtils.log2strict(segmentSize);
this.overflowSegments = new MemorySegment[2];
this.numOverflowSegments = 0;
this.nextOverflowBucket = 0;
this.buildSideWriteBuffer = new BuildSideBuffer(initialBuffer, memSource);
}
/**
* Constructor creating a partition from a spilled partition file that could be read in one because it was
* known to completely fit into memory.
*
* @param buildSideAccessors The data type accessors for the build side data-type.
* @param probeSideAccessors The data type accessors for the probe side data-type.
* @param partitionNumber The number of the partition.
* @param recursionLevel The recursion level of the partition.
* @param buffers The memory segments holding the records.
* @param buildSideRecordCounter The number of records in the buffers.
* @param segmentSize The size of the memory segments.
*/
HashPartition(TypeSerializer buildSideAccessors, TypeSerializer probeSideAccessors,
int partitionNumber, int recursionLevel, List buffers,
long buildSideRecordCounter, int segmentSize, int lastSegmentLimit)
{
super(0);
this.buildSideSerializer = buildSideAccessors;
this.probeSideSerializer = probeSideAccessors;
this.partitionNumber = partitionNumber;
this.recursionLevel = recursionLevel;
this.memorySegmentSize = segmentSize;
this.segmentSizeBits = MathUtils.log2strict(segmentSize);
this.finalBufferLimit = lastSegmentLimit;
this.partitionBuffers = (MemorySegment[]) buffers.toArray(new MemorySegment[buffers.size()]);
this.buildSideRecordCounter = buildSideRecordCounter;
this.overflowSegments = new MemorySegment[2];
this.numOverflowSegments = 0;
this.nextOverflowBucket = 0;
}
// --------------------------------------------------------------------------------------------------
/**
* Gets the partition number of this partition.
*
* @return This partition's number.
*/
public int getPartitionNumber() {
return this.partitionNumber;
}
/**
* Gets this partition's recursion level.
*
* @return The partition's recursion level.
*/
public int getRecursionLevel() {
return this.recursionLevel;
}
/**
* Checks whether this partition is in memory or spilled.
*
* @return True, if the partition is in memory, false if it is spilled.
*/
public final boolean isInMemory() {
return this.buildSideChannel == null;
}
public int getBuildSideBlockCount() {
return this.partitionBuffers == null ? this.buildSideWriteBuffer.getBlockCount() : this.partitionBuffers.length;
}
public int getProbeSideBlockCount() {
return this.probeSideBuffer == null ? -1 : this.probeSideBuffer.getBlockCount();
}
public long getBuildSideRecordCount() {
return this.buildSideRecordCounter;
}
public long getProbeSideRecordCount() {
return this.probeSideRecordCounter;
}
public BlockChannelWriter getBuildSideChannel() {
return this.buildSideChannel;
}
public BlockChannelWriter getProbeSideChannel() {
return this.probeSideChannel;
}
// --------------------------------------------------------------------------------------------------
/**
* Inserts the given object into the current buffer. This method returns a pointer that
* can be used to address the written record in this partition, if it is in-memory. The returned
* pointers have no expressiveness in the case where the partition is spilled.
*
* @param record The object to be written to the partition.
* @return A pointer to the object in the partition, or -1, if the partition is spilled.
* @throws IOException Thrown, when this is a spilled partition and the write failed.
*/
public final long insertIntoBuildBuffer(BT record) throws IOException
{
this.buildSideRecordCounter++;
if (isInMemory()) {
final long pointer = this.buildSideWriteBuffer.getCurrentPointer();
this.buildSideSerializer.serialize(record, this.buildSideWriteBuffer);
return isInMemory() ? pointer : -1;
} else {
this.buildSideSerializer.serialize(record, this.buildSideWriteBuffer);
return -1;
}
}
/**
* Inserts the given record into the probe side buffers. This method is only applicable when the
* partition was spilled while processing the build side.
*
* If this method is invoked when the partition is still being built, it has undefined behavior.
*
* @param object The record to be inserted into the probe side buffers.
* @throws IOException Thrown, if the buffer is full, needs to be spilled, and spilling causes an error.
*/
public final void insertIntoProbeBuffer(PT record) throws IOException
{
this.probeSideSerializer.serialize(record, this.probeSideBuffer);
this.probeSideRecordCounter++;
}
/**
* Spills this partition to disk and sets it up such that it continues spilling records that are added to
* it. The spilling process must free at least one buffer, either in the partition's record buffers, or in
* the memory segments for overflow buckets.
* The partition immediately takes back one buffer to use it for further spilling.
*
* @param target The list to which memory segments from overflow buckets are added.
* @param ioAccess The I/O manager to be used to create a writer to disk.
* @param targetChannel The id of the target channel for this partition.
* @return The number of buffers that were freed by spilling this partition.
* @throws IOException Thrown, if the writing failed.
*/
public int spillPartition(List target, IOManager ioAccess, Channel.ID targetChannel,
LinkedBlockingQueue bufferReturnQueue)
throws IOException
{
// sanity checks
if (!isInMemory()) {
throw new RuntimeException("Bug in Hybrid Hash Join: " +
"Request to spill a partition that has already been spilled.");
}
if (getBuildSideBlockCount() + this.numOverflowSegments < 2) {
throw new RuntimeException("Bug in Hybrid Hash Join: " +
"Request to spill a partition with less than two buffers.");
}
// return the memory from the overflow segments
for (int i = 0; i < this.numOverflowSegments; i++) {
target.add(this.overflowSegments[i]);
}
this.overflowSegments = null;
this.numOverflowSegments = 0;
this.nextOverflowBucket = 0;
// create the channel block writer and spill the current buffers
// that keep the build side buffers current block, as it is most likely not full, yet
// we return the number of blocks that become available
this.buildSideChannel = ioAccess.createBlockChannelWriter(targetChannel, bufferReturnQueue);
return this.buildSideWriteBuffer.spill(this.buildSideChannel);
}
/**
* @param spilledPartitions
* @param ioAccess
* @param probeChannelEnumerator
* @throws IOException
*/
public void finalizeBuildPhase(IOManager ioAccess, Channel.Enumerator probeChannelEnumerator,
LinkedBlockingQueue bufferReturnQueue)
throws IOException
{
this.finalBufferLimit = this.buildSideWriteBuffer.getCurrentPositionInSegment();
this.partitionBuffers = this.buildSideWriteBuffer.close();
if (!isInMemory()) {
// close the channel. note that in the spilled case, the build-side-buffer will have sent off
// the last segment and it will be returned to the write-behind-buffer queue.
this.buildSideChannel.close();
// create the channel for the probe side and claim one buffer for it
this.probeSideChannel = ioAccess.createBlockChannelWriter(probeChannelEnumerator.next(), bufferReturnQueue);
// creating the ChannelWriterOutputView without memory will cause it to draw one segment from the
// write behind queue, which is the spare segment we had above.
this.probeSideBuffer = new ChannelWriterOutputView(this.probeSideChannel, this.memorySegmentSize);
}
}
/**
* @param freeMemory
* @param spilledPartitions
* @return The number of write-behind buffers reclaimable after this method call.
*
* @throws IOException
*/
public int finalizeProbePhase(List freeMemory, List> spilledPartitions)
throws IOException
{
if (isInMemory()) {
// in this case, return all memory buffers
// return the overflow segments
for (int k = 0; k < this.numOverflowSegments; k++) {
freeMemory.add(this.overflowSegments[k]);
}
this.overflowSegments = null;
this.numOverflowSegments = 0;
this.nextOverflowBucket = 0;
// return the partition buffers
for (int i = 0; i < this.partitionBuffers.length; i++) {
freeMemory.add(this.partitionBuffers[i]);
}
this.partitionBuffers = null;
return 0;
}
else if (this.probeSideRecordCounter == 0) {
// partition is empty, no spilled buffers
// return the memory buffer
freeMemory.add(this.probeSideBuffer.getCurrentSegment());
// delete the spill files
this.probeSideChannel.close();
this.buildSideChannel.deleteChannel();
this.probeSideChannel.deleteChannel();
return 0;
}
else {
// flush the last probe side buffer and register this partition as pending
this.probeSideBuffer.close();
this.probeSideChannel.close();
spilledPartitions.add(this);
return 1;
}
}
public void clearAllMemory(List target)
{
// return current buffers from build side and probe side
if (this.buildSideWriteBuffer != null) {
if (this.buildSideWriteBuffer.getCurrentSegment() != null) {
target.add(this.buildSideWriteBuffer.getCurrentSegment());
}
target.addAll(this.buildSideWriteBuffer.targetList);
this.buildSideWriteBuffer.targetList.clear();
this.buildSideWriteBuffer = null;
}
if (this.probeSideBuffer != null && this.probeSideBuffer.getCurrentSegment() != null) {
target.add(this.probeSideBuffer.getCurrentSegment());
this.probeSideBuffer = null;
}
// return the overflow segments
if (this.overflowSegments != null) {
for (int k = 0; k < this.numOverflowSegments; k++) {
target.add(this.overflowSegments[k]);
}
}
// return the partition buffers
if (this.partitionBuffers != null) {
for (int k = 0; k < this.partitionBuffers.length; k++) {
target.add(this.partitionBuffers[k]);
}
this.partitionBuffers = null;
}
// clear the channels
try {
if (this.buildSideChannel != null) {
this.buildSideChannel.close();
this.buildSideChannel.deleteChannel();
}
if (this.probeSideChannel != null) {
this.probeSideChannel.close();
this.probeSideChannel.deleteChannel();
}
}
catch (IOException ioex) {
throw new RuntimeException("Error deleting the partition files. Some temporary files might not be removed.");
}
}
final PartitionIterator getPartitionIterator(TypeComparator comparator) throws IOException
{
return new PartitionIterator(comparator);
}
final int getLastSegmentLimit() {
return this.finalBufferLimit;
}
final SeekableDataOutputView getWriteView() {
if (this.overwriteBuffer == null) {
this.overwriteBuffer = new RandomAccessOutputView(this.partitionBuffers, this.memorySegmentSize);
}
return this.overwriteBuffer;
}
// --------------------------------------------------------------------------------------------------
// ReOpenableHashTable related methods
// --------------------------------------------------------------------------------------------------
public void prepareProbePhase(IOManager ioAccess, Channel.Enumerator probeChannelEnumerator,
LinkedBlockingQueue bufferReturnQueue) throws IOException {
if (isInMemory()) {
return;
}
// ATTENTION: The following lines are duplicated code from finalizeBuildPhase
this.probeSideChannel = ioAccess.createBlockChannelWriter(probeChannelEnumerator.next(), bufferReturnQueue);
this.probeSideBuffer = new ChannelWriterOutputView(this.probeSideChannel, this.memorySegmentSize);
}
// --------------------------------------------------------------------------------------------------
// Methods to provide input view abstraction for reading probe records
// --------------------------------------------------------------------------------------------------
public void setReadPosition(long pointer)
{
final int bufferNum = (int) (pointer >>> this.segmentSizeBits);
final int offset = (int) (pointer & (this.memorySegmentSize - 1));
this.currentBufferNum = bufferNum;
seekInput(this.partitionBuffers[bufferNum], offset,
bufferNum < this.partitionBuffers.length-1 ? this.memorySegmentSize : this.finalBufferLimit);
}
@Override
protected MemorySegment nextSegment(MemorySegment current) throws IOException {
this.currentBufferNum++;
if (this.currentBufferNum < this.partitionBuffers.length) {
return this.partitionBuffers[this.currentBufferNum];
} else {
throw new EOFException();
}
}
@Override
protected int getLimitForSegment(MemorySegment segment) {
return segment == this.partitionBuffers[partitionBuffers.length - 1] ? this.finalBufferLimit : this.memorySegmentSize;
}
// ============================================================================================
protected static final class BuildSideBuffer extends AbstractPagedOutputView
{
private final ArrayList targetList;
private final MemorySegmentSource memSource;
private BlockChannelWriter writer;
private int currentBlockNumber;
private final int sizeBits;
private BuildSideBuffer(MemorySegment initialSegment, MemorySegmentSource memSource)
{
super(initialSegment, initialSegment.size(), 0);
this.targetList = new ArrayList();
this.memSource = memSource;
this.sizeBits = MathUtils.log2strict(initialSegment.size());
}
@Override
protected MemorySegment nextSegment(MemorySegment current, int bytesUsed) throws IOException
{
finalizeSegment(current, bytesUsed);
final MemorySegment next;
if (this.writer == null) {
this.targetList.add(current);
next = this.memSource.nextSegment();
} else {
this.writer.writeBlock(current);
try {
next = this.writer.getReturnQueue().take();
} catch (InterruptedException iex) {
throw new IOException("Hash Join Partition was interrupted while grabbing a new write-behind buffer.");
}
}
this.currentBlockNumber++;
return next;
}
long getCurrentPointer() {
return (((long) this.currentBlockNumber) << this.sizeBits) + getCurrentPositionInSegment();
}
int getBlockCount() {
return this.currentBlockNumber + 1;
}
int spill(BlockChannelWriter writer) throws IOException
{
this.writer = writer;
final int numSegments = this.targetList.size();
for (int i = 0; i < numSegments; i++) {
this.writer.writeBlock(this.targetList.get(i));
}
this.targetList.clear();
return numSegments;
}
MemorySegment[] close() throws IOException
{
final MemorySegment current = getCurrentSegment();
if (current == null) {
throw new IllegalStateException("Illegal State in HashPartition: No current buffer when finilizing build side.");
}
finalizeSegment(current, getCurrentPositionInSegment());
clear();
if (this.writer == null) {
this.targetList.add(current);
MemorySegment[] buffers = (MemorySegment[]) this.targetList.toArray(new MemorySegment[this.targetList.size()]);
this.targetList.clear();
return buffers;
} else {
writer.writeBlock(current);
return null;
}
}
private final void finalizeSegment(MemorySegment seg, int bytesUsed) {
}
}
// ============================================================================================
final class PartitionIterator implements MutableObjectIterator
{
private final TypeComparator comparator;
private long currentPointer;
private int currentHashCode;
private PartitionIterator(final TypeComparator comparator) throws IOException
{
this.comparator = comparator;
setReadPosition(0);
}
public final BT next(BT reuse) throws IOException
{
final int pos = getCurrentPositionInSegment();
final int buffer = HashPartition.this.currentBufferNum;
this.currentPointer = (((long) buffer) << HashPartition.this.segmentSizeBits) + pos;
try {
reuse = HashPartition.this.buildSideSerializer.deserialize(reuse, HashPartition.this);
this.currentHashCode = this.comparator.hash(reuse);
return reuse;
} catch (EOFException eofex) {
return null;
}
}
protected final long getPointer()
{
return this.currentPointer;
}
protected final int getCurrentHashCode()
{
return this.currentHashCode;
}
}
}