Fix [Type]ArrayList elements() method usage (apache#13354)

pinot-common/src/main/java/org/apache/pinot/common/utils/ArrayListUtils.java

@@ -0,0 +1,139 @@
+/**
+ * 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.pinot.common.utils;
+
+import it.unimi.dsi.fastutil.doubles.DoubleArrayList;
+import it.unimi.dsi.fastutil.floats.FloatArrayList;
+import it.unimi.dsi.fastutil.ints.IntArrayList;
+import it.unimi.dsi.fastutil.longs.LongArrayList;
+import it.unimi.dsi.fastutil.objects.ObjectArrayList;
+
+
+/**
+ * Utility class for {@link IntArrayList}, {@link LongArrayList}, {@link FloatArrayList}, {@link DoubleArrayList},
+ * {@link ObjectArrayList}.
+ */
+public class ArrayListUtils {
+  private ArrayListUtils() {
+  }
+
+  /**
+   * Best effort extract the given {@link IntArrayList} to an int array without copying the elements.
+   * The {@link IntArrayList#elements()} returned int array may be longer than the actual size of the
+   * {@link IntArrayList}, and the actual size of the {@link IntArrayList} can be retrieved using
+   * {@link IntArrayList#size()}.
+   * This method checks the length of the returned int array and returns the same if it is equal to the size of the
+   * {@link IntArrayList}, otherwise, it copies the elements to a new int array and returns it.
+   *
+   * <p>Use this method only if you are sure that the returned int array will not be modified.
+   * <p>Otherwise, use {@link IntArrayList#toIntArray()}.
+   *
+   * @param intArrayList Input {@link IntArrayList}
+   * @return Best effort extracted int array without copying the elements
+   */
+  public static int[] toIntArray(IntArrayList intArrayList) {
+    int[] intArrayListElements = intArrayList.elements();
+    return intArrayListElements.length == intArrayList.size() ? intArrayListElements : intArrayList.toIntArray();
+  }
+
+  /**
+   * Best effort extract the given {@link LongArrayList} to a long array without copying the elements.
+   * The {@link LongArrayList#elements()} returned long array may be longer than the actual size of the
+   * {@link LongArrayList}, and the actual size of the {@link LongArrayList} can be retrieved using
+   * {@link LongArrayList#size()}.
+   * This method checks the length of the returned long array and returns the same if it is equal to the size of the
+   * {@link LongArrayList}, otherwise, it copies the elements to a new long array and returns it.
+   *
+   * <p>Use this method only if you are sure that the returned long array will not be modified.
+   * <p>Otherwise, use {@link LongArrayList#toLongArray()}.
+   *
+   * @param longArrayList Input {@link LongArrayList}
+   * @return Best effort extracted long array without copying the elements
+   */
+  public static long[] toLongArray(LongArrayList longArrayList) {
+    long[] longArrayListElements = longArrayList.elements();
+    return longArrayListElements.length == longArrayList.size() ? longArrayListElements : longArrayList.toLongArray();
+  }
+
+  /**
+   * Best effort extract the given {@link FloatArrayList} to a float array without copying the elements.
+   * The {@link FloatArrayList#elements()} returned float array may be longer than the actual size of the
+   * {@link FloatArrayList}, and the actual size of the {@link FloatArrayList} can be retrieved using
+   * {@link FloatArrayList#size()}.
+   * This method checks the length of the returned float array and returns the same if it is equal to the size of the
+   * {@link FloatArrayList}, otherwise, it copies the elements to a new float array and returns it.
+   *
+   * <p>Use this method only if you are sure that the returned float array will not be modified.
+   * <p>Otherwise, use {@link FloatArrayList#toFloatArray()}.
+   *
+   * @param floatArrayList Input {@link FloatArrayList}
+   * @return Best effort extracted float array without copying the elements
+   */
+  public static float[] toFloatArray(FloatArrayList floatArrayList) {
+    float[] floatArrayListElements = floatArrayList.elements();
+    return floatArrayListElements.length == floatArrayList.size() ? floatArrayListElements
+        : floatArrayList.toFloatArray();
+  }
+
+  /**
+   * Best effort extract the given {@link DoubleArrayList} to a double array without copying the elements.
+   * The {@link DoubleArrayList#elements()} returned double array may be longer than the actual size of the
+   * {@link DoubleArrayList}, and the actual size of the {@link DoubleArrayList} can be retrieved using
+   * {@link DoubleArrayList#size()}.
+   * This method checks the length of the returned double array and returns the same if it is equal to the size of the
+   * {@link DoubleArrayList}, otherwise, it copies the elements to a new double array and returns it.
+   *
+   * <p>Use this method only if you are sure that the returned double array will not be modified.
+   * <p>Otherwise, use {@link DoubleArrayList#toDoubleArray()}.
+   *
+   * @param doubleArrayList Input {@link DoubleArrayList}
+   * @return Best effort extracted double array without copying the elements
+   */
+  public static double[] toDoubleArray(DoubleArrayList doubleArrayList) {
+    double[] doubleArrayListElements = doubleArrayList.elements();
+    return doubleArrayListElements.length == doubleArrayList.size() ? doubleArrayListElements
+        : doubleArrayList.toDoubleArray();
+  }
+
+  /**
+   * Convert the given {@link ObjectArrayList} to a string array.
+   * The method {@link ObjectArrayList#elements()} could return either Object[] or String[]. The casting to String[]
+   * is not guaranteed to work, and it may throw {@link ClassCastException} if the internal object is not a String
+   * array.
+   * <p>
+   *   This method first get `elements` as Object, then check if it's instance of String[].
+   *   Only return the reference when the internal object is a String array and the length equals to ObjectArrayList
+   *   size.
+   *   For all the other scenarios, just copy the elements to a new string array and returns it.
+   * <p>
+   *
+   * @param stringArrayList Input {@link ObjectArrayList}
+   * @return Copied string array
+   */
+  public static String[] toStringArray(ObjectArrayList<String> stringArrayList) {
+    Object elements = stringArrayList.elements();
+    if (elements instanceof String[]) {
+      String[] stringArrayListElements = (String[]) elements;
+      if (stringArrayListElements.length == stringArrayList.size()) {
+        return stringArrayListElements;
+      }
+    }
+    return stringArrayList.toArray(new String[0]);
+  }
+}

pinot-common/src/main/java/org/apache/pinot/common/utils/DataSchema.java

@@ -523,7 +523,7 @@ private static int[] toIntArray(Object value) {
         return (int[]) value;
       } else if (value instanceof IntArrayList) {
         // For ArrayAggregationFunction
-        return ((IntArrayList) value).elements();
+        return ArrayListUtils.toIntArray((IntArrayList) value);
       }
       throw new IllegalStateException(String.format("Cannot convert: '%s' to int[]", value));
     }
@@ -533,7 +533,7 @@ private static float[] toFloatArray(Object value) {
         return (float[]) value;
       } else if (value instanceof FloatArrayList) {
         // For ArrayAggregationFunction
-        return ((FloatArrayList) value).elements();
+        return ArrayListUtils.toFloatArray((FloatArrayList) value);
       }
       throw new IllegalStateException(String.format("Cannot convert: '%s' to float[]", value));
     }
@@ -543,7 +543,7 @@ private static double[] toDoubleArray(Object value) {
         return (double[]) value;
       } else if (value instanceof DoubleArrayList) {
         // For HistogramAggregationFunction and ArrayAggregationFunction
-        return ((DoubleArrayList) value).elements();
+        return ArrayListUtils.toDoubleArray((DoubleArrayList) value);
       } else if (value instanceof int[]) {
         int[] intValues = (int[]) value;
         int length = intValues.length;
@@ -576,7 +576,7 @@ private static long[] toLongArray(Object value) {
         return (long[]) value;
       } else if (value instanceof LongArrayList) {
         // For FunnelCountAggregationFunction and ArrayAggregationFunction
-        return ((LongArrayList) value).elements();
+        return ArrayListUtils.toLongArray((LongArrayList) value);
       } else {
         int[] intValues = (int[]) value;
         int length = intValues.length;
@@ -593,7 +593,7 @@ private static String[] toStringArray(Object value) {
         return (String[]) value;
       } else if (value instanceof ObjectArrayList) {
         // For ArrayAggregationFunction
-        return ((ObjectArrayList<String>) value).toArray(new String[0]);
+        return ArrayListUtils.toStringArray((ObjectArrayList<String>) value);
       }
       throw new IllegalStateException(String.format("Cannot convert: '%s' to String[]", value));
     }

pinot-common/src/test/java/org/apache/pinot/common/utils/ArrayListUtilsTest.java

@@ -0,0 +1,146 @@
+/**
+ * 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.pinot.common.utils;
+
+import it.unimi.dsi.fastutil.doubles.DoubleArrayList;
+import it.unimi.dsi.fastutil.floats.FloatArrayList;
+import it.unimi.dsi.fastutil.ints.IntArrayList;
+import it.unimi.dsi.fastutil.longs.LongArrayList;
+import it.unimi.dsi.fastutil.objects.ObjectArrayList;
+import org.testng.annotations.Test;
+
+import static org.testng.Assert.assertEquals;
+
+
+public class ArrayListUtilsTest {
+  @Test
+  public void testToIntArray() {
+    // Test empty list
+    IntArrayList intArrayList = new IntArrayList();
+    int[] intArray = ArrayListUtils.toIntArray(intArrayList);
+    assertEquals(intArray.length, 0);
+
+    // Test list with one element
+    intArrayList.add(1);
+    intArray = ArrayListUtils.toIntArray(intArrayList);
+    assertEquals(intArray.length, 1);
+    assertEquals(intArray[0], 1);
+
+    // Test list with multiple elements
+    intArrayList.add(2);
+    intArrayList.add(3);
+    intArray = ArrayListUtils.toIntArray(intArrayList);
+    assertEquals(intArray.length, 3);
+    assertEquals(intArray[0], 1);
+    assertEquals(intArray[1], 2);
+    assertEquals(intArray[2], 3);
+  }
+
+  @Test
+  public void testToLongArray() {
+    // Test empty list
+    LongArrayList longArrayList = new LongArrayList();
+    long[] longArray = ArrayListUtils.toLongArray(longArrayList);
+    assertEquals(longArray.length, 0);
+
+    // Test list with one element
+    longArrayList.add(1L);
+    longArray = ArrayListUtils.toLongArray(longArrayList);
+    assertEquals(longArray.length, 1);
+    assertEquals(longArray[0], 1L);
+
+    // Test list with multiple elements
+    longArrayList.add(2L);
+    longArrayList.add(3L);
+    longArray = ArrayListUtils.toLongArray(longArrayList);
+    assertEquals(longArray.length, 3);
+    assertEquals(longArray[0], 1L);
+    assertEquals(longArray[1], 2L);
+    assertEquals(longArray[2], 3L);
+  }
+
+  @Test
+  public void testToFloatArray() {
+    // Test empty list
+    FloatArrayList floatArrayList = new FloatArrayList();
+    float[] floatArray = ArrayListUtils.toFloatArray(floatArrayList);
+    assertEquals(floatArray.length, 0);
+
+    // Test list with one element
+    floatArrayList.add(1.0f);
+    floatArray = ArrayListUtils.toFloatArray(floatArrayList);
+    assertEquals(floatArray.length, 1);
+    assertEquals(floatArray[0], 1.0f);
+
+    // Test list with multiple elements
+    floatArrayList.add(2.0f);
+    floatArrayList.add(3.0f);
+    floatArray = ArrayListUtils.toFloatArray(floatArrayList);
+    assertEquals(floatArray.length, 3);
+    assertEquals(floatArray[0], 1.0f);
+    assertEquals(floatArray[1], 2.0f);
+    assertEquals(floatArray[2], 3.0f);
+  }
+
+  @Test
+  public void testToDoubleArray() {
+    // Test empty list
+    DoubleArrayList doubleArrayList = new DoubleArrayList();
+    double[] doubleArray = ArrayListUtils.toDoubleArray(doubleArrayList);
+    assertEquals(doubleArray.length, 0);
+
+    // Test list with one element
+    doubleArrayList.add(1.0);
+    doubleArray = ArrayListUtils.toDoubleArray(doubleArrayList);
+    assertEquals(doubleArray.length, 1);
+    assertEquals(doubleArray[0], 1.0);
+
+    // Test list with multiple elements
+    doubleArrayList.add(2.0);
+    doubleArrayList.add(3.0);
+    doubleArray = ArrayListUtils.toDoubleArray(doubleArrayList);
+    assertEquals(doubleArray.length, 3);
+    assertEquals(doubleArray[0], 1.0);
+    assertEquals(doubleArray[1], 2.0);
+    assertEquals(doubleArray[2], 3.0);
+  }
+
+  @Test
+  public void testToStringArray() {
+    // Test empty list
+    ObjectArrayList<String> stringArrayList = new ObjectArrayList<String>();
+    String[] stringArray = ArrayListUtils.toStringArray(stringArrayList);
+    assertEquals(stringArray.length, 0);
+
+    // Test list with one element
+    stringArrayList.add("1");
+    stringArray = ArrayListUtils.toStringArray(stringArrayList);
+    assertEquals(stringArray.length, 1);
+    assertEquals(stringArray[0], "1");
+
+    // Test list with multiple elements
+    stringArrayList.add("2");
+    stringArrayList.add("3");
+    stringArray = ArrayListUtils.toStringArray(stringArrayList);
+    assertEquals(stringArray.length, 3);
+    assertEquals(stringArray[0], "1");
+    assertEquals(stringArray[1], "2");
+    assertEquals(stringArray[2], "3");
+  }
+}

pinot-core/src/main/java/org/apache/pinot/core/operator/blocks/results/AggregationResultsBlock.java

@@ -30,6 +30,7 @@
 import org.apache.commons.lang3.tuple.Pair;
 import org.apache.pinot.common.datatable.DataTable;
 import org.apache.pinot.common.request.context.FilterContext;
+import org.apache.pinot.common.utils.ArrayListUtils;
 import org.apache.pinot.common.utils.DataSchema;
 import org.apache.pinot.common.utils.DataSchema.ColumnDataType;
 import org.apache.pinot.core.common.datatable.DataTableBuilder;
@@ -195,19 +196,19 @@ private void setFinalResult(DataTableBuilder dataTableBuilder, ColumnDataType[]
         dataTableBuilder.setColumn(index, (ByteArray) result);
         break;
       case INT_ARRAY:
-        dataTableBuilder.setColumn(index, ((IntArrayList) result).elements());
+        dataTableBuilder.setColumn(index, ArrayListUtils.toIntArray((IntArrayList) result));
         break;
       case LONG_ARRAY:
-        dataTableBuilder.setColumn(index, ((LongArrayList) result).elements());
+        dataTableBuilder.setColumn(index, ArrayListUtils.toLongArray((LongArrayList) result));
         break;
       case FLOAT_ARRAY:
-        dataTableBuilder.setColumn(index, ((FloatArrayList) result).elements());
+        dataTableBuilder.setColumn(index, ArrayListUtils.toFloatArray((FloatArrayList) result));
         break;
       case DOUBLE_ARRAY:
-        dataTableBuilder.setColumn(index, ((DoubleArrayList) result).elements());
+        dataTableBuilder.setColumn(index, ArrayListUtils.toDoubleArray((DoubleArrayList) result));
         break;
       case STRING_ARRAY:
-        dataTableBuilder.setColumn(index, ((ObjectArrayList<String>) result).elements());
+        dataTableBuilder.setColumn(index, ArrayListUtils.toStringArray((ObjectArrayList<String>) result));
         break;
       default:
         throw new IllegalStateException("Illegal column data type in final result: " + columnDataType);