relocate method in BufferAggregator.

extensions-core/datasketches/src/main/java/io/druid/query/aggregation/datasketches/theta/SketchBufferAggregator.java

@@ -28,20 +28,19 @@
 import io.druid.query.aggregation.BufferAggregator;
 import io.druid.query.monomorphicprocessing.RuntimeShapeInspector;
 import io.druid.segment.ObjectColumnSelector;
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
 
 import java.nio.ByteBuffer;
-import java.util.HashMap;
-import java.util.Map;
+import java.util.IdentityHashMap;
 
 public class SketchBufferAggregator implements BufferAggregator
 {
   private final ObjectColumnSelector selector;
   private final int size;
   private final int maxIntermediateSize;
-
-  private NativeMemory nm;
-
-  private final Map<Integer, Union> unions = new HashMap<>(); //position in BB -> Union Object
+  private final IdentityHashMap<ByteBuffer, Int2ObjectMap<Union>> unions = new IdentityHashMap<>();
+  private final IdentityHashMap<ByteBuffer, NativeMemory> nmCache = new IdentityHashMap<>();
 
   public SketchBufferAggregator(ObjectColumnSelector selector, int size, int maxIntermediateSize)
   {
@@ -53,12 +52,7 @@ public SketchBufferAggregator(ObjectColumnSelector selector, int size, int maxIn
   @Override
   public void init(ByteBuffer buf, int position)
   {
-    if (nm == null) {
-      nm = new NativeMemory(buf);
-    }
-
-    Memory mem = new MemoryRegion(nm, position, maxIntermediateSize);
-    unions.put(position, (Union) SetOperation.builder().initMemory(mem).build(size, Family.UNION));
+    createNewUnion(buf, position, false);
   }
 
   @Override
@@ -87,12 +81,27 @@ public Object get(ByteBuffer buf, int position)
   //Note that this is not threadsafe and I don't think it needs to be
   private Union getUnion(ByteBuffer buf, int position)
   {
-    Union union = unions.get(position);
-    if (union == null) {
-      Memory mem = new MemoryRegion(nm, position, maxIntermediateSize);
-      union = (Union) SetOperation.wrap(mem);
-      unions.put(position, union);
+    Int2ObjectMap<Union> unionMap = unions.get(buf);
+    Union union = unionMap != null ? unionMap.get(position) : null;
+    if (union != null) {
+      return union;
+    }
+    return createNewUnion(buf, position, true);
+  }
+
+  private Union createNewUnion(ByteBuffer buf, int position, boolean isWrapped)
+  {
+    NativeMemory nm = getNativeMemory(buf);
+    Memory mem = new MemoryRegion(nm, position, maxIntermediateSize);
+    Union union = isWrapped
+                  ? (Union) SetOperation.wrap(mem)
+                  : (Union) SetOperation.builder().initMemory(mem).build(size, Family.UNION);
+    Int2ObjectMap<Union> unionMap = unions.get(buf);
+    if (unionMap == null) {
+      unionMap = new Int2ObjectOpenHashMap<>();
+      unions.put(buf, unionMap);
     }
+    unionMap.put(position, union);
     return union;
   }
 
@@ -119,4 +128,29 @@ public void inspectRuntimeShape(RuntimeShapeInspector inspector)
   {
     inspector.visit("selector", selector);
   }
+
+  @Override
+  public void relocate(int oldPosition, int newPosition, ByteBuffer oldBuffer, ByteBuffer newBuffer)
+  {
+    createNewUnion(newBuffer, newPosition, true);
+    Int2ObjectMap<Union> unionMap = unions.get(oldBuffer);
+    if (unionMap != null) {
+      unionMap.remove(oldPosition);
+      if (unionMap.isEmpty()) {
+        unions.remove(oldBuffer);
+        nmCache.remove(oldBuffer);
+      }
+    }
+  }
+
+  private NativeMemory getNativeMemory(ByteBuffer buffer)
+  {
+    NativeMemory nm = nmCache.get(buffer);
+    if (nm == null) {
+      nm = new NativeMemory(buffer);
+      nmCache.put(buffer, nm);
+    }
+    return nm;
+  }
+
 }

extensions-core/datasketches/src/main/java/io/druid/query/aggregation/datasketches/theta/SketchHolder.java

@@ -290,4 +290,16 @@ public static SketchHolder sketchSetOperation(Func func, int sketchSize, Object.
         throw new IllegalArgumentException("Unknown sketch operation " + func);
     }
   }
+
+  @Override
+  public boolean equals(Object o)
+  {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    return this.getSketch().equals(((SketchHolder) o).getSketch());
+  }
 }

extensions-core/datasketches/src/test/java/io/druid/query/aggregation/datasketches/theta/BufferGrouperUsingSketchMergeAggregatorFactoryTest.java

@@ -0,0 +1,97 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Metamarkets 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 io.druid.query.aggregation.datasketches.theta;
+
+import com.google.common.base.Suppliers;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Lists;
+import com.yahoo.sketches.theta.Sketches;
+import com.yahoo.sketches.theta.UpdateSketch;
+import io.druid.data.input.MapBasedRow;
+import io.druid.query.aggregation.AggregatorFactory;
+import io.druid.query.aggregation.CountAggregatorFactory;
+import io.druid.query.groupby.epinephelinae.BufferGrouper;
+import io.druid.query.groupby.epinephelinae.Grouper;
+import io.druid.query.groupby.epinephelinae.GrouperTestUtil;
+import io.druid.query.groupby.epinephelinae.TestColumnSelectorFactory;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.nio.ByteBuffer;
+
+public class BufferGrouperUsingSketchMergeAggregatorFactoryTest
+{
+  private static BufferGrouper<Integer> makeGrouper(
+      TestColumnSelectorFactory columnSelectorFactory,
+      int bufferSize,
+      int initialBuckets
+  )
+  {
+    final BufferGrouper<Integer> grouper = new BufferGrouper<>(
+        Suppliers.ofInstance(ByteBuffer.allocate(bufferSize)),
+        GrouperTestUtil.intKeySerde(),
+        columnSelectorFactory,
+        new AggregatorFactory[]{
+            new SketchMergeAggregatorFactory("sketch", "sketch", 16, false, true, 2),
+            new CountAggregatorFactory("count")
+        },
+        Integer.MAX_VALUE,
+        0.75f,
+        initialBuckets
+    );
+    grouper.init();
+    return grouper;
+  }
+
+  @Test
+  public void testGrowingBufferGrouper()
+  {
+    final TestColumnSelectorFactory columnSelectorFactory = GrouperTestUtil.newColumnSelectorFactory();
+    final Grouper<Integer> grouper = makeGrouper(columnSelectorFactory, 100000, 2);
+    try {
+      final int expectedMaxSize = 5;
+
+      SketchHolder sketchHolder = SketchHolder.of(Sketches.updateSketchBuilder().build(16));
+      UpdateSketch updateSketch = (UpdateSketch) sketchHolder.getSketch();
+      updateSketch.update(1);
+
+      columnSelectorFactory.setRow(new MapBasedRow(0, ImmutableMap.<String, Object>of("sketch", sketchHolder)));
+
+      for (int i = 0; i < expectedMaxSize; i++) {
+        Assert.assertTrue(String.valueOf(i), grouper.aggregate(i));
+      }
+
+      updateSketch.update(3);
+      columnSelectorFactory.setRow(new MapBasedRow(0, ImmutableMap.<String, Object>of("sketch", sketchHolder)));
+
+      for (int i = 0; i < expectedMaxSize; i++) {
+        Assert.assertTrue(String.valueOf(i), grouper.aggregate(i));
+      }
+
+      Object[] holders = Lists.newArrayList(grouper.iterator(true)).get(0).getValues();
+
+      Assert.assertEquals(2.0d, ((SketchHolder) holders[0]).getEstimate(), 0);
+    }
+    finally {
+      grouper.close();
+    }
+  }
+
+}

extensions-core/datasketches/src/test/java/io/druid/query/aggregation/datasketches/theta/SketchAggregationTest.java

@@ -28,6 +28,7 @@
 import com.yahoo.sketches.theta.Sketch;
 import com.yahoo.sketches.theta.Sketches;
 import com.yahoo.sketches.theta.Union;
+import com.yahoo.sketches.theta.UpdateSketch;
 import io.druid.data.input.MapBasedRow;
 import io.druid.data.input.Row;
 import io.druid.java.util.common.granularity.Granularities;
@@ -39,6 +40,8 @@
 import io.druid.query.aggregation.post.FieldAccessPostAggregator;
 import io.druid.query.groupby.GroupByQueryConfig;
 import io.druid.query.groupby.GroupByQueryRunnerTest;
+import io.druid.query.groupby.epinephelinae.GrouperTestUtil;
+import io.druid.query.groupby.epinephelinae.TestColumnSelectorFactory;
 import org.joda.time.DateTime;
 import org.junit.Assert;
 import org.junit.Rule;
@@ -389,6 +392,23 @@ public void testSketchAggregatorFactoryComparator()
     Assert.assertEquals(1, comparator.compare(SketchHolder.of(union2), SketchHolder.of(sketch1)));
   }
 
+  @Test
+  public void testRelocation()
+  {
+    final TestColumnSelectorFactory columnSelectorFactory = GrouperTestUtil.newColumnSelectorFactory();
+    SketchHolder sketchHolder = SketchHolder.of(Sketches.updateSketchBuilder().build(16));
+    UpdateSketch updateSketch = (UpdateSketch) sketchHolder.getSketch();
+    updateSketch.update(1);
+
+    columnSelectorFactory.setRow(new MapBasedRow(0, ImmutableMap.<String, Object>of("sketch", sketchHolder)));
+    SketchHolder[] holders = helper.runRelocateVerificationTest(
+        new SketchMergeAggregatorFactory("sketch", "sketch", 16, false, true, 2),
+        columnSelectorFactory,
+        SketchHolder.class
+    );
+    Assert.assertEquals(holders[0].getEstimate(), holders[1].getEstimate(), 0);
+  }
+
   private void assertPostAggregatorSerde(PostAggregator agg) throws Exception
   {
     Assert.assertEquals(

extensions-core/datasketches/src/test/java/io/druid/query/aggregation/datasketches/theta/oldapi/OldApiSketchAggregationTest.java

@@ -22,16 +22,21 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Lists;
 import com.google.common.io.Files;
+import com.yahoo.sketches.theta.Sketches;
+import com.yahoo.sketches.theta.UpdateSketch;
 import io.druid.data.input.MapBasedRow;
 import io.druid.java.util.common.granularity.Granularities;
 import io.druid.java.util.common.guava.Sequence;
 import io.druid.java.util.common.guava.Sequences;
 import io.druid.query.aggregation.AggregationTestHelper;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.PostAggregator;
+import io.druid.query.aggregation.datasketches.theta.SketchHolder;
 import io.druid.query.aggregation.post.FieldAccessPostAggregator;
 import io.druid.query.groupby.GroupByQueryConfig;
 import io.druid.query.groupby.GroupByQueryRunnerTest;
+import io.druid.query.groupby.epinephelinae.GrouperTestUtil;
+import io.druid.query.groupby.epinephelinae.TestColumnSelectorFactory;
 import org.joda.time.DateTime;
 import org.junit.Assert;
 import org.junit.Rule;
@@ -194,6 +199,23 @@ public void testSketchSetPostAggregatorSerde() throws Exception
     );
   }
 
+  @Test
+  public void testRelocation()
+  {
+    final TestColumnSelectorFactory columnSelectorFactory = GrouperTestUtil.newColumnSelectorFactory();
+    SketchHolder sketchHolder = SketchHolder.of(Sketches.updateSketchBuilder().build(16));
+    UpdateSketch updateSketch = (UpdateSketch) sketchHolder.getSketch();
+    updateSketch.update(1);
+
+    columnSelectorFactory.setRow(new MapBasedRow(0, ImmutableMap.<String, Object>of("sketch", sketchHolder)));
+    SketchHolder[] holders = helper.runRelocateVerificationTest(
+        new OldSketchMergeAggregatorFactory("sketch", "sketch", 16, false),
+        columnSelectorFactory,
+        SketchHolder.class
+    );
+    Assert.assertEquals(holders[0].getEstimate(), holders[1].getEstimate(), 0);
+  }
+
   private void assertPostAggregatorSerde(PostAggregator agg) throws Exception
   {
     Assert.assertEquals(

processing/src/main/java/io/druid/query/aggregation/BufferAggregator.java

@@ -126,4 +126,28 @@ public interface BufferAggregator extends HotLoopCallee
   default void inspectRuntimeShape(RuntimeShapeInspector inspector)
   {
   }
+
+  /*
+   * Relocates any cached objects.
+   * If underlying ByteBuffer used for aggregation buffer relocates to a new ByteBuffer, positional caches(if any)
+   * built on top of old ByteBuffer can not be used for further {@link BufferAggregator#aggregate(ByteBuffer, int)}
+   * calls. This method tells the BufferAggregator that the cached objects at a certain location has been relocated to
+   * a different location.
+   *
+   * Only used if there is any positional caches/objects in the BufferAggregator implementation.
+   *
+   * If relocate happens to be across multiple new ByteBuffers (say n ByteBuffers), this method should be called
+   * multiple times(n times) given all the new positions/old positions should exist in newBuffer/OldBuffer.
+   *
+   * <b>Implementations must not change the position, limit or mark of the given buffer</b>
+   *
+   * @param oldPosition old position of a cached object before aggregation buffer relocates to a new ByteBuffer.
+   * @param newPosition new position of a cached object after aggregation buffer relocates to a new ByteBuffer.
+   * @param oldBuffer old aggregation buffer.
+   * @param newBuffer new aggregation buffer.
+   */
+  default void relocate(int oldPosition, int newPosition, ByteBuffer oldBuffer, ByteBuffer newBuffer)
+  {
+  }
+
 }

processing/src/main/java/io/druid/query/groupby/epinephelinae/BufferGrouper.java

@@ -430,8 +430,9 @@ private void growIfPossible()
 
     for (int oldBucket = 0; oldBucket < buckets; oldBucket++) {
       if (isUsed(oldBucket)) {
+        int oldPosition = oldBucket * bucketSize;
         entryBuffer.limit((oldBucket + 1) * bucketSize);
-        entryBuffer.position(oldBucket * bucketSize);
+        entryBuffer.position(oldPosition);
         keyBuffer.limit(entryBuffer.position() + HASH_SIZE + keySize);
         keyBuffer.position(entryBuffer.position() + HASH_SIZE);
 
@@ -442,9 +443,19 @@ private void growIfPossible()
           throw new ISE("WTF?! Couldn't find a bucket while resizing?!");
         }
 
-        newTableBuffer.position(newBucket * bucketSize);
+        int newPosition = newBucket * bucketSize;
+        newTableBuffer.position(newPosition);
         newTableBuffer.put(entryBuffer);
 
+        for (int i = 0; i < aggregators.length; i++) {
+          aggregators[i].relocate(
+              oldPosition + aggregatorOffsets[i],
+              newPosition + aggregatorOffsets[i],
+              tableBuffer,
+              newTableBuffer
+          );
+        }
+
         buffer.putInt(tableArenaSize + newSize * Ints.BYTES, newBucket * bucketSize);
         newSize++;
       }