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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.sql.execution;
import java.io.IOException;
import scala.collection.Iterator;
import scala.math.Ordering;
import com.google.common.annotations.VisibleForTesting;
import org.apache.spark.SparkEnv;
import org.apache.spark.TaskContext;
import org.apache.spark.sql.catalyst.InternalRow;
import org.apache.spark.sql.catalyst.expressions.UnsafeRow;
import org.apache.spark.sql.catalyst.util.AbstractScalaRowIterator;
import org.apache.spark.sql.types.StructType;
import org.apache.spark.unsafe.Platform;
import org.apache.spark.util.collection.unsafe.sort.PrefixComparator;
import org.apache.spark.util.collection.unsafe.sort.RecordComparator;
import org.apache.spark.util.collection.unsafe.sort.UnsafeExternalSorter;
import org.apache.spark.util.collection.unsafe.sort.UnsafeSorterIterator;
public final class UnsafeExternalRowSorter {
/**
* If positive, forces records to be spilled to disk at the given frequency (measured in numbers
* of records). This is only intended to be used in tests.
*/
private int testSpillFrequency = 0;
private long numRowsInserted = 0;
private final StructType schema;
private final PrefixComputer prefixComputer;
private final UnsafeExternalSorter sorter;
public abstract static class PrefixComputer {
abstract long computePrefix(InternalRow row);
}
public UnsafeExternalRowSorter(
StructType schema,
Ordering<InternalRow> ordering,
PrefixComparator prefixComparator,
PrefixComputer prefixComputer,
long pageSizeBytes) throws IOException {
this.schema = schema;
this.prefixComputer = prefixComputer;
final SparkEnv sparkEnv = SparkEnv.get();
final TaskContext taskContext = TaskContext.get();
sorter = UnsafeExternalSorter.create(
taskContext.taskMemoryManager(),
sparkEnv.blockManager(),
sparkEnv.serializerManager(),
taskContext,
new RowComparator(ordering, schema.length()),
prefixComparator,
/* initialSize */ 4096,
pageSizeBytes
);
}
/**
* Forces spills to occur every `frequency` records. Only for use in tests.
*/
@VisibleForTesting
void setTestSpillFrequency(int frequency) {
assert frequency > 0 : "Frequency must be positive";
testSpillFrequency = frequency;
}
public void insertRow(UnsafeRow row) throws IOException {
final long prefix = prefixComputer.computePrefix(row);
sorter.insertRecord(
row.getBaseObject(),
row.getBaseOffset(),
row.getSizeInBytes(),
prefix
);
numRowsInserted++;
if (testSpillFrequency > 0 && (numRowsInserted % testSpillFrequency) == 0) {
sorter.spill();
}
}
/**
* Return the peak memory used so far, in bytes.
*/
public long getPeakMemoryUsage() {
return sorter.getPeakMemoryUsedBytes();
}
private void cleanupResources() {
sorter.cleanupResources();
}
public Iterator<UnsafeRow> sort() throws IOException {
try {
final UnsafeSorterIterator sortedIterator = sorter.getSortedIterator();
if (!sortedIterator.hasNext()) {
// Since we won't ever call next() on an empty iterator, we need to clean up resources
// here in order to prevent memory leaks.
cleanupResources();
}
return new AbstractScalaRowIterator<UnsafeRow>() {
private final int numFields = schema.length();
private UnsafeRow row = new UnsafeRow(numFields);
@Override
public boolean hasNext() {
return sortedIterator.hasNext();
}
@Override
public UnsafeRow next() {
try {
sortedIterator.loadNext();
row.pointTo(
sortedIterator.getBaseObject(),
sortedIterator.getBaseOffset(),
sortedIterator.getRecordLength());
if (!hasNext()) {
UnsafeRow copy = row.copy(); // so that we don't have dangling pointers to freed page
row = null; // so that we don't keep references to the base object
cleanupResources();
return copy;
} else {
return row;
}
} catch (IOException e) {
cleanupResources();
// Scala iterators don't declare any checked exceptions, so we need to use this hack
// to re-throw the exception:
Platform.throwException(e);
}
throw new RuntimeException("Exception should have been re-thrown in next()");
};
};
} catch (IOException e) {
cleanupResources();
throw e;
}
}
public Iterator<UnsafeRow> sort(Iterator<UnsafeRow> inputIterator) throws IOException {
while (inputIterator.hasNext()) {
insertRow(inputIterator.next());
}
return sort();
}
private static final class RowComparator extends RecordComparator {
private final Ordering<InternalRow> ordering;
private final int numFields;
private final UnsafeRow row1;
private final UnsafeRow row2;
RowComparator(Ordering<InternalRow> ordering, int numFields) {
this.numFields = numFields;
this.row1 = new UnsafeRow(numFields);
this.row2 = new UnsafeRow(numFields);
this.ordering = ordering;
}
@Override
public int compare(Object baseObj1, long baseOff1, Object baseObj2, long baseOff2) {
// TODO: Why are the sizes -1?
row1.pointTo(baseObj1, baseOff1, -1);
row2.pointTo(baseObj2, baseOff2, -1);
return ordering.compare(row1, row2);
}
}
}
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