Github user kiszk commented on a diff in the pull request:
https://github.com/apache/spark/pull/23124#discussion_r235950148
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/ArrayBasedMapBuilder.scala
---
@@ -0,0 +1,118 @@
+/*
+ * 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.spark.sql.catalyst.util
+
+import scala.collection.mutable
+
+import org.apache.spark.sql.catalyst.InternalRow
+import org.apache.spark.sql.types.{AtomicType, CalendarIntervalType,
DataType, MapType}
+
+/**
+ * A builder of [[ArrayBasedMapData]], which fails if a null map key is
detected, and removes
+ * duplicated map keys w.r.t. the last wins policy.
+ */
+class ArrayBasedMapBuilder(keyType: DataType, valueType: DataType) extends
Serializable {
+ assert(!keyType.existsRecursively(_.isInstanceOf[MapType]), "key of map
cannot be/contain map")
+
+ private lazy val keyToIndex = keyType match {
+ case _: AtomicType | _: CalendarIntervalType =>
mutable.HashMap.empty[Any, Int]
+ case _ =>
+ // for complex types, use interpreted ordering to be able to compare
unsafe data with safe
+ // data, e.g. UnsafeRow vs GenericInternalRow.
+ mutable.TreeMap.empty[Any,
Int](TypeUtils.getInterpretedOrdering(keyType))
+ }
+
+ // TODO: specialize it
+ private lazy val keys = mutable.ArrayBuffer.empty[Any]
+ private lazy val values = mutable.ArrayBuffer.empty[Any]
+
+ private lazy val keyGetter = InternalRow.getAccessor(keyType)
+ private lazy val valueGetter = InternalRow.getAccessor(valueType)
+
+ def reset(): Unit = {
+ keyToIndex.clear()
+ keys.clear()
+ values.clear()
+ }
+
+ def put(key: Any, value: Any): Unit = {
+ if (key == null) {
+ throw new RuntimeException("Cannot use null as map key.")
+ }
+
+ val maybeExistingIdx = keyToIndex.get(key)
+ if (maybeExistingIdx.isDefined) {
+ // Overwrite the previous value, as the policy is last wins.
+ values(maybeExistingIdx.get) = value
+ } else {
+ keyToIndex.put(key, values.length)
+ keys.append(key)
+ values.append(value)
+ }
+ }
+
+ // write a 2-field row, the first field is key and the second field is
value.
+ def put(entry: InternalRow): Unit = {
+ if (entry.isNullAt(0)) {
+ throw new RuntimeException("Cannot use null as map key.")
+ }
+ put(keyGetter(entry, 0), valueGetter(entry, 1))
+ }
+
+ def putAll(keyArray: Array[Any], valueArray: Array[Any]): Unit = {
+ if (keyArray.length != valueArray.length) {
+ throw new RuntimeException(
+ "The key array and value array of MapData must have the same
length.")
+ }
+
+ var i = 0
+ while (i < keyArray.length) {
+ put(keyArray(i), valueArray(i))
+ i += 1
+ }
+ }
+
+ def putAll(keyArray: ArrayData, valueArray: ArrayData): Unit = {
+ if (keyArray.numElements() != valueArray.numElements()) {
+ throw new RuntimeException(
+ "The key array and value array of MapData must have the same
length.")
+ }
+
+ var i = 0
+ while (i < keyArray.numElements()) {
+ put(keyGetter(keyArray, i), valueGetter(valueArray, i))
+ i += 1
+ }
+ }
+
+ def build(): ArrayBasedMapData = {
+ new ArrayBasedMapData(new GenericArrayData(keys.toArray), new
GenericArrayData(values.toArray))
+ }
--- End diff --
Is it better to call `reset()` after calling `new ArrayBasedMapData` to
reduce memory consumption?
At caller side, `ArrayBasedMapBuilder` is not released. Therefore, until
reset() will be called next time, each `ArrayBasedMapBuilder` keeps unused data
in `keys`, `values`, and `keyToIndex`. They consumes Java heap unexpectedly.
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