Fix Issue 484.

The serDe of min and max were mingled with the serDe of Boolean Items
and they should not have been.

The fix was in two places. Added a test for this issue.

Author: leerho

src/main/java/org/apache/datasketches/kll/KllDirectCompactItemsSketch.java

@@ -32,6 +32,7 @@
 import java.lang.reflect.Array;
 import java.util.Comparator;
 
+import org.apache.datasketches.common.ArrayOfBooleansSerDe;
 import org.apache.datasketches.common.ArrayOfItemsSerDe;
 import org.apache.datasketches.common.SketchesArgumentException;
 import org.apache.datasketches.memory.Memory;
@@ -154,6 +155,7 @@ byte[] getMinMaxByteArr() { //this is only used by COMPACT_FULL
   @Override
   int getMinMaxSizeBytes() { //this is only used by COMPACT_FULL
     final int offset = DATA_START_ADR + getNumLevels() * Integer.BYTES;
+    if (serDe instanceof ArrayOfBooleansSerDe) { return 2; }
     return serDe.sizeOf(mem, offset, 2);
   }
 

src/main/java/org/apache/datasketches/kll/KllHelper.java

@@ -432,13 +432,13 @@ static  byte[] toByteArray(final KllSketch srcSk, final boolean updatable) {
     final byte m = (byte) srcSk.getM();
 
     //load first 8 bytes
-    wbuf.putByte(preInts);
+    wbuf.putByte(preInts); //byte 0
     wbuf.putByte(serVer);
     wbuf.putByte(famId);
     wbuf.putByte(flags);
     wbuf.putShort(k);
     wbuf.putByte(m);
-    wbuf.incrementPosition(1);
+    wbuf.incrementPosition(1); //byte 7 is unused
 
     if (tgtStructure == COMPACT_EMPTY) {
       return bytesOut;

src/main/java/org/apache/datasketches/kll/KllMemoryValidate.java

@@ -36,6 +36,7 @@
 import static org.apache.datasketches.kll.KllSketch.SketchType.FLOATS_SKETCH;
 import static org.apache.datasketches.kll.KllSketch.SketchType.ITEMS_SKETCH;
 
+import org.apache.datasketches.common.ArrayOfBooleansSerDe;
 import org.apache.datasketches.common.ArrayOfItemsSerDe;
 import org.apache.datasketches.common.Family;
 import org.apache.datasketches.common.SketchesArgumentException;
@@ -175,7 +176,11 @@ static int computeSketchBytes( //for COMPACT_FULL or UPDATABLE only
 
     int offsetBytes = DATA_START_ADR + levelsLen * Integer.BYTES;
     if (sketchType == ITEMS_SKETCH) {
-      offsetBytes += serDe.sizeOf(srcMem, offsetBytes, numItems + 2); //2 for min & max
+      if (serDe instanceof ArrayOfBooleansSerDe) {
+        offsetBytes += serDe.sizeOf(srcMem, offsetBytes, numItems) + 2; //2 for min & max
+      } else {
+        offsetBytes += serDe.sizeOf(srcMem, offsetBytes, numItems + 2); //2 for min & max
+      }
     } else {
       final int typeBytes = sketchType.getBytes();
       offsetBytes += (numItems + 2) * typeBytes; //2 for min & max

src/test/java/org/apache/datasketches/common/ArrayOfXSerDeTest.java

@@ -34,7 +34,7 @@ public void checkBooleanItems() {
     WritableMemory wmem;
     ArrayOfBooleansSerDe serDe = new ArrayOfBooleansSerDe();
 
-    Boolean[] items = {true,false,true,true,false,false};
+    Boolean[] items = {true,false,true,false,true,false,true,false,true,false};
     bytes = serDe.sizeOf(items);
     byteArr = serDe.serializeToByteArray(items);
     assertEquals(byteArr.length, bytes);

src/test/java/org/apache/datasketches/kll/KllMiscItemsTest.java

@@ -27,6 +27,7 @@
 
 import java.util.Comparator;
 
+import org.apache.datasketches.common.ArrayOfBooleansSerDe;
 import org.apache.datasketches.common.ArrayOfStringsSerDe;
 import org.apache.datasketches.common.SketchesArgumentException;
 import org.apache.datasketches.common.Util;
@@ -437,6 +438,33 @@ public void checkGetSingleItem() {
     assertEquals(skCompact.getSingleItem(), "1");
   }
 
+  @Test
+  public void checkIssue484() {
+    Boolean[] items = { true,false,true,false,true,false,true,false,true,false };
+    KllItemsSketch<Boolean> sketch = KllItemsSketch.newHeapInstance(Boolean::compareTo, new ArrayOfBooleansSerDe());
+    for (int i = 0; i < items.length; i++) { sketch.update(items[i]); }
+    byte[] serialized = sketch.toByteArray();
+    KllItemsSketch<Boolean> deserialized =
+        KllItemsSketch.wrap(Memory.wrap(serialized), Boolean::compareTo, new ArrayOfBooleansSerDe());
+    checkSketchesEqual(items, sketch, deserialized);
+  }
+
+  private static <T> void checkSketchesEqual(T[] items, KllItemsSketch<T> expected, KllItemsSketch<T> actual) {
+    KllItemsSketchSortedView<T> expSV = expected.getSortedView();
+    KllItemsSketchSortedView<T> actSV = actual.getSortedView();
+    long N = actSV.getN();
+    long[] expCumWts = expSV.getCumulativeWeights();
+    Boolean[] expItemsArr = (Boolean[])expSV.getQuantiles();
+    long[] actCumWts = actSV.getCumulativeWeights();
+    Boolean[] actItemsArr = (Boolean[])actSV.getQuantiles();
+    printf("%3s %8s %8s\n", "i","Actual", "Expected");
+    for (int i = 0; i < N; i++) {
+      printf("%3d %8s %8s\n", i, actItemsArr[i].toString(), expItemsArr[i].toString());
+    }
+    assertEquals(actCumWts, expCumWts);
+    assertEquals(actItemsArr, expItemsArr);
+  }
+
   private final static boolean enablePrinting = false;
 
   /**