org.apache.datasketches.tuple.QuickSelectSketch Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* 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.datasketches.tuple;
import static org.apache.datasketches.Util.REBUILD_THRESHOLD;
import static org.apache.datasketches.Util.RESIZE_THRESHOLD;
import static org.apache.datasketches.Util.ceilingPowerOf2;
import static org.apache.datasketches.Util.simpleIntLog2;
import java.lang.reflect.Array;
import java.nio.ByteOrder;
import org.apache.datasketches.ByteArrayUtil;
import org.apache.datasketches.Family;
import org.apache.datasketches.HashOperations;
import org.apache.datasketches.QuickSelect;
import org.apache.datasketches.ResizeFactor;
import org.apache.datasketches.SketchesArgumentException;
import org.apache.datasketches.memory.Memory;
/**
* A generic tuple sketch using the QuickSelect algorithm.
*
* @param type of Summary
*/
class QuickSelectSketch extends Sketch {
//private static final byte serialVersionWithSummaryFactoryUID = 1;
private static final byte serialVersionUID = 2;
private enum Flags { IS_BIG_ENDIAN, IS_IN_SAMPLING_MODE, IS_EMPTY, HAS_ENTRIES, IS_THETA_INCLUDED }
static final int DEFAULT_LG_RESIZE_FACTOR = ResizeFactor.X8.lg();
private final int nomEntries_;
private int lgCurrentCapacity_;
private final int lgResizeFactor_;
private int count_;
private final SummaryFactory summaryFactory_;
private final float samplingProbability_;
private int rebuildThreshold_;
/**
* This is to create an instance of a QuickSelectSketch with default resize factor.
* @param nomEntries Nominal number of entries. Forced to the nearest power of 2 greater than
* given value.
* @param summaryFactory An instance of a SummaryFactory.
*/
QuickSelectSketch(final int nomEntries, final SummaryFactory summaryFactory) {
this(nomEntries, DEFAULT_LG_RESIZE_FACTOR, summaryFactory);
}
/**
* This is to create an instance of a QuickSelectSketch with custom resize factor
* @param nomEntries Nominal number of entries. Forced to the nearest power of 2 greater than
* given value.
* @param lgResizeFactor log2(resizeFactor) - value from 0 to 3:
*
* 0 - no resizing (max size allocated),
* 1 - double internal hash table each time it reaches a threshold
* 2 - grow four times
* 3 - grow eight times (default)
*
* @param summaryFactory An instance of a SummaryFactory.
*/
QuickSelectSketch(final int nomEntries, final int lgResizeFactor,
final SummaryFactory summaryFactory) {
this(nomEntries, lgResizeFactor, 1f, summaryFactory);
}
/**
* This is to create an instance of a QuickSelectSketch with custom resize factor and sampling
* probability
* @param nomEntries Nominal number of entries. Forced to the nearest power of 2 greater than
* given value.
* @param lgResizeFactor log2(resizeFactor) - value from 0 to 3:
*
* 0 - no resizing (max size allocated),
* 1 - double internal hash table each time it reaches a threshold
* 2 - grow four times
* 3 - grow eight times (default)
*
* @param samplingProbability the given sampling probability
* @param summaryFactory An instance of a SummaryFactory.
*/
QuickSelectSketch(final int nomEntries, final int lgResizeFactor, final float samplingProbability,
final SummaryFactory summaryFactory) {
this(
nomEntries,
lgResizeFactor,
samplingProbability,
summaryFactory,
Util.getStartingCapacity(nomEntries, lgResizeFactor)
);
}
QuickSelectSketch(final int nomEntries, final int lgResizeFactor, final float samplingProbability,
final SummaryFactory summaryFactory, final int startingSize) {
nomEntries_ = ceilingPowerOf2(nomEntries);
lgResizeFactor_ = lgResizeFactor;
samplingProbability_ = samplingProbability;
summaryFactory_ = summaryFactory;
theta_ = (long) (Long.MAX_VALUE * (double) samplingProbability);
lgCurrentCapacity_ = Integer.numberOfTrailingZeros(startingSize);
keys_ = new long[startingSize];
summaries_ = null; // wait for the first summary to call Array.newInstance()
setRebuildThreshold();
}
/**
* This is to create an instance of a QuickSelectSketch given a serialized form
* @param mem Memory object with serialized QukckSelectSketch
* @param deserializer the SummaryDeserializer
* @param summaryFactory the SummaryFactory
*/
QuickSelectSketch(final Memory mem, final SummaryDeserializer deserializer,
final SummaryFactory summaryFactory) {
summaryFactory_ = summaryFactory;
int offset = 0;
final byte preambleLongs = mem.getByte(offset++);
final byte version = mem.getByte(offset++);
final byte familyId = mem.getByte(offset++);
SerializerDeserializer.validateFamily(familyId, preambleLongs);
if (version > serialVersionUID) {
throw new SketchesArgumentException(
"Unsupported serial version. Expected: " + serialVersionUID + " or lower, actual: "
+ version);
}
SerializerDeserializer.validateType(mem.getByte(offset++),
SerializerDeserializer.SketchType.QuickSelectSketch);
final byte flags = mem.getByte(offset++);
final boolean isBigEndian = (flags & (1 << Flags.IS_BIG_ENDIAN.ordinal())) > 0;
if (isBigEndian ^ ByteOrder.nativeOrder().equals(ByteOrder.BIG_ENDIAN)) {
throw new SketchesArgumentException("Endian byte order mismatch");
}
nomEntries_ = 1 << mem.getByte(offset++);
lgCurrentCapacity_ = mem.getByte(offset++);
lgResizeFactor_ = mem.getByte(offset++);
final boolean isInSamplingMode = (flags & (1 << Flags.IS_IN_SAMPLING_MODE.ordinal())) > 0;
samplingProbability_ = isInSamplingMode ? mem.getFloat(offset) : 1f;
if (isInSamplingMode) {
offset += Float.BYTES;
}
final boolean isThetaIncluded = (flags & (1 << Flags.IS_THETA_INCLUDED.ordinal())) > 0;
if (isThetaIncluded) {
theta_ = mem.getLong(offset);
offset += Long.BYTES;
} else {
theta_ = (long) (Long.MAX_VALUE * (double) samplingProbability_);
}
int count = 0;
final boolean hasEntries = (flags & (1 << Flags.HAS_ENTRIES.ordinal())) > 0;
if (hasEntries) {
count = mem.getInt(offset);
offset += Integer.BYTES;
}
// if (version == serialVersionWithSummaryFactoryUID) {
// final DeserializeResult> factoryResult =
// SerializerDeserializer.deserializeFromMemory(mem, offset);
// offset += factoryResult.getSize();
// }
final int currentCapacity = 1 << lgCurrentCapacity_;
keys_ = new long[currentCapacity];
for (int i = 0; i < count; i++) {
final long key = mem.getLong(offset);
offset += Long.BYTES;
final Memory memRegion = mem.region(offset, mem.getCapacity() - offset);
final DeserializeResult summaryResult = deserializer.heapifySummary(memRegion);
final S summary = summaryResult.getObject();
offset += summaryResult.getSize();
insert(key, summary);
}
isEmpty_ = (flags & (1 << Flags.IS_EMPTY.ordinal())) > 0;
setRebuildThreshold();
}
@Override
public int getRetainedEntries() {
return count_;
}
/**
* Get configured nominal number of entries
* @return nominal number of entries
*/
public int getNominalEntries() {
return nomEntries_;
}
/**
* Get log_base2 of Nominal Entries
* @return log_base2 of Nominal Entries
*/
public int getLgK() {
return simpleIntLog2(nomEntries_);
}
/**
* Get configured sampling probability
* @return sampling probability
*/
public float getSamplingProbability() {
return samplingProbability_;
}
/**
* Get current capacity
* @return current capacity
*/
public int getCurrentCapacity() {
return 1 << lgCurrentCapacity_;
}
/**
* Get configured resize factor
* @return resize factor
*/
public ResizeFactor getResizeFactor() {
return ResizeFactor.getRF(lgResizeFactor_);
}
/**
* Rebuilds reducing the actual number of entries to the nominal number of entries if needed
*/
public void trim() {
if (count_ > nomEntries_) {
updateTheta();
rebuild(keys_.length);
}
}
/**
* Resets this sketch an empty state.
*/
public void reset() {
isEmpty_ = true;
count_ = 0;
theta_ = (long) (Long.MAX_VALUE * (double) samplingProbability_);
final int startingCapacity = Util.getStartingCapacity(nomEntries_, lgResizeFactor_);
lgCurrentCapacity_ = Integer.numberOfTrailingZeros(startingCapacity);
keys_ = new long[startingCapacity];
summaries_ = null; // wait for the first summary to call Array.newInstance()
setRebuildThreshold();
}
/**
* Converts the current state of the sketch into a compact sketch
* @return compact sketch
*/
@SuppressWarnings("unchecked")
public CompactSketch compact() {
if (getRetainedEntries() == 0) {
return new CompactSketch<>(null, null, theta_, isEmpty_);
}
final long[] keys = new long[getRetainedEntries()];
final S[] summaries = (S[])
Array.newInstance(summaries_.getClass().getComponentType(), getRetainedEntries());
int i = 0;
for (int j = 0; j < keys_.length; j++) {
if (summaries_[j] != null) {
keys[i] = keys_[j];
summaries[i] = (S)summaries_[j].copy();
i++;
}
}
return new CompactSketch<>(keys, summaries, theta_, isEmpty_);
}
// Layout of first 8 bytes:
// Long || Start Byte Adr:
// Adr:
// || 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
// 0 || RF | lgArr | lgNom | Flags | SkType | FamID | SerVer | Preamble_Longs |
@SuppressWarnings("null")
@Override
public byte[] toByteArray() {
byte[][] summariesBytes = null;
int summariesBytesLength = 0;
if (count_ > 0) {
summariesBytes = new byte[count_][];
int i = 0;
for (int j = 0; j < summaries_.length; j++) {
if (summaries_[j] != null) {
summariesBytes[i] = summaries_[j].toByteArray();
summariesBytesLength += summariesBytes[i].length;
i++;
}
}
}
int sizeBytes =
Byte.BYTES // preamble longs
+ Byte.BYTES // serial version
+ Byte.BYTES // family
+ Byte.BYTES // sketch type
+ Byte.BYTES // flags
+ Byte.BYTES // log2(nomEntries)
+ Byte.BYTES // log2(currentCapacity)
+ Byte.BYTES; // log2(resizeFactor)
if (isInSamplingMode()) {
sizeBytes += Float.BYTES; // samplingProbability
}
final boolean isThetaIncluded = isInSamplingMode()
? theta_ < samplingProbability_ : theta_ < Long.MAX_VALUE;
if (isThetaIncluded) {
sizeBytes += Long.BYTES;
}
if (count_ > 0) {
sizeBytes += Integer.BYTES; // count
}
sizeBytes += (Long.BYTES * count_) + summariesBytesLength;
final byte[] bytes = new byte[sizeBytes];
int offset = 0;
bytes[offset++] = PREAMBLE_LONGS;
bytes[offset++] = serialVersionUID;
bytes[offset++] = (byte) Family.TUPLE.getID();
bytes[offset++] = (byte) SerializerDeserializer.SketchType.QuickSelectSketch.ordinal();
final boolean isBigEndian = ByteOrder.nativeOrder().equals(ByteOrder.BIG_ENDIAN);
bytes[offset++] = (byte) (
(isBigEndian ? 1 << Flags.IS_BIG_ENDIAN.ordinal() : 0)
| (isInSamplingMode() ? 1 << Flags.IS_IN_SAMPLING_MODE.ordinal() : 0)
| (isEmpty_ ? 1 << Flags.IS_EMPTY.ordinal() : 0)
| (count_ > 0 ? 1 << Flags.HAS_ENTRIES.ordinal() : 0)
| (isThetaIncluded ? 1 << Flags.IS_THETA_INCLUDED.ordinal() : 0)
);
bytes[offset++] = (byte) Integer.numberOfTrailingZeros(nomEntries_);
bytes[offset++] = (byte) lgCurrentCapacity_;
bytes[offset++] = (byte) lgResizeFactor_;
if (samplingProbability_ < 1f) {
ByteArrayUtil.putFloatLE(bytes, offset, samplingProbability_);
offset += Float.BYTES;
}
if (isThetaIncluded) {
ByteArrayUtil.putLongLE(bytes, offset, theta_);
offset += Long.BYTES;
}
if (count_ > 0) {
ByteArrayUtil.putIntLE(bytes, offset, count_);
offset += Integer.BYTES;
}
if (count_ > 0) {
int i = 0;
for (int j = 0; j < keys_.length; j++) {
if (summaries_[j] != null) {
ByteArrayUtil.putLongLE(bytes, offset, keys_[j]);
offset += Long.BYTES;
System.arraycopy(summariesBytes[i], 0, bytes, offset, summariesBytes[i].length);
offset += summariesBytes[i].length;
i++;
}
}
}
return bytes;
}
// non-public methods below
// this is a special back door insert for merging
// not sufficient by itself without keeping track of theta of another sketch
@SuppressWarnings("unchecked")
void merge(final long key, final S summary, final SummarySetOperations summarySetOps) {
isEmpty_ = false;
if (key < theta_) {
final int index = findOrInsert(key);
if (index < 0) {
insertSummary(~index, (S)summary.copy());
} else {
insertSummary(index, summarySetOps.union(summaries_[index], summary));
}
rebuildIfNeeded();
}
}
boolean isInSamplingMode() {
return samplingProbability_ < 1f;
}
void setThetaLong(final long theta) {
theta_ = theta;
}
void setNotEmpty() {
isEmpty_ = false;
}
SummaryFactory getSummaryFactory() {
return summaryFactory_;
}
int findOrInsert(final long key) {
final int index = HashOperations.hashSearchOrInsert(keys_, lgCurrentCapacity_, key);
if (index < 0) {
count_++;
}
return index;
}
S find(final long key) {
final int index = HashOperations.hashSearch(keys_, lgCurrentCapacity_, key);
if (index == -1) { return null; }
return summaries_[index];
}
boolean rebuildIfNeeded() {
if (count_ < rebuildThreshold_) {
return false;
}
if (keys_.length > nomEntries_) {
updateTheta();
rebuild();
} else {
rebuild(keys_.length * (1 << lgResizeFactor_));
}
return true;
}
void rebuild() {
rebuild(keys_.length);
}
void insert(final long key, final S summary) {
final int index = HashOperations.hashInsertOnly(keys_, lgCurrentCapacity_, key);
insertSummary(index, summary);
count_++;
}
private void updateTheta() {
final long[] keys = new long[count_];
int i = 0;
for (int j = 0; j < keys_.length; j++) {
if (summaries_[j] != null) {
keys[i++] = keys_[j];
}
}
theta_ = QuickSelect.select(keys, 0, count_ - 1, nomEntries_);
}
@SuppressWarnings({"unchecked"})
private void rebuild(final int newSize) {
final long[] oldKeys = keys_;
final S[] oldSummaries = summaries_;
keys_ = new long[newSize];
summaries_ = (S[]) Array.newInstance(oldSummaries.getClass().getComponentType(), newSize);
lgCurrentCapacity_ = Integer.numberOfTrailingZeros(newSize);
count_ = 0;
for (int i = 0; i < oldKeys.length; i++) {
if ((oldSummaries[i] != null) && (oldKeys[i] < theta_)) {
insert(oldKeys[i], oldSummaries[i]);
}
}
setRebuildThreshold();
}
private void setRebuildThreshold() {
if (keys_.length > nomEntries_) {
rebuildThreshold_ = (int) (keys_.length * REBUILD_THRESHOLD);
} else {
rebuildThreshold_ = (int) (keys_.length * RESIZE_THRESHOLD);
}
}
@SuppressWarnings("unchecked")
protected void insertSummary(final int index, final S summary) {
if (summaries_ == null) {
summaries_ = (S[]) Array.newInstance(summary.getClass(), keys_.length);
}
summaries_[index] = summary;
}
}
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