breejesh Submission (#670)

* 1BRC breejesh

* Fix output

* Fix formatting

* Format and remove preview feature

* Optimize merge

* Revert "Optimize merge"

This reverts commit 28c9b4a.

---------

Co-authored-by: Breejesh Rathod <breejesh.rathod@m2pfintech.com>

calculate_average_breejesh.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=""
+java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_breejesh

prepare_breejesh.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+#
+#  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.
+#
+
+# Uncomment below to use sdk
+# source "$HOME/.sdkman/bin/sdkman-init.sh"
+# sdk use java 21.0.1-graal 1>&2

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

@@ -0,0 +1,180 @@
+/*
+ *  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.File;
+import java.io.IOException;
+import java.nio.MappedByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.StandardOpenOption;
+import java.util.*;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class CalculateAverage_breejesh {
+    private static final String FILE = "./measurements.txt";
+    private static final int TWO_BYTE_TO_INT = 480 + 48; // 48 is the ASCII code for '0'
+    private static final int THREE_BYTE_TO_INT = 4800 + 480 + 48;
+
+    private static final class Measurement {
+
+        private int min;
+        private int max;
+        private int total;
+        private int count;
+
+        public Measurement(int value) {
+            this.min = value;
+            this.max = value;
+            this.total = value;
+            this.count = 1;
+        }
+
+        @Override
+        public String toString() {
+            StringBuilder result = new StringBuilder();
+            result.append(min / 10.0);
+            result.append("/");
+            result.append(Math.round(((double) total) / count) / 10.0);
+            result.append("/");
+            result.append(max / 10.0);
+            return result.toString();
+        }
+
+        private void append(int min, int max, int total, int count) {
+            if (min < this.min)
+                this.min = min;
+            if (max > this.max)
+                this.max = max;
+            this.total += total;
+            this.count += count;
+        }
+
+        public void append(int value) {
+            append(value, value, value, 1);
+        }
+
+        public void merge(Measurement other) {
+            append(other.min, other.max, other.total, other.count);
+        }
+    }
+
+    public static void main(String[] args) throws Exception {
+        // long start = System.currentTimeMillis();
+        // Find system details to determine cores and
+        var file = new File(args.length > 0 ? args[0] : FILE);
+        long fileSize = file.length();
+        var numberOfCores = fileSize > 1_000_000 ? Runtime.getRuntime().availableProcessors() : 1;
+        var splitSectionSize = (int) Math.min(Integer.MAX_VALUE, fileSize / numberOfCores); // bytebuffer position is an int, so can be max Integer.MAX_VALUE
+        var segmentCount = (int) (fileSize / splitSectionSize);
+
+        // Divide file into segments
+        ExecutorService executor = Executors.newFixedThreadPool(segmentCount);
+        List<CompletableFuture<Map<String, Measurement>>> futures = new ArrayList<>();
+        for (int i = 0; i < segmentCount; i++) {
+            long sectionStart = i * (long) splitSectionSize;
+            long sectionEnd = Math.min(fileSize, sectionStart + splitSectionSize + 100);
+            var fileChannel = (FileChannel) Files.newByteChannel(file.toPath(), StandardOpenOption.READ);
+            CompletableFuture<Map<String, Measurement>> future = CompletableFuture.supplyAsync(() -> {
+                MappedByteBuffer currentBuffer = null;
+                try {
+                    currentBuffer = fileChannel.map(FileChannel.MapMode.READ_ONLY, sectionStart, sectionEnd - sectionStart);
+                }
+                catch (IOException e) {
+                    throw new RuntimeException(e);
+                }
+                // Skip till new line for unequal segments, not to be done for first section
+                if (sectionStart > 0) {
+                    while (currentBuffer.get() != '\n')
+                        ;
+                }
+                Map<String, Measurement> map = new HashMap<>();
+                while (currentBuffer.position() < splitSectionSize) {
+                    // Read station
+                    String str = getStationFromBuffer(currentBuffer);
+                    // Read number
+                    int value = getValueFromBuffer(currentBuffer);
+                    if (map.containsKey(str)) {
+                        map.get(str).append(value);
+                    }
+                    else {
+                        map.put(str, new Measurement(value));
+                    }
+                }
+                return map;
+            }, executor);
+            futures.add(future);
+        }
+
+        CompletableFuture.allOf(futures.toArray(new CompletableFuture[0])).join();
+        Map<String, Measurement> finalMap = new TreeMap<>();
+        for (CompletableFuture<Map<String, Measurement>> future : futures) {
+            Map<String, Measurement> map = future.get();
+            map.keySet().stream().forEach(
+                    key -> {
+                        if (finalMap.containsKey(key)) {
+                            finalMap.get(key).merge(map.get(key));
+                        }
+                        else {
+                            finalMap.put(key, map.get(key));
+                        }
+                    });
+        }
+
+        System.out.println(finalMap);
+        // System.out.printf("Time %s", System.currentTimeMillis() - start);
+        System.exit(0);
+    }
+
+    private static String getStationFromBuffer(MappedByteBuffer currentBuffer) {
+        byte currentByte;
+        var byteCounter = 0;
+        var buffer = new byte[100];
+        while ((currentByte = currentBuffer.get()) != ';') {
+            buffer[byteCounter++] = currentByte;
+        }
+        return new String(buffer, 0, byteCounter, StandardCharsets.UTF_8);
+    }
+
+    private static int getValueFromBuffer(MappedByteBuffer currentBuffer) {
+        int value;
+        byte[] nums = new byte[4];
+        currentBuffer.get(nums);
+        if (nums[1] == '.') {
+            // case of n.n
+            value = (nums[0] * 10 + nums[2] - TWO_BYTE_TO_INT);
+        }
+        else {
+            if (nums[3] == '.') {
+                // case of -nn.n
+                value = -(nums[1] * 100 + nums[2] * 10 + currentBuffer.get() - THREE_BYTE_TO_INT);
+            }
+            else if (nums[0] == '-') {
+                // case of -n.n
+                value = -(nums[1] * 10 + nums[3] - TWO_BYTE_TO_INT);
+            }
+            else {
+                // case of nn.n
+                value = (nums[0] * 100 + nums[1] * 10 + nums[3] - THREE_BYTE_TO_INT);
+            }
+            currentBuffer.get(); // new line
+        }
+        return value;
+    }
+}