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Faster version of the data generator

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Rene Schwietzke 2024-01-03 00:13:11 +01:00 committed by Gunnar Morling
parent 7d485d0e8b
commit 04bd2d69b6
5 changed files with 1435 additions and 2 deletions
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create_measurements2.sh Executable file
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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 --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CreateMeasurements2 $1

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src/main/java/dev/morling/onebrc/CreateMeasurements2.java Normal file
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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.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.ThreadLocalRandom;
import org.rschwietzke.CheaperCharBuffer;
import org.rschwietzke.FastRandom;
/**
* Faster version with some data faking instead of a real Gaussian distribution
* Good enough for our purppose I guess.
*/
public class CreateMeasurements2 {
private static final String FILE = "./measurements2.txt";
static class WeatherStation {
final static char[] NUMBERS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
final String id;
final int meanTemperature;
final char[] firstPart;
final FastRandom r = new FastRandom(ThreadLocalRandom.current().nextLong());
WeatherStation(String id, double meanTemperature) {
this.id = id;
this.meanTemperature = (int) meanTemperature;
// make it directly copyable
this.firstPart = (id + ";").toCharArray();
}
/**
* We write out data into the buffer to avoid string conversion
* We also no longer use double and gaussian, because for our
* purpose, the fake numbers here will do it. Less
*
* @param buffer the buffer to append to
*/
void measurement(final CheaperCharBuffer buffer) {
// fake -10.9 to +10.9 variance without double operations and rounding
// gives us -10 to +10
int m = meanTemperature + (r.nextInt(21) - 10);
// gives us a decimal digit 0 to 9 as char
char d = NUMBERS[r.nextInt(10)];
// just append, only one number has to be converted and we can do
// better... if we watn
buffer.append(firstPart, 0, firstPart.length)
.append(String.valueOf(m)).append('.').append(d)
.append('\n');
}
}
public static void main(String[] args) throws Exception {
long start = System.currentTimeMillis();
if (args.length != 1) {
System.out.println("Usage: create_measurements.sh <number of records to create>");
System.exit(1);
}
int size = 0;
try {
size = Integer.parseInt(args[0]);
}
catch (NumberFormatException e) {
System.out.println("Invalid value for <number of records to create>");
System.out.println("Usage: CreateMeasurements <number of records to create>");
System.exit(1);
}
// @formatter:off
// data from https://en.wikipedia.org/wiki/List_of_cities_by_average_temperature;
// converted using https://wikitable2csv.ggor.de/
// brought to form using DuckDB:
// D copy (
// select City, regexp_extract(Year,'(.*)\n.*', 1) as AverageTemp
// from (
// select City,Year
// from read_csv_auto('List_of_cities_by_average_temperature_1.csv', header = true)
// union
// select City,Year
// from read_csv_auto('List_of_cities_by_average_temperature_2.csv', header = true)
// union
// select City,Year
// from read_csv_auto('List_of_cities_by_average_temperature_3.csv', header = true)
// union
// select City,Year
// from read_csv_auto('List_of_cities_by_average_temperature_4.csv', header = true)
// union
// select City,Year
// from read_csv_auto('List_of_cities_by_average_temperature_5.csv', header = true)
// )
// ) TO 'output.csv' (HEADER, DELIMITER ',');
// @formatter:on
final List<WeatherStation> stations = Arrays.asList(
new WeatherStation("Abha", 18.0),
new WeatherStation("Abidjan", 26.0),
new WeatherStation("Abéché", 29.4),
new WeatherStation("Accra", 26.4),
new WeatherStation("Addis Ababa", 16.0),
new WeatherStation("Adelaide", 17.3),
new WeatherStation("Aden", 29.1),
new WeatherStation("Ahvaz", 25.4),
new WeatherStation("Albuquerque", 14.0),
new WeatherStation("Alexandra", 11.0),
new WeatherStation("Alexandria", 20.0),
new WeatherStation("Algiers", 18.2),
new WeatherStation("Alice Springs", 21.0),
new WeatherStation("Almaty", 10.0),
new WeatherStation("Amsterdam", 10.2),
new WeatherStation("Anadyr", -6.9),
new WeatherStation("Anchorage", 2.8),
new WeatherStation("Andorra la Vella", 9.8),
new WeatherStation("Ankara", 12.0),
new WeatherStation("Antananarivo", 17.9),
new WeatherStation("Antsiranana", 25.2),
new WeatherStation("Arkhangelsk", 1.3),
new WeatherStation("Ashgabat", 17.1),
new WeatherStation("Asmara", 15.6),
new WeatherStation("Assab", 30.5),
new WeatherStation("Astana", 3.5),
new WeatherStation("Athens", 19.2),
new WeatherStation("Atlanta", 17.0),
new WeatherStation("Auckland", 15.2),
new WeatherStation("Austin", 20.7),
new WeatherStation("Baghdad", 22.77),
new WeatherStation("Baguio", 19.5),
new WeatherStation("Baku", 15.1),
new WeatherStation("Baltimore", 13.1),
new WeatherStation("Bamako", 27.8),
new WeatherStation("Bangkok", 28.6),
new WeatherStation("Bangui", 26.0),
new WeatherStation("Banjul", 26.0),
new WeatherStation("Barcelona", 18.2),
new WeatherStation("Bata", 25.1),
new WeatherStation("Batumi", 14.0),
new WeatherStation("Beijing", 12.9),
new WeatherStation("Beirut", 20.9),
new WeatherStation("Belgrade", 12.5),
new WeatherStation("Belize City", 26.7),
new WeatherStation("Benghazi", 19.9),
new WeatherStation("Bergen", 7.7),
new WeatherStation("Berlin", 10.3),
new WeatherStation("Bilbao", 14.7),
new WeatherStation("Birao", 26.5),
new WeatherStation("Bishkek", 11.3),
new WeatherStation("Bissau", 27.0),
new WeatherStation("Blantyre", 22.2),
new WeatherStation("Bloemfontein", 15.6),
new WeatherStation("Boise", 11.4),
new WeatherStation("Bordeaux", 14.2),
new WeatherStation("Bosaso", 30.0),
new WeatherStation("Boston", 10.9),
new WeatherStation("Bouaké", 26.0),
new WeatherStation("Bratislava", 10.5),
new WeatherStation("Brazzaville", 25.0),
new WeatherStation("Bridgetown", 27.0),
new WeatherStation("Brisbane", 21.4),
new WeatherStation("Brussels", 10.5),
new WeatherStation("Bucharest", 10.8),
new WeatherStation("Budapest", 11.3),
new WeatherStation("Bujumbura", 23.8),
new WeatherStation("Bulawayo", 18.9),
new WeatherStation("Burnie", 13.1),
new WeatherStation("Busan", 15.0),
new WeatherStation("Cabo San Lucas", 23.9),
new WeatherStation("Cairns", 25.0),
new WeatherStation("Cairo", 21.4),
new WeatherStation("Calgary", 4.4),
new WeatherStation("Canberra", 13.1),
new WeatherStation("Cape Town", 16.2),
new WeatherStation("Changsha", 17.4),
new WeatherStation("Charlotte", 16.1),
new WeatherStation("Chiang Mai", 25.8),
new WeatherStation("Chicago", 9.8),
new WeatherStation("Chihuahua", 18.6),
new WeatherStation("Chișinău", 10.2),
new WeatherStation("Chittagong", 25.9),
new WeatherStation("Chongqing", 18.6),
new WeatherStation("Christchurch", 12.2),
new WeatherStation("City of San Marino", 11.8),
new WeatherStation("Colombo", 27.4),
new WeatherStation("Columbus", 11.7),
new WeatherStation("Conakry", 26.4),
new WeatherStation("Copenhagen", 9.1),
new WeatherStation("Cotonou", 27.2),
new WeatherStation("Cracow", 9.3),
new WeatherStation("Da Lat", 17.9),
new WeatherStation("Da Nang", 25.8),
new WeatherStation("Dakar", 24.0),
new WeatherStation("Dallas", 19.0),
new WeatherStation("Damascus", 17.0),
new WeatherStation("Dampier", 26.4),
new WeatherStation("Dar es Salaam", 25.8),
new WeatherStation("Darwin", 27.6),
new WeatherStation("Denpasar", 23.7),
new WeatherStation("Denver", 10.4),
new WeatherStation("Detroit", 10.0),
new WeatherStation("Dhaka", 25.9),
new WeatherStation("Dikson", -11.1),
new WeatherStation("Dili", 26.6),
new WeatherStation("Djibouti", 29.9),
new WeatherStation("Dodoma", 22.7),
new WeatherStation("Dolisie", 24.0),
new WeatherStation("Douala", 26.7),
new WeatherStation("Dubai", 26.9),
new WeatherStation("Dublin", 9.8),
new WeatherStation("Dunedin", 11.1),
new WeatherStation("Durban", 20.6),
new WeatherStation("Dushanbe", 14.7),
new WeatherStation("Edinburgh", 9.3),
new WeatherStation("Edmonton", 4.2),
new WeatherStation("El Paso", 18.1),
new WeatherStation("Entebbe", 21.0),
new WeatherStation("Erbil", 19.5),
new WeatherStation("Erzurum", 5.1),
new WeatherStation("Fairbanks", -2.3),
new WeatherStation("Fianarantsoa", 17.9),
new WeatherStation("Flores, Petén", 26.4),
new WeatherStation("Frankfurt", 10.6),
new WeatherStation("Fresno", 17.9),
new WeatherStation("Fukuoka", 17.0),
new WeatherStation("Gabès", 19.5),
new WeatherStation("Gaborone", 21.0),
new WeatherStation("Gagnoa", 26.0),
new WeatherStation("Gangtok", 15.2),
new WeatherStation("Garissa", 29.3),
new WeatherStation("Garoua", 28.3),
new WeatherStation("George Town", 27.9),
new WeatherStation("Ghanzi", 21.4),
new WeatherStation("Gjoa Haven", -14.4),
new WeatherStation("Guadalajara", 20.9),
new WeatherStation("Guangzhou", 22.4),
new WeatherStation("Guatemala City", 20.4),
new WeatherStation("Halifax", 7.5),
new WeatherStation("Hamburg", 9.7),
new WeatherStation("Hamilton", 13.8),
new WeatherStation("Hanga Roa", 20.5),
new WeatherStation("Hanoi", 23.6),
new WeatherStation("Harare", 18.4),
new WeatherStation("Harbin", 5.0),
new WeatherStation("Hargeisa", 21.7),
new WeatherStation("Hat Yai", 27.0),
new WeatherStation("Havana", 25.2),
new WeatherStation("Helsinki", 5.9),
new WeatherStation("Heraklion", 18.9),
new WeatherStation("Hiroshima", 16.3),
new WeatherStation("Ho Chi Minh City", 27.4),
new WeatherStation("Hobart", 12.7),
new WeatherStation("Hong Kong", 23.3),
new WeatherStation("Honiara", 26.5),
new WeatherStation("Honolulu", 25.4),
new WeatherStation("Houston", 20.8),
new WeatherStation("Ifrane", 11.4),
new WeatherStation("Indianapolis", 11.8),
new WeatherStation("Iqaluit", -9.3),
new WeatherStation("Irkutsk", 1.0),
new WeatherStation("Istanbul", 13.9),
new WeatherStation("İzmir", 17.9),
new WeatherStation("Jacksonville", 20.3),
new WeatherStation("Jakarta", 26.7),
new WeatherStation("Jayapura", 27.0),
new WeatherStation("Jerusalem", 18.3),
new WeatherStation("Johannesburg", 15.5),
new WeatherStation("Jos", 22.8),
new WeatherStation("Juba", 27.8),
new WeatherStation("Kabul", 12.1),
new WeatherStation("Kampala", 20.0),
new WeatherStation("Kandi", 27.7),
new WeatherStation("Kankan", 26.5),
new WeatherStation("Kano", 26.4),
new WeatherStation("Kansas City", 12.5),
new WeatherStation("Karachi", 26.0),
new WeatherStation("Karonga", 24.4),
new WeatherStation("Kathmandu", 18.3),
new WeatherStation("Khartoum", 29.9),
new WeatherStation("Kingston", 27.4),
new WeatherStation("Kinshasa", 25.3),
new WeatherStation("Kolkata", 26.7),
new WeatherStation("Kuala Lumpur", 27.3),
new WeatherStation("Kumasi", 26.0),
new WeatherStation("Kunming", 15.7),
new WeatherStation("Kuopio", 3.4),
new WeatherStation("Kuwait City", 25.7),
new WeatherStation("Kyiv", 8.4),
new WeatherStation("Kyoto", 15.8),
new WeatherStation("La Ceiba", 26.2),
new WeatherStation("La Paz", 23.7),
new WeatherStation("Lagos", 26.8),
new WeatherStation("Lahore", 24.3),
new WeatherStation("Lake Havasu City", 23.7),
new WeatherStation("Lake Tekapo", 8.7),
new WeatherStation("Las Palmas de Gran Canaria", 21.2),
new WeatherStation("Las Vegas", 20.3),
new WeatherStation("Launceston", 13.1),
new WeatherStation("Lhasa", 7.6),
new WeatherStation("Libreville", 25.9),
new WeatherStation("Lisbon", 17.5),
new WeatherStation("Livingstone", 21.8),
new WeatherStation("Ljubljana", 10.9),
new WeatherStation("Lodwar", 29.3),
new WeatherStation("Lomé", 26.9),
new WeatherStation("London", 11.3),
new WeatherStation("Los Angeles", 18.6),
new WeatherStation("Louisville", 13.9),
new WeatherStation("Luanda", 25.8),
new WeatherStation("Lubumbashi", 20.8),
new WeatherStation("Lusaka", 19.9),
new WeatherStation("Luxembourg City", 9.3),
new WeatherStation("Lviv", 7.8),
new WeatherStation("Lyon", 12.5),
new WeatherStation("Madrid", 15.0),
new WeatherStation("Mahajanga", 26.3),
new WeatherStation("Makassar", 26.7),
new WeatherStation("Makurdi", 26.0),
new WeatherStation("Malabo", 26.3),
new WeatherStation("Malé", 28.0),
new WeatherStation("Managua", 27.3),
new WeatherStation("Manama", 26.5),
new WeatherStation("Mandalay", 28.0),
new WeatherStation("Mango", 28.1),
new WeatherStation("Manila", 28.4),
new WeatherStation("Maputo", 22.8),
new WeatherStation("Marrakesh", 19.6),
new WeatherStation("Marseille", 15.8),
new WeatherStation("Maun", 22.4),
new WeatherStation("Medan", 26.5),
new WeatherStation("Mek'ele", 22.7),
new WeatherStation("Melbourne", 15.1),
new WeatherStation("Memphis", 17.2),
new WeatherStation("Mexicali", 23.1),
new WeatherStation("Mexico City", 17.5),
new WeatherStation("Miami", 24.9),
new WeatherStation("Milan", 13.0),
new WeatherStation("Milwaukee", 8.9),
new WeatherStation("Minneapolis", 7.8),
new WeatherStation("Minsk", 6.7),
new WeatherStation("Mogadishu", 27.1),
new WeatherStation("Mombasa", 26.3),
new WeatherStation("Monaco", 16.4),
new WeatherStation("Moncton", 6.1),
new WeatherStation("Monterrey", 22.3),
new WeatherStation("Montreal", 6.8),
new WeatherStation("Moscow", 5.8),
new WeatherStation("Mumbai", 27.1),
new WeatherStation("Murmansk", 0.6),
new WeatherStation("Muscat", 28.0),
new WeatherStation("Mzuzu", 17.7),
new WeatherStation("N'Djamena", 28.3),
new WeatherStation("Naha", 23.1),
new WeatherStation("Nairobi", 17.8),
new WeatherStation("Nakhon Ratchasima", 27.3),
new WeatherStation("Napier", 14.6),
new WeatherStation("Napoli", 15.9),
new WeatherStation("Nashville", 15.4),
new WeatherStation("Nassau", 24.6),
new WeatherStation("Ndola", 20.3),
new WeatherStation("New Delhi", 25.0),
new WeatherStation("New Orleans", 20.7),
new WeatherStation("New York City", 12.9),
new WeatherStation("Ngaoundéré", 22.0),
new WeatherStation("Niamey", 29.3),
new WeatherStation("Nicosia", 19.7),
new WeatherStation("Niigata", 13.9),
new WeatherStation("Nouadhibou", 21.3),
new WeatherStation("Nouakchott", 25.7),
new WeatherStation("Novosibirsk", 1.7),
new WeatherStation("Nuuk", -1.4),
new WeatherStation("Odesa", 10.7),
new WeatherStation("Odienné", 26.0),
new WeatherStation("Oklahoma City", 15.9),
new WeatherStation("Omaha", 10.6),
new WeatherStation("Oranjestad", 28.1),
new WeatherStation("Oslo", 5.7),
new WeatherStation("Ottawa", 6.6),
new WeatherStation("Ouagadougou", 28.3),
new WeatherStation("Ouahigouya", 28.6),
new WeatherStation("Ouarzazate", 18.9),
new WeatherStation("Oulu", 2.7),
new WeatherStation("Palembang", 27.3),
new WeatherStation("Palermo", 18.5),
new WeatherStation("Palm Springs", 24.5),
new WeatherStation("Palmerston North", 13.2),
new WeatherStation("Panama City", 28.0),
new WeatherStation("Parakou", 26.8),
new WeatherStation("Paris", 12.3),
new WeatherStation("Perth", 18.7),
new WeatherStation("Petropavlovsk-Kamchatsky", 1.9),
new WeatherStation("Philadelphia", 13.2),
new WeatherStation("Phnom Penh", 28.3),
new WeatherStation("Phoenix", 23.9),
new WeatherStation("Pittsburgh", 10.8),
new WeatherStation("Podgorica", 15.3),
new WeatherStation("Pointe-Noire", 26.1),
new WeatherStation("Pontianak", 27.7),
new WeatherStation("Port Moresby", 26.9),
new WeatherStation("Port Sudan", 28.4),
new WeatherStation("Port Vila", 24.3),
new WeatherStation("Port-Gentil", 26.0),
new WeatherStation("Portland (OR)", 12.4),
new WeatherStation("Porto", 15.7),
new WeatherStation("Prague", 8.4),
new WeatherStation("Praia", 24.4),
new WeatherStation("Pretoria", 18.2),
new WeatherStation("Pyongyang", 10.8),
new WeatherStation("Rabat", 17.2),
new WeatherStation("Rangpur", 24.4),
new WeatherStation("Reggane", 28.3),
new WeatherStation("Reykjavík", 4.3),
new WeatherStation("Riga", 6.2),
new WeatherStation("Riyadh", 26.0),
new WeatherStation("Rome", 15.2),
new WeatherStation("Roseau", 26.2),
new WeatherStation("Rostov-on-Don", 9.9),
new WeatherStation("Sacramento", 16.3),
new WeatherStation("Saint Petersburg", 5.8),
new WeatherStation("Saint-Pierre", 5.7),
new WeatherStation("Salt Lake City", 11.6),
new WeatherStation("San Antonio", 20.8),
new WeatherStation("San Diego", 17.8),
new WeatherStation("San Francisco", 14.6),
new WeatherStation("San Jose", 16.4),
new WeatherStation("San José", 22.6),
new WeatherStation("San Juan", 27.2),
new WeatherStation("San Salvador", 23.1),
new WeatherStation("Sana'a", 20.0),
new WeatherStation("Santo Domingo", 25.9),
new WeatherStation("Sapporo", 8.9),
new WeatherStation("Sarajevo", 10.1),
new WeatherStation("Saskatoon", 3.3),
new WeatherStation("Seattle", 11.3),
new WeatherStation("Ségou", 28.0),
new WeatherStation("Seoul", 12.5),
new WeatherStation("Seville", 19.2),
new WeatherStation("Shanghai", 16.7),
new WeatherStation("Singapore", 27.0),
new WeatherStation("Skopje", 12.4),
new WeatherStation("Sochi", 14.2),
new WeatherStation("Sofia", 10.6),
new WeatherStation("Sokoto", 28.0),
new WeatherStation("Split", 16.1),
new WeatherStation("St. John's", 5.0),
new WeatherStation("St. Louis", 13.9),
new WeatherStation("Stockholm", 6.6),
new WeatherStation("Surabaya", 27.1),
new WeatherStation("Suva", 25.6),
new WeatherStation("Suwałki", 7.2),
new WeatherStation("Sydney", 17.7),
new WeatherStation("Tabora", 23.0),
new WeatherStation("Tabriz", 12.6),
new WeatherStation("Taipei", 23.0),
new WeatherStation("Tallinn", 6.4),
new WeatherStation("Tamale", 27.9),
new WeatherStation("Tamanrasset", 21.7),
new WeatherStation("Tampa", 22.9),
new WeatherStation("Tashkent", 14.8),
new WeatherStation("Tauranga", 14.8),
new WeatherStation("Tbilisi", 12.9),
new WeatherStation("Tegucigalpa", 21.7),
new WeatherStation("Tehran", 17.0),
new WeatherStation("Tel Aviv", 20.0),
new WeatherStation("Thessaloniki", 16.0),
new WeatherStation("Thiès", 24.0),
new WeatherStation("Tijuana", 17.8),
new WeatherStation("Timbuktu", 28.0),
new WeatherStation("Tirana", 15.2),
new WeatherStation("Toamasina", 23.4),
new WeatherStation("Tokyo", 15.4),
new WeatherStation("Toliara", 24.1),
new WeatherStation("Toluca", 12.4),
new WeatherStation("Toronto", 9.4),
new WeatherStation("Tripoli", 20.0),
new WeatherStation("Tromsø", 2.9),
new WeatherStation("Tucson", 20.9),
new WeatherStation("Tunis", 18.4),
new WeatherStation("Ulaanbaatar", -0.4),
new WeatherStation("Upington", 20.4),
new WeatherStation("Ürümqi", 7.4),
new WeatherStation("Vaduz", 10.1),
new WeatherStation("Valencia", 18.3),
new WeatherStation("Valletta", 18.8),
new WeatherStation("Vancouver", 10.4),
new WeatherStation("Veracruz", 25.4),
new WeatherStation("Vienna", 10.4),
new WeatherStation("Vientiane", 25.9),
new WeatherStation("Villahermosa", 27.1),
new WeatherStation("Vilnius", 6.0),
new WeatherStation("Virginia Beach", 15.8),
new WeatherStation("Vladivostok", 4.9),
new WeatherStation("Warsaw", 8.5),
new WeatherStation("Washington, D.C.", 14.6),
new WeatherStation("Wau", 27.8),
new WeatherStation("Wellington", 12.9),
new WeatherStation("Whitehorse", -0.1),
new WeatherStation("Wichita", 13.9),
new WeatherStation("Willemstad", 28.0),
new WeatherStation("Winnipeg", 3.0),
new WeatherStation("Wrocław", 9.6),
new WeatherStation("Xi'an", 14.1),
new WeatherStation("Yakutsk", -8.8),
new WeatherStation("Yangon", 27.5),
new WeatherStation("Yaoundé", 23.8),
new WeatherStation("Yellowknife", -4.3),
new WeatherStation("Yerevan", 12.4),
new WeatherStation("Yinchuan", 9.0),
new WeatherStation("Zagreb", 10.7),
new WeatherStation("Zanzibar City", 26.0),
new WeatherStation("Zürich", 9.3));
File file = new File(FILE);
// break the loop and unroll it manually
int strideSize = 50_000_000;
int outer = size / strideSize;
int remainder = size - (outer * strideSize);
try (final BufferedWriter bw = new BufferedWriter(new FileWriter(file))) {
for (int i = 0; i < outer; i++) {
produce(bw, stations, strideSize);
// we avoid a modulo if here and use the stride size to print and update
System.out.println("Wrote %,d measurements in %s ms".formatted((i + 1) * strideSize, System.currentTimeMillis() - start));
}
// there might be a rest
produce(bw, stations, remainder);
// write fully before taking measurements
bw.flush();
System.out.println("Created file with %,d measurements in %s ms".formatted(size, System.currentTimeMillis() - start));
}
}
private static void produce(BufferedWriter bw, List<WeatherStation> stations, int count) throws IOException {
final int stationCount = stations.size();
final int rest = count % 8;
// use a fast ranodm impl without atomics to be able to utilize the cpu better
// and avoid sideeffects, FastRandom is very fake random and does not have a state
final FastRandom r1 = new FastRandom(ThreadLocalRandom.current().nextLong());
final FastRandom r2 = new FastRandom(ThreadLocalRandom.current().nextLong());
final FastRandom r3 = new FastRandom(ThreadLocalRandom.current().nextLong());
final FastRandom r4 = new FastRandom(ThreadLocalRandom.current().nextLong());
// write to a fix buffer first, don't create strings ever
// reuse buffer
final CheaperCharBuffer sb = new CheaperCharBuffer(200);
// manual loop unroll for less jumps
for (int i = 0; i < count; i = i + 8) {
{
// try to fill teh cpu pipeline as much as possible with
// independent operations
int s1 = r1.nextInt(stationCount);
int s2 = r2.nextInt(stationCount);
int s3 = r3.nextInt(stationCount);
int s4 = r4.nextInt(stationCount);
// get us the ojects one after the other to have the array
// in our L1 cache and not push it out with other data
var w1 = stations.get(s1);
var w2 = stations.get(s2);
var w3 = stations.get(s3);
var w4 = stations.get(s4);
// write our data to our buffer
w1.measurement(sb);
w2.measurement(sb);
w3.measurement(sb);
w4.measurement(sb);
}
{
int s1 = r1.nextInt(stationCount);
int s2 = r2.nextInt(stationCount);
int s3 = r3.nextInt(stationCount);
int s4 = r4.nextInt(stationCount);
var w1 = stations.get(s1);
var w2 = stations.get(s2);
var w3 = stations.get(s3);
var w4 = stations.get(s4);
w1.measurement(sb);
w2.measurement(sb);
w3.measurement(sb);
w4.measurement(sb);
}
// write the buffer directly, no intermediate string copy
bw.write(sb.data_, 0, sb.length_);
// reuse buffer, reset only, no cleaning
sb.clear();
}
// there might be a rest to write
for (int i = 0; i < rest; i++) {
sb.clear();
int s = r1.nextInt(stationCount);
var w = stations.get(s);
w.measurement(sb);
bw.write(sb.data_, 0, sb.length_);
}
}
}

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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 org.rschwietzke;
import java.util.Arrays;
/**
* <p>This class is meant to replaces the old {@link CheaperCharBuffer} in all areas
* where performance and memory-efficency is key. XMLString compatibility
* remains in place in case one has used that in their own code.
*
* <p>This buffer is mutable and when you use it, make sure you work with
* it responsibly. In many cases, we will reuse the buffer to avoid fresh
* memory allocations, hence you have to pay attention to its usage pattern.
* It is not meant to be a general String replacement.
*
* <p>This class avoids many of the standard runtime checks that will result
* in a runtime or array exception anyway. Why check twice and raise the
* same exception?
*
* @author René Schwietzke
* @since 3.10.0
*/
public class CheaperCharBuffer implements CharSequence {
// our data, can grow - that is not safe and has be altered from the original code
// to allow speed
public char[] data_;
// the current size of the string data
public int length_;
// the current size of the string data
private final int growBy_;
// how much do we grow if needed, half a cache line
public static final int CAPACITY_GROWTH = 64 / 2;
// what is our start size?
// a cache line is 64 byte mostly, the overhead is mostly 24 bytes
// a char is two bytes, let's use one cache lines
public static final int INITIAL_CAPACITY = (64 - 24) / 2;
// static empty version; DON'T MODIFY IT
public static final CheaperCharBuffer EMPTY = new CheaperCharBuffer(0);
// the <EFBFBD> character
private static final char REPLACEMENT_CHARACTER = '\uFFFD';
/**
* Constructs an XMLCharBuffer with a default size.
*/
public CheaperCharBuffer() {
this.data_ = new char[INITIAL_CAPACITY];
this.length_ = 0;
this.growBy_ = CAPACITY_GROWTH;
}
/**
* Constructs an XMLCharBuffer with a desired size.
*
* @param startSize the size of the buffer to start with
*/
public CheaperCharBuffer(final int startSize) {
this(startSize, CAPACITY_GROWTH);
}
/**
* Constructs an XMLCharBuffer with a desired size.
*
* @param startSize the size of the buffer to start with
* @param growBy by how much do we want to grow when needed
*/
public CheaperCharBuffer(final int startSize, final int growBy) {
this.data_ = new char[startSize];
this.length_ = 0;
this.growBy_ = Math.max(1, growBy);
}
/**
* Constructs an XMLCharBuffer from another buffer. Copies the data
* over. The new buffer capacity matches the length of the source.
*
* @param src the source buffer to copy from
*/
public CheaperCharBuffer(final CheaperCharBuffer src) {
this(src, 0);
}
/**
* Constructs an XMLCharBuffer from another buffer. Copies the data
* over. You can add more capacity on top of the source length. If
* you specify 0, the capacity will match the src length.
*
* @param src the source buffer to copy from
* @param addCapacity how much capacity to add to origin length
*/
public CheaperCharBuffer(final CheaperCharBuffer src, final int addCapacity) {
this.data_ = Arrays.copyOf(src.data_, src.length_ + Math.max(0, addCapacity));
this.length_ = src.length();
this.growBy_ = Math.max(1, CAPACITY_GROWTH);
}
/**
* Constructs an XMLCharBuffer from a string. To avoid
* too much allocation, we just take the string array as is and
* don't allocate extra space in the first place.
*
* @param src the string to copy from
*/
public CheaperCharBuffer(final String src) {
this.data_ = src.toCharArray();
this.length_ = src.length();
this.growBy_ = CAPACITY_GROWTH;
}
/**
* Constructs an XMLString structure preset with the specified values.
* There will not be any room to grow, if you need that, construct an
* empty one and append.
*
* <p>There are not range checks performed. Make sure your data is correct.
*
* @param ch The character array, must not be null
* @param offset The offset into the character array.
* @param length The length of characters from the offset.
*/
public CheaperCharBuffer(final char[] ch, final int offset, final int length) {
// just as big as we need it
this(length);
append(ch, offset, length);
}
/**
* Check capacity and grow if needed automatically
*
* @param minimumCapacity how much space do we need at least
*/
private void ensureCapacity(final int minimumCapacity) {
if (minimumCapacity > this.data_.length) {
final int newSize = Math.max(minimumCapacity + this.growBy_, (this.data_.length << 1) + 2);
this.data_ = Arrays.copyOf(this.data_, newSize);
}
}
/**
* Returns the current max capacity without growth. Does not
* indicate how much capacity is already in use. Use {@link #length()}
* for that.
*
* @return the current capacity, not taken any usage into account
*/
public int capacity() {
return this.data_.length;
}
/**
* Appends a single character to the buffer.
*
* @param c the character to append
* @return this instance
*/
public CheaperCharBuffer append(final char c) {
final int oldLength = this.length_++;
// ensureCapacity is not inlined by the compiler, so put that here for the most
// called method of all appends. Duplicate code, but for a reason.
if (oldLength == this.data_.length) {
final int newSize = Math.max(oldLength + this.growBy_, (this.data_.length << 1) + 2);
this.data_ = Arrays.copyOf(this.data_, newSize);
}
this.data_[oldLength] = c;
return this;
}
/**
* Append a string to this buffer without copying the string first.
*
* @param src the string to append
* @return this instance
*/
public CheaperCharBuffer append(final String src) {
final int start = this.length_;
this.length_ = this.length_ + src.length();
ensureCapacity(this.length_);
// copy char by char because we don't get a copy for free
// from a string yet, this might change when immutable arrays
// make it into Java, but that will not be very soon
for (int i = 0; i < src.length(); i++) {
this.data_[start + i] = src.charAt(i);
}
return this;
}
/**
* Add another buffer to this one.
*
* @param src the buffer to append
* @return this instance
*/
public CheaperCharBuffer append(final CheaperCharBuffer src) {
final int start = this.length_;
this.length_ = this.length_ + src.length();
ensureCapacity(this.length_);
System.arraycopy(src.data_, 0, this.data_, start, src.length_);
return this;
}
/**
* Add data from a char array to this buffer with the ability to specify
* a range to copy from
*
* @param src the source char array
* @param offset the pos to start to copy from
* @param length the length of the data to copy
*
* @return this instance
*/
public CheaperCharBuffer append(final char[] src, final int offset, final int length) {
final int start = this.length_;
this.length_ = start + length;
ensureCapacity(this.length_);
System.arraycopy(src, offset, this.data_, start, length);
return this;
}
/**
* Returns the current length
*
* @return the length of the charbuffer data
*/
public int length() {
return length_;
}
/**
* Tell us how much the capacity grows if needed
*
* @return the value that determines how much we grow the backing
* array in case we have to
*/
public int getGrowBy() {
return this.growBy_;
}
/**
* Resets the buffer to 0 length. It won't resize it to avoid memory
* churn.
*
* @return this instance for fluid programming
*/
public CheaperCharBuffer clear() {
this.length_ = 0;
return this;
}
/**
* Resets the buffer to 0 length and sets the new data. This
* is a little cheaper than clear().append(c) depending on
* the where and the inlining decisions.
*
* @param c the char to set
* @return this instance for fluid programming
*/
public CheaperCharBuffer clearAndAppend(final char c) {
this.length_ = 0;
if (this.data_.length > 0) {
this.data_[this.length_] = c;
this.length_++;
}
else {
// the rare case when we don't have any buffer at hand
append(c);
}
return this;
}
/**
* Does this buffer end with this string? If we check for
* the empty string, we get true. If we would support JDK 11, we could
* use Arrays.mismatch and be way faster.
*
* @param s the string to check the end against
* @return true of the end matches the buffer, false otherwise
*/
public boolean endsWith(final String s) {
// length does not match, cannot be the end
if (this.length_ < s.length()) {
return false;
}
// check the string by each char, avoids a copy of the string
final int start = this.length_ - s.length();
// change this to Arrays.mismatch when going JDK 11 or higher
for (int i = 0; i < s.length(); i++) {
if (this.data_[i + start] != s.charAt(i)) {
return false;
}
}
return true;
}
/**
* Reduces the buffer to the content between start and end marker when
* only whitespaces are found before the startMarker as well as after the end marker.
* If both strings overlap due to identical characters such as "foo" and "oof"
* and the buffer is " foof ", we don't do anything.
*
* <p>If a marker is empty, it behaves like {@link java.lang.String#trim()} on that side.
*
* @param startMarker the start string to find, must not be null
* @param endMarker the end string to find, must not be null
* @return this instance
*
* @deprecated Use the new method {@link #trimToContent(String, String)} instead.
*/
public CheaperCharBuffer reduceToContent(final String startMarker, final String endMarker) {
return trimToContent(startMarker, endMarker);
}
/**
* Reduces the buffer to the content between start and end marker when
* only whitespaces are found before the startMarker as well as after the end marker.
* If both strings overlap due to identical characters such as "foo" and "oof"
* and the buffer is " foof ", we don't do anything.
*
* <p>If a marker is empty, it behaves like {@link java.lang.String#trim()} on that side.
*
* @param startMarker the start string to find, must not be null
* @param endMarker the end string to find, must not be null
* @return this instance
*/
public CheaperCharBuffer trimToContent(final String startMarker, final String endMarker) {
// if both are longer or same length than content, don't do anything
final int markerLength = startMarker.length() + endMarker.length();
if (markerLength >= this.length_) {
return this;
}
// run over starting whitespaces
int sPos = 0;
for (; sPos < this.length_ - markerLength; sPos++) {
if (!Character.isWhitespace(this.data_[sPos])) {
break;
}
}
// run over ending whitespaces
int ePos = this.length_ - 1;
for (; ePos > sPos - markerLength; ePos--) {
if (!Character.isWhitespace(this.data_[ePos])) {
break;
}
}
// if we have less content than marker length, give up
// this also helps when markers overlap such as
// <!-- and --> and the string is " <!---> "
if (ePos - sPos + 1 < markerLength) {
return this;
}
// check the start
for (int i = 0; i < startMarker.length(); i++) {
if (startMarker.charAt(i) != this.data_[i + sPos]) {
// no start match, stop and don't do anything
return this;
}
}
// check the end, ePos is when the first good char
// occurred
final int endStartCheckPos = ePos - endMarker.length() + 1;
for (int i = 0; i < endMarker.length(); i++) {
if (endMarker.charAt(i) != this.data_[endStartCheckPos + i]) {
// no start match, stop and don't do anything
return this;
}
}
// shift left and cut length
final int newLength = ePos - sPos + 1 - markerLength;
System.arraycopy(this.data_,
sPos + startMarker.length(),
this.data_,
0, newLength);
this.length_ = newLength;
return this;
}
/**
* Check if we have only whitespaces
*
* @return true if we have only whitespace, false otherwise
*/
public boolean isWhitespace() {
for (int i = 0; i < this.length_; i++) {
if (!Character.isWhitespace(this.data_[i])) {
return false;
}
}
return true;
}
/**
* Trims the string similar to {@link java.lang.String#trim()}
*
* @return a string with removed whitespace at the beginning and the end
*/
public CheaperCharBuffer trim() {
// clean the end first, because it is cheap
return trimTrailing().trimLeading();
}
/**
* Removes all whitespace before the first non-whitespace char.
* If all are whitespaces, we get an empty buffer
*
* @return this instance
*/
public CheaperCharBuffer trimLeading() {
// run over starting whitespace
int sPos = 0;
for (; sPos < this.length_; sPos++) {
if (!Character.isWhitespace(this.data_[sPos])) {
break;
}
}
if (sPos == 0) {
// nothing to do
return this;
}
else if (sPos == this.length_) {
// only whitespace
this.length_ = 0;
return this;
}
// shift left
final int newLength = this.length_ - sPos;
System.arraycopy(this.data_,
sPos,
this.data_,
0, newLength);
this.length_ = newLength;
return this;
}
/**
* Removes all whitespace at the end.
* If all are whitespace, we get an empty buffer
*
* @return this instance
*
* @deprecated Use {@link #trimTrailing()} instead.
*/
public CheaperCharBuffer trimWhitespaceAtEnd() {
return trimTrailing();
}
/**
* Removes all whitespace at the end.
* If all are whitespace, we get an empty buffer
*
* @return this instance
*/
public CheaperCharBuffer trimTrailing() {
// run over ending whitespaces
int ePos = this.length_ - 1;
for (; ePos >= 0; ePos--) {
if (!Character.isWhitespace(this.data_[ePos])) {
break;
}
}
this.length_ = ePos + 1;
return this;
}
/**
* Shortens the buffer by that many positions. If the count is
* larger than the length, we get just an empty buffer. If you pass in negative
* values, we are failing, likely often silently. It is all about performance and
* not a general all-purpose API.
*
* @param count a positive number, no runtime checks, if count is larger than
* length, we get length = 0
* @return this instance
*/
public CheaperCharBuffer shortenBy(final int count) {
final int newLength = this.length_ - count;
this.length_ = newLength < 0 ? 0 : newLength;
return this;
}
/**
* Get the characters as char array, this will be a copy!
*
* @return a copy of the underlying char darta
*/
public char[] getChars() {
return Arrays.copyOf(this.data_, this.length_);
}
/**
* Returns a string representation of this buffer. This will be a copy
* operation. If the buffer is emoty, we get a constant empty String back
* to avoid any overhead.
*
* @return a string of the content of this buffer
*/
@Override
public String toString() {
if (this.length_ > 0) {
return new String(this.data_, 0, this.length_);
}
else {
return "";
}
}
/**
* Returns the char a the given position. Will complain if
* we try to read outside the range. We do a range check here
* because we might not notice when we are within the buffer
* but outside the current length.
*
* @param index the position to read from
* @return the char at the position
* @throws IndexOutOfBoundsException
* in case one tries to read outside of valid buffer range
*/
@Override
public char charAt(final int index) {
if (index > this.length_ - 1 || index < 0) {
throw new IndexOutOfBoundsException(
"Tried to read outside of the valid buffer data");
}
return this.data_[index];
}
/**
* Returns the char at the given position. No checks are
* performed. It is up to the caller to make sure we
* read correctly. Reading outside of the array will
* cause an {@link IndexOutOfBoundsException} but using an
* incorrect position in the array (such as beyond length)
* might stay unnoticed! This is a performance method,
* use at your own risk.
*
* @param index the position to read from
* @return the char at the position
*/
public char unsafeCharAt(final int index) {
return this.data_[index];
}
/**
* Returns a content copy of this buffer
*
* @return a copy of this buffer, the capacity might differ
*/
@Override
public CheaperCharBuffer clone() {
return new CheaperCharBuffer(this);
}
/**
* Returns a <code>CharSequence</code> that is a subsequence of this sequence.
* The subsequence starts with the <code>char</code> value at the specified index and
* ends with the <code>char</code> value at index <tt>end - 1</tt>. The length
* (in <code>char</code>s) of the
* returned sequence is <tt>end - start</tt>, so if <tt>start == end</tt>
* then an empty sequence is returned.
*
* @param start the start index, inclusive
* @param end the end index, exclusive
*
* @return the specified subsequence
*
* @throws IndexOutOfBoundsException
* if <tt>start</tt> or <tt>end</tt> are negative,
* if <tt>end</tt> is greater than <tt>length()</tt>,
* or if <tt>start</tt> is greater than <tt>end</tt>
*
* @return a charsequence of this buffer
*/
@Override
public CharSequence subSequence(final int start, final int end) {
if (start < 0) {
throw new StringIndexOutOfBoundsException(start);
}
if (end > this.length_) {
throw new StringIndexOutOfBoundsException(end);
}
final int l = end - start;
if (l < 0) {
throw new StringIndexOutOfBoundsException(l);
}
return new String(this.data_, start, l);
}
/**
* Two buffers are identical when the length and
* the content of the backing array (only for the
* data in view) are identical.
*
* @param o the object to compare with
* @return true if length and array content match, false otherwise
*/
@Override
public boolean equals(final Object o) {
if (o instanceof CharSequence) {
final CharSequence ob = (CharSequence) o;
if (ob.length() != this.length_) {
return false;
}
// ok, in JDK 11 or up, we could use an
// Arrays.mismatch, but we cannot do that
// due to JDK 8 compatibility
for (int i = 0; i < this.length_; i++) {
if (ob.charAt(i) != this.data_[i]) {
return false;
}
}
// length and content match, be happy
return true;
}
return false;
}
/**
* We don't cache the hashcode because we mutate often. Don't use this in
* hashmaps as key. But you can use that to look up in a hashmap against
* a string using the CharSequence interface.
*
* @return the hashcode, similar to what a normal string would deliver
*/
@Override
public int hashCode() {
int h = 0;
for (int i = 0; i < this.length_; i++) {
h = ((h << 5) - h) + this.data_[i];
}
return h;
}
/**
* Append a character to an XMLCharBuffer. The character is an int value, and
* can either be a single UTF-16 character or a supplementary character
* represented by two UTF-16 code points.
*
* @param value The character value.
* @return this instance for fluid programming
*
* @throws IllegalArgumentException if the specified
* {@code codePoint} is not a valid Unicode code point.
*/
public CheaperCharBuffer appendCodePoint(final int value) {
if (value <= Character.MAX_VALUE) {
return this.append((char) value);
}
else {
try {
final char[] chars = Character.toChars(value);
return this.append(chars, 0, chars.length);
}
catch (final IllegalArgumentException e) {
// when value is not valid as UTF-16
this.append(REPLACEMENT_CHARACTER);
throw e;
}
}
}
}

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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 org.rschwietzke;
/**
* Ultra-fast pseudo random generator that is not synchronized!
* Don't use anything from Random by inheritance, this will inherit
* a volatile! Not my idea, copyied in parts some demo random
* generator lessons.
*
* @author rschwietzke
*
*/
public class FastRandom {
private long seed;
public FastRandom() {
this.seed = System.currentTimeMillis();
}
public FastRandom(long seed) {
this.seed = seed;
}
protected int next(int nbits) {
// N.B. Not thread-safe!
long x = this.seed;
x ^= (x << 21);
x ^= (x >>> 35);
x ^= (x << 4);
this.seed = x;
x &= ((1L << nbits) - 1);
return (int) x;
}
/**
* Borrowed from the JDK
*
* @param bound
* @return
*/
public int nextInt(int bound) {
int r = next(31);
int m = bound - 1;
if ((bound & m) == 0) // i.e., bound is a power of 2
r = (int) ((bound * (long) r) >> 31);
else {
for (int u = r; u - (r = u % bound) + m < 0; u = next(31))
;
}
return r;
}
/**
* Borrowed from the JDK
* @return
*/
public int nextInt() {
return next(32);
}
}