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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 java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.*;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
public class CalculateAverage_tkosachev {
private static final String FILE = "./measurements.txt";
public static int numThreads = Math.min(Runtime.getRuntime().availableProcessors(), 8);
private record ResultRow(int min, double mean, int max) {
public String toString() {
return STR."\{round(min)}/\{round(mean)}/\{round(max)}";
}
private double round(double value) {
return Math.round(value) / 10.0;
}
}
private static class MeasurementAggregator {
private int min = Integer.MAX_VALUE;
private int max = Integer.MIN_VALUE;
private long sum = 0;
private long count = 0;
public void newValue(int m) {
if (m < min) {
min = m;
}
if (m > max) {
max = m;
}
sum += m;
count++;
}
public void mergeIn(MeasurementAggregator add) {
if (add.min < min) {
min = add.min;
}
if (add.max > max) {
max = add.max;
}
sum += add.sum;
count += add.count;
}
}
public static void main(String[] args) {
Path path = Paths.get(args.length == 0 ? FILE : args[0]);
Map<String, MeasurementAggregator> total;
try (RandomAccessFile aFile = new RandomAccessFile(path.toFile(), "r");
ExecutorService executorService = Executors.newFixedThreadPool(numThreads)) {
FileChannel inChannel = aFile.getChannel();
int numChunks = args.length > 1 ? Integer.parseInt(args[1]) : 100;
if (inChannel.size() < 1024 * 1024 * 1024) {
numThreads = 1;
numChunks = 1;
}
List<Future<Map<String, MeasurementAggregator>>> futures = new ArrayList<>(numThreads);
int bufferSize = (int) (inChannel.size() / numChunks) + 100;
for (int i = 0; i < numChunks; i++) {
final int finalI = i;
futures.add(executorService.submit(() -> processBuffer(inChannel, bufferSize, finalI)));
}
executorService.shutdown();
total = new HashMap<>();
for (Future<Map<String, MeasurementAggregator>> future : futures) {
mergeIn(total, future.get());
}
}
catch (IOException | InterruptedException | ExecutionException e) {
throw new RuntimeException(e);
}
printResults(total);
}
private static void mergeIn(Map<String, MeasurementAggregator> total, Map<String, MeasurementAggregator> result) {
for (String name : result.keySet()) {
MeasurementAggregator totalAggregator = total.computeIfAbsent(name, _ -> new MeasurementAggregator());
totalAggregator.mergeIn(result.get(name));
}
}
private static Map<String, MeasurementAggregator> processBuffer(FileChannel channel, int bufferSize, int nr) throws IOException {
HashMap<String, MeasurementAggregator> aggregatorMap = new HashMap<>();
long start = ((long) nr) * bufferSize;
long length = Math.min(bufferSize, channel.size() - start);
ByteBuffer byteBuffer = channel.map(
FileChannel.MapMode.READ_ONLY,
start,
length);
int i = 0;
int smcIndex = -1;
byte[] buf = new byte[1024];
int count = 0;
if (nr > 0) {
do {
i++;
} while (byteBuffer.get() != '\n');
}
while (i < length) {
byte b = byteBuffer.get();
buf[count] = b;
if (b == ';') {
smcIndex = count;
}
count++;
if (b == '\n') {
String name = new String(buf, 0, smcIndex);
int value = fastParse(buf, smcIndex + 1, count - smcIndex - 2);
aggregatorMap.computeIfAbsent(name, _ -> new MeasurementAggregator()).newValue(value);
count = 0;
}
i++;
}
return aggregatorMap;
}
private static void printResults(Map<String, MeasurementAggregator> result) {
Map<String, ResultRow> measurements = new TreeMap<>();
for (Map.Entry<String, MeasurementAggregator> entry : result.entrySet()) {
MeasurementAggregator value = entry.getValue();
measurements.put(entry.getKey(), new ResultRow(value.min, ((double) value.sum / value.count), value.max));
}
System.out.println(measurements);
}
public static int fastParse(byte[] buf, int start, int len) {
int i = 0;
int sign = 1;
for (int index = start; index < start + len; index++) {
byte b = buf[index];
if (b == '-') {
sign = -1;
}
if (b >= '0' && b <= '9') {
i = i * 10 + (b - '0');
}
}
return i * sign;
}
}
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