faster random generation in skiplist

src/jmh/java/com/tomfran/lsm/sstable/SSTableBenchmark.java

@@ -45,8 +45,8 @@ public void setup() throws IOException {
 
         // sort and divide into inserted and skipped
         var items = l.stream()
-                .sorted((a, b) -> ByteArrayComparator.compare(a.key(), b.key()))
-                .toList();
+                     .sorted((a, b) -> ByteArrayComparator.compare(a.key(), b.key()))
+                     .toList();
 
         var inserted = new ObjectArrayList<ByteArrayPair>();
         var skipped = new ObjectArrayList<ByteArrayPair>();
@@ -106,4 +106,5 @@ public void negativeAccess(Blackhole bh) {
 
         index = (index + 1) % skippedArray.length;
     }
+
 }

src/main/java/com/tomfran/lsm/bloom/BloomFilter.java

@@ -141,4 +141,5 @@ public void writeToFile(String filename) {
 
         os.close();
     }
+
 }

src/main/java/com/tomfran/lsm/io/BaseInputStream.java

@@ -105,4 +105,5 @@ public void close() {
             throw new RuntimeException(e);
         }
     }
+
 }

src/main/java/com/tomfran/lsm/io/BaseOutputStream.java

@@ -92,4 +92,5 @@ public void close() {
             throw new RuntimeException(e);
         }
     }
+
 }

src/main/java/com/tomfran/lsm/memtable/SkipList.java

@@ -72,7 +72,8 @@ public void add(ByteArrayPair item) {
 
     private int randomLevel() {
         int level = 1;
-        while (rn.nextBoolean() && level < levels)
+        long n = rn.nextLong();
+        while (level < levels && (n & (1L << level)) != 0)
             level++;
         return level;
     }
@@ -155,13 +156,15 @@ public String toString() {
     }
 
     private static final class Node {
+
         ByteArrayPair val;
         Node[] next;
 
         Node(ByteArrayPair val, int numLevels) {
             this.val = val;
             this.next = new Node[numLevels];
         }
+
     }
 
     private record SkipListIterator(Node node) implements Iterator<ByteArrayPair> {
@@ -175,6 +178,7 @@ public boolean hasNext() {
         public ByteArrayPair next() {
             return node.next[0].val;
         }
+
     }
 
 }

src/main/java/com/tomfran/lsm/sstable/SSTable.java

@@ -273,6 +273,7 @@ public ByteArrayPair next() {
             remaining--;
             return table.is.readBytePair();
         }
+
     }
 
     /**
@@ -313,6 +314,7 @@ public ByteArrayPair next() {
         public Iterator<ByteArrayPair> iterator() {
             return this;
         }
+
     }
 
 }

src/main/java/com/tomfran/lsm/tree/LSMTree.java

@@ -53,4 +53,5 @@ public byte[] get(byte[] key) {
 
         return null;
     }
+
 }

src/main/java/com/tomfran/lsm/types/ByteArrayPair.java

@@ -31,4 +31,5 @@ public String toString() {
         sb.append(")");
         return sb.toString();
     }
+
 }

src/main/java/com/tomfran/lsm/utils/IteratorMerger.java

@@ -60,4 +60,5 @@ public T next() {
 
         return result;
     }
+
 }

src/test/java/com/tomfran/lsm/TestUtils.java

@@ -34,12 +34,13 @@ public static byte[] getRandomByteArray() {
 
     public static List<byte[]> getRandomByteArrayList(int size) {
         return IntStream.range(0, size)
-                .mapToObj(i -> getRandomByteArray())
-                .toList();
+                        .mapToObj(i -> getRandomByteArray())
+                        .toList();
     }
 
     public static void assertPairEqual(ByteArrayPair a, ByteArrayPair b) {
         assert compare(a.key(), b.key()) == 0;
         assert compare(a.value(), b.value()) == 0;
     }
+
 }

src/test/java/com/tomfran/lsm/bloom/BloomFilterAccuracyTest.java

@@ -32,9 +32,10 @@ void testAdd() {
         });
 
         int falsePositives = data.stream().limit(INSERTIONS)
-                .mapToInt(d -> b.mightContain(d) ? 1 : 0).sum();
+                                 .mapToInt(d -> b.mightContain(d) ? 1 : 0).sum();
 
         double falsePositiveRate = falsePositives / (double) INSERTIONS;
         results.add(falsePositiveRate);
     }
+
 }

src/test/java/com/tomfran/lsm/bloom/BloomFilterFileTest.java

@@ -29,4 +29,5 @@ public void shouldReconstruct() {
             assert bf.bits[i] == bf2.bits[i];
         }
     }
+
 }

src/test/java/com/tomfran/lsm/memtable/SkipListTest.java

@@ -24,8 +24,8 @@ public static void setup() {
         items = new ObjectArrayList<>();
 
         Stream.generate(TestUtils::getRandomPair)
-                .limit(100)
-                .forEach(items::add);
+              .limit(100)
+              .forEach(items::add);
 
         items.forEach(l::add);
     }

src/test/java/com/tomfran/lsm/sstable/SSTableReconstructTest.java

@@ -31,8 +31,8 @@ static void setup() throws IOException {
         }
 
         var items = l.stream()
-                .sorted((a, b) -> compare(a.key(), b.key()))
-                .toList();
+                     .sorted((a, b) -> compare(a.key(), b.key()))
+                     .toList();
 
         t1 = new SSTable(tempDirectory + FILE1, items, 3, items.size());
 

src/test/java/com/tomfran/lsm/sstable/SSTableTest.java

@@ -37,8 +37,8 @@ public static void setup() {
 
         // sort and divide into inserted and skipped
         var items = l.stream()
-                .sorted((a, b) -> ByteArrayComparator.compare(a.key(), b.key()))
-                .toList();
+                     .sorted((a, b) -> ByteArrayComparator.compare(a.key(), b.key()))
+                     .toList();
 
         inserted = new ObjectArrayList<>();
         skipped = new ObjectArrayList<>();
@@ -88,4 +88,5 @@ public void iteratorTest() {
 
         assert !it2.hasNext();
     }
+
 }

src/test/java/com/tomfran/lsm/utils/IteratorMergerTest.java

@@ -14,8 +14,8 @@ class IteratorMergerTest {
     public void shouldMerge() {
 
         List<Iterator<Integer>> iteratorList = IntStream.range(0, 10)
-                .mapToObj(i -> IntStream.range(i * 10, i * 10 + 10).boxed().iterator())
-                .collect(Collectors.toList());
+                                                        .mapToObj(i -> IntStream.range(i * 10, i * 10 + 10).boxed().iterator())
+                                                        .collect(Collectors.toList());
 
         Collections.shuffle(iteratorList);