/***********************************************************************************************************************
* 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.sort;
import java.io.EOFException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import eu.stratosphere.api.common.typeutils.TypeComparator;
import eu.stratosphere.api.common.typeutils.TypeSerializer;
import eu.stratosphere.core.memory.MemorySegment;
import eu.stratosphere.nephele.services.iomanager.ChannelWriterOutputView;
import eu.stratosphere.nephele.services.memorymanager.AbstractPagedInputView;
import eu.stratosphere.nephele.services.memorymanager.AbstractPagedOutputView;
import eu.stratosphere.util.MutableObjectIterator;
/**
*
*/
public final class FixedLengthRecordSorter<T> implements InMemorySorter<T> {
private static final int MIN_REQUIRED_BUFFERS = 3;
// ------------------------------------------------------------------------
// Members
// ------------------------------------------------------------------------
private final byte[] swapBuffer;
private final TypeSerializer<T> serializer;
private final TypeComparator<T> comparator;
private final SingleSegmentOutputView outView;
private final SingleSegmentInputView inView;
private MemorySegment currentSortBufferSegment;
private int currentSortBufferOffset;
private final ArrayList<MemorySegment> freeMemory;
private final ArrayList<MemorySegment> sortBuffer;
private long sortBufferBytes;
private int numRecords;
private final int numKeyBytes;
private final int recordSize;
private final int recordsPerSegment;
private final int lastEntryOffset;
private final int segmentSize;
private final int totalNumBuffers;
private final boolean useNormKeyUninverted;
private final T recordInstance;
// -------------------------------------------------------------------------
// Constructors / Destructors
// -------------------------------------------------------------------------
public FixedLengthRecordSorter(TypeSerializer<T> serializer, TypeComparator<T> comparator,
List<MemorySegment> memory)
{
if (serializer == null || comparator == null || memory == null) {
throw new NullPointerException();
}
this.serializer = serializer;
this.comparator = comparator;
this.useNormKeyUninverted = !comparator.invertNormalizedKey();
// check the size of the first buffer and record it. all further buffers must have the same size.
// the size must also be a power of 2
this.totalNumBuffers = memory.size();
if (this.totalNumBuffers < MIN_REQUIRED_BUFFERS) {
throw new IllegalArgumentException("Normalized-Key sorter requires at least " + MIN_REQUIRED_BUFFERS + " memory buffers.");
}
this.segmentSize = memory.get(0).size();
this.recordSize = serializer.getLength();
this.numKeyBytes = this.comparator.getNormalizeKeyLen();
// check that the serializer and comparator allow our operations
if (this.recordSize <= 0) {
throw new IllegalArgumentException("This sorter works only for fixed-length data types.");
} else if (this.recordSize > this.segmentSize) {
throw new IllegalArgumentException("This sorter works only for record lengths below the memory segment size.");
} else if (!comparator.supportsSerializationWithKeyNormalization()) {
throw new IllegalArgumentException("This sorter requires a comparator that supports serialization with key normalization.");
}
// compute the entry size and limits
this.recordsPerSegment = segmentSize / this.recordSize;
this.lastEntryOffset = (this.recordsPerSegment - 1) * this.recordSize;
this.swapBuffer = new byte[this.recordSize];
if (memory instanceof ArrayList<?>) {
this.freeMemory = (ArrayList<MemorySegment>) memory;
}
else {
this.freeMemory = new ArrayList<MemorySegment>(memory.size());
this.freeMemory.addAll(memory);
}
// create the buffer collections
this.sortBuffer = new ArrayList<MemorySegment>(16);
this.outView = new SingleSegmentOutputView(this.segmentSize);
this.inView = new SingleSegmentInputView(this.lastEntryOffset + this.recordSize);
this.currentSortBufferSegment = nextMemorySegment();
this.sortBuffer.add(this.currentSortBufferSegment);
this.outView.set(this.currentSortBufferSegment);
this.recordInstance = this.serializer.createInstance();
}
// -------------------------------------------------------------------------
// Memory Segment
// -------------------------------------------------------------------------
/**
* Resets the sort buffer back to the state where it is empty. All contained data is discarded.
*/
@Override
public void reset() {
// reset all offsets
this.numRecords = 0;
this.currentSortBufferOffset = 0;
this.sortBufferBytes = 0;
// return all memory
this.freeMemory.addAll(this.sortBuffer);
this.sortBuffer.clear();
// grab first buffers
this.currentSortBufferSegment = nextMemorySegment();
this.sortBuffer.add(this.currentSortBufferSegment);
this.outView.set(this.currentSortBufferSegment);
}
/**
* Checks whether the buffer is empty.
*
* @return True, if no record is contained, false otherwise.
*/
@Override
public boolean isEmpty() {
return this.numRecords == 0;
}
/**
* Collects all memory segments from this sorter.
*
* @return All memory segments from this sorter.
*/
@Override
public List<MemorySegment> dispose() {
this.freeMemory.addAll(this.sortBuffer);
this.sortBuffer.clear();
return this.freeMemory;
}
/**
* Gets the total capacity of this sorter, in bytes.
*
* @return The sorter's total capacity.
*/
@Override
public long getCapacity() {
return ((long) this.totalNumBuffers) * this.segmentSize;
}
/**
* Gets the number of bytes currently occupied in this sorter.
*
* @return The number of bytes occupied.
*/
@Override
public long getOccupancy() {
return this.sortBufferBytes;
}
// -------------------------------------------------------------------------
// Retrieving and Writing
// -------------------------------------------------------------------------
/**
* Gets the record at the given logical position.
*
* @param reuse The reuse object to deserialize the record into.
* @param logicalPosition The logical position of the record.
* @throws IOException Thrown, if an exception occurred during deserialization.
*/
@Override
public T getRecord(T reuse, int logicalPosition) throws IOException {
final int buffer = logicalPosition / this.recordsPerSegment;
final int inBuffer = (logicalPosition % this.recordsPerSegment) * this.recordSize;
this.inView.set(this.sortBuffer.get(buffer), inBuffer);
return this.comparator.readWithKeyDenormalization(reuse, this.inView);
}
/**
* Writes a given record to this sort buffer. The written record will be appended and take
* the last logical position.
*
* @param record The record to be written.
* @return True, if the record was successfully written, false, if the sort buffer was full.
* @throws IOException Thrown, if an error occurred while serializing the record into the buffers.
*/
@Override
public boolean write(T record) throws IOException {
// check whether we need a new memory segment for the sort index
if (this.currentSortBufferOffset > this.lastEntryOffset) {
if (memoryAvailable()) {
this.currentSortBufferSegment = nextMemorySegment();
this.sortBuffer.add(this.currentSortBufferSegment);
this.outView.set(this.currentSortBufferSegment);
this.currentSortBufferOffset = 0;
this.sortBufferBytes += this.segmentSize;
}
else {
return false;
}
}
// serialize the record into the data buffers
try {
this.comparator.writeWithKeyNormalization(record, this.outView);
this.numRecords++;
this.currentSortBufferOffset += this.recordSize;
return true;
} catch (EOFException eofex) {
throw new IOException("Error: Serialization consumes more bytes than announced by the serializer.");
}
}
// ------------------------------------------------------------------------
// Access Utilities
// ------------------------------------------------------------------------
private final boolean memoryAvailable() {
return !this.freeMemory.isEmpty();
}
private final MemorySegment nextMemorySegment() {
return this.freeMemory.remove(this.freeMemory.size() - 1);
}
// -------------------------------------------------------------------------
// Sorting
// -------------------------------------------------------------------------
@Override
public int compare(int i, int j) {
final int bufferNumI = i / this.recordsPerSegment;
final int segmentOffsetI = (i % this.recordsPerSegment) * this.recordSize;
final int bufferNumJ = j / this.recordsPerSegment;
final int segmentOffsetJ = (j % this.recordsPerSegment) * this.recordSize;
final MemorySegment segI = this.sortBuffer.get(bufferNumI);
final MemorySegment segJ = this.sortBuffer.get(bufferNumJ);
int val = MemorySegment.compare(segI, segJ, segmentOffsetI, segmentOffsetJ, this.numKeyBytes);
return this.useNormKeyUninverted ? val : -val;
}
@Override
public void swap(int i, int j) {
final int bufferNumI = i / this.recordsPerSegment;
final int segmentOffsetI = (i % this.recordsPerSegment) * this.recordSize;
final int bufferNumJ = j / this.recordsPerSegment;
final int segmentOffsetJ = (j % this.recordsPerSegment) * this.recordSize;
final MemorySegment segI = this.sortBuffer.get(bufferNumI);
final MemorySegment segJ = this.sortBuffer.get(bufferNumJ);
MemorySegment.swapBytes(segI, segJ, this.swapBuffer, segmentOffsetI, segmentOffsetJ, this.recordSize);
}
@Override
public int size() {
return this.numRecords;
}
// -------------------------------------------------------------------------
/**
* Gets an iterator over all records in this buffer in their logical order.
*
* @return An iterator returning the records in their logical order.
*/
@Override
public final MutableObjectIterator<T> getIterator() {
final SingleSegmentInputView startIn = new SingleSegmentInputView(this.recordsPerSegment * this.recordSize);
startIn.set(this.sortBuffer.get(0), 0);
return new MutableObjectIterator<T>() {
private final SingleSegmentInputView in = startIn;
private final TypeComparator<T> comp = comparator;
private final int numTotal = size();
private final int numPerSegment = recordsPerSegment;
private int currentTotal = 0;
private int currentInSegment = 0;
private int currentSegmentIndex = 0;
@Override
public T next(T reuse) {
if (this.currentTotal < this.numTotal) {
if (this.currentInSegment >= this.numPerSegment) {
this.currentInSegment = 0;
this.currentSegmentIndex++;
this.in.set(sortBuffer.get(this.currentSegmentIndex), 0);
}
this.currentTotal++;
this.currentInSegment++;
try {
return this.comp.readWithKeyDenormalization(reuse, this.in);
}
catch (IOException ioe) {
throw new RuntimeException(ioe);
}
}
else {
return null;
}
}
};
}
// ------------------------------------------------------------------------
// Writing to a DataOutputView
// ------------------------------------------------------------------------
/**
* Writes the records in this buffer in their logical order to the given output.
*
* @param output The output view to write the records to.
* @throws IOException Thrown, if an I/O exception occurred writing to the output view.
*/
@Override
public void writeToOutput(final ChannelWriterOutputView output) throws IOException {
final TypeComparator<T> comparator = this.comparator;
final TypeSerializer<T> serializer = this.serializer;
T record = this.recordInstance;
final SingleSegmentInputView inView = this.inView;
final int recordsPerSegment = this.recordsPerSegment;
int recordsLeft = this.numRecords;
int currentMemSeg = 0;
while (recordsLeft > 0) {
final MemorySegment currentIndexSegment = this.sortBuffer.get(currentMemSeg++);
inView.set(currentIndexSegment, 0);
// check whether we have a full or partially full segment
if (recordsLeft >= recordsPerSegment) {
// full segment
for (int numInMemSeg = 0; numInMemSeg < recordsPerSegment; numInMemSeg++) {
record = comparator.readWithKeyDenormalization(record, inView);
serializer.serialize(record, output);
}
recordsLeft -= recordsPerSegment;
} else {
// partially filled segment
for (; recordsLeft > 0; recordsLeft--) {
record = comparator.readWithKeyDenormalization(record, inView);
serializer.serialize(record, output);
}
}
}
}
/**
* Writes a subset of the records in this buffer in their logical order to the given output.
*
* @param output The output view to write the records to.
* @param start The logical start position of the subset.
* @param len The number of elements to write.
* @throws IOException Thrown, if an I/O exception occurred writing to the output view.
*/
@Override
public void writeToOutput(final ChannelWriterOutputView output, final int start, int num) throws IOException {
final TypeComparator<T> comparator = this.comparator;
final TypeSerializer<T> serializer = this.serializer;
T record = this.recordInstance;
final SingleSegmentInputView inView = this.inView;
final int recordsPerSegment = this.recordsPerSegment;
int currentMemSeg = start / recordsPerSegment;
int offset = (start % recordsPerSegment) * this.recordSize;
while (num > 0) {
final MemorySegment currentIndexSegment = this.sortBuffer.get(currentMemSeg++);
inView.set(currentIndexSegment, offset);
// check whether we have a full or partially full segment
if (num >= recordsPerSegment && offset == 0) {
// full segment
for (int numInMemSeg = 0; numInMemSeg < recordsPerSegment; numInMemSeg++) {
record = comparator.readWithKeyDenormalization(record, inView);
serializer.serialize(record, output);
}
num -= recordsPerSegment;
} else {
// partially filled segment
for (; num > 0; num--) {
record = comparator.readWithKeyDenormalization(record, inView);
serializer.serialize(record, output);
}
}
}
}
private static final class SingleSegmentOutputView extends AbstractPagedOutputView {
SingleSegmentOutputView(int segmentSize) {
super(segmentSize, 0);
}
void set(MemorySegment segment) {
seekOutput(segment, 0);
}
@Override
protected MemorySegment nextSegment(MemorySegment current, int positionInCurrent) throws IOException {
throw new EOFException();
}
}
private static final class SingleSegmentInputView extends AbstractPagedInputView {
private final int limit;
SingleSegmentInputView(int limit) {
super(0);
this.limit = limit;
}
protected void set(MemorySegment segment, int offset) {
seekInput(segment, offset, this.limit);
}
@Override
protected MemorySegment nextSegment(MemorySegment current) throws EOFException {
throw new EOFException();
}
@Override
protected int getLimitForSegment(MemorySegment segment) {
return this.limit;
}
}
}