Dkarampi solution (#614)
* Simple multi-threaded version * Format code * Formatted code * More formatting
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Dimitris Karampinas
GitHub
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19
calculate_average_dkarampi.sh
Executable file
19
calculate_average_dkarampi.sh
Executable file
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#!/bin/sh
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#
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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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JAVA_OPTS="-XX:+AlwaysCompileLoopMethods"
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java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_dkarampi
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260
src/main/java/dev/morling/onebrc/CalculateAverage_dkarampi.java
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src/main/java/dev/morling/onebrc/CalculateAverage_dkarampi.java
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/*
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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 java.nio.ByteBuffer;
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import java.nio.MappedByteBuffer;
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import java.nio.channels.FileChannel;
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import java.nio.file.Path;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.Map;
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import java.util.TreeMap;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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import java.util.concurrent.Future;
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import static java.nio.channels.FileChannel.MapMode.READ_ONLY;
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public class CalculateAverage_dkarampi {
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private static final String FILE = "./measurements.txt";
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private static final int BUFFER_SIZE = (1 << 29); // 500mb
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private static final int HT_SIZE = nextPowerOfTwo(10000);
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private static final int NUM_THREADS = 8;
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private final List<Station[]> stationHashTables = new ArrayList<>();
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public static void main(String[] args) throws Exception {
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new CalculateAverage_dkarampi().runFast();
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}
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private static double round(double value) {
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return Math.round(value * 10.0) / 10.0;
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}
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private static boolean areEqual(byte[] a, int aLen, byte[] b, int bLen) {
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if (aLen != bLen) {
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return false;
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}
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for (byte i = 0; i < aLen; i++) {
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if (a[i] != b[i]) {
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return false;
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}
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}
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return true;
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}
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public static int nextPowerOfTwo(int n) {
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for (int i = 1; i < 32; i <<= 1) {
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n |= n >> i;
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}
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return n + 1;
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}
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private void runFast() throws Exception {
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createStationHashTables();
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FileChannel channel = FileChannel.open(Path.of(FILE));
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List<List<Buffer>> buffersList = new ArrayList<>();
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for (int i = 0; i < NUM_THREADS; i++) {
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buffersList.add(new ArrayList<>());
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}
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List<Buffer> buffers = createBuffers(channel);
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for (int i = 0; i < buffers.size(); i++) {
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buffersList.get(i % NUM_THREADS).add(buffers.get(i));
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}
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List<Task> tasks = new ArrayList<>();
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for (int i = 0; i < NUM_THREADS; i++) {
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tasks.add(new Task(stationHashTables.get(i), buffersList.get(i)));
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}
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ExecutorService executorService = Executors.newFixedThreadPool(NUM_THREADS);
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Future<?>[] futures = new Future<?>[NUM_THREADS];
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for (int i = 0; i < NUM_THREADS; i++) {
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futures[i] = executorService.submit(tasks.get(i));
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}
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for (Future<?> future : futures) {
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future.get();
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}
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sortAndPrint();
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executorService.shutdown();
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channel.close();
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}
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private void createStationHashTables() {
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for (int i = 0; i < NUM_THREADS; i++) {
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Station[] stationsHashTable = new Station[HT_SIZE];
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for (int j = 0; j < HT_SIZE; j++) {
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stationsHashTable[j] = new Station();
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}
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stationHashTables.add(stationsHashTable);
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}
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}
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private List<Buffer> createBuffers(FileChannel channel) throws Exception {
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List<Buffer> buffers = new ArrayList<>();
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long size = channel.size();
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int lastByte;
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for (long offset = 0; offset < size; offset += lastByte + 1) {
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long sizeToMap = Math.min(size - offset, BUFFER_SIZE);
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MappedByteBuffer buffer = channel.map(READ_ONLY, offset, sizeToMap);
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lastByte = (int) sizeToMap - 1;
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while (buffer.get(lastByte) != '\n')
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--lastByte;
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buffers.add(new Buffer(buffer, lastByte + 1));
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}
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return buffers;
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}
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private void sortAndPrint() {
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TreeMap<String, Station> sortedStations = new TreeMap<>();
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for (Station[] stationHashTable : stationHashTables) {
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for (Station station : stationHashTable) {
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if (station.freq == 0) {
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continue;
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}
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String key = new String(station.name, 0, station.nameLen);
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Station st = sortedStations.get(key);
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if (st == null) {
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sortedStations.put(key, station);
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}
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else {
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st.min = Math.min(st.min, station.min);
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st.max = Math.max(st.max, station.max);
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st.sum += station.sum;
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st.freq += station.freq;
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}
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}
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}
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StringBuilder sb = new StringBuilder();
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sb.append("{");
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for (Map.Entry<String, Station> entry : sortedStations.entrySet()) {
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String name = entry.getKey();
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Station station = entry.getValue();
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sb.append(name);
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sb.append("=");
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sb.append(round(station.min));
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sb.append("/");
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sb.append(round(round(station.sum) / station.freq));
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sb.append("/");
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sb.append(round(station.max));
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sb.append(", ");
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}
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sb.delete(sb.length() - 2, sb.length());
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sb.append("}");
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System.out.println(sb);
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}
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private record Buffer(ByteBuffer byteBuffer, int length) {
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}
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private static class Station {
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double sum;
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double min = 100;
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double max = -100;
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int freq;
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short nameLen;
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byte[] name = new byte[nextPowerOfTwo(100)];
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}
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private record Task(Station[] stations, List<Buffer> buffers) implements Runnable {
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@Override
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public void run() {
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for (Buffer buffer : buffers) {
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process(buffer);
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}
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}
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private void process(Buffer buffer) {
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short nameLen = 0;
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int hash = 5381;
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int temperature;
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byte[] name = new byte[100];
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for (int i = 0; i < buffer.length; i++) {
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byte c = buffer.byteBuffer.get(i);
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if (c == ';') {
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int sign = 1;
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c = buffer.byteBuffer.get(++i);
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if (c == '-') {
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sign = -1;
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c = buffer.byteBuffer.get(++i);
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temperature = (c - '0') * 10;
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c = buffer.byteBuffer.get(++i);
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if (c == '.') {
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c = buffer.byteBuffer.get(++i);
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temperature = temperature + c - '0';
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}
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else {
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temperature = temperature + c - '0';
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++i; // dot
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c = buffer.byteBuffer.get(++i);
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temperature = temperature * 10 + c - '0';
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}
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}
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else {
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temperature = (c - '0') * 10;
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c = buffer.byteBuffer.get(++i);
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if (c == '.') {
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c = buffer.byteBuffer.get(++i);
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temperature = temperature + c - '0';
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}
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else {
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temperature = temperature + c - '0';
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++i; // dot
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c = buffer.byteBuffer.get(++i);
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temperature = temperature * 10 + c - '0';
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}
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}
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hash = hash & 0x7FFFFFFF;
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updateStations(hash, name, nameLen, sign * (double) temperature / 10);
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++i; // For '\n'
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nameLen = 0;
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hash = 5383;
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}
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else {
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name[nameLen++] = c;
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hash = ((hash << 5) + hash) + c;
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}
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}
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}
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private void updateStations(int hash, byte[] name, short nameLen, double temperature) {
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int idx;
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for (idx = hash % HT_SIZE; stations[idx].freq != 0; idx = (idx + 1) % HT_SIZE) {
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if (areEqual(stations[idx].name, stations[idx].nameLen, name, nameLen)) {
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stations[idx].sum += temperature;
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stations[idx].min = Math.min(stations[idx].min, temperature);
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stations[idx].max = Math.max(stations[idx].max, temperature);
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++stations[idx].freq;
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return;
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}
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}
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stations[idx].sum = temperature;
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stations[idx].min = temperature;
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stations[idx].max = temperature;
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stations[idx].nameLen = nameLen;
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System.arraycopy(name, 0, stations[idx].name, 0, nameLen);
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stations[idx].freq = 1;
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}
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}}
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