1 files changed, 83 insertions, 0 deletions
diff --git a/src/main/java/dev/morling/onebrc/CreateMeasurements.java b/src/main/java/dev/morling/onebrc/CreateMeasurements.java
new file mode 100644
index 0000000..583c9b1
--- /dev/null
+++ b/src/main/java/dev/morling/onebrc/CreateMeasurements.java
@@ -0,0 +1,83 @@
+/*
+ *  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.FileOutputStream;
+import java.io.OutputStreamWriter;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+
+public class CreateMeasurements {
+
+    private static final String FILE = "./measurements.txt";
+
+    private record WeatherStation(String id, double meanTemperature) {
+        double measurement() {
+            double m = ThreadLocalRandom.current().nextGaussian(meanTemperature, 10);
+            return Math.round(m * 10.0) / 10.0;
+        }
+    }
+
+    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);
+        }
+
+        List<WeatherStation> stations = Arrays.asList(
+                new WeatherStation("auckland", 15.2),
+                new WeatherStation("concordia", -51.7),
+                new WeatherStation("lima", 19.2),
+                new WeatherStation("hamburg", 9.4),
+                new WeatherStation("hammerfest", 2.7),
+                new WeatherStation("maui", 15.2),
+                new WeatherStation("miami", 24.5),
+                new WeatherStation("nairobi", 17.8),
+                new WeatherStation("newdelhi", 25.3),
+                new WeatherStation("tokio", 15.8));
+
+        File measurements = new File(FILE);
+        try (FileOutputStream fos = new FileOutputStream(measurements); BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(fos));) {
+            for (int i = 0; i < size; i++) {
+                if (i > 0 && i % 50_000_000 == 0) {
+                    System.out.println("Wrote %,d measurements in %s ms".formatted(i, System.currentTimeMillis() - start));
+                }
+                WeatherStation station = stations.get(ThreadLocalRandom.current().nextInt(stations.size()));
+                bw.write(station.id());
+                bw.write(";" + station.measurement());
+                bw.newLine();
+            }
+            bw.flush();
+
+            System.out.println("Created file with %,d measurements in %s ms".formatted(size, System.currentTimeMillis() - start));
+        }
+    }
+}