114ba76d20
* refactoring * segregated heap for names also a different hashing function. turns out hashing just first word is good enough
465 lines
20 KiB
Java
465 lines
20 KiB
Java
/*
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* Copyright 2023 The original authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package dev.morling.onebrc;
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import sun.misc.Unsafe;
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import java.io.File;
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import java.io.RandomAccessFile;
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import java.lang.foreign.Arena;
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import java.lang.reflect.Field;
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import java.nio.channels.FileChannel.MapMode;
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import java.util.*;
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/**
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* I figured out it would be very hard to win the main competition of the One Billion Rows Challenge.
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* but I think this code has a good chance to win a special prize for the Ugliest Solution ever! :)
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*
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* Anyway, if you can make sense out of not exactly idiomatic Java code, and you enjoy pushing performance limits
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* then QuestDB - the fastest open-source time-series database - is hiring: https://questdb.io/careers/core-database-engineer/
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*
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*/
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public class CalculateAverage_jerrinot {
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private static final Unsafe UNSAFE = unsafe();
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private static final String MEASUREMENTS_TXT = "measurements.txt";
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// todo: with hyper-threading enable we would be better of with availableProcessors / 2;
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// todo: validate the testing env. params.
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private static final int THREAD_COUNT = Runtime.getRuntime().availableProcessors();
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// private static final int THREAD_COUNT = 1;
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private static final long SEPARATOR_PATTERN = 0x3B3B3B3B3B3B3B3BL;
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private static Unsafe unsafe() {
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try {
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Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
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theUnsafe.setAccessible(true);
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return (Unsafe) theUnsafe.get(Unsafe.class);
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}
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catch (NoSuchFieldException | IllegalAccessException e) {
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throw new RuntimeException(e);
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}
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}
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public static void main(String[] args) throws Exception {
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calculate();
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}
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static void calculate() throws Exception {
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final File file = new File(MEASUREMENTS_TXT);
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final long length = file.length();
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// final int chunkCount = Runtime.getRuntime().availableProcessors();
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int chunkPerThread = 4;
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final int chunkCount = THREAD_COUNT * chunkPerThread;
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final var chunkStartOffsets = new long[chunkCount + 1];
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try (var raf = new RandomAccessFile(file, "r")) {
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// credit - chunking code: mtopolnik
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final var inputBase = raf.getChannel().map(MapMode.READ_ONLY, 0, length, Arena.global()).address();
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for (int i = 1; i < chunkStartOffsets.length - 1; i++) {
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var start = length * i / (chunkStartOffsets.length - 1);
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raf.seek(start);
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while (raf.read() != (byte) '\n') {
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}
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start = raf.getFilePointer();
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chunkStartOffsets[i] = start + inputBase;
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}
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chunkStartOffsets[0] = inputBase;
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chunkStartOffsets[chunkCount] = inputBase + length;
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Processor[] processors = new Processor[THREAD_COUNT];
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Thread[] threads = new Thread[THREAD_COUNT];
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for (int i = 0; i < THREAD_COUNT - 1; i++) {
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long startA = chunkStartOffsets[i * chunkPerThread];
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long endA = chunkStartOffsets[i * chunkPerThread + 1];
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long startB = chunkStartOffsets[i * chunkPerThread + 1];
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long endB = chunkStartOffsets[i * chunkPerThread + 2];
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long startC = chunkStartOffsets[i * chunkPerThread + 2];
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long endC = chunkStartOffsets[i * chunkPerThread + 3];
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long startD = chunkStartOffsets[i * chunkPerThread + 3];
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long endD = chunkStartOffsets[i * chunkPerThread + 4];
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Processor processor = new Processor(startA, endA, startB, endB, startC, endC, startD, endD);
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processors[i] = processor;
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Thread thread = new Thread(processor);
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threads[i] = thread;
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thread.start();
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}
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int ownIndex = THREAD_COUNT - 1;
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long startA = chunkStartOffsets[ownIndex * chunkPerThread];
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long endA = chunkStartOffsets[ownIndex * chunkPerThread + 1];
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long startB = chunkStartOffsets[ownIndex * chunkPerThread + 1];
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long endB = chunkStartOffsets[ownIndex * chunkPerThread + 2];
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long startC = chunkStartOffsets[ownIndex * chunkPerThread + 2];
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long endC = chunkStartOffsets[ownIndex * chunkPerThread + 3];
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long startD = chunkStartOffsets[ownIndex * chunkPerThread + 3];
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long endD = chunkStartOffsets[ownIndex * chunkPerThread + 4];
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Processor processor = new Processor(startA, endA, startB, endB, startC, endC, startD, endD);
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processor.run();
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var accumulator = new TreeMap<String, Processor.StationStats>();
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processor.accumulateStatus(accumulator);
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for (int i = 0; i < THREAD_COUNT - 1; i++) {
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Thread t = threads[i];
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t.join();
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processors[i].accumulateStatus(accumulator);
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}
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var sb = new StringBuilder();
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boolean first = true;
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for (Map.Entry<String, Processor.StationStats> statsEntry : accumulator.entrySet()) {
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if (first) {
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sb.append("{");
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first = false;
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}
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else {
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sb.append(", ");
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}
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var value = statsEntry.getValue();
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var name = statsEntry.getKey();
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int min = value.min;
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int max = value.max;
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int count = value.count;
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long sum2 = value.sum;
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sb.append(String.format("%s=%.1f/%.1f/%.1f", name, min / 10.0, Math.round((double) sum2 / count) / 10.0, max / 10.0));
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}
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System.out.print(sb);
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System.out.println('}');
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}
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}
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public static int ceilPow2(int i) {
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i--;
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i |= i >> 1;
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i |= i >> 2;
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i |= i >> 4;
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i |= i >> 8;
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i |= i >> 16;
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return i + 1;
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}
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private static class Processor implements Runnable {
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private static final int MAX_UNIQUE_KEYS = 10000;
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private static final int MAP_SLOT_COUNT = ceilPow2(MAX_UNIQUE_KEYS);
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private static final int STATION_MAX_NAME_BYTES = 104;
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private static final long COUNT_OFFSET = 0;
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private static final long MIN_OFFSET = 4;
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private static final long MAX_OFFSET = 8;
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private static final long SUM_OFFSET = 12;
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private static final long LEN_OFFSET = 20;
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private static final long NAME_OFFSET = 24;
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private static final int MAP_ENTRY_SIZE_BYTES = Integer.BYTES // count // 0
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+ Integer.BYTES // min // +4
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+ Integer.BYTES // max // +8
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+ Long.BYTES // sum // +12
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+ Integer.BYTES // station name len // +20
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+ Long.BYTES; // station name ptr // 24
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private static final int MAP_SIZE_BYTES = MAP_SLOT_COUNT * MAP_ENTRY_SIZE_BYTES;
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private static final int MAP_NAMES_BYTES = MAX_UNIQUE_KEYS * STATION_MAX_NAME_BYTES;
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private static final long MAP_MASK = MAP_SLOT_COUNT - 1;
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private final long map;
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private long currentNamesPtr;
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private final long namesHi;
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private long cursorA;
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private long endA;
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private long cursorB;
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private long endB;
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private long cursorC;
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private long endC;
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private long cursorD;
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private long endD;
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// private long maxClusterLen;
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// credit: merykitty
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private long parseAndStoreTemperature(long startCursor, long baseEntryPtr, long word) {
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// long word = UNSAFE.getLong(startCursor);
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long countPtr = baseEntryPtr + COUNT_OFFSET;
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int cnt = UNSAFE.getInt(countPtr);
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UNSAFE.putInt(countPtr, cnt + 1);
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long minPtr = baseEntryPtr + MIN_OFFSET;
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long maxPtr = baseEntryPtr + MAX_OFFSET;
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long sumPtr = baseEntryPtr + SUM_OFFSET;
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int min = UNSAFE.getInt(minPtr);
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int max = UNSAFE.getInt(maxPtr);
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long sum = UNSAFE.getLong(sumPtr);
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final long negateda = ~word;
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final int dotPos = Long.numberOfTrailingZeros(negateda & 0x10101000);
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final long signed = (negateda << 59) >> 63;
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final long removeSignMask = ~(signed & 0xFF);
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final long digits = ((word & removeSignMask) << (28 - dotPos)) & 0x0F000F0F00L;
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final long absValue = ((digits * 0x640a0001) >>> 32) & 0x3FF;
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final int temperature = (int) ((absValue ^ signed) - signed);
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sum += temperature;
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UNSAFE.putLong(sumPtr, sum);
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if (temperature > max) {
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UNSAFE.putInt(maxPtr, temperature);
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}
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if (temperature < min) {
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UNSAFE.putInt(minPtr, temperature);
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}
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return startCursor + (dotPos / 8) + 3;
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}
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private static long getDelimiterMask(final long word) {
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// credit royvanrijn
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final long match = word ^ SEPARATOR_PATTERN;
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return (match - 0x0101010101010101L) & (~match & 0x8080808080808080L);
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}
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// todo: immutability cost us in allocations, but that's probably peanuts in the grand scheme of things. still worth checking
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// maybe JVM trusting Final in Records offsets it ..a test is needed
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record StationStats(int min, int max, int count, long sum) {
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}
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void accumulateStatus(TreeMap<String, StationStats> accumulator) {
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for (long baseAddress = map; baseAddress < map + MAP_SIZE_BYTES; baseAddress += MAP_ENTRY_SIZE_BYTES) {
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long len = UNSAFE.getInt(baseAddress + LEN_OFFSET);
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if (len == 0) {
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continue;
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}
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byte[] nameArr = new byte[(int) len];
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long baseNameAddr = UNSAFE.getLong(baseAddress + NAME_OFFSET);
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for (int i = 0; i < len; i++) {
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nameArr[i] = UNSAFE.getByte(baseNameAddr + i);
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}
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String name = new String(nameArr);
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int min = UNSAFE.getInt(baseAddress + MIN_OFFSET);
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int max = UNSAFE.getInt(baseAddress + MAX_OFFSET);
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int count = UNSAFE.getInt(baseAddress + COUNT_OFFSET);
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long sum = UNSAFE.getLong(baseAddress + SUM_OFFSET);
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var v = accumulator.get(name);
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if (v == null) {
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accumulator.put(name, new StationStats(min, max, count, sum));
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}
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else {
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accumulator.put(name, new StationStats(Math.min(v.min, min), Math.max(v.max, max), v.count + count, v.sum + sum));
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}
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}
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}
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Processor(long startA, long endA, long startB, long endB, long startC, long endC, long startD, long endD) {
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this.cursorA = startA;
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this.cursorB = startB;
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this.cursorC = startC;
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this.cursorD = startD;
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this.endA = endA;
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this.endB = endB;
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this.endC = endC;
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this.endD = endD;
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this.map = UNSAFE.allocateMemory(MAP_SIZE_BYTES);
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this.currentNamesPtr = UNSAFE.allocateMemory(MAP_NAMES_BYTES);
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this.namesHi = currentNamesPtr + MAP_NAMES_BYTES;
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int i;
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for (i = 0; i < MAP_SIZE_BYTES; i += 8) {
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UNSAFE.putLong(map + i, 0);
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}
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for (i = i - 8; i < MAP_SIZE_BYTES; i++) {
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UNSAFE.putByte(map + i, (byte) 0);
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}
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UNSAFE.setMemory(currentNamesPtr, MAP_NAMES_BYTES, (byte) 0);
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}
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private void doTail() {
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// todo: we would be probably better of without all that code dup. ("compilers hates him!")
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// System.out.println("done ILP");
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doOne(cursorA, endA);
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// System.out.println("done A");
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doOne(cursorB, endB);
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// System.out.println("done B");
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doOne(cursorC, endC);
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// System.out.println("done C");
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doOne(cursorD, endD);
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// System.out.println("done D");
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}
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private void doOne(long cursor, long endA) {
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while (cursor < endA) {
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long start = cursor;
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long currentWord = UNSAFE.getLong(cursor);
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long mask = getDelimiterMask(currentWord);
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long maskedFirstWord = currentWord & ((mask - 1) ^ mask) >>> 8;
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long hash = hash(maskedFirstWord);
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while (mask == 0) {
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cursor += 8;
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currentWord = UNSAFE.getLong(cursor);
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mask = getDelimiterMask(currentWord);
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}
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final int delimiterByte = Long.numberOfTrailingZeros(mask);
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final long semicolon = cursor + (delimiterByte >> 3);
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final long maskedWord = currentWord & ((mask - 1) ^ mask) >>> 8;
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long baseEntryPtr = getOrCreateEntryBaseOffset(semicolon, start, (int) hash, maskedWord);
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long temperatureWord = UNSAFE.getLong(semicolon + 1);
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cursor = parseAndStoreTemperature(semicolon + 1, baseEntryPtr, temperatureWord);
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}
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}
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private static long hash(long word1) {
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// credit: mtopolnik
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long seed = 0x51_7c_c1_b7_27_22_0a_95L;
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int rotDist = 17;
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long hash = word1;
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hash *= seed;
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hash = Long.rotateLeft(hash, rotDist);
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return hash;
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}
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@Override
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public void run() {
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while (cursorA < endA && cursorB < endB && cursorC < endC && cursorD < endD) {
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long startA = cursorA;
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long startB = cursorB;
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long startC = cursorC;
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long startD = cursorD;
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long currentWordA = UNSAFE.getLong(startA);
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long currentWordB = UNSAFE.getLong(startB);
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long currentWordC = UNSAFE.getLong(startC);
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long currentWordD = UNSAFE.getLong(startD);
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// credits for the hashing idea: mtopolnik
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long maskA = getDelimiterMask(currentWordA);
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long maskedFirstWordA = currentWordA & ((maskA - 1) ^ maskA) >>> 8;
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long hashA = hash(maskedFirstWordA);
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while (maskA == 0) {
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cursorA += 8;
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currentWordA = UNSAFE.getLong(cursorA);
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maskA = getDelimiterMask(currentWordA);
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}
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final int delimiterByteA = Long.numberOfTrailingZeros(maskA);
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final long semicolonA = cursorA + (delimiterByteA >> 3);
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long temperatureWordA = UNSAFE.getLong(semicolonA + 1);
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final long maskedWordA = currentWordA & ((maskA - 1) ^ maskA) >>> 8;
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long maskB = getDelimiterMask(currentWordB);
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long maskedFirstWordB = currentWordB & ((maskB - 1) ^ maskB) >>> 8;
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long hashB = hash(maskedFirstWordB);
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while (maskB == 0) {
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cursorB += 8;
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currentWordB = UNSAFE.getLong(cursorB);
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maskB = getDelimiterMask(currentWordB);
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}
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final int delimiterByteB = Long.numberOfTrailingZeros(maskB);
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final long semicolonB = cursorB + (delimiterByteB >> 3);
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long temperatureWordB = UNSAFE.getLong(semicolonB + 1);
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final long maskedWordB = currentWordB & ((maskB - 1) ^ maskB) >>> 8;
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long maskC = getDelimiterMask(currentWordC);
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long maskedFirstWordC = currentWordC & ((maskC - 1) ^ maskC) >>> 8;
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long hashC = hash(maskedFirstWordC);
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while (maskC == 0) {
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cursorC += 8;
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currentWordC = UNSAFE.getLong(cursorC);
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maskC = getDelimiterMask(currentWordC);
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}
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final int delimiterByteC = Long.numberOfTrailingZeros(maskC);
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final long semicolonC = cursorC + (delimiterByteC >> 3);
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long temperatureWordC = UNSAFE.getLong(semicolonC + 1);
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final long maskedWordC = currentWordC & ((maskC - 1) ^ maskC) >>> 8;
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long maskD = getDelimiterMask(currentWordD);
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long maskedFirstWordD = currentWordD & ((maskD - 1) ^ maskD) >>> 8;
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long hashD = hash(maskedFirstWordD);
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while (maskD == 0) {
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cursorD += 8;
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currentWordD = UNSAFE.getLong(cursorD);
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maskD = getDelimiterMask(currentWordD);
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}
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final int delimiterByteD = Long.numberOfTrailingZeros(maskD);
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final long semicolonD = cursorD + (delimiterByteD >> 3);
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long temperatureWordD = UNSAFE.getLong(semicolonD + 1);
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final long maskedWordD = currentWordD & ((maskD - 1) ^ maskD) >>> 8;
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long baseEntryPtrA = getOrCreateEntryBaseOffset(semicolonA, startA, (int) hashA, maskedWordA);
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long baseEntryPtrB = getOrCreateEntryBaseOffset(semicolonB, startB, (int) hashB, maskedWordB);
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long baseEntryPtrC = getOrCreateEntryBaseOffset(semicolonC, startC, (int) hashC, maskedWordC);
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long baseEntryPtrD = getOrCreateEntryBaseOffset(semicolonD, startD, (int) hashD, maskedWordD);
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cursorA = parseAndStoreTemperature(semicolonA + 1, baseEntryPtrA, temperatureWordA);
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cursorB = parseAndStoreTemperature(semicolonB + 1, baseEntryPtrB, temperatureWordB);
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cursorC = parseAndStoreTemperature(semicolonC + 1, baseEntryPtrC, temperatureWordC);
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cursorD = parseAndStoreTemperature(semicolonD + 1, baseEntryPtrD, temperatureWordD);
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}
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doTail();
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}
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private long getOrCreateEntryBaseOffset(long semicolonPtr, long startPtr, int hash, long maskedWord) {
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long lenLong = semicolonPtr - startPtr;
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int lenA = (int) lenLong;
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long mapIndexA = hash & MAP_MASK;
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for (;;) {
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long basePtr = mapIndexA * MAP_ENTRY_SIZE_BYTES + map;
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long lenPtr = basePtr + LEN_OFFSET;
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long namePtr = basePtr + NAME_OFFSET;
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int len = UNSAFE.getInt(lenPtr);
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if (len == lenA) {
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namePtr = UNSAFE.getLong(basePtr + NAME_OFFSET);
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if (nameMatch(startPtr, maskedWord, namePtr, lenLong)) {
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return basePtr;
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}
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}
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else if (len == 0) {
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// todo: uncommon branch maybe?
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// empty slot
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UNSAFE.putLong(namePtr, currentNamesPtr);
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UNSAFE.putInt(lenPtr, lenA);
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// todo: this could be a single putLong()
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UNSAFE.putInt(basePtr + MAX_OFFSET, Integer.MIN_VALUE);
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UNSAFE.putInt(basePtr + MIN_OFFSET, Integer.MAX_VALUE);
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UNSAFE.copyMemory(startPtr, currentNamesPtr, lenA);
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long consume = (lenLong & ~7L) + 8;
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currentNamesPtr += consume;
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assert currentNamesPtr <= namesHi;
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return basePtr;
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}
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mapIndexA = ++mapIndexA & MAP_MASK;
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}
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}
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private static boolean nameMatch(long startA, long maskedWordA, long namePtr, long len) {
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// long namePtr = basePtr + NAME_OFFSET;
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long fullLen = len & ~7L;
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long offset;
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// todo: this is worth exploring further.
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// @mtopolnik has an interesting algo with 2 unconditioned long loads: this is sufficient
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// for majority of names. so we would be left with just a single branch which is almost never taken?
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for (offset = 0; offset < fullLen; offset += 8) {
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if (UNSAFE.getLong(startA + offset) != UNSAFE.getLong(namePtr + offset)) {
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return false;
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}
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}
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long maskedWordInMap = UNSAFE.getLong(namePtr + fullLen);
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return (maskedWordInMap == maskedWordA);
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}
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}
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}
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