Remove SizeEstimator from o.a.spark package.

See comments on https://github.com/apache/spark/pull/3913

Author: Reynold Xin <rxin@databricks.com>

Closes #6471 from rxin/sizeestimator and squashes the following commits:

c057095 [Reynold Xin] Fixed import.
2da478b [Reynold Xin] Remove SizeEstimator from o.a.spark package.

2 files changed, 17 insertions, 47 deletions

diff --git a/core/src/main/scala/org/apache/spark/SizeEstimator.scala b/core/src/main/scala/org/apache/spark/SizeEstimator.scala
deleted file mode 100644
index 54fc3a856a..0000000000
--- a/core/src/main/scala/org/apache/spark/SizeEstimator.scala
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * 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
-
-import org.apache.spark.annotation.DeveloperApi
-
-/**
- * Estimates the sizes of Java objects (number of bytes of memory they occupy), for use in
- * memory-aware caches.
- *
- * Based on the following JavaWorld article:
- * http://www.javaworld.com/javaworld/javaqa/2003-12/02-qa-1226-sizeof.html
- */
-@DeveloperApi
-object SizeEstimator {
-  /**
-   * :: DeveloperApi ::
-   * Estimate the number of bytes that the given object takes up on the JVM heap. The estimate
-   * includes space taken up by objects referenced by the given object, their references, and so on
-   * and so forth.
-   *
-   * This is useful for determining the amount of heap space a broadcast variable will occupy on
-   * each executor or the amount of space each object will take when caching objects in
-   * deserialized form. This is not the same as the serialized size of the object, which will
-   * typically be much smaller.
-   */
-  @DeveloperApi
-  def estimate(obj: AnyRef): Long = org.apache.spark.util.SizeEstimator.estimate(obj)
-}
diff --git a/core/src/main/scala/org/apache/spark/util/SizeEstimator.scala b/core/src/main/scala/org/apache/spark/util/SizeEstimator.scala
index 968a72d5ad..f38949c3cb 100644
--- a/core/src/main/scala/org/apache/spark/util/SizeEstimator.scala
+++ b/core/src/main/scala/org/apache/spark/util/SizeEstimator.scala
@@ -21,21 +21,37 @@ import java.lang.management.ManagementFactory
 import java.lang.reflect.{Field, Modifier}
 import java.util.{IdentityHashMap, Random}
 import java.util.concurrent.ConcurrentHashMap
+
 import scala.collection.mutable.ArrayBuffer
 import scala.runtime.ScalaRunTime
 
 import org.apache.spark.Logging
+import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.util.collection.OpenHashSet
 
 
 /**
+ * :: DeveloperApi ::
  * Estimates the sizes of Java objects (number of bytes of memory they occupy), for use in
  * memory-aware caches.
  *
  * Based on the following JavaWorld article:
  * http://www.javaworld.com/javaworld/javaqa/2003-12/02-qa-1226-sizeof.html
  */
-private[spark] object SizeEstimator extends Logging {
+@DeveloperApi
+object SizeEstimator extends Logging {
+
+  /**
+   * Estimate the number of bytes that the given object takes up on the JVM heap. The estimate
+   * includes space taken up by objects referenced by the given object, their references, and so on
+   * and so forth.
+   *
+   * This is useful for determining the amount of heap space a broadcast variable will occupy on
+   * each executor or the amount of space each object will take when caching objects in
+   * deserialized form. This is not the same as the serialized size of the object, which will
+   * typically be much smaller.
+   */
+  def estimate(obj: AnyRef): Long = estimate(obj, new IdentityHashMap[AnyRef, AnyRef])
 
   // Sizes of primitive types
   private val BYTE_SIZE    = 1
@@ -161,8 +177,6 @@ private[spark] object SizeEstimator extends Logging {
     val shellSize: Long,
     val pointerFields: List[Field]) {}
 
-  def estimate(obj: AnyRef): Long = estimate(obj, new IdentityHashMap[AnyRef, AnyRef])
-
   private def estimate(obj: AnyRef, visited: IdentityHashMap[AnyRef, AnyRef]): Long = {
     val state = new SearchState(visited)
     state.enqueue(obj)