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serkan-ozal: Initial impl (#553)

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* Initial impl

* Fix bad file descriptor error in the `calculate_average_serkan-ozal.sh`

* Disable Epsilon GC and rely on default GC. Because apparently, JIT and Epsilon GC don't play well together in the eval machine for short lived Vector API's `ByteVector` objects

* Take care of byte order before processing key length with bit shift operators

* Fix key equality check for long keys
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Serkan ÖZAL 2024-01-28 11:53:09 +03:00 committed by GitHub
parent 9dde50872f
commit 3e208be741
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30
calculate_average_serkan-ozal.sh Executable file
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#!/bin/bash
#
# Copyright 2023 The original authors
#
# 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.
#
JAVA_OPTS="--enable-preview --enable-native-access=ALL-UNNAMED --add-modules=jdk.incubator.vector"
JAVA_OPTS="$JAVA_OPTS -XX:-TieredCompilation -XX:MaxInlineSize=10000 -XX:InlineSmallCode=10000 -XX:FreqInlineSize=10000"
JAVA_OPTS="$JAVA_OPTS -Djdk.incubator.vector.VECTOR_ACCESS_OOB_CHECK=0"
#JAVA_OPTS="$JAVA_OPTS -XX:+UnlockExperimentalVMOptions -XX:+UseEpsilonGC -Xms256m -Xmx256m -XX:+AlwaysPreTouch"
if [[ ! "$(uname -s)" = "Darwin" ]]; then
JAVA_OPTS="$JAVA_OPTS -XX:+UseTransparentHugePages"
fi
#echo "Process started at $(date +%s%N | cut -b1-13)"
eval "exec 3< <({ CLOSE_STDOUT_ON_RESULT=true USE_SHARED_ARENA=true java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_serkan_ozal; })"
read <&3 result
echo -e "$result"
#echo "Process finished at $(date +%s%N | cut -b1-13)"

674
src/main/java/dev/morling/onebrc/CalculateAverage_serkan_ozal.java Normal file
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/*
* Copyright 2023 The original authors
*
* 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 dev.morling.onebrc;
import jdk.incubator.vector.ByteVector;
import jdk.incubator.vector.VectorOperators;
import jdk.incubator.vector.VectorSpecies;
import sun.misc.Unsafe;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.lang.foreign.Arena;
import java.lang.foreign.MemorySegment;
import java.lang.reflect.Field;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.channels.FileChannel;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* @author serkan-ozal
*/
public class CalculateAverage_serkan_ozal {
private static final String FILE = "./measurements.txt";
private static final VectorSpecies<Byte> BYTE_SPECIES = ByteVector.SPECIES_PREFERRED.length() >= 16
// Since majority (99%) of the city names <= 16 bytes, according to my experiments,
// 128 bit (16 byte) vectors perform better than 256 bit (32 byte) or 512 bit (64 byte) vectors
// even though supported by platform.
? ByteVector.SPECIES_128
: ByteVector.SPECIES_64;
private static final int BYTE_SPECIES_SIZE = BYTE_SPECIES.vectorByteSize();
private static final ByteOrder NATIVE_BYTE_ORDER = ByteOrder.nativeOrder();
private static final char NEW_LINE_SEPARATOR = '\n';
private static final char KEY_VALUE_SEPARATOR = ';';
private static final int MAX_LINE_LENGTH = 128;
// Get configurations
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
private static final boolean VERBOSE = getBooleanConfig("VERBOSE", false);
private static final int THREAD_COUNT = getIntegerConfig("THREAD_COUNT", Runtime.getRuntime().availableProcessors());
private static final boolean USE_VTHREADS = getBooleanConfig("USE_VTHREADS", false);
private static final int VTHREAD_COUNT = getIntegerConfig("VTHREAD_COUNT", 1024);
private static final int REGION_COUNT = getIntegerConfig("REGION_COUNT", -1);
private static final boolean USE_SHARED_ARENA = getBooleanConfig("USE_SHARED_ARENA", false);
private static final int MAP_CAPACITY = getIntegerConfig("MAP_CAPACITY", 1 << 17);
private static final boolean CLOSE_STDOUT_ON_RESULT = getBooleanConfig("CLOSE_STDOUT_ON_RESULT", false);
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// My dear old friend Unsafe
private static final Unsafe U;
static {
try {
Field f = Unsafe.class.getDeclaredField("theUnsafe");
f.setAccessible(true);
U = (Unsafe) f.get(null);
}
catch (Exception e) {
throw new IllegalStateException(e);
}
}
public static void main(String[] args) throws Exception {
long start = System.currentTimeMillis();
if (VERBOSE) {
System.out.println("Processing started at " + start);
System.out.println("Vector byte size: " + BYTE_SPECIES.vectorByteSize());
System.out.println("Use shared memory arena: " + USE_SHARED_ARENA);
if (USE_VTHREADS) {
System.out.println("Virtual thread count: " + VTHREAD_COUNT);
}
else {
System.out.println("Thread count: " + THREAD_COUNT);
}
System.out.println("Map capacity: " + MAP_CAPACITY);
}
int concurrency = USE_VTHREADS ? VTHREAD_COUNT : THREAD_COUNT;
int regionCount = REGION_COUNT > 0 ? REGION_COUNT : concurrency;
ByteBuffer lineBuffer = getByteBuffer(MAX_LINE_LENGTH);
Result result = new Result();
RandomAccessFile file = new RandomAccessFile(FILE, "r");
FileChannel fc = file.getChannel();
Arena arena = USE_SHARED_ARENA ? Arena.ofShared() : null;
try {
long fileSize = fc.size();
long regionSize = fileSize / regionCount;
long startPos = 0;
ExecutorService executor = USE_VTHREADS
? Executors.newVirtualThreadPerTaskExecutor()
: Executors.newFixedThreadPool(concurrency, new RegionProcessorThreadFactory());
// Split whole file into regions and start region processors to handle those regions
List<Future<Response>> futures = new ArrayList<>(regionCount);
for (int i = 0; i < regionCount; i++) {
long endPos = Math.min(fileSize, startPos + regionSize);
// Lines might split into different regions.
// If so, move back to the line starting at the end of previous region
long closestLineEndPos = (i < regionCount - 1)
? findClosestLineEnd(fc, endPos, lineBuffer)
: fileSize;
Request request = new Request(fc, arena, startPos, closestLineEndPos, result);
RegionProcessor regionProcessor = createRegionProcessor(request);
Future<Response> future = executor.submit(regionProcessor);
futures.add(future);
startPos = closestLineEndPos;
}
// Wait processors to complete
for (Future<Response> future : futures) {
future.get();
}
long finish = System.currentTimeMillis();
if (VERBOSE) {
System.out.println("Processing completed at " + finish);
System.out.println("Processing completed in " + (finish - start) + " milliseconds");
}
// Print result to stdout
result.print();
if (CLOSE_STDOUT_ON_RESULT) {
// After printing result, close stdout.
// So parent process can complete without waiting this process completed.
// Saves a few hundred milliseconds caused by unmap.
System.out.close();
}
}
finally {
// Close memory arena if it is managed globally here (shared arena)
if (arena != null) {
arena.close();
}
fc.close();
if (VERBOSE) {
long finish = System.currentTimeMillis();
System.out.println("All completed at " + finish);
System.out.println("All Completed in " + ((finish - start)) + " milliseconds");
}
}
}
private static boolean getBooleanConfig(String envVarName, boolean defaultValue) {
String envVarValue = System.getenv(envVarName);
if (envVarValue == null) {
return defaultValue;
}
else {
return Boolean.parseBoolean(envVarValue);
}
}
private static int getIntegerConfig(String envVarName, int defaultValue) {
String envVarValue = System.getenv(envVarName);
if (envVarValue == null) {
return defaultValue;
}
else {
return Integer.parseInt(envVarValue);
}
}
private static ByteBuffer getByteBuffer(int size) {
ByteBuffer bb = ByteBuffer.allocateDirect(size);
bb.order(NATIVE_BYTE_ORDER);
return bb;
}
private static long findClosestLineEnd(FileChannel fc, long endPos, ByteBuffer lineBuffer) throws IOException {
long lineCheckStartPos = Math.max(0, endPos - MAX_LINE_LENGTH);
lineBuffer.rewind();
fc.read(lineBuffer, lineCheckStartPos);
int i = MAX_LINE_LENGTH;
while (lineBuffer.get(i - 1) != NEW_LINE_SEPARATOR) {
i--;
}
return lineCheckStartPos + i;
}
private static RegionProcessor createRegionProcessor(Request request) {
return new RegionProcessor(request);
}
private static class RegionProcessorThreadFactory implements ThreadFactory {
@Override
public Thread newThread(Runnable r) {
Thread t = new Thread(r);
t.setDaemon(true);
t.setPriority(Thread.MAX_PRIORITY);
return t;
}
}
/**
* Region processor
*/
private static class RegionProcessor implements Callable<Response> {
private final FileChannel fc;
private final Arena arena;
private final long start;
private final long end;
private final long size;
private final OpenMap map;
private final Result result;
private RegionProcessor(Request request) {
this.fc = request.fileChannel;
this.arena = request.arena;
this.start = request.start;
this.end = request.end;
this.size = end - start;
this.map = new OpenMap();
this.result = request.result;
}
@Override
public Response call() throws Exception {
if (VERBOSE) {
System.out.println("[Processor-" + Thread.currentThread().getName() + "] Processing started at " + System.currentTimeMillis());
}
try {
processRegion();
return new Response(map);
}
finally {
if (VERBOSE) {
System.out.println("[Processor-" + Thread.currentThread().getName() + "] Processing finished at " + System.currentTimeMillis());
}
}
}
private void processRegion() throws Exception {
boolean arenaGiven = arena != null;
// If no shared global memory arena is used, create and use its own local memory arena
Arena a = arenaGiven ? arena : Arena.ofConfined();
try {
MemorySegment region = fc.map(FileChannel.MapMode.READ_ONLY, start, size, a);
doProcessRegion(region);
if (VERBOSE) {
System.out.println("[Processor-" + Thread.currentThread().getName() + "] Region processed at " + System.currentTimeMillis());
}
// Some threads/processors might finish slightly before others.
// So, instead of releasing their cores idle, merge their own results here.
// If there is no another processor merging its results now, merge now.
// Otherwise (there is already another thread/processor got the lock of merging),
// Close current processor's own local memory arena (if no shared global memory arena is used) now
// and merge its own results after then.
boolean merged = result.tryMergeInto(map);
if (VERBOSE && merged) {
System.out.println("[Processor-" + Thread.currentThread().getName() + "] Result merged at " + System.currentTimeMillis());
}
if (!merged) {
if (!arenaGiven) {
a.close();
a = null;
if (VERBOSE) {
System.out.println("[Processor-" + Thread.currentThread().getName() + "] Arena closed at " + System.currentTimeMillis());
}
}
result.mergeInto(map);
if (VERBOSE) {
System.out.println("[Processor-" + Thread.currentThread().getName() + "] Result merged at " + System.currentTimeMillis());
}
}
}
finally {
// If local memory arena is managed here and not closed yet, close it here
if (!arenaGiven && a != null) {
a.close();
if (VERBOSE) {
System.out.println("[Processor-" + Thread.currentThread().getName() + "] Arena closed at " + System.currentTimeMillis());
}
}
}
}
private void doProcessRegion(MemorySegment region) {
final long regionAddress = region.address();
final long regionSize = region.byteSize();
final int vectorSize = BYTE_SPECIES.vectorByteSize();
final long regionMainLimit = regionSize - MAX_LINE_LENGTH;
int regionPtr;
// Read and process region - main
for (regionPtr = 0; regionPtr < regionMainLimit;) {
regionPtr = doProcessLine(region, regionAddress, vectorSize, regionPtr);
}
// Read and process region - tail
for (int i = regionPtr, j = regionPtr; i < regionSize;) {
byte b = U.getByte(regionAddress + i);
if (b == KEY_VALUE_SEPARATOR) {
long baseOffset = map.putKey(null, regionAddress, j, i - j);
i = extractValue(regionAddress, i + 1, map, baseOffset);
j = i;
}
else {
i++;
}
}
}
private int doProcessLine(MemorySegment region, long regionAddress, int vectorSize, int i) {
// Find key/value separator
////////////////////////////////////////////////////////////////////////////////////////////////////////
int keyStartIdx = i;
// Vectorized search for key/value separator
ByteVector keyVector = ByteVector.fromMemorySegment(BYTE_SPECIES, region, i, NATIVE_BYTE_ORDER);
int keyValueSepOffset = keyVector.compare(VectorOperators.EQ, KEY_VALUE_SEPARATOR).firstTrue();
// Check whether key/value separator is found in the first vector (city name is <= vector size)
if (keyValueSepOffset == vectorSize) {
i += vectorSize;
keyValueSepOffset = 0;
for (; U.getByte(regionAddress + i) != KEY_VALUE_SEPARATOR; i++)
;
// I have tried vectorized search for key/value separator in the remaining part,
// but since majority (99%) of the city names <= 16 bytes
// and other a few longer city names (have length < 16 and <= 32) not close to 32 bytes,
// byte by byte search is better in terms of performance (according to my experiments) and simplicity.
}
i += keyValueSepOffset;
int keyLength = i - keyStartIdx;
i++;
////////////////////////////////////////////////////////////////////////////////////////////////////////
// Put key and get map offset to put value
long baseOffset = map.putKey(keyVector, regionAddress, keyStartIdx, keyLength);
// Extract value, put it into map and return next position in the region to continue processing from there
return extractValue(regionAddress, i, map, baseOffset);
}
}
// Credits: merykitty
private static int extractValue(long regionAddress, int idx, OpenMap map, long baseOffset) {
long word = U.getLong(regionAddress + idx);
if (NATIVE_BYTE_ORDER == ByteOrder.BIG_ENDIAN) {
word = Long.reverseBytes(word);
}
// Parse and extract value
int decimalSepPos = Long.numberOfTrailingZeros(~word & 0x10101000);
int shift = 28 - decimalSepPos;
long signed = (~word << 59) >> 63;
long designMask = ~(signed & 0xFF);
long digits = ((word & designMask) << shift) & 0x0F000F0F00L;
long absValue = ((digits * 0x640a0001) >>> 32) & 0x3FF;
int value = (int) ((absValue ^ signed) - signed);
// Put extracted value into map
map.putValue(baseOffset, value);
// Return new position
return idx + (decimalSepPos >>> 3) + 3;
}
/**
* Region processor request
*/
private static final class Request {
private final FileChannel fileChannel;
private final Arena arena;
private final long start;
private final long end;
private final Result result;
private Request(FileChannel fileChannel, Arena arena, long start, long end, Result result) {
this.fileChannel = fileChannel;
this.arena = arena;
this.start = start;
this.end = end;
this.result = result;
}
}
/**
* Region processor response
*/
private static final class Response {
private final OpenMap map;
private Response(OpenMap map) {
this.map = map;
}
}
/**
* Result of each key (city)
*/
private static final class KeyResult {
private int count;
private int minValue;
private int maxValue;
private long sum;
private KeyResult(int count, int minValue, int maxValue, long sum) {
this.count = count;
this.minValue = minValue;
this.maxValue = maxValue;
this.sum = sum;
}
private void merge(KeyResult result) {
count += result.count;
minValue = Math.min(minValue, result.minValue);
maxValue = Math.max(maxValue, result.maxValue);
sum += result.sum;
}
@Override
public String toString() {
return (minValue / 10.0) + "/" + round(sum / (double) (count * 10)) + "/" + (maxValue / 10.0);
}
private double round(double value) {
return Math.round(value * 10.0) / 10.0;
}
}
/**
* Global result
*/
private static final class Result {
private final Lock lock = new ReentrantLock();
private final Map<String, KeyResult> resultMap;
private Result() {
this.resultMap = new TreeMap<>();
}
private boolean tryMergeInto(OpenMap map) {
// Use lock (not "synchronized" block) to be virtual threads friendly
if (!lock.tryLock()) {
return false;
}
try {
map.merge(this.resultMap);
return true;
}
finally {
lock.unlock();
}
}
private void mergeInto(OpenMap map) {
// Use lock (not "synchronized" block) to be virtual threads friendly
lock.lock();
try {
map.merge(this.resultMap);
}
finally {
lock.unlock();
}
}
private void print() {
System.out.println(resultMap);
}
}
private static final class OpenMap {
// Layout
// ================================
// 0 : 4 bytes - count
// 4 : 2 bytes - min value
// 6 : 2 bytes - max value
// 8 : 8 bytes - value sum
// 16 : 4 bytes - key size
// 20 : 4 bytes - padding
// 24 : 100 bytes - key
// 124 : 4 bytes - padding
// ================================
// 128 bytes - total
private static final int ENTRY_SIZE = 128;
private static final int COUNT_OFFSET = 0;
private static final int MIN_VALUE_OFFSET = 4;
private static final int MAX_VALUE_OFFSET = 6;
private static final int VALUE_SUM_OFFSET = 8;
private static final int KEY_SIZE_OFFSET = 16;
private static final int KEY_OFFSET = 24;
private static final int ENTRY_HASH_MASK = MAP_CAPACITY - 1;
private static final int MAP_SIZE = ENTRY_SIZE * MAP_CAPACITY;
private static final int ENTRY_MASK = MAP_SIZE - 1;
private final byte[] data;
private OpenMap() {
this.data = new byte[MAP_SIZE];
}
// Credits: merykitty
private static int calculateKeyHash(long address, int keyLength) {
int seed = 0x9E3779B9;
int rotate = 5;
int x, y;
if (keyLength >= Integer.BYTES) {
x = U.getInt(address);
y = U.getInt(address + keyLength - Integer.BYTES);
}
else {
x = U.getByte(address);
y = U.getByte(address + keyLength - Byte.BYTES);
}
return (Integer.rotateLeft(x * seed, rotate) ^ y) * seed;
}
private long putKey(ByteVector keyVector, long regionAddress, long keyStartIdx, int keyLength) {
long keyStartAddress = regionAddress + keyStartIdx;
// Calculate hash of key
int keyHash = calculateKeyHash(keyStartAddress, keyLength);
// and get the position of the entry in the linear map based on calculated hash
int idx = keyHash & ENTRY_HASH_MASK;
// Start searching from the calculated position
// and continue until find an available slot in case of hash collision
// TODO Prevent infinite loop if all the slots are in use for other keys
for (long baseOffset = Unsafe.ARRAY_BYTE_BASE_OFFSET + (idx * ENTRY_SIZE);; baseOffset = (baseOffset + ENTRY_SIZE) & ENTRY_MASK) {
int keyStartOffset = (int) baseOffset + KEY_OFFSET;
int keySize = U.getInt(data, baseOffset + KEY_SIZE_OFFSET);
// Check whether current index is empty (no another key is inserted yet)
if (keySize == 0) {
// Initialize entry slot for new key
U.putShort(data, baseOffset + MIN_VALUE_OFFSET, Short.MAX_VALUE);
U.putShort(data, baseOffset + MAX_VALUE_OFFSET, Short.MIN_VALUE);
U.putInt(data, baseOffset + KEY_SIZE_OFFSET, keyLength);
U.copyMemory(null, keyStartAddress, data, keyStartOffset, keyLength);
return baseOffset;
}
// Check for hash collision (hashes are same, but keys are different).
// If there is no collision (both hashes and keys are equals), return current slot's offset.
// Otherwise, continue iterating until find an available slot.
if (keySize == keyLength && keysEqual(keyVector, keyStartAddress, keyLength, keyStartOffset)) {
return baseOffset;
}
}
}
private boolean keysEqual(ByteVector keyVector, long keyStartAddress, int keyLength, int keyStartOffset) {
int keyCheckIdx = 0;
if (keyVector != null) {
// Use vectorized search for the comparison of keys.
// Since majority of the city names >= 8 bytes and <= 16 bytes,
// this way is more efficient (according to my experiments) than any other comparisons (byte by byte or 2 longs).
int keyCheckLength = Math.min(BYTE_SPECIES_SIZE, keyLength);
ByteVector entryKeyVector = ByteVector.fromArray(BYTE_SPECIES, data, keyStartOffset - Unsafe.ARRAY_BYTE_BASE_OFFSET);
long eqMask = keyVector.compare(VectorOperators.EQ, entryKeyVector).toLong();
int eqCount = Long.numberOfTrailingZeros(~eqMask);
if (eqCount < keyCheckLength) {
return false;
}
if (keyCheckLength == keyLength) {
return true;
}
keyCheckIdx = BYTE_SPECIES_SIZE;
}
// Compare remaining parts of the keys
int normalizedKeyLength = keyLength;
if (NATIVE_BYTE_ORDER == ByteOrder.BIG_ENDIAN) {
normalizedKeyLength = Integer.reverseBytes(normalizedKeyLength);
}
int alignedKeyLength = normalizedKeyLength & 0xFFFFFFF8;
int i;
for (i = keyCheckIdx; i < alignedKeyLength; i += Long.BYTES) {
if (U.getLong(keyStartAddress + i) != U.getLong(data, keyStartOffset + i)) {
return false;
}
}
long wordA = U.getLong(keyStartAddress + i);
long wordB = U.getLong(data, keyStartOffset + i);
if (NATIVE_BYTE_ORDER == ByteOrder.BIG_ENDIAN) {
wordA = Long.reverseBytes(wordA);
wordB = Long.reverseBytes(wordB);
}
int halfShift = (Long.BYTES - (normalizedKeyLength & 0x00000007)) << 2;
long mask = (0xFFFFFFFFFFFFFFFFL >>> halfShift) >> halfShift;
wordA = wordA & mask;
// No need to mask "wordB" (word from key in the map), because it is already padded with 0s
return wordA == wordB;
}
private void putValue(long baseOffset, int value) {
U.putInt(data, baseOffset + COUNT_OFFSET,
U.getInt(data, baseOffset + COUNT_OFFSET) + 1);
U.putShort(data, baseOffset + MIN_VALUE_OFFSET,
(short) Math.min(value, U.getShort(data, baseOffset + MIN_VALUE_OFFSET)));
U.putShort(data, baseOffset + MAX_VALUE_OFFSET,
(short) Math.max(value, U.getShort(data, baseOffset + MAX_VALUE_OFFSET)));
U.putLong(data, baseOffset + VALUE_SUM_OFFSET,
value + U.getLong(data, baseOffset + VALUE_SUM_OFFSET));
}
private void merge(Map<String, KeyResult> resultMap) {
// Merge this local map into global result map
for (int i = 0; i < MAP_SIZE; i += ENTRY_SIZE) {
int baseOffset = Unsafe.ARRAY_BYTE_BASE_OFFSET + i;
int keyLength = U.getInt(data, baseOffset + KEY_SIZE_OFFSET);
if (keyLength == 0) {
// No entry is available for this index, so continue iterating
continue;
}
String key = new String(data, i + KEY_OFFSET, keyLength, StandardCharsets.UTF_8);
int count = U.getInt(data, baseOffset + COUNT_OFFSET);
short minValue = U.getShort(data, baseOffset + MIN_VALUE_OFFSET);
short maxValue = U.getShort(data, baseOffset + MAX_VALUE_OFFSET);
long sum = U.getLong(data, baseOffset + VALUE_SUM_OFFSET);
KeyResult result = new KeyResult(count, minValue, maxValue, sum);
KeyResult existingResult = resultMap.get(key);
if (existingResult == null) {
resultMap.put(key, result);
}
else {
existingResult.merge(result);
}
}
}
}
}