Mudit/initial attempt (#41)

* Initial version with multiple ideas

* Added virtual thread implementation based on certain task size

* Removed evaluate file

* Fixed test issues

* Added a custom input split

calculate_average_mudit-saxena.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+#
+#  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.
+#
+
+JAVA_OPTS=""
+time java $JAVA_OPTS --enable-preview --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_muditsaxena -Xmx16384m

src/main/java/dev/morling/onebrc/CalculateAverage_muditsaxena.java

@@ -0,0 +1,157 @@
+/*
+ *  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);
+        }
+    }
+}