Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/5868#discussion_r30107117
--- Diff:
core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleSorter.java ---
@@ -0,0 +1,112 @@
+/*
+ * 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.util.Comparator;
+
+import org.apache.spark.util.collection.Sorter;
+
+final class UnsafeShuffleSorter {
+
+ private final Sorter<PackedRecordPointer, long[]> sorter;
+ private static final class SortComparator implements
Comparator<PackedRecordPointer> {
+ @Override
+ public int compare(PackedRecordPointer left, PackedRecordPointer
right) {
+ return left.getPartitionId() - right.getPartitionId();
+ }
+ }
+ private static final SortComparator SORT_COMPARATOR = new
SortComparator();
+
+ private long[] sortBuffer;
+
+ /**
+ * The position in the sort buffer where new records can be inserted.
+ */
+ private int sortBufferInsertPosition = 0;
+
+ public UnsafeShuffleSorter(int initialSize) {
+ assert (initialSize > 0);
+ this.sortBuffer = new long[initialSize];
+ this.sorter = new Sorter<PackedRecordPointer,
long[]>(UnsafeShuffleSortDataFormat.INSTANCE);
+ }
+
+ public void expandSortBuffer() {
+ final long[] oldBuffer = sortBuffer;
+ sortBuffer = new long[oldBuffer.length * 2];
+ System.arraycopy(oldBuffer, 0, sortBuffer, 0, oldBuffer.length);
+ }
+
+ public boolean hasSpaceForAnotherRecord() {
+ return sortBufferInsertPosition + 1 < sortBuffer.length;
+ }
+
+ public long getMemoryUsage() {
+ return sortBuffer.length * 8L;
+ }
+
+ /**
+ * Inserts a record to be sorted.
+ *
+ * @param recordPointer a pointer to the record, encoded by the task
memory manager. Due to
+ * certain pointer compression techniques used by
the sorter, the sort can
+ * only operate on pointers that point to locations
in the first
+ * {@link
PackedRecordPointer#MAXIMUM_PAGE_SIZE_BYTES} bytes of a data page.
+ * @param partitionId the partition id, which must be less than or equal
to
+ * {@link PackedRecordPointer#MAXIMUM_PARTITION_ID}.
+ */
+ public void insertRecord(long recordPointer, int partitionId) {
+ if (!hasSpaceForAnotherRecord()) {
+ expandSortBuffer();
+ }
+ sortBuffer[sortBufferInsertPosition] =
+ PackedRecordPointer.packPointer(recordPointer, partitionId);
+ sortBufferInsertPosition++;
+ }
+
+ public static abstract class UnsafeShuffleSorterIterator {
--- End diff --
maybe add comment to explain why we don't just use scala or java iterator?
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