Use own ByteBufferOutputStream rather than Kryo's

core/src/main/java/org/apache/spark/shuffle/unsafe/ByteBufferOutputStream.java

@@ -0,0 +1,46 @@
+/*
+ * 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.shuffle.unsafe;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.ByteBuffer;
+
+class ByteBufferOutputStream extends OutputStream {
+
+  private final ByteBuffer byteBuffer;
+
+  public ByteBufferOutputStream(ByteBuffer byteBuffer) {
+    this.byteBuffer = byteBuffer;
+  }
+
+  @Override
+  public void write(int b) throws IOException {
+    byteBuffer.put((byte) b);
+  }
+
+  @Override
+  public void write(byte[] b) throws IOException {
+    byteBuffer.put(b);
+  }
+
+  @Override
+  public void write(byte[] b, int off, int len) throws IOException {
+    byteBuffer.put(b, off, len);
+  }
+}

core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleExternalSorter.java

@@ -53,7 +53,7 @@
  * spill files. Instead, this merging is performed in {@link UnsafeShuffleWriter}, which uses a
  * specialized merge procedure that avoids extra serialization/deserialization.
  */
-public final class UnsafeShuffleExternalSorter {
+final class UnsafeShuffleExternalSorter {
 
   private final Logger logger = LoggerFactory.getLogger(UnsafeShuffleExternalSorter.class);
 

core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleSorter.java

@@ -21,7 +21,7 @@
 
 import org.apache.spark.util.collection.Sorter;
 
-public final class UnsafeShuffleSorter {
+final class UnsafeShuffleSorter {
 
   private final Sorter<PackedRecordPointer, long[]> sorter;
   private static final class SortComparator implements Comparator<PackedRecordPointer> {

core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleWriter.java

@@ -28,7 +28,6 @@
 import scala.reflect.ClassTag;
 import scala.reflect.ClassTag$;
 
-import com.esotericsoftware.kryo.io.ByteBufferOutputStream;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.io.ByteStreams;
 import com.google.common.io.Closeables;
@@ -75,7 +74,6 @@ public class UnsafeShuffleWriter<K, V> extends ShuffleWriter<K, V> {
   private UnsafeShuffleExternalSorter sorter = null;
   private byte[] serArray = null;
   private ByteBuffer serByteBuffer;
-  // TODO: we should not depend on this class from Kryo; copy its source or find an alternative
   private SerializationStream serOutputStream;
 
   /**