My attempt to parse it quickly (#401)
* My approach * Update calculate_average_arjenw.sh --------- Co-authored-by: Gunnar Morling <gunnar.morling@googlemail.com>
This commit is contained in:
Arjen Wisse
GitHub
233
src/main/java/dev/morling/onebrc/CalculateAverage_arjenw.java
Normal file
233
src/main/java/dev/morling/onebrc/CalculateAverage_arjenw.java
Normal file
@@ -0,0 +1,233 @@
|
||||
/*
|
||||
* 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.channels.FileChannel;
|
||||
import java.nio.charset.StandardCharsets;
|
||||
import java.nio.file.Files;
|
||||
import java.nio.file.StandardOpenOption;
|
||||
import java.util.Arrays;
|
||||
import java.util.Comparator;
|
||||
import java.util.Iterator;
|
||||
import java.util.NoSuchElementException;
|
||||
import java.util.function.Consumer;
|
||||
import java.util.function.Supplier;
|
||||
import java.util.stream.IntStream;
|
||||
|
||||
// Calculate Average
|
||||
// * baseline: 3m7s
|
||||
// * single-threaded chunk-based reading: 0m45s
|
||||
// * multi-threaded chunk-based reading: 0m14s
|
||||
// * less branches in parsing: 0m12s
|
||||
// * list approach iso map: 0m5.5s
|
||||
// * chunk finetuning: 0m4.5s
|
||||
// * threadlocal result gathering: 0m4.3s (trying graalvm-ce)
|
||||
// * memory-mapped file approach: 0m3.2s (also way simpler and neater code; inspired by spullara)
|
||||
// * smarter number parsing: 0m2.95s (inspired by iziamos)
|
||||
// * switching back to 21-tem vm 0m2.6s
|
||||
|
||||
public class CalculateAverage_arjenw {
|
||||
private static final int TWO_BYTE_TO_INT = 480 + 48;
|
||||
private static final int THREE_BYTE_TO_INT = 4800 + 480 + 48;
|
||||
private static final String FILE = "./measurements.txt";
|
||||
|
||||
public static void main(String[] args) {
|
||||
var file = new File(FILE);
|
||||
var fileSize = file.length();
|
||||
var numberOfProcessors = fileSize > 1_000_000 ? Runtime.getRuntime().availableProcessors() : 1;
|
||||
var segmentSize = fileSize / numberOfProcessors;
|
||||
var results = IntStream.range(0, numberOfProcessors)
|
||||
.mapToObj(segmentNr -> parseSegment(file, fileSize, segmentSize, segmentNr))
|
||||
.parallel()
|
||||
.reduce(StationList::merge)
|
||||
.orElseGet(StationList::new)
|
||||
.toStringArray();
|
||||
Arrays.sort(results, Comparator.comparing(o -> take(o, '=')));
|
||||
System.out.format("{%s}%n", String.join(", ", results));
|
||||
}
|
||||
|
||||
private static StationList parseSegment(File file, long fileSize, long segmentSize, int segmentNr) {
|
||||
long segmentStart = segmentNr * segmentSize;
|
||||
long segmentEnd = Math.min(fileSize, segmentStart + segmentSize + 100);
|
||||
StationList stationList = new StationList();
|
||||
try (var fileChannel = (FileChannel) Files.newByteChannel(file.toPath(), StandardOpenOption.READ)) {
|
||||
var bb = fileChannel.map(FileChannel.MapMode.READ_ONLY, segmentStart, segmentEnd - segmentStart);
|
||||
if (segmentStart > 0) {
|
||||
while (bb.get() != '\n')
|
||||
; // skip to first new line
|
||||
}
|
||||
var buffer = new byte[100];
|
||||
while (bb.position() < segmentSize) {
|
||||
byte b;
|
||||
var i = 0;
|
||||
int hash = 0;
|
||||
while ((b = bb.get()) != ';') {
|
||||
hash = hash * 31 + b;
|
||||
buffer[i++] = b;
|
||||
}
|
||||
|
||||
int value;
|
||||
byte b1 = bb.get();
|
||||
byte b2 = bb.get();
|
||||
byte b3 = bb.get();
|
||||
byte b4 = bb.get();
|
||||
if (b2 == '.') {// value is n.n
|
||||
value = (b1 * 10 + b3 - TWO_BYTE_TO_INT);
|
||||
// b4 == \n
|
||||
}
|
||||
else {
|
||||
if (b4 == '.') { // value is -nn.n
|
||||
value = -(b2 * 100 + b3 * 10 + bb.get() - THREE_BYTE_TO_INT);
|
||||
}
|
||||
else if (b1 == '-') { // value is -n.n
|
||||
value = -(b2 * 10 + b4 - TWO_BYTE_TO_INT);
|
||||
}
|
||||
else { // value is nn.n
|
||||
value = (b1 * 100 + b2 * 10 + b4 - THREE_BYTE_TO_INT);
|
||||
}
|
||||
bb.get(); // new line
|
||||
}
|
||||
|
||||
stationList.add(buffer, i, Math.abs(hash), value);
|
||||
}
|
||||
return stationList;
|
||||
}
|
||||
catch (IOException e) {
|
||||
throw new RuntimeException(e);
|
||||
}
|
||||
}
|
||||
|
||||
private static final class Station {
|
||||
private final byte[] data;
|
||||
private final int hash;
|
||||
private final int length;
|
||||
|
||||
private int min;
|
||||
private int max;
|
||||
private int total;
|
||||
private int count;
|
||||
|
||||
private Station(byte[] data, int length, int hash, int value) {
|
||||
this.data = data;
|
||||
this.hash = hash;
|
||||
this.length = length;
|
||||
|
||||
min = max = total = value;
|
||||
count = 1;
|
||||
}
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return STR."\{new String(data, 0, length, StandardCharsets.UTF_8)}=\{min / 10.0}/\{Math.round(((double) total) / count) / 10.0}/\{max / 10.0}";
|
||||
}
|
||||
|
||||
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(Station other) {
|
||||
append(other.min, other.max, other.total, other.count);
|
||||
}
|
||||
}
|
||||
|
||||
private static class StationList implements Iterable<Station> {
|
||||
private final static int MAX_ENTRY = 32767; // choose a value that is binary all 1's.
|
||||
private final Station[] array = new Station[MAX_ENTRY + 1];
|
||||
private int size = 0;
|
||||
|
||||
private void add(int hash, Supplier<Station> create, Consumer<Station> update) {
|
||||
var position = hash & MAX_ENTRY;
|
||||
Station existing;
|
||||
while ((existing = array[position]) != null && existing.hash != hash) {
|
||||
position = (position + 1) & MAX_ENTRY;
|
||||
}
|
||||
if (existing == null) {
|
||||
array[position] = create.get();
|
||||
size++;
|
||||
}
|
||||
else {
|
||||
update.accept(existing);
|
||||
}
|
||||
}
|
||||
|
||||
public void add(byte[] data, int stationNameLength, int stationHash, int value) {
|
||||
add(stationHash, () -> {
|
||||
var stationName = new byte[stationNameLength];
|
||||
System.arraycopy(data, 0, stationName, 0, stationNameLength);
|
||||
return new Station(stationName, stationNameLength, stationHash, value);
|
||||
}, existing -> existing.append(value));
|
||||
}
|
||||
|
||||
public void add(Station station) {
|
||||
add(station.hash, () -> station, existing -> existing.merge(station));
|
||||
}
|
||||
|
||||
public String[] toStringArray() {
|
||||
var destination = new String[size];
|
||||
|
||||
var i = 0;
|
||||
for (Station station : this)
|
||||
destination[i++] = station.toString();
|
||||
|
||||
return destination;
|
||||
}
|
||||
|
||||
public StationList merge(StationList other) {
|
||||
for (Station station : other)
|
||||
add(station);
|
||||
return this;
|
||||
}
|
||||
|
||||
@Override
|
||||
public Iterator<Station> iterator() {
|
||||
return new Iterator<>() {
|
||||
private int index = 0;
|
||||
|
||||
@Override
|
||||
public boolean hasNext() {
|
||||
Station station = null;
|
||||
while (index <= MAX_ENTRY && (station = array[index]) == null)
|
||||
index++;
|
||||
return station != null;
|
||||
}
|
||||
|
||||
@Override
|
||||
public Station next() {
|
||||
if (hasNext()) {
|
||||
return array[index++];
|
||||
}
|
||||
throw new NoSuchElementException();
|
||||
}
|
||||
};
|
||||
}
|
||||
}
|
||||
|
||||
private static String take(String s, char c) {
|
||||
var pos = s.indexOf(c);
|
||||
return pos > -1 ? s.substring(0, pos) : s;
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user