CalculateAverage_gonix initial attempt (#413)
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gonix
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354
src/main/java/dev/morling/onebrc/CalculateAverage_gonix.java
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354
src/main/java/dev/morling/onebrc/CalculateAverage_gonix.java
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/*
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* Copyright 2023 The original authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package dev.morling.onebrc;
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import java.io.IOException;
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import java.io.RandomAccessFile;
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import java.nio.ByteBuffer;
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import java.nio.ByteOrder;
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import java.nio.MappedByteBuffer;
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import java.nio.channels.FileChannel;
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import java.nio.charset.StandardCharsets;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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import java.util.TreeMap;
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import java.util.stream.Collectors;
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import java.util.stream.Stream;
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public class CalculateAverage_gonix {
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private static final String FILE = "./measurements.txt";
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public static void main(String[] args) throws IOException {
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var file = new RandomAccessFile(FILE, "r");
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var res = buildChunks(file).stream().parallel()
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.flatMap(chunk -> new Aggregator().processChunk(chunk).stream())
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.collect(Collectors.toMap(
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Aggregator.Entry::getKey,
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Aggregator.Entry::getValue,
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Aggregator.Entry::add,
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TreeMap::new));
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System.out.println(res);
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}
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private static List<MappedByteBuffer> buildChunks(RandomAccessFile file) throws IOException {
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var fileSize = file.length();
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var chunkSize = Math.min(Integer.MAX_VALUE - 512, fileSize / Runtime.getRuntime().availableProcessors());
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if (chunkSize <= 0) {
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chunkSize = fileSize;
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}
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var chunks = new ArrayList<MappedByteBuffer>((int) (fileSize / chunkSize) + 1);
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var start = 0L;
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while (start < fileSize) {
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var pos = start + chunkSize;
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if (pos < fileSize) {
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file.seek(pos);
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while (file.read() != '\n') {
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pos += 1;
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}
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pos += 1;
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}
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else {
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pos = fileSize;
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}
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var buf = file.getChannel().map(FileChannel.MapMode.READ_ONLY, start, pos - start);
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buf.order(ByteOrder.nativeOrder());
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chunks.add(buf);
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start = pos;
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}
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return chunks;
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}
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}
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class Aggregator {
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private static final int MAX_STATIONS = 10_000;
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private static final int MAX_STATION_SIZE = (100 * 4) / 8 + 5;
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private static final int INDEX_SIZE = 1024 * 1024;
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private static final int INDEX_MASK = INDEX_SIZE - 1;
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private static final int FLD_MAX = 0;
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private static final int FLD_MIN = 1;
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private static final int FLD_SUM = 2;
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private static final int FLD_COUNT = 3;
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// Poor man's hash map: hash code to offset in `mem`.
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private final int[] index;
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// Contiguous storage of key (station name) and stats fields of all
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// unique stations.
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// The idea here is to improve locality so that stats fields would
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// possibly be already in the CPU cache after we are done comparing
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// the key.
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private final long[] mem;
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private int memUsed;
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Aggregator() {
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assert ((INDEX_SIZE & (INDEX_SIZE - 1)) == 0) : "INDEX_SIZE must be power of 2";
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assert (INDEX_SIZE > MAX_STATIONS) : "INDEX_SIZE must be greater than MAX_STATIONS";
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index = new int[INDEX_SIZE];
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mem = new long[1 + (MAX_STATIONS * MAX_STATION_SIZE)];
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memUsed = 1;
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}
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Aggregator processChunk(MappedByteBuffer buf) {
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// To avoid checking if it is safe to read a whole long near the
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// end of a chunk, we copy last couple of lines to a padded buffer
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// and process that part separately.
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int limit = buf.limit();
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int pos = Math.max(limit - 16, -1);
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while (pos >= 0 && buf.get(pos) != '\n') {
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pos--;
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}
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pos++;
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if (pos > 0) {
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processChunkLongs(buf, pos);
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}
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int tailLen = limit - pos;
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var tailBuf = ByteBuffer.allocate(tailLen + 8).order(ByteOrder.nativeOrder());
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buf.get(pos, tailBuf.array(), 0, tailLen);
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processChunkLongs(tailBuf, tailLen);
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return this;
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}
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Aggregator processChunkLongs(ByteBuffer buf, int limit) {
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int pos = 0;
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while (pos < limit) {
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int start = pos;
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int hash = 0;
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while (true) {
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// This is a bit ugly, but it is faster than reading by byte.
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long tmpLong = buf.getLong(pos);
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if ((tmpLong & 0xFF) == ';') {
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break;
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}
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if (((tmpLong >>> 8) & 0xFF) == ';') {
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hash = (33 * hash) ^ (int) (tmpLong & 0xFF);
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pos += 1;
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break;
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}
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if (((tmpLong >>> 16) & 0xFF) == ';') {
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hash = (33 * hash) ^ (int) (tmpLong & 0xFFFF);
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pos += 2;
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break;
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}
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if (((tmpLong >>> 24) & 0xFF) == ';') {
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hash = (33 * hash) ^ (int) (tmpLong & 0xFFFFFF);
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pos += 3;
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break;
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}
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if (((tmpLong >>> 32) & 0xFF) == ';') {
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hash = (33 * hash) ^ (int) (tmpLong & 0xFFFFFFFF);
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pos += 4;
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break;
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}
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if (((tmpLong >>> 40) & 0xFF) == ';') {
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hash = ((33 * hash) ^ (int) (tmpLong & 0xFFFFFFFF)) + (int) ((tmpLong >>> 33) & 0xFF);
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pos += 5;
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break;
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}
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if (((tmpLong >>> 48) & 0xFF) == ';') {
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hash = ((33 * hash) ^ (int) (tmpLong & 0xFFFFFFFF)) + (int) ((tmpLong >>> 33) & 0xFFFF);
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pos += 6;
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break;
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}
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if (((tmpLong >>> 56) & 0xFF) == ';') {
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hash = ((33 * hash) ^ (int) (tmpLong & 0xFFFFFFFF)) + (int) ((tmpLong >>> 33) & 0xFFFFFF);
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pos += 7;
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break;
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}
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hash = ((33 * hash) ^ (int) (tmpLong & 0xFFFFFFFF)) + (int) ((tmpLong >>> 33) & 0xFFFFFFFF);
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pos += 8;
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}
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hash = (33 * hash) ^ (hash >>> 15);
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int len = pos - start;
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assert (buf.get(pos) == ';') : "Expected ';'";
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pos++;
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int measurement;
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{
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long tmpLong = buf.getLong(pos);
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int sign = 1;
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if ((tmpLong & 0xFF) == '-') {
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sign = -1;
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tmpLong >>>= 8;
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pos++;
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}
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int value;
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if (((tmpLong >>> 8) & 0xFF) == '.') {
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value = (int) (((tmpLong & 0xFF) - '0') * 10 + (((tmpLong >>> 16) & 0xFF) - '0'));
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pos += 4;
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}
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else {
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value = (int) (((tmpLong & 0xFF) - '0') * 100 + (((tmpLong >>> 8) & 0xFF) - '0') * 10 + (((tmpLong >>> 24) & 0xFF) - '0'));
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pos += 5;
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}
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measurement = sign * value;
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}
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assert (buf.get(pos - 1) == '\n') : "Expected '\\n'";
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add(buf, start, len, hash, measurement);
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}
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return this;
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}
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public Stream<Entry> stream() {
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return Arrays.stream(index)
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.filter(offset -> offset != 0)
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.mapToObj(offset -> new Entry(mem, offset));
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}
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private void add(ByteBuffer buf, int start, int len, int hash, int measurement) {
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int idx = hash & INDEX_MASK;
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while (true) {
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if (index[idx] != 0) {
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int offset = index[idx];
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if (keyEqual(offset, buf, start, len)) {
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int pos = offset + (len >> 3) + 2;
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mem[pos + FLD_MIN] = Math.min((int) measurement, (int) mem[pos + FLD_MIN]);
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mem[pos + FLD_MAX] = Math.max((int) measurement, (int) mem[pos + FLD_MAX]);
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mem[pos + FLD_SUM] += measurement;
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mem[pos + FLD_COUNT] += 1;
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return;
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}
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}
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else {
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index[idx] = create(buf, start, len, hash, measurement);
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return;
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}
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idx = (idx + 1) & INDEX_MASK;
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}
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}
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private int create(ByteBuffer buf, int start, int len, int hash, int measurement) {
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int offset = memUsed;
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mem[offset] = len;
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int memPos = offset + 1;
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int memEndEarly = memPos + (len >> 3);
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int bufPos = start;
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int bufEnd = start + len;
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while (memPos < memEndEarly) {
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mem[memPos] = buf.getLong(bufPos);
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memPos += 1;
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bufPos += 8;
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}
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if (bufPos < bufEnd) {
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int shift = (8 - (len & 7)) << 3; // (8 - (len % 8)) * 8
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long tmpLong = buf.getLong(bufPos) << shift >>> shift;
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mem[memPos] = tmpLong;
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}
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else {
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// "consume" extra long - makes math a bit simpler to calculate
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// fields offset for update.
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mem[memPos] = 0;
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}
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memPos += 1;
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mem[memPos + FLD_MIN] = measurement;
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mem[memPos + FLD_MAX] = measurement;
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mem[memPos + FLD_SUM] = measurement;
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mem[memPos + FLD_COUNT] = 1;
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memUsed = memPos + 4;
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return offset;
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}
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private boolean keyEqual(int offset, ByteBuffer buf, int start, int len) {
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if (len != mem[offset]) {
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return false;
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}
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int memPos = offset + 1;
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int memEndEarly = memPos + (len >> 3);
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int bufPos = start;
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int bufEnd = start + len;
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while (memPos < memEndEarly) {
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if (mem[memPos] != buf.getLong(bufPos)) {
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return false;
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}
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memPos += 1;
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bufPos += 8;
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}
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if (bufPos < bufEnd) {
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int shift = (8 - (len & 7)) << 3; // (8 - (len % 8)) * 8
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long tmpLong = buf.getLong(bufPos) << shift >>> shift;
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if (mem[memPos] != tmpLong) {
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return false;
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}
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}
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return true;
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}
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public static class Entry {
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private final long[] mem;
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private final int offset;
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private String key;
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Entry(long[] mem, int offset) {
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this.mem = mem;
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this.offset = offset;
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}
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public String getKey() {
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if (key == null) {
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int pos = this.offset;
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int keyLen = (int) mem[pos++];
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var tmpBuf = ByteBuffer.allocate(keyLen + 8).order(ByteOrder.nativeOrder());
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for (int i = 0; i < keyLen; i += 8) {
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tmpBuf.putLong(mem[pos++]);
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}
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key = new String(tmpBuf.array(), 0, keyLen, StandardCharsets.UTF_8);
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}
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return key;
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}
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public Entry add(Entry other) {
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int keyLen = (int) mem[offset];
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int fldOffset = (keyLen >> 3) + 2;
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int pos = offset + fldOffset;
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int otherPos = other.offset + fldOffset;
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long[] otherMem = other.mem;
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mem[pos + FLD_MIN] = Math.min((int) mem[pos + FLD_MIN], (int) otherMem[otherPos + FLD_MIN]);
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mem[pos + FLD_MAX] = Math.max((int) mem[pos + FLD_MAX], (int) otherMem[otherPos + FLD_MAX]);
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mem[pos + FLD_SUM] += otherMem[otherPos + FLD_SUM];
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mem[pos + FLD_COUNT] += otherMem[otherPos + FLD_COUNT];
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return this;
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}
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public Entry getValue() {
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return this;
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}
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@Override
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public String toString() {
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int keyLen = (int) mem[offset];
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int pos = offset + (keyLen >> 3) + 2;
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return round(mem[pos + FLD_MIN])
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+ "/" + round(((double) mem[pos + FLD_SUM]) / mem[pos + FLD_COUNT])
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+ "/" + round(mem[pos + FLD_MAX]);
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}
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private static double round(double value) {
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return Math.round(value) / 10.0;
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}
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}
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}
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