This fixes the "getResultAndReset" issue flagged by Copilot.

Author: leerho

src/main/java/org/apache/datasketches/quantiles/DirectUpdateDoublesSketch.java

@@ -100,8 +100,9 @@ static DirectUpdateDoublesSketch newInstance(final int k, final MemorySegment ds
     return new DirectUpdateDoublesSketch(k, dstSeg, mSegReq);
   }
 
-  static DirectUpdateDoublesSketch(final DirectUpdateDoublesSketch skIn) {
-    return null;
+  static HeapUpdateDoublesSketch heapify(final DirectUpdateDoublesSketch skIn) {
+    final MemorySegment segIn = skIn.getMemorySegment();
+    return HeapUpdateDoublesSketch.heapifyInstance(segIn);
   }
 
   /**
@@ -214,6 +215,23 @@ public void reset() {
   }
 
   //Restricted overrides
+
+  @Override
+  HeapUpdateDoublesSketch getSketchAndReset() {
+    final HeapUpdateDoublesSketch skCopy = heapify(this);
+    reset();
+    return skCopy;
+  }
+
+  @Override
+  double[] growCombinedBuffer(final int curCombBufItemCap, final int itemSpaceNeeded) {
+    seg_ = growCombinedSegBuffer(itemSpaceNeeded);
+    // copy out any data that was there
+    final double[] newCombBuf = new double[itemSpaceNeeded];
+    MemorySegment.copy(seg_, JAVA_DOUBLE_UNALIGNED, COMBINED_BUFFER, newCombBuf, 0, curCombBufItemCap);
+    return newCombBuf;
+  }
+
   //Puts
 
   @Override
@@ -249,15 +267,6 @@ void putBitPattern(final long bitPattern) {
     //intentionally a no-op, not kept on-heap, always derived.
   }
 
-  @Override
-  double[] growCombinedBuffer(final int curCombBufItemCap, final int itemSpaceNeeded) {
-    seg_ = growCombinedSegBuffer(itemSpaceNeeded);
-    // copy out any data that was there
-    final double[] newCombBuf = new double[itemSpaceNeeded];
-    MemorySegment.copy(seg_, JAVA_DOUBLE_UNALIGNED, COMBINED_BUFFER, newCombBuf, 0, curCombBufItemCap);
-    return newCombBuf;
-  }
-
   //Direct supporting methods
 
   private MemorySegment growCombinedSegBuffer(final int itemSpaceNeeded) {

src/main/java/org/apache/datasketches/quantiles/DirectUpdateDoublesSketchR.java

@@ -160,7 +160,6 @@ int getCombinedBufferItemCapacity() {
     final double[] combinedBuffer = new double[itemCap];
     MemorySegment.copy(seg_, JAVA_DOUBLE_UNALIGNED, COMBINED_BUFFER, combinedBuffer, 0, itemCap);
 
-
     return combinedBuffer;
   }
 
@@ -176,41 +175,46 @@ MemorySegment getMemorySegment() {
     return seg_;
   }
 
+  @Override
+  UpdateDoublesSketch getSketchAndReset() {
+    throw new SketchesReadOnlyException("Call to getResultAndReset() on read-only sketch");
+  }
+
   //Puts
 
   @Override
   void putMinItem(final double minQuantile) {
-    throw new SketchesReadOnlyException("Call to putMinQuantile() on read-only buffer");
+    throw new SketchesReadOnlyException("Call to putMinQuantile() on read-only sketch");
   }
 
   @Override
   void putMaxItem(final double maxQuantile) {
-    throw new SketchesReadOnlyException("Call to putMaxQuantile() on read-only buffer");
+    throw new SketchesReadOnlyException("Call to putMaxQuantile() on read-only sketch");
   }
 
   @Override
   void putN(final long n) {
-    throw new SketchesReadOnlyException("Call to putN() on read-only buffer");
+    throw new SketchesReadOnlyException("Call to putN() on read-only sketch");
   }
 
   @Override
   void putCombinedBuffer(final double[] combinedBuffer) {
-    throw new SketchesReadOnlyException("Call to putCombinedBuffer() on read-only buffer");
+    throw new SketchesReadOnlyException("Call to putCombinedBuffer() on read-only sketch");
   }
 
   @Override
   void putBaseBufferCount(final int baseBufferCount) {
-    throw new SketchesReadOnlyException("Call to putBaseBufferCount() on read-only buffer");
+    throw new SketchesReadOnlyException("Call to putBaseBufferCount() on read-only sketch");
   }
 
   @Override
   void putBitPattern(final long bitPattern) {
-    throw new SketchesReadOnlyException("Call to putBaseBufferCount() on read-only buffer");
+    throw new SketchesReadOnlyException("Call to putBaseBufferCount() on read-only sketch");
   }
 
   @Override
   double[] growCombinedBuffer(final int curCombBufItemCap, final int itemSpaceNeeded) {
-    throw new SketchesReadOnlyException("Call to growCombinedBuffer() on read-only buffer");
+    throw new SketchesReadOnlyException("Call to growCombinedBuffer() on read-only sketch");
   }
 
   //Checks

src/main/java/org/apache/datasketches/quantiles/DoublesUnionImpl.java

@@ -143,7 +143,7 @@ public void update(final double quantile) {
   @Override
   public UpdateDoublesSketch getResultAndReset() {
     if (gadget_ == null) { return null; } //Intentionally return null here for speed.
-    final UpdateDoublesSketch ds = gadget_;
+    final UpdateDoublesSketch ds = gadget_.getSketchAndReset();
     gadget_ = null;
     return ds;
   }

src/main/java/org/apache/datasketches/quantiles/HeapUpdateDoublesSketch.java

@@ -141,13 +141,13 @@ static HeapUpdateDoublesSketch copy(final HeapUpdateDoublesSketch skIn) {
   /**
    * Heapifies the given srcSeg, which must be a MemorySegment image of a DoublesSketch and may have data.
    *
-   * @param srcSeg a MemorySegment image of a sketch, which may be in compact or not compact form.
+   * @param srcSeg a MemorySegment image of a sketch, which may be in compact or updatable form.
    * @return a DoublesSketch on the Java heap.
    */
   static HeapUpdateDoublesSketch heapifyInstance(final MemorySegment srcSeg) {
     final long segCapBytes = srcSeg.byteSize();
-    if (segCapBytes < 8) {
-      throw new SketchesArgumentException("Source MemorySegment too small: " + segCapBytes + " < 8");
+    if ((segCapBytes < 8) || (segCapBytes > Integer.MAX_VALUE)) {
+      throw new SketchesArgumentException("Source MemorySegment byteSize must be >= 8 and <= Integer.MAX_VALUE: " + segCapBytes);
     }
 
     final int preLongs = extractPreLongs(srcSeg);
@@ -203,13 +203,6 @@ public long getN() {
     return n_;
   }
 
-  @Override
-  HeapUpdateDoublesSketch getResultAndReset() {
-    final HeapUpdateDoublesSketch skCopy = HeapUpdateDoublesSketch.copy(this);
-    reset();
-    return skCopy;
-  }
-
   @Override
   public boolean hasMemorySegment() {
     return false;
@@ -361,8 +354,8 @@ int getBaseBufferCount() {
   }
 
   @Override
-  int getCombinedBufferItemCapacity() {
-    return combinedBuffer_.length;
+  long getBitPattern() {
+    return bitPattern_;
   }
 
   @Override
@@ -371,30 +364,38 @@ int getCombinedBufferItemCapacity() {
   }
 
   @Override
-  long getBitPattern() {
-    return bitPattern_;
+  int getCombinedBufferItemCapacity() {
+    return combinedBuffer_.length;
   }
 
   @Override
   MemorySegment getMemorySegment() {
     return null;
   }
 
-  //Puts
-
   @Override
-  void putMinItem(final double minItem) {
-    minItem_ = minItem;
+  HeapUpdateDoublesSketch getSketchAndReset() {
+    final HeapUpdateDoublesSketch skCopy = HeapUpdateDoublesSketch.copy(this);
+    reset();
+    return skCopy;
+  }
+
+  @Override //the returned array is not always used
+  double[] growCombinedBuffer(final int currentSpace, final int spaceNeeded) {
+    combinedBuffer_ = Arrays.copyOf(combinedBuffer_, spaceNeeded);
+    return combinedBuffer_;
   }
 
+  //Puts
+
   @Override
-  void putMaxItem(final double maxItem) {
-    maxItem_ = maxItem;
+  void putBaseBufferCount(final int baseBufferCount) {
+    baseBufferCount_ = baseBufferCount;
   }
 
   @Override
-  void putN(final long n) {
-    n_ = n;
+  void putBitPattern(final long bitPattern) {
+    bitPattern_ = bitPattern;
   }
 
   @Override
@@ -403,19 +404,18 @@ void putCombinedBuffer(final double[] combinedBuffer) {
   }
 
   @Override
-  void putBaseBufferCount(final int baseBufferCount) {
-    baseBufferCount_ = baseBufferCount;
+  void putMaxItem(final double maxItem) {
+    maxItem_ = maxItem;
   }
 
   @Override
-  void putBitPattern(final long bitPattern) {
-    bitPattern_ = bitPattern;
+  void putMinItem(final double minItem) {
+    minItem_ = minItem;
   }
 
-  @Override //the returned array is not always used
-  double[] growCombinedBuffer(final int currentSpace, final int spaceNeeded) {
-    combinedBuffer_ = Arrays.copyOf(combinedBuffer_, spaceNeeded);
-    return combinedBuffer_;
+  @Override
+  void putN(final long n) {
+    n_ = n;
   }
 
   /**

src/main/java/org/apache/datasketches/quantiles/ItemsSketch.java

@@ -72,7 +72,7 @@
  *
  * @see QuantilesAPI
  *
- * @param <T> The sketch data type
+ * @param <T> The sketch item data type.
  */
 public final class ItemsSketch<T> implements QuantilesGenericAPI<T> {
   final Class<T> clazz;
@@ -124,6 +124,8 @@ public final class ItemsSketch<T> implements QuantilesGenericAPI<T> {
    */
   public static final Random rand = new Random();
 
+  //**Constructors**
+
   private ItemsSketch(
       final int k,
       final Class<T> clazz,
@@ -138,9 +140,9 @@ private ItemsSketch(
 
   /**
    * Obtains a new instance of an ItemsSketch using the DEFAULT_K.
-   * @param <T> The sketch data type
-   * @param clazz the given class of T
-   * @param comparator to compare items
+   * @param <T> The sketch item data type.
+   * @param clazz the given class of T.
+   * @param comparator to compare items.
    * @return an ItemSketch&lt;T&gt;.
    */
   public static <T> ItemsSketch<T> getInstance(
@@ -150,12 +152,12 @@ public static <T> ItemsSketch<T> getInstance(
   }
 
   /**
-   * Obtains a new instance of an ItemsSketch.
-   * @param <T> The sketch data type
-   * @param clazz the given class of T
+   * Obtains a new instance of an ItemsSketch using the given <i>k</i>.
+   * @param <T> The sketch item data type.
+   * @param clazz the given class of T.
    * @param k Parameter that controls space usage of sketch and accuracy of estimates.
    * Must be greater than 2 and less than 65536 and a power of 2.
-   * @param comparator to compare items
+   * @param comparator to compare items.
    * @return an ItemSketch&lt;T&gt;.
    */
   public static <T> ItemsSketch<T> getInstance(
@@ -175,15 +177,15 @@ public static <T> ItemsSketch<T> getInstance(
   }
 
   /**
-   * Heapifies the given srcSeg, which must be a MemorySegment image of a ItemsSketch
-   * @param clazz the given class of T
-   * @param srcSeg a MemorySegment image of a sketch.
-   * @param comparator to compare items
-   * @param serDe an instance of ArrayOfItemsSerDe
-   * @param <T> The sketch data type
-   * @return a ItemSketch&lt;T&gt; on the Java heap.
+   * Heapifies the given srcSeg, which must be a MemorySegment image of a ItemsSketch.
+   * @param <T> The sketch item data type.
+   * @param clazz the given class of T.
+   * @param srcSeg a MemorySegment image of a sketch generated from this class.
+   * @param comparator to compare items.
+   * @param serDe an instance of ArrayOfItemsSerDe.
+   * @return a ItemsSketch&lt;T&gt; on the Java heap.
    */
-  public static <T> ItemsSketch<T> getInstance(
+  public static <T> ItemsSketch<T> heapify(
       final Class<T> clazz,
       final MemorySegment srcSeg,
       final Comparator<? super T> comparator,
@@ -192,7 +194,6 @@ public static <T> ItemsSketch<T> getInstance(
     if (segCapBytes < 8) {
       throw new SketchesArgumentException("MemorySegment too small: " + segCapBytes);
     }
-
     final int preambleLongs = extractPreLongs(srcSeg);
     final int serVer = extractSerVer(srcSeg);
     final int familyID = extractFamilyID(srcSeg);
@@ -233,10 +234,10 @@ public static <T> ItemsSketch<T> getInstance(
   }
 
   /**
-   * Returns a copy of the given sketch
-   * @param <T> The sketch data type
-   * @param sketch the given sketch
-   * @return a copy of the given sketch
+   * Returns a copy of the given sketch.
+   * @param <T> The sketch item data type.
+   * @param sketch the given sketch.
+   * @return a copy of the given sketch.
    */
   static <T> ItemsSketch<T> copy(final ItemsSketch<T> sketch) {
     final ItemsSketch<T> qsCopy = ItemsSketch.getInstance(sketch.clazz, sketch.k_, sketch.comparator_);
@@ -251,7 +252,7 @@ static <T> ItemsSketch<T> copy(final ItemsSketch<T> sketch) {
     return qsCopy;
   }
 
-  //END of Constructors
+  //**END of Constructors**
 
   @Override
   public double[] getCDF(final T[] splitPoints, final QuantileSearchCriteria searchCrit) {
@@ -581,6 +582,16 @@ Object[] getCombinedBuffer() {
     return combinedBuffer_;
   }
 
+  /**
+   * Returns a copy of this sketch and then resets.
+   * @return a copy of this sketch and then resets.
+   */
+  ItemsSketch<T> getSketchAndReset() {
+    final ItemsSketch<T> skCopy = copy(this);
+    reset();
+    return skCopy;
+  }
+
   /**
    * Loads the Combined Buffer, min and max from the given items array.
    * The Combined Buffer is always in non-compact form and must be pre-allocated.