/**
* Copyright 2012 Twitter, Inc.
*
* Licensed 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 parquet.column.values.deltalengthbytearray;
import java.io.IOException;
import parquet.Log;
import parquet.bytes.BytesInput;
import parquet.bytes.CapacityByteArrayOutputStream;
import parquet.bytes.LittleEndianDataOutputStream;
import parquet.column.Encoding;
import parquet.column.values.ValuesWriter;
import parquet.column.values.delta.DeltaBinaryPackingValuesWriter;
import parquet.io.ParquetEncodingException;
import parquet.io.api.Binary;
/**
* Write lengths of byte-arrays using delta encoding, followed by concatenated byte-arrays
* <pre>
* {@code
* delta-length-byte-array : length* byte-array*
* }
* </pre>
* @author Aniket Mokashi
*
*/
public class DeltaLengthByteArrayValuesWriter extends ValuesWriter {
private static final Log LOG = Log.getLog(DeltaLengthByteArrayValuesWriter.class);
private ValuesWriter lengthWriter;
private CapacityByteArrayOutputStream arrayOut;
private LittleEndianDataOutputStream out;
public DeltaLengthByteArrayValuesWriter(int initialSize) {
arrayOut = new CapacityByteArrayOutputStream(initialSize);
out = new LittleEndianDataOutputStream(arrayOut);
lengthWriter = new DeltaBinaryPackingValuesWriter(
DeltaBinaryPackingValuesWriter.DEFAULT_NUM_BLOCK_VALUES,
DeltaBinaryPackingValuesWriter.DEFAULT_NUM_MINIBLOCKS,
initialSize);
}
@Override
public void writeBytes(Binary v) {
try {
lengthWriter.writeInteger(v.length());
out.write(v.getBytes());
} catch (IOException e) {
throw new ParquetEncodingException("could not write bytes", e);
}
}
@Override
public long getBufferedSize() {
return lengthWriter.getBufferedSize() + arrayOut.size();
}
@Override
public BytesInput getBytes() {
try {
out.flush();
} catch (IOException e) {
throw new ParquetEncodingException("could not write page", e);
}
if (Log.DEBUG) LOG.debug("writing a buffer of size " + arrayOut.size());
return BytesInput.concat(lengthWriter.getBytes(), BytesInput.from(arrayOut));
}
@Override
public Encoding getEncoding() {
return Encoding.DELTA_LENGTH_BYTE_ARRAY;
}
@Override
public void reset() {
lengthWriter.reset();
arrayOut.reset();
}
@Override
public long getAllocatedSize() {
return lengthWriter.getAllocatedSize() + arrayOut.getCapacity();
}
@Override
public String memUsageString(String prefix) {
return arrayOut.memUsageString(lengthWriter.memUsageString(prefix) + " DELTA_LENGTH_BYTE_ARRAY");
}
}