Github user Ngone51 commented on a diff in the pull request:
https://github.com/apache/spark/pull/21440#discussion_r191182696
--- Diff:
core/src/test/scala/org/apache/spark/io/ChunkedByteBufferFileRegionSuite.scala
---
@@ -0,0 +1,154 @@
+/*
+ * 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.io
+
+import java.nio.ByteBuffer
+import java.nio.channels.WritableByteChannel
+
+import scala.util.Random
+
+import org.mockito.Mockito.when
+import org.scalatest.BeforeAndAfterEach
+import org.scalatest.mockito.MockitoSugar
+
+import org.apache.spark.{SparkConf, SparkEnv, SparkFunSuite}
+import org.apache.spark.internal.config
+import org.apache.spark.util.io.ChunkedByteBuffer
+
+class ChunkedByteBufferFileRegionSuite extends SparkFunSuite with
MockitoSugar
+ with BeforeAndAfterEach {
+
+ override protected def beforeEach(): Unit = {
+ super.beforeEach()
+ val conf = new SparkConf()
+ val env = mock[SparkEnv]
+ SparkEnv.set(env)
+ when(env.conf).thenReturn(conf)
+ }
+
+ override protected def afterEach(): Unit = {
+ SparkEnv.set(null)
+ }
+
+ private def generateChunkByteBuffer(nChunks: Int, perChunk: Int):
ChunkedByteBuffer = {
+ val bytes = (0 until nChunks).map { chunkIdx =>
+ val bb = ByteBuffer.allocate(perChunk)
+ (0 until perChunk).foreach { idx =>
+ bb.put((chunkIdx * perChunk + idx).toByte)
+ }
+ bb.position(0)
+ bb
+ }.toArray
+ new ChunkedByteBuffer(bytes)
+ }
+
+ test("transferTo can stop and resume correctly") {
+ SparkEnv.get.conf.set(config.BUFFER_WRITE_CHUNK_SIZE, 9L)
+ val cbb = generateChunkByteBuffer(4, 10)
+ val fileRegion = cbb.toNetty
+
+ val targetChannel = new LimitedWritableByteChannel(40)
+
+ var pos = 0L
+ // write the fileregion to the channel, but with the transfer limited
at various spots along
+ // the way.
+
+ // limit to within the first chunk
+ targetChannel.acceptNBytes = 5
+ pos = fileRegion.transferTo(targetChannel, pos)
+ assert(targetChannel.pos === 5)
+
+ // a little bit further within the first chunk
+ targetChannel.acceptNBytes = 2
+ pos += fileRegion.transferTo(targetChannel, pos)
+ assert(targetChannel.pos === 7)
+
+ // past the first chunk, into the 2nd
+ targetChannel.acceptNBytes = 6
+ pos += fileRegion.transferTo(targetChannel, pos)
+ assert(targetChannel.pos === 13)
+
+ // right to the end of the 2nd chunk
+ targetChannel.acceptNBytes = 7
+ pos += fileRegion.transferTo(targetChannel, pos)
+ assert(targetChannel.pos === 20)
+
+ // rest of 2nd chunk, all of 3rd, some of 4th
+ targetChannel.acceptNBytes = 15
+ pos += fileRegion.transferTo(targetChannel, pos)
+ assert(targetChannel.pos === 35)
+
+ // now till the end
+ targetChannel.acceptNBytes = 5
+ pos += fileRegion.transferTo(targetChannel, pos)
+ assert(targetChannel.pos === 40)
+
+ // calling again at the end should be OK
+ targetChannel.acceptNBytes = 20
+ fileRegion.transferTo(targetChannel, pos)
+ assert(targetChannel.pos === 40)
+ }
+
+ test(s"transfer to with random limits") {
+ val rng = new Random()
+ val seed = System.currentTimeMillis()
+ logInfo(s"seed = $seed")
+ rng.setSeed(seed)
+ val chunkSize = 1e4.toInt
+ SparkEnv.get.conf.set(config.BUFFER_WRITE_CHUNK_SIZE,
rng.nextInt(chunkSize).toLong)
+
+ val cbb = generateChunkByteBuffer(50, chunkSize)
+ val fileRegion = cbb.toNetty
+ val transferLimit = 1e5.toInt
+ val targetChannel = new LimitedWritableByteChannel(transferLimit)
+ while (targetChannel.pos < cbb.size) {
+ val nextTransferSize = rng.nextInt(transferLimit)
+ targetChannel.acceptNBytes = nextTransferSize
+ fileRegion.transferTo(targetChannel, targetChannel.pos)
+ }
+ assert(0 === fileRegion.transferTo(targetChannel, targetChannel.pos))
+ }
+
+ /**
+ * This mocks a channel which only accepts a limited number of bytes at
a time. It also verifies
+ * the written data matches our expectations as the data is received.
+ * @param maxWriteSize
+ */
+ private class LimitedWritableByteChannel(maxWriteSize: Int) extends
WritableByteChannel {
+ val bytes = new Array[Byte](maxWriteSize)
+ var acceptNBytes = 0
+ var pos = 0
+
+ override def write(src: ByteBuffer): Int = {
+ val origSrcPos = src.position()
+ val length = math.min(acceptNBytes, src.remaining())
+ src.get(bytes, 0, length)
--- End diff --
We override 'bytes' array's previously written data ?
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