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1brc/src/main/java/dev/morling/onebrc/CalculateAverage_jerrinot.java
Jaromir Hamala dbdd89a847
jerrinot's initial submission (#424) 
* initial version

let's exploit that superscalar beauty!

* give credits where credits is due

also: added ideas I don't want to forget
2024-01-15 18:55:22 +01:00

483 lines
21 KiB
Java
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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 sun.misc.Unsafe;
import java.io.File;
import java.io.RandomAccessFile;
import java.lang.foreign.Arena;
import java.lang.reflect.Field;
import java.nio.channels.FileChannel.MapMode;
import java.util.Map;
import java.util.TreeMap;
public class CalculateAverage_jerrinot {
private static final Unsafe UNSAFE = unsafe();
private static final String MEASUREMENTS_TXT = "measurements.txt";
// todo: with hyper-threading enable we would be better of with availableProcessors / 2;
// todo: validate the testing env. params.
private static final int THREAD_COUNT = Runtime.getRuntime().availableProcessors();
private static final long SEPARATOR_PATTERN = 0x3B3B3B3B3B3B3B3BL;
private static Unsafe unsafe() {
try {
Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
theUnsafe.setAccessible(true);
return (Unsafe) theUnsafe.get(Unsafe.class);
}
catch (NoSuchFieldException | IllegalAccessException e) {
throw new RuntimeException(e);
}
}
public static void main(String[] args) throws Exception {
calculate();
}
static void calculate() throws Exception {
final File file = new File(MEASUREMENTS_TXT);
final long length = file.length();
// final int chunkCount = Runtime.getRuntime().availableProcessors();
int chunkPerThread = 4;
final int chunkCount = THREAD_COUNT * chunkPerThread;
final var chunkStartOffsets = new long[chunkCount + 1];
try (var raf = new RandomAccessFile(file, "r")) {
// credit - chunking code: mtopolnik
final var inputBase = raf.getChannel().map(MapMode.READ_ONLY, 0, length, Arena.global()).address();
for (int i = 1; i < chunkStartOffsets.length - 1; i++) {
var start = length * i / (chunkStartOffsets.length - 1);
raf.seek(start);
while (raf.read() != (byte) '\n') {
}
start = raf.getFilePointer();
chunkStartOffsets[i] = start + inputBase;
}
chunkStartOffsets[0] = inputBase;
chunkStartOffsets[chunkCount] = inputBase + length;
Processor[] processors = new Processor[THREAD_COUNT];
Thread[] threads = new Thread[THREAD_COUNT];
for (int i = 0; i < THREAD_COUNT; i++) {
long startA = chunkStartOffsets[i * chunkPerThread];
long endA = chunkStartOffsets[i * chunkPerThread + 1];
long startB = chunkStartOffsets[i * chunkPerThread + 1];
long endB = chunkStartOffsets[i * chunkPerThread + 2];
long startC = chunkStartOffsets[i * chunkPerThread + 2];
long endC = chunkStartOffsets[i * chunkPerThread + 3];
long startD = chunkStartOffsets[i * chunkPerThread + 3];
long endD = chunkStartOffsets[i * chunkPerThread + 4];
Processor processor = new Processor(startA, endA, startB, endB, startC, endC, startD, endD);
processors[i] = processor;
Thread thread = new Thread(processor);
threads[i] = thread;
thread.start();
}
var accumulator = new TreeMap<String, Processor.StationStats>();
for (int i = 0; i < THREAD_COUNT; i++) {
Thread t = threads[i];
t.join();
processors[i].accumulateStatus(accumulator);
}
var sb = new StringBuilder();
boolean first = true;
for (Map.Entry<String, Processor.StationStats> statsEntry : accumulator.entrySet()) {
if (first) {
sb.append("{");
first = false;
}
else {
sb.append(", ");
}
var value = statsEntry.getValue();
var name = statsEntry.getKey();
int min = value.min;
int max = value.max;
int count = value.count;
long sum2 = value.sum;
sb.append(String.format("%s=%.1f/%.1f/%.1f", name, min / 10.0, Math.round((double) sum2 / count) / 10.0, max / 10.0));
}
System.out.print(sb);
System.out.println('}');
}
}
public static int ceilPow2(int i) {
i--;
i |= i >> 1;
i |= i >> 2;
i |= i >> 4;
i |= i >> 8;
i |= i >> 16;
return i + 1;
}
private static class Processor implements Runnable {
private static final int MAP_SLOT_COUNT = ceilPow2(10000);
private static final int STATION_MAX_NAME_BYTES = 104;
private static final long COUNT_OFFSET = 0;
private static final long MIN_OFFSET = 4;
private static final long MAX_OFFSET = 8;
private static final long SUM_OFFSET = 12;
private static final long LEN_OFFSET = 20;
private static final long NAME_OFFSET = 24;
private static final int MAP_ENTRY_SIZE_BYTES = +Integer.BYTES // count // 0
+ Integer.BYTES // min // +4
+ Integer.BYTES // max // +8
+ Long.BYTES // sum // +12
+ Integer.BYTES // station name len // +20
+ STATION_MAX_NAME_BYTES; // +24
private static final int MAP_SIZE_BYTES = MAP_SLOT_COUNT * MAP_ENTRY_SIZE_BYTES;
private static final long MAP_MASK = MAP_SLOT_COUNT - 1;
// todo: some fields could probably be converted to locals
private final long map;
private long cursorA;
private long endA;
private long cursorB;
private long endB;
private long cursorC;
private long endC;
private long cursorD;
private long endD;
private long maskA;
private long maskB;
private long maskC;
private long maskD;
// credit: merykitty
private long parseAndStoreTemperature(long startCursor, long baseEntryPtr) {
long word = UNSAFE.getLong(startCursor);
final long negateda = ~word;
final int dotPos = Long.numberOfTrailingZeros(negateda & 0x10101000);
final long signed = (negateda << 59) >> 63;
final long removeSignMask = ~(signed & 0xFF);
final long digits = ((word & removeSignMask) << (28 - dotPos)) & 0x0F000F0F00L;
final long absValue = ((digits * 0x640a0001) >>> 32) & 0x3FF;
final int temperature = (int) ((absValue ^ signed) - signed);
long countPtr = baseEntryPtr + COUNT_OFFSET;
long minPtr = baseEntryPtr + MIN_OFFSET;
long maxPtr = baseEntryPtr + MAX_OFFSET;
long sumPtr = baseEntryPtr + SUM_OFFSET;
int min = UNSAFE.getInt(minPtr);
int max = UNSAFE.getInt(maxPtr);
long sum = UNSAFE.getLong(sumPtr);
// try if min/max intrinsics are paying off
// maybe braching is better? the branch is becoming more predictable with
// each new sample.
max = Math.max(max, temperature);
min = Math.min(min, temperature);
sum += temperature;
UNSAFE.putInt(countPtr, UNSAFE.getInt(countPtr) + 1);
UNSAFE.putInt(minPtr, min);
UNSAFE.putInt(maxPtr, max);
UNSAFE.putLong(sumPtr, sum);
return startCursor + (dotPos / 8) + 3;
}
private static long getDelimiterMask(final long word) {
// credit royvanrijn
final long match = word ^ SEPARATOR_PATTERN;
return (match - 0x0101010101010101L) & (~match & 0x8080808080808080L);
}
// todo: immutability cost us in allocations, but that's probably peanuts in the grand scheme of things. still worth checking
// maybe JVM trusting Final in Records offsets it ..a test is needed
record StationStats(int min, int max, int count, long sum) {
}
void accumulateStatus(TreeMap<String, StationStats> accumulator) {
for (long baseAddress = map; baseAddress < map + MAP_SIZE_BYTES; baseAddress += MAP_ENTRY_SIZE_BYTES) {
long len = UNSAFE.getInt(baseAddress + LEN_OFFSET);
if (len == 0) {
continue;
}
byte[] nameArr = new byte[(int) len];
long baseNameAddr = baseAddress + NAME_OFFSET;
for (int i = 0; i < len; i++) {
nameArr[i] = UNSAFE.getByte(baseNameAddr + i);
}
String name = new String(nameArr);
int min = UNSAFE.getInt(baseAddress + MIN_OFFSET);
int max = UNSAFE.getInt(baseAddress + MAX_OFFSET);
int count = UNSAFE.getInt(baseAddress + COUNT_OFFSET);
long sum = UNSAFE.getLong(baseAddress + SUM_OFFSET);
// todo: lambdas bootstrap probably cost us
accumulator.compute(name, (_, v) -> {
if (v == null) {
return new StationStats(min, max, count, sum);
}
return new StationStats(Math.min(v.min, min), Math.max(v.max, max), v.count + count, v.sum + sum);
});
}
}
Processor(long startA, long endA, long startB, long endB, long startC, long endC, long startD, long endD) {
this.cursorA = startA;
this.cursorB = startB;
this.cursorC = startC;
this.cursorD = startD;
this.endA = endA;
this.endB = endB;
this.endC = endC;
this.endD = endD;
this.map = UNSAFE.allocateMemory(MAP_SIZE_BYTES);
int i;
for (i = 0; i < MAP_SIZE_BYTES; i += 8) {
UNSAFE.putLong(map + i, 0);
}
for (i = i - 8; i < MAP_SIZE_BYTES; i++) {
UNSAFE.putByte(map + i, (byte) 0);
}
}
private void doTail() {
// todo: we would be probably better of without all that code dup. ("compilers hates him!")
// System.out.println("done ILP");
while (cursorA < endA) {
long startA = cursorA;
long delimiterWordA = UNSAFE.getLong(cursorA);
long hashA = 0;
maskA = getDelimiterMask(delimiterWordA);
while (maskA == 0) {
hashA ^= delimiterWordA;
cursorA += 8;
delimiterWordA = UNSAFE.getLong(cursorA);
maskA = getDelimiterMask(delimiterWordA);
}
final int delimiterByteA = Long.numberOfTrailingZeros(maskA);
final long semicolonA = cursorA + (delimiterByteA >> 3);
final long maskedWordA = delimiterWordA & ((maskA >>> 7) - 1);
hashA ^= maskedWordA;
int intHashA = (int) (hashA ^ (hashA >> 32));
intHashA = intHashA ^ (intHashA >> 17);
long baseEntryPtrA = getOrCreateEntryBaseOffset(semicolonA, startA, intHashA, maskedWordA);
cursorA = parseAndStoreTemperature(semicolonA + 1, baseEntryPtrA);
}
// System.out.println("done A");
while (cursorB < endB) {
long startB = cursorB;
long delimiterWordB = UNSAFE.getLong(cursorB);
long hashB = 0;
maskB = getDelimiterMask(delimiterWordB);
while (maskB == 0) {
hashB ^= delimiterWordB;
cursorB += 8;
delimiterWordB = UNSAFE.getLong(cursorB);
maskB = getDelimiterMask(delimiterWordB);
}
final int delimiterByteB = Long.numberOfTrailingZeros(maskB);
final long semicolonB = cursorB + (delimiterByteB >> 3);
final long maskedWordB = delimiterWordB & ((maskB >>> 7) - 1);
hashB ^= maskedWordB;
int intHashB = (int) (hashB ^ (hashB >> 32));
intHashB = intHashB ^ (intHashB >> 17);
long baseEntryPtrB = getOrCreateEntryBaseOffset(semicolonB, startB, intHashB, maskedWordB);
cursorB = parseAndStoreTemperature(semicolonB + 1, baseEntryPtrB);
}
// System.out.println("done B");
while (cursorC < endC) {
long startC = cursorC;
long delimiterWordC = UNSAFE.getLong(cursorC);
long hashC = 0;
maskC = getDelimiterMask(delimiterWordC);
while (maskC == 0) {
hashC ^= delimiterWordC;
cursorC += 8;
delimiterWordC = UNSAFE.getLong(cursorC);
maskC = getDelimiterMask(delimiterWordC);
}
final int delimiterByteC = Long.numberOfTrailingZeros(maskC);
final long semicolonC = cursorC + (delimiterByteC >> 3);
final long maskedWordC = delimiterWordC & ((maskC >>> 7) - 1);
hashC ^= maskedWordC;
int intHashC = (int) (hashC ^ (hashC >> 32));
intHashC = intHashC ^ (intHashC >> 17);
long baseEntryPtrC = getOrCreateEntryBaseOffset(semicolonC, startC, intHashC, maskedWordC);
cursorC = parseAndStoreTemperature(semicolonC + 1, baseEntryPtrC);
}
// System.out.println("done C");
while (cursorD < endD) {
long startD = cursorD;
long delimiterWordD = UNSAFE.getLong(cursorD);
long hashD = 0;
maskD = getDelimiterMask(delimiterWordD);
while (maskD == 0) {
hashD ^= delimiterWordD;
cursorD += 8;
delimiterWordD = UNSAFE.getLong(cursorD);
maskD = getDelimiterMask(delimiterWordD);
}
final int delimiterByteD = Long.numberOfTrailingZeros(maskD);
final long semicolonD = cursorD + (delimiterByteD >> 3);
final long maskedWordD = delimiterWordD & ((maskD >>> 7) - 1);
hashD ^= maskedWordD;
int intHashD = (int) (hashD ^ (hashD >> 32));
intHashD = intHashD ^ (intHashD >> 17);
long baseEntryPtrD = getOrCreateEntryBaseOffset(semicolonD, startD, intHashD, maskedWordD);
cursorD = parseAndStoreTemperature(semicolonD + 1, baseEntryPtrD);
}
// System.out.println("done D");
}
@Override
public void run() {
while (cursorA < endA && cursorB < endB && cursorC < endC && cursorD < endD) {
// todo: experiment with different inter-leaving
long startA = cursorA;
long startB = cursorB;
long startC = cursorC;
long startD = cursorD;
long delimiterWordA = UNSAFE.getLong(cursorA);
long delimiterWordB = UNSAFE.getLong(cursorB);
long delimiterWordC = UNSAFE.getLong(cursorC);
long delimiterWordD = UNSAFE.getLong(cursorD);
long hashA = 0;
long hashB = 0;
long hashC = 0;
long hashD = 0;
// credits for the hashing idea: royvanrijn
maskA = getDelimiterMask(delimiterWordA);
while (maskA == 0) {
hashA ^= delimiterWordA;
cursorA += 8;
delimiterWordA = UNSAFE.getLong(cursorA);
maskA = getDelimiterMask(delimiterWordA);
}
final int delimiterByteA = Long.numberOfTrailingZeros(maskA);
final long semicolonA = cursorA + (delimiterByteA >> 3);
final long maskedWordA = delimiterWordA & ((maskA >>> 7) - 1);
hashA ^= maskedWordA;
int intHashA = (int) (hashA ^ (hashA >> 32));
intHashA = intHashA ^ (intHashA >> 17);
maskB = getDelimiterMask(delimiterWordB);
while (maskB == 0) {
hashB ^= delimiterWordB;
cursorB += 8;
delimiterWordB = UNSAFE.getLong(cursorB);
maskB = getDelimiterMask(delimiterWordB);
}
final int delimiterByteB = Long.numberOfTrailingZeros(maskB);
final long semicolonB = cursorB + (delimiterByteB >> 3);
final long maskedWordB = delimiterWordB & ((maskB >>> 7) - 1);
hashB ^= maskedWordB;
int intHashB = (int) (hashB ^ (hashB >> 32));
intHashB = intHashB ^ (intHashB >> 17);
maskC = getDelimiterMask(delimiterWordC);
while (maskC == 0) {
hashC ^= delimiterWordC;
cursorC += 8;
delimiterWordC = UNSAFE.getLong(cursorC);
maskC = getDelimiterMask(delimiterWordC);
}
final int delimiterByteC = Long.numberOfTrailingZeros(maskC);
final long semicolonC = cursorC + (delimiterByteC >> 3);
final long maskedWordC = delimiterWordC & ((maskC >>> 7) - 1);
hashC ^= maskedWordC;
int intHashC = (int) (hashC ^ (hashC >> 32));
intHashC = intHashC ^ (intHashC >> 17);
maskD = getDelimiterMask(delimiterWordD);
while (maskD == 0) {
hashD ^= delimiterWordD;
cursorD += 8;
delimiterWordD = UNSAFE.getLong(cursorD);
maskD = getDelimiterMask(delimiterWordD);
}
final int delimiterByteD = Long.numberOfTrailingZeros(maskD);
final long semicolonD = cursorD + (delimiterByteD >> 3);
final long maskedWordD = delimiterWordD & ((maskD >>> 7) - 1);
hashD ^= maskedWordD;
int intHashD = (int) (hashD ^ (hashD >> 32));
intHashD = intHashD ^ (intHashD >> 17);
long baseEntryPtrA = getOrCreateEntryBaseOffset(semicolonA, startA, intHashA, maskedWordA);
long baseEntryPtrB = getOrCreateEntryBaseOffset(semicolonB, startB, intHashB, maskedWordB);
long baseEntryPtrC = getOrCreateEntryBaseOffset(semicolonC, startC, intHashC, maskedWordC);
long baseEntryPtrD = getOrCreateEntryBaseOffset(semicolonD, startD, intHashD, maskedWordD);
cursorA = parseAndStoreTemperature(semicolonA + 1, baseEntryPtrA);
cursorB = parseAndStoreTemperature(semicolonB + 1, baseEntryPtrB);
cursorC = parseAndStoreTemperature(semicolonC + 1, baseEntryPtrC);
cursorD = parseAndStoreTemperature(semicolonD + 1, baseEntryPtrD);
}
doTail();
}
private long getOrCreateEntryBaseOffset(long semicolonA, long startA, int intHashA, long maskedWordA) {
int lenA = (int) (semicolonA - startA);
long mapIndexA = intHashA & MAP_MASK;
for (;;) {
long basePtr = mapIndexA * MAP_ENTRY_SIZE_BYTES + map;
long lenPtr = basePtr + LEN_OFFSET;
int len = UNSAFE.getInt(lenPtr);
if (len == 0) {
// todo: uncommon branch maybe?
// empty slot
UNSAFE.copyMemory(semicolonA - lenA, basePtr + NAME_OFFSET, lenA);
UNSAFE.putInt(lenPtr, lenA);
UNSAFE.putInt(basePtr + MAX_OFFSET, Integer.MIN_VALUE);
UNSAFE.putInt(basePtr + MIN_OFFSET, Integer.MAX_VALUE);
return basePtr;
}
if (len == lenA) {
boolean match = true;
long namePtr = basePtr + NAME_OFFSET;
int fullLen = (len >> 3) << 3;
long offset;
// todo: this is worth exploring further.
// @mtopolnik has an interesting algo with 2 unconditioned long loads: this is sufficient
// for majority of names. so we would be left with just a single branch which is almost never taken?
for (offset = 0; offset < fullLen; offset += 8) {
match &= (UNSAFE.getLong(startA + offset) == UNSAFE.getLong(namePtr + offset));
}
long maskedWordInMap = UNSAFE.getLong(namePtr + offset);
match &= (maskedWordInMap == maskedWordA);
if (match) {
return basePtr;
}
}
mapIndexA = ++mapIndexA & MAP_MASK;
}
}
}
}
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