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/*
* 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.util.collection.unsafe.sort;
import java.io.File;
import java.io.IOException;
import scala.Tuple2;
import org.apache.spark.executor.ShuffleWriteMetrics;
import org.apache.spark.serializer.DummySerializerInstance;
import org.apache.spark.storage.BlockId;
import org.apache.spark.storage.BlockManager;
import org.apache.spark.storage.DiskBlockObjectWriter;
import org.apache.spark.storage.TempLocalBlockId;
import org.apache.spark.unsafe.PlatformDependent;
/**
* Spills a list of sorted records to disk. Spill files have the following format:
*
* [# of records (int)] [[len (int)][prefix (long)][data (bytes)]...]
*/
final class UnsafeSorterSpillWriter {
static final int DISK_WRITE_BUFFER_SIZE = 1024 * 1024;
// Small writes to DiskBlockObjectWriter will be fairly inefficient. Since there doesn't seem to
// be an API to directly transfer bytes from managed memory to the disk writer, we buffer
// data through a byte array.
private byte[] writeBuffer = new byte[DISK_WRITE_BUFFER_SIZE];
private final File file;
private final BlockId blockId;
private final int numRecordsToWrite;
private DiskBlockObjectWriter writer;
private int numRecordsSpilled = 0;
public UnsafeSorterSpillWriter(
BlockManager blockManager,
int fileBufferSize,
ShuffleWriteMetrics writeMetrics,
int numRecordsToWrite) throws IOException {
final Tuple2<TempLocalBlockId, File> spilledFileInfo =
blockManager.diskBlockManager().createTempLocalBlock();
this.file = spilledFileInfo._2();
this.blockId = spilledFileInfo._1();
this.numRecordsToWrite = numRecordsToWrite;
// Unfortunately, we need a serializer instance in order to construct a DiskBlockObjectWriter.
// Our write path doesn't actually use this serializer (since we end up calling the `write()`
// OutputStream methods), but DiskBlockObjectWriter still calls some methods on it. To work
// around this, we pass a dummy no-op serializer.
writer = blockManager.getDiskWriter(
blockId, file, DummySerializerInstance.INSTANCE, fileBufferSize, writeMetrics);
// Write the number of records
writeIntToBuffer(numRecordsToWrite, 0);
writer.write(writeBuffer, 0, 4);
}
// Based on DataOutputStream.writeLong.
private void writeLongToBuffer(long v, int offset) throws IOException {
writeBuffer[offset + 0] = (byte)(v >>> 56);
writeBuffer[offset + 1] = (byte)(v >>> 48);
writeBuffer[offset + 2] = (byte)(v >>> 40);
writeBuffer[offset + 3] = (byte)(v >>> 32);
writeBuffer[offset + 4] = (byte)(v >>> 24);
writeBuffer[offset + 5] = (byte)(v >>> 16);
writeBuffer[offset + 6] = (byte)(v >>> 8);
writeBuffer[offset + 7] = (byte)(v >>> 0);
}
// Based on DataOutputStream.writeInt.
private void writeIntToBuffer(int v, int offset) throws IOException {
writeBuffer[offset + 0] = (byte)(v >>> 24);
writeBuffer[offset + 1] = (byte)(v >>> 16);
writeBuffer[offset + 2] = (byte)(v >>> 8);
writeBuffer[offset + 3] = (byte)(v >>> 0);
}
/**
* Write a record to a spill file.
*
* @param baseObject the base object / memory page containing the record
* @param baseOffset the base offset which points directly to the record data.
* @param recordLength the length of the record.
* @param keyPrefix a sort key prefix
*/
public void write(
Object baseObject,
long baseOffset,
int recordLength,
long keyPrefix) throws IOException {
if (numRecordsSpilled == numRecordsToWrite) {
throw new IllegalStateException(
"Number of records written exceeded numRecordsToWrite = " + numRecordsToWrite);
} else {
numRecordsSpilled++;
}
writeIntToBuffer(recordLength, 0);
writeLongToBuffer(keyPrefix, 4);
int dataRemaining = recordLength;
int freeSpaceInWriteBuffer = DISK_WRITE_BUFFER_SIZE - 4 - 8; // space used by prefix + len
long recordReadPosition = baseOffset;
while (dataRemaining > 0) {
final int toTransfer = Math.min(freeSpaceInWriteBuffer, dataRemaining);
PlatformDependent.copyMemory(
baseObject,
recordReadPosition,
writeBuffer,
PlatformDependent.BYTE_ARRAY_OFFSET + (DISK_WRITE_BUFFER_SIZE - freeSpaceInWriteBuffer),
toTransfer);
writer.write(writeBuffer, 0, (DISK_WRITE_BUFFER_SIZE - freeSpaceInWriteBuffer) + toTransfer);
recordReadPosition += toTransfer;
dataRemaining -= toTransfer;
freeSpaceInWriteBuffer = DISK_WRITE_BUFFER_SIZE;
}
if (freeSpaceInWriteBuffer < DISK_WRITE_BUFFER_SIZE) {
writer.write(writeBuffer, 0, (DISK_WRITE_BUFFER_SIZE - freeSpaceInWriteBuffer));
}
writer.recordWritten();
}
public void close() throws IOException {
writer.commitAndClose();
writer = null;
writeBuffer = null;
}
public UnsafeSorterSpillReader getReader(BlockManager blockManager) throws IOException {
return new UnsafeSorterSpillReader(blockManager, file, blockId);
}
}
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