Merge pull request #1375 from metamx/MetricManipulatorFnInstances

Modify MetricManipulatorFns to use instanced classes

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

@@ -21,39 +21,45 @@ package io.druid.query.aggregation;
  */
 public class MetricManipulatorFns
 {
-  public static MetricManipulationFn identity()
-  {
-    return new MetricManipulationFn()
+  private static final MetricManipulationFn IDENTITY_INSTANCE = new MetricManipulationFn()
   {
     @Override
-      public Object manipulate(AggregatorFactory factory, Object object)
+    public Object manipulate(final AggregatorFactory factory, final Object object)
     {
       return object;
     }
   };
+
+  public static MetricManipulationFn identity()
+  {
+    return IDENTITY_INSTANCE;
   }
 
-  public static MetricManipulationFn finalizing()
-  {
-    return new MetricManipulationFn()
+  private static final MetricManipulationFn FINALIZING_INSTANCE = new MetricManipulationFn()
   {
     @Override
-      public Object manipulate(AggregatorFactory factory, Object object)
+    public Object manipulate(final AggregatorFactory factory, final Object object)
     {
       return factory.finalizeComputation(object);
     }
   };
+
+  public static MetricManipulationFn finalizing()
+  {
+    return FINALIZING_INSTANCE;
   }
 
-  public static MetricManipulationFn deserializing()
-  {
-    return new MetricManipulationFn()
+  private static final MetricManipulationFn DESERIALIZING_INSTANCE = new MetricManipulationFn()
   {
     @Override
-      public Object manipulate(AggregatorFactory factory, Object object)
+    public Object manipulate(final AggregatorFactory factory, final Object object)
     {
       return factory.deserialize(object);
     }
   };
+
+  public static MetricManipulationFn deserializing()
+  {
+    return DESERIALIZING_INSTANCE;
   }
 }

processing/src/test/java/io/druid/query/aggregation/MetricManipulatorFnsTest.java

@@ -0,0 +1,161 @@
+/*
+ * 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;
+
+import io.druid.query.aggregation.hyperloglog.HyperLogLogCollector;
+import io.druid.query.aggregation.hyperloglog.HyperUniquesAggregatorFactory;
+import io.druid.segment.LongColumnSelector;
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+
+@RunWith(Parameterized.class)
+public class MetricManipulatorFnsTest
+{
+  private static final String NAME = "name";
+  private static final String FIELD = "field";
+
+  @Parameterized.Parameters(name = "{0}")
+  public static Iterable<Object[]> constructorFeeder()
+  {
+    final ArrayList<Object[]> constructorArrays = new ArrayList<>();
+    final long longVal = 13789;
+    LongMinAggregator longMinAggregator = new LongMinAggregator(
+        NAME, new LongColumnSelector()
+    {
+      @Override
+      public long get()
+      {
+        return longVal;
+      }
+    }
+    );
+    LongMinAggregatorFactory longMinAggregatorFactory = new LongMinAggregatorFactory(NAME, FIELD);
+    constructorArrays.add(
+        new Object[]{
+            longMinAggregatorFactory,
+            longMinAggregator,
+            longMinAggregator,
+            longMinAggregator,
+            longVal,
+            longVal
+        }
+    );
+
+    HyperUniquesAggregatorFactory hyperUniquesAggregatorFactory = new HyperUniquesAggregatorFactory(NAME, FIELD);
+    HyperLogLogCollector collector = HyperLogLogCollector.makeLatestCollector();
+    collector.add((short) 1, (byte) 5);
+
+    constructorArrays.add(
+        new Object[]{
+            hyperUniquesAggregatorFactory,
+            collector,
+            collector,
+            collector.estimateCardinality(),
+            collector.toByteArray(),
+            collector
+        }
+    );
+
+
+    LongSumAggregatorFactory longSumAggregatorFactory = new LongSumAggregatorFactory(NAME, FIELD);
+    LongSumAggregator longSumAggregator = new LongSumAggregator(
+        NAME, new LongColumnSelector()
+    {
+      @Override
+      public long get()
+      {
+        return longVal;
+      }
+    }
+    );
+    constructorArrays.add(
+        new Object[]{
+            longSumAggregatorFactory,
+            longSumAggregator,
+            longSumAggregator,
+            longSumAggregator,
+            longVal,
+            longVal
+        }
+    );
+
+
+    for (Object[] argList : constructorArrays) {
+      Assert.assertEquals(
+          String.format(
+              "Arglist %s is too short. Expected 6 found %d",
+              Arrays.toString(argList),
+              argList.length
+          ), 6, argList.length
+      );
+    }
+    return constructorArrays;
+  }
+
+  private final AggregatorFactory aggregatorFactory;
+  private final Object agg;
+  private final Object identity;
+  private final Object finalize;
+  private final Object serialForm;
+  private final Object deserForm;
+
+  public MetricManipulatorFnsTest(
+      AggregatorFactory aggregatorFactory,
+      Object agg,
+      Object identity,
+      Object finalize,
+      Object serialForm,
+      Object deserForm
+  )
+  {
+    this.aggregatorFactory = aggregatorFactory;
+    this.agg = agg;
+    this.identity = identity;
+    this.finalize = finalize;
+    this.serialForm = serialForm;
+    this.deserForm = deserForm;
+  }
+
+  @Test
+  public void testIdentity()
+  {
+    Assert.assertEquals(identity, agg);
+    Assert.assertEquals(identity, MetricManipulatorFns.identity().manipulate(aggregatorFactory, agg));
+  }
+
+  @Test
+  public void testFinalize()
+  {
+    Assert.assertEquals(identity, agg);
+    Assert.assertEquals(finalize, MetricManipulatorFns.finalizing().manipulate(aggregatorFactory, agg));
+  }
+
+  @Test
+  public void testDeserialize()
+  {
+    Assert.assertEquals(identity, agg);
+    Assert.assertEquals(deserForm, MetricManipulatorFns.deserializing().manipulate(aggregatorFactory, serialForm));
+  }
+}