Generate measurements with random names

Name length goes from 1 to 100.

create_measurements3.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 --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CreateMeasurements3 $1

src/main/java/dev/morling/onebrc/CreateMeasurements3.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.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.FileReader;
+import java.io.FileWriter;
+import java.io.StringReader;
+import java.util.ArrayList;
+import java.util.concurrent.ThreadLocalRandom;
+
+public class CreateMeasurements3 {
+
+    public static final int MAX_NAME_LEN = 100;
+    public static final int KEYSET_SIZE = 10_000;
+
+    public static void main(String[] args) throws Exception {
+        if (args.length != 1) {
+            System.out.println("Usage: create_measurements3.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: create_measurements3.sh <number of records to create>");
+            System.exit(1);
+        }
+        final var weatherStations = generateWeatherStations();
+        final var start = System.currentTimeMillis();
+        final var rnd = ThreadLocalRandom.current();
+        try (var out = new BufferedWriter(new FileWriter("measurements.txt"))) {
+            for (int i = 1; i <= size; i++) {
+                var station = weatherStations.get(rnd.nextInt(KEYSET_SIZE));
+                double temp = rnd.nextGaussian(station.avgTemp, 7.0);
+                out.write(station.name);
+                out.write(';');
+                out.write(Double.toString(Math.round(temp * 10.0) / 10.0));
+                out.newLine();
+                if (i % 50_000_000 == 0) {
+                    System.out.printf("Wrote %,d measurements in %,d ms%n", i, System.currentTimeMillis() - start);
+                }
+            }
+        }
+    }
+
+    record WeatherStation(String name, float avgTemp) {
+    }
+
+    private static ArrayList<WeatherStation> generateWeatherStations() throws Exception {
+        // Use a public list of city names and concatenate them all into a long string,
+        // which we'll use as a "source of city name randomness"
+        var bigName = new StringBuilder(1 << 20);
+        // Source: https://simplemaps.com/data/world-cities
+        try (var rows = new BufferedReader(new FileReader("data/weather_stations.csv"));) {
+            while (true) {
+                var row = rows.readLine();
+                if (row == null) {
+                    break;
+                }
+                bigName.append(row, 0, row.indexOf(';'));
+            }
+        }
+        final var weatherStations = new ArrayList<WeatherStation>();
+        var minLen = Integer.MAX_VALUE;
+        var maxLen = Integer.MIN_VALUE;
+        try (var rows = new BufferedReader(new FileReader("data/weather_stations.csv"))) {
+            final var nameSource = new StringReader(bigName.toString());
+            final var buf = new char[MAX_NAME_LEN];
+            final var rnd = ThreadLocalRandom.current();
+            final double yOffset = 4;
+            final double factor = 2500;
+            final double xOffset = 0.372;
+            final double power = 7;
+            for (int i = 0; i < KEYSET_SIZE; i++) {
+                var row = rows.readLine();
+                if (row == null) {
+                    break;
+                }
+                // Use a 7th-order curve to simulate the name length distribution.
+                // It gives us mostly short names, but with large outliers.
+                var nameLen = (int) (yOffset + factor * Math.pow(rnd.nextDouble() - xOffset, power));
+                minLen = Integer.min(minLen, nameLen);
+                maxLen = Integer.max(maxLen, nameLen);
+                var count = nameSource.read(buf, 0, nameLen);
+                if (count == -1) {
+                    throw new Exception("Name source exhausted");
+                }
+                var name = new String(buf, 0, nameLen).trim();
+                while (name.length() < nameLen) {
+                    var n = nameSource.read();
+                    if (n == -1) {
+                        throw new Exception("Name source exhausted");
+                    }
+                    var ch = (char) n;
+                    if (ch != ' ') {
+                        name += ch;
+                    }
+                }
+                if (name.indexOf(';') != -1) {
+                    throw new Exception("Station name contains a semicolon!");
+                }
+                var lat = Float.parseFloat(row.substring(row.indexOf(';') + 1));
+                // Guesstimate mean temperature using cosine of latitude
+                var avgTemp = (float) (30 * Math.cos(Math.toRadians(lat))) - 10;
+                weatherStations.add(new WeatherStation(name, avgTemp));
+            }
+        }
+        System.out.format("Generated %,d station names with length from %,d to %,d%n", KEYSET_SIZE, minLen, maxLen);
+        return weatherStations;
+    }
+}