benchmark preparations

app/src/jmh/java/de/uni_marburg/powersort/benchmark/BenchmarkJmh.java

@@ -8,9 +8,9 @@ import org.openjdk.jmh.infra.Blackhole;
 import java.util.concurrent.TimeUnit;
 
 // TODO: The parameters are way too low. Use for debugging only!
-@Fork(0)
-@Warmup(iterations = 0)
-@Measurement(iterations = 3)
+@Fork(1)
+@Warmup(iterations = 3)
+@Measurement(iterations = 6)
 public class BenchmarkJmh {
     @State(Scope.Benchmark)
     public static class State1 {

app/src/main/java/de/uni_marburg/powersort/benchmark/LongFormatter.java

@@ -0,0 +1,36 @@
+package de.uni_marburg.powersort.benchmark;
+
+public class LongFormatter {
+    /**
+     * @param l Number to format.
+     * @return Number as formatted String. Thousands are separated by underscore `_`.
+     */
+    public static String formatUnderscore(long l) {
+        int firstDigitIdx = 0;
+        // If l is negative, its string starts with '-'.
+        // Thus, the first digit is at idx 1.
+        if (l < 0) {
+            firstDigitIdx = 1;
+        }
+
+        StringBuilder durFormatted = new StringBuilder();
+        char[] digits = String.valueOf(l).toCharArray();
+        int remainder = digits.length % 3;
+        for (int i = 0; i < digits.length; i++) {
+            boolean firstOrLastDigit = i <= firstDigitIdx || i == digits.length - 1;
+            if (!firstOrLastDigit && i % 3 == remainder) {
+                durFormatted.append('_');
+            }
+            durFormatted.append(digits[i]);
+        }
+        return durFormatted.toString();
+    }
+
+    /**
+     * @param i Number to format.
+     * @return Number as formatted String. Thousands are separated by underscore `_`.
+     */
+    public static String formatUnderscore(int i) {
+        return formatUnderscore((long) i);
+    }
+}

app/src/main/java/de/uni_marburg/powersort/benchmark/Main.java

@@ -7,6 +7,7 @@ import de.uni_marburg.powersort.data.ObjectSupplier;
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.concurrent.TimeUnit;
 import java.util.function.Supplier;
 
 /**
@@ -24,12 +25,14 @@ public class Main {
             for (SortImpl sortImplementation : sortImplementations) {
                 Object[] sortInput = objectSupplier.get();
 
-                final long startTime = System.nanoTime();
+                final long startNanos = System.nanoTime();
                 sortImplementation.sort(sortInput);
-                final long stopTime = System.nanoTime();
-                final long duration = stopTime - startTime;
+                final long stopNanos = System.nanoTime();
 
-                System.out.println(duration + "," + sortImplementation.title);
+                final long durNanos = stopNanos - startNanos;
+                final long durMillis = TimeUnit.NANOSECONDS.toMillis(durNanos);
+                final String durFormatted = LongFormatter.formatUnderscore(durMillis);
+                System.out.println(durFormatted + "," + sortImplementation.title);
             }
         }
     }

app/src/main/java/de/uni_marburg/powersort/data/DescendingIntegers.java

@@ -1,6 +1,7 @@
 package de.uni_marburg.powersort.data;
 
 import de.uni_marburg.powersort.benchmark.IntegerArray;
+import de.uni_marburg.powersort.benchmark.LongFormatter;
 
 public class DescendingIntegers extends IntegerSupplier {
     private static final int SIZE = 50_000_000;
@@ -11,6 +12,6 @@ public class DescendingIntegers extends IntegerSupplier {
 
     @Override
     public String title() {
-        return "Array of " + SIZE + " descending Integer objects.";
+        return "Array of " + LongFormatter.formatUnderscore(SIZE) + " descending Integer objects.";
     }
 }

app/src/main/java/de/uni_marburg/powersort/data/RandomIntegers.java

@@ -1,6 +1,7 @@
 package de.uni_marburg.powersort.data;
 
 import de.uni_marburg.powersort.benchmark.IntegerArray;
+import de.uni_marburg.powersort.benchmark.LongFormatter;
 
 public class RandomIntegers extends IntegerSupplier {
     private static final int SIZE = 50_000_000;
@@ -11,6 +12,6 @@ public class RandomIntegers extends IntegerSupplier {
 
     @Override
     public String title() {
-        return "Array of " + SIZE + " random Integer objects.";
+        return "Array of " + LongFormatter.formatUnderscore(SIZE) + " random Integer objects.";
     }
 }

app/src/test/java/de/uni_marburg/powersort/benchmark/LongFormatterTest.java

@@ -0,0 +1,57 @@
+package de.uni_marburg.powersort.benchmark;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class LongFormatterTest {
+    @Test
+    void negDigit4() {
+        assertEquals("-1_234", LongFormatter.formatUnderscore(-1234));
+    }
+    @Test
+    void negDigit3() {
+        assertEquals("-123", LongFormatter.formatUnderscore(-123));
+    }
+    @Test
+    void negDigit2() {
+        assertEquals("-12", LongFormatter.formatUnderscore(-12));
+    }
+    @Test
+    void negDigit1() {
+        assertEquals("-1", LongFormatter.formatUnderscore(-1));
+    }
+    @Test
+    void digit1() {
+        assertEquals("0", LongFormatter.formatUnderscore(0));
+    }
+
+    @Test
+    void digit2() {
+        assertEquals("12", LongFormatter.formatUnderscore(12));
+    }
+
+    @Test
+    void digit3() {
+        assertEquals("123", LongFormatter.formatUnderscore(123));
+    }
+
+    @Test
+    void digit4() {
+        assertEquals("1_234", LongFormatter.formatUnderscore(1234));
+    }
+
+    @Test
+    void digit5() {
+        assertEquals("12_345", LongFormatter.formatUnderscore(12345));
+    }
+
+    @Test
+    void digit6() {
+        assertEquals("123_456", LongFormatter.formatUnderscore(123456));
+    }
+    @Test
+    void digit7() {
+        assertEquals("1_234_567", LongFormatter.formatUnderscore(1234567));
+    }
+}