Adding itaske's implementation

calculate_average_patrick.sh

@@ -0,0 +1,20 @@
+#!/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_OPTS=""
+time java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_patrick

src/main/java/dev/morling/onebrc/CalculateAverage_patrick.java

@@ -0,0 +1,76 @@
+/*
+ *  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.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.AbstractMap;
+import java.util.Comparator;
+import java.util.Map;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.stream.Collectors;
+
+public class CalculateAverage_patrick {
+
+    private static final String FILE = "./measurements.txt";
+
+    private record Measurement(long count, double sum, double min, double max) {
+
+        Measurement(double value) {
+            this(1, value, value, value);
+        }
+
+
+        public String toString() {
+            StringBuilder builder = new StringBuilder();
+            builder.append(round(min));
+            builder.append("/");
+            builder.append(round(sum/count));
+            builder.append("/");
+            builder.append(round(max));
+
+            return builder.toString();
+        }
+
+        private double round(double value) {
+            return Math.round(value * 10.0) / 10.0;
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+
+        Map<String, Measurement> resultMap = Files.lines(Path.of(FILE)).parallel()
+                .map(line -> {
+                    int separatorIndex = line.indexOf(";");
+                    String key = line.substring(0, separatorIndex);
+                    double value = Double.parseDouble(line.substring(separatorIndex + 1));
+                    return new AbstractMap.SimpleEntry<>(key, value);
+                })
+                .collect(Collectors.toConcurrentMap(
+                        entry -> entry.getKey(),
+                        entry -> new Measurement(entry.getValue()),
+                        ((measurement1, measurement2) -> new Measurement(
+                                measurement1.count + measurement2.count,
+                                measurement1.sum + measurement2.sum,
+                                Math.min(measurement1.min, measurement2.min),
+                                Math.max(measurement1.max, measurement2.max)))));
+
+        System.out.print(
+                resultMap.entrySet().stream().sorted(Map.Entry.comparingByKey()).map(Object::toString).collect(Collectors.joining(", ", "{", "}")));
+
+    }
+}