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CalculateAverage_muditsaxena.java
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CalculateAverage_muditsaxena.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 java.io.BufferedReader;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
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.CompletableFuture;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.FutureTask;
public class CalculateAverage_muditsaxena {
private static final String FILE = "./measurements.txt";
private static record Measurement(String station, double value) {
private Measurement(String[] parts) {
this(parts[0], Double.parseDouble(parts[1]));
}
}
private static record ResultRow(double min, double mean, double max) {
public String toString() {
return round(min) + "/" + round(mean) + "/" + round(max);
}
private double round(double value) {
return Math.round(value * 10.0) / 10.0;
}
};
private static class MeasurementAggregator {
private double min = Double.POSITIVE_INFINITY;
private double max = Double.NEGATIVE_INFINITY;
private double sum;
private long count;
}
static class TaskRunner<V> implements Callable<V> {
List<String> inputList;
String input;
TaskRunner(List<String> taskList) {
this.inputList = taskList;
}
TaskRunner(String input) {
this.input = input;
}
String[] readInput(String inputTask) {
StringBuilder stationName = new StringBuilder();
String[] values = new String[2];
int index = 0;
char ch = inputTask.charAt(index);
while (ch != ';') {
stationName.append(ch);
ch = inputTask.charAt(++index);
}
index++;
values[0] = stationName.toString();
values[1] = inputTask.substring(index);
return values;
}
@Override
public V call() {
for (String inputTask : inputList) {
if (inputTask.isEmpty()) {
continue;
}
String[] values = readInput(inputTask);
double value = Double.parseDouble(values[1]);
MeasurementAggregator measurementAggregator = map.getOrDefault(values[0], new MeasurementAggregator());
measurementAggregator.count += 1;
measurementAggregator.sum += value;
measurementAggregator.max = Math.max(measurementAggregator.max, value);
measurementAggregator.min = Math.min(measurementAggregator.min, value);
map.put(values[0], measurementAggregator);
}
inputList = null;
return null;
}
}
static ConcurrentMap<String, MeasurementAggregator> map = new ConcurrentHashMap<>();
static final int TASK_LIST_CAPACITY = 10000;
// 100000 - 1:23
// 10000 - 1:10
// 1000 - 1:21
// Optimising split
// 10000 - 1:15, 1:12, 1:11
// 1000 - 1:18, 1:23
public static void main(String[] args) throws IOException {
try (ExecutorService virtualThreadExecutors = Executors.newVirtualThreadPerTaskExecutor()) {
List<String> taskList = new ArrayList<>(TASK_LIST_CAPACITY);
List<CompletableFuture<Void>> tasks = new ArrayList<>();
try (BufferedReader br = Files.newBufferedReader(Paths.get(FILE))) {
String line = br.readLine();
while (line != null) {
taskList.add(line);
if (taskList.size() >= TASK_LIST_CAPACITY) {
tasks.add(CompletableFuture.runAsync(new FutureTask<>(new TaskRunner<>(taskList)), virtualThreadExecutors));
taskList = null;
taskList = new ArrayList<>(TASK_LIST_CAPACITY);
}
line = br.readLine();
}
}
if (!taskList.isEmpty()) {
tasks.add(CompletableFuture.runAsync(new FutureTask<>(new TaskRunner<>(taskList)), virtualThreadExecutors));
}
for (CompletableFuture<Void> task : tasks) {
if (task != null) {
task.join();
}
}
Map<String, ResultRow> resultRowMap = new TreeMap<>();
map.forEach((key, value) -> resultRowMap.put(key, new ResultRow(value.min, value.sum / value.count, value.max)));
System.out.println(resultRowMap);
}
}
}