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reduce bytearray copy to minimal optimize VSizeIndexedWriter #2079

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Merged
xvrl merged 1 commit into from
Dec 11, 2015
Merged

reduce bytearray copy to minimal optimize VSizeIndexedWriter #2079

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22 changes: 20 additions & 2 deletions processing/src/main/java/io/druid/segment/data/VSizeIndexedInts.java
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Original file line number Diff line number Diff line change
Expand Up @@ -50,11 +50,31 @@ public static VSizeIndexedInts empty()
return fromList(Lists.<Integer>newArrayList(), 0);
}

/**
* provide for performance reason.
*/
public static byte[] getBytesNoPaddingfromList(List<Integer> list, int maxValue)
{
int numBytes = getNumBytesForMax(maxValue);
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@xvrl xvrl Dec 10, 2015

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can we refactor to reduce copy-paste with fromList?


final ByteBuffer buffer = ByteBuffer.allocate((list.size() * numBytes));
writeToBuffer(buffer, list, numBytes, maxValue);

return buffer.array();
}

public static VSizeIndexedInts fromList(List<Integer> list, int maxValue)
{
int numBytes = getNumBytesForMax(maxValue);

final ByteBuffer buffer = ByteBuffer.allocate((list.size() * numBytes) + (4 - numBytes));
writeToBuffer(buffer, list, numBytes, maxValue);

return new VSizeIndexedInts(buffer.asReadOnlyBuffer(), numBytes);
}

private static void writeToBuffer(ByteBuffer buffer, List<Integer> list, int numBytes, int maxValue)
{
int i = 0;
for (Integer val : list) {
if (val < 0) {
Expand All @@ -69,8 +89,6 @@ public static VSizeIndexedInts fromList(List<Integer> list, int maxValue)
++i;
}
buffer.position(0);

return new VSizeIndexedInts(buffer.asReadOnlyBuffer(), numBytes);
}

public static byte getNumBytesForMax(int maxValue)
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2 changes: 1 addition & 1 deletion processing/src/main/java/io/druid/segment/data/VSizeIndexedWriter.java
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Expand Up @@ -70,7 +70,7 @@ public void open() throws IOException

public void write(List<Integer> ints) throws IOException
{
byte[] bytesToWrite = ints == null ? EMPTY_ARRAY : VSizeIndexedInts.fromList(ints, maxId).getBytesNoPadding();
byte[] bytesToWrite = ints == null ? EMPTY_ARRAY : VSizeIndexedInts.getBytesNoPaddingfromList(ints, maxId);

valuesOut.write(bytesToWrite);

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14 changes: 14 additions & 0 deletions processing/src/test/java/io/druid/segment/data/VSizeIndexedIntsTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -22,9 +22,12 @@
import org.junit.Assert;
import org.junit.Test;

import com.google.common.primitives.Ints;

import java.io.ByteArrayOutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.util.List;

/**
*/
Expand Down Expand Up @@ -63,4 +66,15 @@ public void testSerialization() throws Exception
}
}

@Test
public void testGetBytesNoPaddingfromList() throws Exception
{
final int[] array = {1, 2, 4, 5, 6, 8, 9, 10};
List<Integer> list = Ints.asList(array);
int maxValue = Ints.max(array);
VSizeIndexedInts ints = VSizeIndexedInts.fromList(list, maxValue);
byte[] bytes1 = ints.getBytesNoPadding();
byte[] bytes2 = VSizeIndexedInts.getBytesNoPaddingfromList(list, maxValue);
Assert.assertArrayEquals(bytes1, bytes2);
}
}