Add 0xshivamagarwal Implementation (#508)

* 0xshivamagarwal implementation

* .

---------

Co-authored-by: Shivam Agarwal <>

calculate_average_0xshivamagarwal.sh

@@ -0,0 +1,22 @@
+#!/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="--enable-preview -XX:+UnlockExperimentalVMOptions -XX:+TrustFinalNonStaticFields -dsa -XX:+UseNUMA"
+if [[ ! "$(uname -s)" = "Darwin" ]]; then
+    JAVA_OPTS="$JAVA_OPTS -XX:+UseTransparentHugePages"
+fi
+java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_0xshivamagarwal

src/main/java/dev/morling/onebrc/CalculateAverage_0xshivamagarwal.java

@@ -0,0 +1,137 @@
+/*
+ *  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 static java.lang.foreign.ValueLayout.JAVA_BYTE;
+import static java.nio.file.StandardOpenOption.READ;
+
+import java.io.IOException;
+import java.lang.foreign.Arena;
+import java.lang.foreign.MemorySegment;
+import java.nio.channels.FileChannel;
+import java.nio.file.Path;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class CalculateAverage_0xshivamagarwal {
+    private static final Path FILE = Path.of("./measurements.txt");
+    private static final byte COLON = ';';
+    private static final byte NEW_LINE = '\n';
+    private static final byte HYPHEN = '-';
+    private static final byte DOT = '.';
+    private static final int NO_OF_THREADS = Runtime.getRuntime().availableProcessors();
+
+    private static long[] mergeFn(final long[] v1, final long[] v2) {
+        v1[0] = Math.min(v1[0], v2[0]);
+        v1[1] = Math.max(v1[1], v2[1]);
+        v1[2] += v2[2];
+        v1[3] += v2[3];
+        return v1;
+    }
+
+    private static String toString(final Map.Entry<String, long[]> entry) {
+        var m = entry.getValue();
+
+        return entry.getKey()
+                + '='
+                + m[0] / 10.0
+                + '/'
+                + Math.round(1.0 * m[2] / m[3]) / 10.0
+                + '/'
+                + m[1] / 10.0;
+    }
+
+    private static Map<String, long[]> parseData(
+                                                 final MemorySegment data, long offset, final long limit) {
+        var map = new HashMap<String, long[]>(10000, 1);
+        var sep = false;
+        var neg = false;
+        var key = new byte[100];
+        var len = 0;
+        var val = 0;
+
+        while (offset < limit) {
+            var b = data.get(JAVA_BYTE, offset++);
+            if (sep) {
+                if (b == NEW_LINE) {
+                    val = neg ? -val : val;
+                    map.merge(
+                            new String(key, 0, len),
+                            new long[]{ val, val, val, 1 },
+                            CalculateAverage_0xshivamagarwal::mergeFn);
+                    sep = false;
+                    neg = false;
+                    len = 0;
+                    val = 0;
+                }
+                else if (b == HYPHEN) {
+                    neg = true;
+                }
+                else if (b != DOT) {
+                    val = val * 10 + (b - 48);
+                }
+            }
+            else if (b == COLON) {
+                sep = true;
+            }
+            else {
+                key[len++] = b;
+            }
+        }
+
+        return map;
+    }
+
+    public static void main(String[] args) throws IOException {
+        final String result;
+
+        try (var channel = FileChannel.open(FILE, READ);
+                var arena = Arena.ofShared()) {
+            var data = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size(), arena);
+            var chunkSize = data.byteSize() / NO_OF_THREADS;
+            var chunks = new long[NO_OF_THREADS + 1];
+            chunks[NO_OF_THREADS] = data.byteSize();
+
+            for (int i = 1; i < NO_OF_THREADS; ++i) {
+                var chunkPos = i * chunkSize;
+
+                while (data.get(JAVA_BYTE, chunkPos++) != NEW_LINE) {
+                }
+
+                chunks[i] = chunkPos;
+            }
+
+            result = IntStream.range(0, NO_OF_THREADS)
+                    .mapToObj(i -> parseData(data, chunks[i], chunks[i + 1]))
+                    .parallel()
+                    .reduce(
+                            (m1, m2) -> {
+                                m2.forEach((k, v) -> m1.merge(k, v, CalculateAverage_0xshivamagarwal::mergeFn));
+                                return m1;
+                            })
+                    .map(
+                            map -> map.entrySet().parallelStream()
+                                    .sorted(Map.Entry.comparingByKey())
+                                    .map(CalculateAverage_0xshivamagarwal::toString)
+                                    .collect(Collectors.joining(", ", "{", "}")))
+                    .orElse(null);
+        }
+
+        System.out.println(result);
+    }
+}