sudhirtumati implementation

calculate_average_sudhirtumati.sh

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+#!/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="--enable-preview -Xmx128m -XX:+UseSerialGC -XX:-TieredCompilation"
+java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_sudhirtumati

prepare_sudhirtumati.sh

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+#!/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 21.0.2-open 1>&2

src/main/java/dev/morling/onebrc/CalculateAverage_sudhirtumati.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.FileInputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.TreeMap;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.Semaphore;
+
+public class CalculateAverage_sudhirtumati {
+
+    private static final String FILE = "./measurements.txt";
+    private static final int bufferSize = 8192;
+    private static final byte SEMICOLON = (byte) ';';
+    private static final byte NEW_LINE = (byte) '\n';
+    private static final int THREAD_COUNT = Runtime.getRuntime().availableProcessors();
+    private static final Semaphore PERMITS = new Semaphore(THREAD_COUNT);
+    private static final MeasurementAggregator globalAggregator = new MeasurementAggregator();
+    private static final Semaphore AGGREGATOR_PERMITS = new Semaphore(1);
+    private static final Map<Integer, String> LOCATION_STORE = new ConcurrentHashMap<>();
+
+    public static void main(String[] args) throws IOException, InterruptedException {
+        CalculateAverage_sudhirtumati instance = new CalculateAverage_sudhirtumati();
+        instance.chunkProcess();
+    }
+
+    private void chunkProcess() throws IOException, InterruptedException {
+        try (FileInputStream is = new FileInputStream(FILE);
+             FileChannel fc = is.getChannel()) {
+            for (int i = 0; i < THREAD_COUNT; i++) {
+                PERMITS.acquire();
+                Thread t = new ChunkProcessingThread(i, fc);
+                t.setName(STR."T\{i}");
+                t.start();
+            }
+            do {
+                Thread.sleep(100);
+            } while (PERMITS.availablePermits() != THREAD_COUNT);
+        }
+        System.out.println(globalAggregator.getResult());
+    }
+
+    static class ChunkProcessingThread extends Thread {
+
+        private int index;
+        private final FileChannel fc;
+        private final MeasurementAggregator aggregator;
+
+        ChunkProcessingThread(int index, FileChannel fc) {
+            this.index = index;
+            this.fc = fc;
+            aggregator = new MeasurementAggregator();
+        }
+
+        @Override
+        public void run() {
+            ByteBuffer buffer = ByteBuffer.allocate(index == 0 ? bufferSize : bufferSize + 50);
+            long fcPosition = index == 0 ? 0 : (((long) index * bufferSize) - 50);
+            try {
+                while (fc.read(buffer, fcPosition) != -1) {
+                    buffer.flip();
+                    if (index != 0 /* && fc.position() != bufferSize */) {
+                        seekStartPos(buffer);
+                    }
+                    processBuffer(buffer);
+                    index += THREAD_COUNT;
+                    fcPosition = ((long) index * bufferSize) - 50L;
+                    if (buffer.capacity() == 8192) {
+                        buffer = ByteBuffer.allocate(bufferSize + 50);
+                    }
+                    buffer.position(0);
+                }
+                AGGREGATOR_PERMITS.acquire();
+                globalAggregator.process(aggregator);
+                AGGREGATOR_PERMITS.release();
+            }
+            catch (IOException | InterruptedException e) {
+                throw new RuntimeException(e);
+            }
+            PERMITS.release();
+        }
+
+        private void processBuffer(ByteBuffer buffer) throws IOException {
+            int mStartMark = buffer.position();
+            int tStartMark = -1;
+            int count = buffer.position();
+            do {
+                byte b = buffer.get(count);
+                if (b == SEMICOLON) {
+                    tStartMark = count;
+                }
+                else if (b == NEW_LINE) {
+                    byte[] locArr = new byte[tStartMark - mStartMark];
+                    byte[] tempArr = new byte[count - tStartMark];
+                    buffer.get(mStartMark, locArr);
+                    buffer.get(mStartMark + locArr.length + 1, tempArr);
+                    aggregator.process(locArr, tempArr);
+                    mStartMark = count + 1;
+                }
+                count++;
+            } while (count < buffer.limit());
+        }
+
+        private void seekStartPos(ByteBuffer buffer) {
+            int i = buffer.limit() > 50 ? 49 : buffer.limit() - 2;
+            for (; i >= 0; i--) {
+                if (buffer.get(i) == NEW_LINE) {
+                    buffer.position(i + 1);
+                    break;
+                }
+            }
+        }
+    }
+
+    static final class MeasurementAggregator {
+        private static final long MAX_VALUE_DIVIDE_10 = Long.MAX_VALUE / 10;
+        private final Map<Integer, Measurement> store = new HashMap<>();
+
+        public void process(MeasurementAggregator other) {
+            other.store.forEach((k, v) -> {
+                Measurement m = store.get(k);
+                if (m == null) {
+                    m = new Measurement();
+                    store.put(k, m);
+                }
+                m.process(v);
+            });
+        }
+
+        public void process(byte[] location, byte[] temperature) throws IOException {
+            Integer hashCode = Arrays.hashCode(location);
+            LOCATION_STORE.computeIfAbsent(hashCode, _ -> new String(location));
+            // String loc = new String(location);
+            Measurement measurement = store.get(hashCode);
+            if (measurement == null) {
+                measurement = new Measurement();
+                store.put(hashCode, measurement);
+            }
+            double tempD = parseDouble(temperature);
+            measurement.process(tempD);
+        }
+
+        public double parseDouble(byte[] bytes) {
+            long value = 0;
+            int exp = 0;
+            boolean negative = false;
+            int decimalPlaces = Integer.MIN_VALUE;
+            int index = 0;
+            int ch = bytes[index];
+            if (ch == '-') {
+                negative = true;
+                ch = bytes[++index];
+            }
+            while (index < bytes.length) {
+                if (ch >= '0' && ch <= '9') {
+                    while (value >= MAX_VALUE_DIVIDE_10) {
+                        value >>>= 1;
+                        exp++;
+                    }
+                    value = value * 10 + (ch - '0');
+                    decimalPlaces++;
+
+                }
+                else if (ch == '.') {
+                    decimalPlaces = 0;
+                }
+                if (index == bytes.length - 1) {
+                    break;
+                }
+                else {
+                    ch = bytes[++index];
+                }
+            }
+            return asDouble(value, exp, negative, decimalPlaces);
+        }
+
+        private static double asDouble(long value, int exp, boolean negative, int decimalPlaces) {
+            if (decimalPlaces > 0 && value < Long.MAX_VALUE / 2) {
+                if (value < Long.MAX_VALUE / (1L << 32)) {
+                    exp -= 32;
+                    value <<= 32;
+                }
+                if (value < Long.MAX_VALUE / (1L << 16)) {
+                    exp -= 16;
+                    value <<= 16;
+                }
+                if (value < Long.MAX_VALUE / (1L << 8)) {
+                    exp -= 8;
+                    value <<= 8;
+                }
+                if (value < Long.MAX_VALUE / (1L << 4)) {
+                    exp -= 4;
+                    value <<= 4;
+                }
+                if (value < Long.MAX_VALUE / (1L << 2)) {
+                    exp -= 2;
+                    value <<= 2;
+                }
+                if (value < Long.MAX_VALUE / (1L << 1)) {
+                    exp -= 1;
+                    value <<= 1;
+                }
+            }
+            for (; decimalPlaces > 0; decimalPlaces--) {
+                exp--;
+                long mod = value % 5;
+                value /= 5;
+                int modDiv = 1;
+                if (value < Long.MAX_VALUE / (1L << 4)) {
+                    exp -= 4;
+                    value <<= 4;
+                    modDiv <<= 4;
+                }
+                if (value < Long.MAX_VALUE / (1L << 2)) {
+                    exp -= 2;
+                    value <<= 2;
+                    modDiv <<= 2;
+                }
+                if (value < Long.MAX_VALUE / (1L << 1)) {
+                    exp -= 1;
+                    value <<= 1;
+                    modDiv <<= 1;
+                }
+                if (decimalPlaces > 1)
+                    value += modDiv * mod / 5;
+                else
+                    value += (modDiv * mod + 4) / 5;
+            }
+            final double d = Math.scalb((double) value, exp);
+            return negative ? -d : d;
+        }
+
+        public String getResult() {
+            Map<String, Measurement> sortedMap = new TreeMap<>();
+            store.forEach((k, v) -> sortedMap.put(LOCATION_STORE.get(k), v));
+            return sortedMap.toString();
+        }
+    }
+
+    static final class Measurement {
+        private double min = Double.POSITIVE_INFINITY;
+        private double max = Double.NEGATIVE_INFINITY;
+        private double sum;
+        private long count;
+
+        public void process(double value) {
+            if (value < min) {
+                min = value;
+            }
+            if (value > max) {
+                max = value;
+            }
+            sum += value;
+            count++;
+        }
+
+        public void process(Measurement other) {
+            if (other.min < min) {
+                this.min = other.min;
+            }
+            if (other.max > max) {
+                this.max = other.max;
+            }
+            this.sum += other.sum;
+            this.count += other.count;
+        }
+
+        public String toString() {
+            ResultRow result = new ResultRow(min, sum, count, max);
+            return result.toString();
+        }
+    }
+
+    private record ResultRow(double min, double sum, double count, double max) {
+
+        public String toString() {
+            return STR."\{round(min)}/\{round((Math.round(sum * 10.0) / 10.0) / count)}/\{round(max)}";
+        }
+
+        private double round(double value) {
+            return Math.round(value * 10.0) / 10.0;
+        }
+    }
+
+}