Add new MemoryStatus interface to Theta.

src/main/java/org/apache/datasketches/common/MemoryStatus.java

@@ -0,0 +1,53 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.datasketches.common;
+
+import org.apache.datasketches.memory.Memory;
+
+/**
+ * Methods for inquiring the status of a backing Memory object.
+ */
+public interface MemoryStatus {
+
+  /**
+   * Returns true if this object's internal data is backed by a Memory object,
+   * which may be on-heap or off-heap.
+   * @return true if this object's internal data is backed by a Memory object.
+   */
+  default boolean hasMemory() { return false; }
+
+  /**
+   * Returns true if this object's internal data is backed by direct (off-heap) Memory.
+   * @return true if this object's internal data is backed by direct (off-heap) Memory.
+   */
+  default boolean isDirect() { return false; }
+
+  /**
+   * Returns true if the backing resource of <i>this</i> is identical with the backing resource
+   * of <i>that</i>. The capacities must be the same.  If <i>this</i> is a region,
+   * the region offset must also be the same.
+   *
+   * @param that A different non-null and alive Memory object.
+   * @return true if the backing resource of <i>this</i> is identical with the backing resource
+   * of <i>that</i>.
+   * @throws SketchesArgumentException if <i>that</i> is not alive (already closed).
+   */
+  default boolean isSameResource(final Memory that) { return false; }
+
+}

src/main/java/org/apache/datasketches/theta/AnotBimpl.java

@@ -26,7 +26,6 @@
 import java.util.Arrays;
 
 import org.apache.datasketches.common.SketchesArgumentException;
-import org.apache.datasketches.memory.Memory;
 import org.apache.datasketches.memory.WritableMemory;
 import org.apache.datasketches.thetacommon.ThetaUtil;
 
@@ -148,11 +147,6 @@ int getRetainedEntries() {
     return curCount_;
   }
 
-  @Override
-  public boolean isSameResource(final Memory that) {
-    return false;
-  }
-
   //restricted
 
   private static long[] getHashArrA(final Sketch skA) { //returns a new array

src/main/java/org/apache/datasketches/theta/ConcurrentHeapThetaBuffer.java

@@ -26,6 +26,7 @@
 import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.apache.datasketches.common.ResizeFactor;
+import org.apache.datasketches.memory.Memory;
 import org.apache.datasketches.thetacommon.HashOperations;
 
 /**
@@ -167,6 +168,11 @@ public boolean isEstimationMode() {
     return shared.isEstimationMode();
   }
 
+  @Override
+  public boolean isSameResource(final Memory that) {
+    return shared.isSameResource(that);
+  }
+
   //End of proxies
 
   @Override

src/main/java/org/apache/datasketches/theta/ConcurrentSharedThetaSketch.java

@@ -21,6 +21,7 @@
 
 import java.util.concurrent.atomic.AtomicBoolean;
 
+import org.apache.datasketches.common.MemoryStatus;
 import org.apache.datasketches.memory.WritableMemory;
 
 /**
@@ -30,7 +31,7 @@
  *
  * @author eshcar
  */
-interface ConcurrentSharedThetaSketch {
+interface ConcurrentSharedThetaSketch extends MemoryStatus {
 
   long NOT_SINGLE_HASH = -1L;
   double MIN_ERROR = 0.0000001;
@@ -127,7 +128,7 @@ boolean propagate(final AtomicBoolean localPropagationInProgress, final Sketch s
   //attempt to access these methods from the local buffer will be diverted to the shared
   //sketch.
 
-  //From Sketch
+  //From Sketch and MemoryStatus
 
   int getCompactBytes();
 
@@ -139,10 +140,6 @@ boolean propagate(final AtomicBoolean localPropagationInProgress, final Sketch s
 
   double getUpperBound(int numStdDev);
 
-  boolean hasMemory();
-
-  boolean isDirect();
-
   boolean isEmpty();
 
   boolean isEstimationMode();

src/main/java/org/apache/datasketches/theta/DirectCompactSketch.java

@@ -109,12 +109,12 @@ public long getThetaLong() {
 
   @Override
   public boolean hasMemory() {
-    return true;
+    return mem_ != null;
   }
 
   @Override
   public boolean isDirect() {
-    return mem_.isDirect();
+    return hasMemory() ? mem_.isDirect() : false;
   }
 
   @Override
@@ -132,7 +132,7 @@ public boolean isOrdered() {
 
   @Override
   public boolean isSameResource(final Memory that) {
-    return mem_.isSameResource(that);
+    return hasMemory() ? mem_.isSameResource(that) : false;
   }
 
   @Override

src/main/java/org/apache/datasketches/theta/DirectQuickSelectSketchR.java

@@ -144,12 +144,12 @@ public long getThetaLong() {
 
   @Override
   public boolean hasMemory() {
-    return true;
+    return wmem_ != null;
   }
 
   @Override
   public boolean isDirect() {
-    return wmem_.isDirect();
+    return hasMemory() ? wmem_.isDirect() : false;
   }
 
   @Override
@@ -159,7 +159,7 @@ public boolean isEmpty() {
 
   @Override
   public boolean isSameResource(final Memory that) {
-    return wmem_.isSameResource(that);
+    return hasMemory() ? wmem_.isSameResource(that) : false;
   }
 
   @Override

src/main/java/org/apache/datasketches/theta/EmptyCompactSketch.java

@@ -91,16 +91,6 @@ public long getThetaLong() {
     return Long.MAX_VALUE;
   }
 
-  @Override
-  public boolean hasMemory() {
-    return false;
-  }
-
-  @Override
-  public boolean isDirect() {
-    return false;
-  }
-
   @Override
   public boolean isEmpty() {
     return true;

src/main/java/org/apache/datasketches/theta/HeapCompactSketch.java

@@ -102,16 +102,6 @@ public long getThetaLong() {
     return thetaLong_;
   }
 
-  @Override
-  public boolean hasMemory() {
-    return false;
-  }
-
-  @Override
-  public boolean isDirect() {
-    return false;
-  }
-
   @Override
   public boolean isEmpty() {
     return empty_;

src/main/java/org/apache/datasketches/theta/HeapUpdateSketch.java

@@ -66,16 +66,6 @@ public int getCurrentBytes() {
     return (preLongs + dataLongs) << 3;
   }
 
-  @Override
-  public boolean isDirect() {
-    return false;
-  }
-
-  @Override
-  public boolean hasMemory() {
-    return false;
-  }
-
   //UpdateSketch
 
   @Override

src/main/java/org/apache/datasketches/theta/IntersectionImpl.java

@@ -336,14 +336,24 @@ public CompactSketch getResult(final boolean dstOrdered, final WritableMemory ds
         dstMem, compactCache);
   }
 
+  @Override
+  public boolean hasMemory() {
+    return wmem_ != null;
+  }
+
   @Override
   public boolean hasResult() {
-    return wmem_ != null ? wmem_.getInt(RETAINED_ENTRIES_INT) >= 0 : curCount_ >= 0;
+    return hasMemory() ? wmem_.getInt(RETAINED_ENTRIES_INT) >= 0 : curCount_ >= 0;
+  }
+
+  @Override
+  public boolean isDirect() {
+    return hasMemory() ? wmem_.isDirect() : false;
   }
 
   @Override
   public boolean isSameResource(final Memory that) {
-    return wmem_ != null ? wmem_.isSameResource(that) : false;
+    return hasMemory() ? wmem_.isSameResource(that) : false;
   }
 
   @Override

src/main/java/org/apache/datasketches/theta/SetOperation.java

@@ -25,6 +25,7 @@
 import static org.apache.datasketches.theta.PreambleUtil.SER_VER_BYTE;
 
 import org.apache.datasketches.common.Family;
+import org.apache.datasketches.common.MemoryStatus;
 import org.apache.datasketches.common.SketchesArgumentException;
 import org.apache.datasketches.memory.Memory;
 import org.apache.datasketches.memory.WritableMemory;
@@ -35,7 +36,7 @@
  *
  * @author Lee Rhodes
  */
-public abstract class SetOperation {
+public abstract class SetOperation implements MemoryStatus {
   static final int CONST_PREAMBLE_LONGS = 3;
 
   SetOperation() {}
@@ -237,20 +238,6 @@ public static int getMaxAnotBResultBytes(final int nomEntries) {
    */
   public abstract Family getFamily();
 
-  /**
-   * Returns true if the backing resource of <i>this</i> is identical with the backing resource
-   * of <i>that</i>. The capacities must be the same.  If <i>this</i> is a region,
-   * the region offset must also be the same.
-   *
-   * <p>Note: Only certain set operators during stateful operations can be serialized.
-   * Only when they are stored into Memory will this be relevant.</p>
-   *
-   * @param that A different non-null and alive object
-   * @return true if the backing resource of <i>this</i> is the same as the backing resource
-   * of <i>that</i>.
-   */
-  public abstract boolean isSameResource(Memory that);
-
   //restricted
 
   /**

src/main/java/org/apache/datasketches/theta/SingleItemSketch.java

@@ -343,16 +343,6 @@ public double getUpperBound(final int numStdDev) {
     return 1.0;
   }
 
-  @Override
-  public boolean hasMemory() {
-    return false;
-  }
-
-  @Override
-  public boolean isDirect() {
-    return false;
-  }
-
   @Override
   public boolean isEmpty() {
     return false;

src/main/java/org/apache/datasketches/theta/Sketch.java

@@ -32,6 +32,7 @@
 import static org.apache.datasketches.thetacommon.HashOperations.count;
 
 import org.apache.datasketches.common.Family;
+import org.apache.datasketches.common.MemoryStatus;
 import org.apache.datasketches.common.SketchesArgumentException;
 import org.apache.datasketches.memory.Memory;
 import org.apache.datasketches.memory.WritableMemory;
@@ -44,7 +45,7 @@
  *
  * @author Lee Rhodes
  */
-public abstract class Sketch {
+public abstract class Sketch implements MemoryStatus {
   static final int DEFAULT_LG_RESIZE_FACTOR = 3;   //Unique to Heap
 
   Sketch() {}
@@ -383,26 +384,12 @@ public double getUpperBound(final int numStdDev) {
         : getRetainedEntries(true);
   }
 
-  /**
-   * Returns true if this sketch's data structure is backed by Memory or WritableMemory.
-   * @return true if this sketch's data structure is backed by Memory or WritableMemory.
-   */
-  public abstract boolean hasMemory();
-
   /**
    * Returns true if this sketch is in compact form.
    * @return true if this sketch is in compact form.
    */
   public abstract boolean isCompact();
 
-  /**
-   * Returns true if the this sketch's internal data structure is backed by direct (off-heap)
-   * Memory.
-   * @return true if the this sketch's internal data structure is backed by direct (off-heap)
-   * Memory.
-   */
-  public abstract boolean isDirect();
-
   /**
    * <a href="{@docRoot}/resources/dictionary.html#empty">See Empty</a>
    * @return true if empty.
@@ -424,18 +411,6 @@ public boolean isEstimationMode() {
    */
   public abstract boolean isOrdered();
 
-  /**
-   * Returns true if the backing resource of <i>this</i> is identical with the backing resource
-   * of <i>that</i>. The capacities must be the same.  If <i>this</i> is a region,
-   * the region offset must also be the same.
-   * @param that A different non-null object
-   * @return true if the backing resource of <i>this</i> is the same as the backing resource
-   * of <i>that</i>.
-   */
-  public boolean isSameResource(final Memory that) {
-    return false;
-  }
-
   /**
    * Returns a HashIterator that can be used to iterate over the retained hash values of the
    * Theta sketch.

src/main/java/org/apache/datasketches/theta/UnionImpl.java

@@ -262,10 +262,22 @@ public CompactSketch getResult(final boolean dstOrdered, final WritableMemory ds
         minThetaLong, curCountOut, seedHash, empty, true, dstOrdered, dstOrdered, dstMem, compactCacheOut);
   }
 
+  @Override
+  public boolean hasMemory() {
+    return gadget_ instanceof DirectQuickSelectSketchR
+        ? gadget_.hasMemory() : false;
+  }
+
+  @Override
+  public boolean isDirect() {
+    return gadget_ instanceof DirectQuickSelectSketchR
+        ? gadget_.isDirect() : false;
+  }
+
   @Override
   public boolean isSameResource(final Memory that) {
     return gadget_ instanceof DirectQuickSelectSketchR
-        ? gadget_.getMemory().isSameResource(that) : false;
+        ? gadget_.isSameResource(that) : false;
   }
 
   @Override