CalculateAverage_truelive second attempt

* cleanup

* getDouble new double parser

* parseBuffer more reliable

* use graalvm to execute

* cleanup

* cleanup

* fix formatting

* fix graalvm init and launch script

calculate_average_truelive.sh

@@ -15,6 +15,8 @@
 #  limitations under the License.
 #
 
+source "$HOME/.sdkman/bin/sdkman-init.sh"
+sdk use java 21.0.1-graalce 1>&2
 
-JAVA_OPTS="-Xmx4G"
+JAVA_OPTS="-Xmx8G -Xms2G"
 time java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_truelive

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

@@ -23,6 +23,7 @@ import java.nio.channels.FileChannel;
 import java.util.*;
 import java.util.concurrent.atomic.DoubleAccumulator;
 import java.util.concurrent.atomic.LongAdder;
+import java.util.stream.Collector;
 import java.util.stream.Collectors;
 import java.util.stream.StreamSupport;
 
@@ -31,31 +32,19 @@ public class CalculateAverage_truelive {
     private static final String FILE = "./measurements.txt";
     private static final long CHUNK_SIZE = 1024 * 1024 * 10L;
 
-    private static int branchlessParseInt(final byte[] input, final int length) {
+    private static double getDouble(final byte[] arr, int pos) {
-        // 0 if positive, 1 if negative
+        final int negative = ~(arr[pos] >> 4) & 1;
-        final int negative = ~(input[0] >> 4) & 1;
+        int sig = 1;
-        // 0 if nr length is 3, 1 if length is 4
+        sig -= 2 * negative;
-        final int has4 = ((length - negative) >> 2) & 1;
+        pos += negative;
-
+        final int digit1 = arr[pos] - '0';
-        final int digit1 = input[negative] - '0';
+        pos++;
-        final int digit2 = input[negative + has4] - '0';
+        if (arr[pos] == '.') {
-        final int digit3 = input[2 + negative + has4] - '0';
+            return sig * (digit1 + (arr[pos + 1] - '0') / 10.0);
-
-        return (-negative ^ (has4 * (digit1 * 100) + digit2 * 10 + digit3) - negative);
         }
-
+        else {
-    // branchless max (unprecise for large numbers, but good enough)
+            return sig * (digit1 * 10 + (arr[pos] - '0') + (arr[pos + 2] - '0') / 10.0);
-    static int max(final int a, final int b) {
-        final int diff = a - b;
-        final int dsgn = diff >> 31;
-        return a - (diff & dsgn);
         }
-
-    // branchless min (unprecise for large numbers, but good enough)
-    static int min(final int a, final int b) {
-        final int diff = a - b;
-        final int dsgn = diff >> 31;
-        return b + (diff & dsgn);
     }
 
     private record Measurement(DoubleAccumulator min, DoubleAccumulator max, DoubleAccumulator sum, LongAdder count) {
@@ -104,16 +93,6 @@ public class CalculateAverage_truelive {
         }
     }
 
-    private static Map<String, Measurement> combineMaps(
-                                                        final Map<String, Measurement> map1,
-                                                        final Map<String, Measurement> map2) {
-        for (final var entry : map2.entrySet()) {
-            map1.merge(entry.getKey(), entry.getValue(), Measurement::combineWith);
-        }
-
-        return map1;
-    }
-
     public static void main(final String[] args) throws IOException {
         // long before = System.currentTimeMillis();
         /**
@@ -152,23 +131,17 @@ public class CalculateAverage_truelive {
                 }
             }
         };
+
         final Map<String, Measurement> reduce = StreamSupport.stream(Spliterators.spliteratorUnknownSize(
                 iterator, Spliterator.IMMUTABLE), true)
-                .parallel()
                 .map(CalculateAverage_truelive::parseBuffer)
-                .reduce(CalculateAverage_truelive::combineMaps).get();
+                .flatMap(map -> map.entrySet().stream())
-
+                .collect(Collectors.toMap(
-        System.out.print("{");
+                        Map.Entry::getKey,
-        System.out.print(
+                        Map.Entry::getValue,
-                reduce
+                        Measurement::combineWith,
-                        .entrySet()
+                        TreeMap::new));
-                        .stream()
+        System.out.println(reduce);
-                        .sorted(Map.Entry.comparingByKey())
-                        .map(Object::toString)
-                        .collect(Collectors.joining(", ")));
-        System.out.println("}");
-
-        // System.out.println("Took: " + (System.currentTimeMillis() - before));
 
     }
 
@@ -178,28 +151,25 @@ public class CalculateAverage_truelive {
         bug.mark();
         String name = null;
         final byte[] arr = new byte[128];
+        int cur = 0;
         while (bug.hasRemaining()) {
-            final char c = (char) bug.get();
+            char c = (char) bug.get();
-            if (c == ';') {
+            arr[cur++] = (byte) c;
-                final int pos = bug.position();
+            while (c != ';') {
-                bug.reset();
+                c = (char) bug.get();
-                final int len = pos - bug.position() - 1;
+                arr[cur++] = (byte) c;
-                bug.get(bug.position(), arr, 0, len);
-                name = new String(arr, 0, len);
-                bug.position(pos);
-                bug.mark();
             }
-            else if (c == '\n') {
+            name = new String(arr, 0, cur - 1);
-                final int pos = bug.position();
+            cur = 0;
-                bug.reset();
+            while (c != '\n') {
-                final int len = pos - bug.position();
+                c = (char) bug.get();
-                bug.get(bug.position(), arr, 0, len);
+                arr[cur++] = (byte) c;
-                final double temp = Double.parseDouble(new String(arr, 0, len));
+            }
+            final double temp = getDouble(arr, 0);
             resultMap.compute(name, (k, v) -> (v == null) ? Measurement.of(temp) : v.add(temp));
-                bug.position(pos);
+            cur = 0;
-                bug.mark();
-            }
         }
         return resultMap;
     }
+
 }