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A module that is everything required to understands Druid Segments
/*
* 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.druid.segment.data;
import org.apache.druid.segment.writeout.WriteOutBytes;
import java.io.IOException;
import java.nio.ByteBuffer;
public class DeltaLongEncodingWriter implements CompressionFactory.LongEncodingWriter
{
private final long base;
private VSizeLongSerde.LongSerializer serializer;
private int bitsPerValue;
public DeltaLongEncodingWriter(long base, long delta)
{
this.base = base;
this.bitsPerValue = VSizeLongSerde.getBitsForMax(delta + 1);
}
@Override
public void setBuffer(ByteBuffer buffer)
{
serializer = VSizeLongSerde.getSerializer(bitsPerValue, buffer, buffer.position());
}
@Override
public void setOutputStream(WriteOutBytes output)
{
serializer = VSizeLongSerde.getSerializer(bitsPerValue, output);
}
@Override
public void write(long value) throws IOException
{
serializer.write(value - base);
}
@Override
public void putMeta(ByteBuffer metaOut, CompressionStrategy strategy)
{
metaOut.put(CompressionFactory.setEncodingFlag(strategy.getId()));
metaOut.put(CompressionFactory.LongEncodingFormat.DELTA.getId());
metaOut.put(CompressionFactory.DELTA_ENCODING_VERSION);
metaOut.putLong(base);
metaOut.putInt(bitsPerValue);
}
@Override
public int metaSize()
{
return 1 + 1 + 1 + Long.BYTES + Integer.BYTES;
}
@Override
public int getBlockSize(int bytesPerBlock)
{
return VSizeLongSerde.getNumValuesPerBlock(bitsPerValue, bytesPerBlock);
}
@Override
public int getNumBytes(int values)
{
return VSizeLongSerde.getSerializedSize(bitsPerValue, values);
}
@Override
public void flush() throws IOException
{
if (serializer != null) {
serializer.close();
}
}
}