Revert "Adding Nils Semmelrock's submission"

This reverts commit 12ae36ad

1 files changed, 0 insertions, 271 deletions

diff --git a/src/main/java/dev/morling/onebrc/CalculateAverage_nstng.java b/src/main/java/dev/morling/onebrc/CalculateAverage_nstng.java
deleted file mode 100644
index ab032e6..0000000
--- a/src/main/java/dev/morling/onebrc/CalculateAverage_nstng.java
+++ /dev/null
@@ -1,271 +0,0 @@
-/*
- *  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.*;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.TreeMap;
-
-public class CalculateAverage_nstng {
-
-    private static final File FILE = new File("./measurements.txt");
-
-    private static class MeasurementAggregator {
-        private double min;
-        private double max;
-        private long sum;
-        private long count;
-
-        public MeasurementAggregator(double min, double max, long sum, long count) {
-
-            this.min = min;
-            this.max = max;
-            this.sum = sum;
-            this.count = count;
-        }
-
-        @Override
-        public String toString() {
-            return "%s/%s/%s".formatted(min, round(sum / 10.0 / count), max);
-        }
-
-        private double round(double value) {
-            return Math.round(value * 10.0) / 10.0;
-        }
-    }
-
-    public static void main(String[] args) throws InterruptedException {
-        HashMap<BytesKey, MeasurementAggregator>[] maps;
-        Thread[] threads;
-        try (RandomAccessFile raf = new RandomAccessFile(FILE, "r")) {
-            // calc num threads to use
-            int availCpus = Runtime.getRuntime().availableProcessors();
-            // make sure to use at least num of threads so that byte chunks fit into an array
-            long fileLength = raf.length();
-            int minThreads = (int) Math.ceil(fileLength / (1.0 * Integer.MAX_VALUE));
-            int numThreads = Math.max(minThreads, availCpus);
-
-            // create threads - each thread processes a chunk of the file
-            // the chunks have all equal size (modulo take care that a chunk does not
-            // start/end in the middle of a line)
-            threads = new Thread[numThreads];
-            maps = new HashMap[numThreads];
-            long chunkSize = fileLength / numThreads;
-            long lastChunkEnd = 0;
-            for (int i = 0; i < numThreads; i++) {
-                raf.seek(Math.min(lastChunkEnd + chunkSize, fileLength));
-                readUntilLineBreak(raf);
-                long chunkEnd = raf.getFilePointer();
-                long finalLastChunkEnd = lastChunkEnd;
-                // 413 possible cities
-                maps[i] = new HashMap<>(413);
-                HashMap<BytesKey, MeasurementAggregator> finalMap = maps[i];
-                threads[i] = new Thread(() -> {
-                    try {
-                        // do not work on empty chunks
-                        if (chunkEnd - finalLastChunkEnd <= 0)
-                            return;
-                        // -1: left from found line break
-                        processChunk(finalLastChunkEnd, chunkEnd - 1, finalMap);
-                    }
-                    catch (IOException e) {
-                        throw new RuntimeException(e);
-                    }
-                });
-                lastChunkEnd = chunkEnd;
-            }
-
-        }
-        catch (IOException e) {
-            throw new RuntimeException(e);
-        }
-
-        // run it ...
-        for (Thread thread : threads) {
-            thread.start();
-        }
-        // ... and wait for all threads to finish
-        for (Thread thread : threads) {
-            thread.join();
-        }
-
-        // merge results
-        TreeMap<String, MeasurementAggregator> resultMap = new TreeMap<>();
-        for (HashMap<BytesKey, MeasurementAggregator> map : maps) {
-            for (Map.Entry<BytesKey, MeasurementAggregator> entry : map.entrySet()) {
-                String stringKey = entry.getKey().asString();
-                MeasurementAggregator agg = resultMap.get(stringKey);
-                if (agg == null) {
-                    resultMap.put(stringKey, entry.getValue());
-                }
-                else {
-                    agg.min = Math.min(entry.getValue().min, agg.min);
-                    agg.max = Math.max(entry.getValue().max, agg.max);
-                    agg.count = entry.getValue().count + agg.count;
-                    agg.sum = entry.getValue().sum + agg.sum;
-                }
-            }
-        }
-        System.out.println(resultMap);
-    }
-
-    private static void processChunk(long fromPos, long toPos, HashMap<BytesKey, MeasurementAggregator> map)
-            throws IOException {
-
-        byte[] byteChunk = new byte[(int) (toPos - fromPos)];
-        try (RandomAccessFile raf = new RandomAccessFile(FILE, "r")) {
-            raf.seek(fromPos);
-            raf.read(byteChunk);
-        }
-        IndexedByteArray chunk = new IndexedByteArray(byteChunk);
-
-        // reads one line from right to left in each iteration
-        while (chunk.pos > 0) {
-            double mes = getMeasurement(chunk);
-            BytesKey cityKey = getCityKey(chunk);
-            addOrUpdateEntry(map, cityKey, mes);
-        }
-    }
-
-    private static void addOrUpdateEntry(HashMap<BytesKey, MeasurementAggregator> map, BytesKey cityKey, double mes) {
-        MeasurementAggregator agg = map.get(cityKey);
-        if (agg == null) {
-            map.put(cityKey, new MeasurementAggregator(mes, mes, (long) (mes * 10), 1));
-        }
-        else {
-            agg.min = Math.min(agg.min, mes);
-            agg.max = Math.max(agg.max, mes);
-            agg.sum += (long) (mes * 10);
-            agg.count++;
-        }
-    }
-
-    // did not know how much of a bottleneck new String(byteArray) can be :)
-    // use the byte array representation of a city as a HashMap key
-    // needs to be wrapped so that hashCode/equals can be defined
-    private static BytesKey getCityKey(IndexedByteArray chunk) {
-        // city name length >=3 known
-        int cityLength = 3;
-        chunk.dec(3);
-        while (chunk.pos >= 0 && chunk.getCurrent() != '\n') {
-            chunk.dec();
-            cityLength++;
-        }
-        byte[] cityBytes = new byte[cityLength];
-        // we are on '\n' or out of bounds by -1 -> srcPos is chunk.pos + 1
-        System.arraycopy(chunk.array, chunk.pos + 1, cityBytes, 0, cityLength);
-        chunk.dec(); // move away from '\n' (or further out of bounds)
-
-        return new BytesKey(cityBytes);
-    }
-
-    // did not know how much of a bottleneck Double.parseDouble(s) can be :)
-    // parses a double value from right to left
-    // massively uses that a measurement value is very restricted
-    // (<100, >-100, exactly one decimal place)
-    private static double getMeasurement(IndexedByteArray chunk) {
-        int asciiNumbersOffset = 48;
-        double mes = (chunk.getCurrent() - asciiNumbersOffset) / 10.0; // 10^-1 place
-        chunk.dec(2); // jump over '.'
-        mes += chunk.getCurrent() - asciiNumbersOffset; // 10^0 place
-        chunk.dec();
-        switch (chunk.getCurrent()) {
-            case '-' -> {
-                mes *= -1; // <10 and negative
-                chunk.dec();
-            }
-            case ';' -> {
-                // do nothing - we will move to the left at the end
-            }
-            default -> {
-                mes += (chunk.getCurrent() - asciiNumbersOffset) * 10; // 10^1 place
-                chunk.dec();
-            }
-        }
-        if (chunk.getCurrent() == '-') {
-            mes *= -1; // >=10 and negative
-            chunk.dec();
-        }
-        chunk.dec(); // move away from ';'
-        return mes;
-    }
-
-    // just a thin wrapper around a byte array - makes handling return values and
-    // position updates more easy
-    private static class IndexedByteArray {
-        private final byte[] array;
-        private int pos;
-
-        public IndexedByteArray(byte[] array) {
-
-            this.array = array;
-            this.pos = array.length - 1;
-        }
-
-        public void dec(int by) {
-            pos -= by;
-        }
-
-        public void dec() {
-            pos--;
-        }
-
-        public int getCurrent() {
-            return array[pos];
-        }
-    }
-
-    private static void readUntilLineBreak(RandomAccessFile raf) throws IOException {
-        boolean eor = false;
-
-        while (!eor) {
-            int c = raf.read();
-            if (c == -1 || c == '\n') {
-                eor = true;
-            }
-        }
-    }
-
-    // inspired by https://www.baeldung.com/java-map-key-byte-array
-    private static class BytesKey {
-        private final byte[] array;
-        private int hash;
-
-        public BytesKey(byte[] array) {
-            this.array = array;
-            // pre-calculated value with perfect hash function (by trial and error :P)
-            // -> i.e., can be used also for equals
-            this.hash = 1;
-            for (byte b : array)
-                this.hash = 11 * this.hash + b;
-        }
-
-        @Override
-        public boolean equals(Object o) {
-            return hash == o.hashCode();
-        }
-
-        @Override
-        public int hashCode() {
-            return hash;
-        }
-
-        public String asString() {
-            return new String(array);
-        }
-    }
-}