/**
* 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.deltastrings;
import parquet.bytes.BytesInput;
import parquet.column.Encoding;
import parquet.column.values.ValuesWriter;
import parquet.column.values.delta.DeltaBinaryPackingValuesWriter;
import parquet.column.values.deltalengthbytearray.DeltaLengthByteArrayValuesWriter;
import parquet.io.api.Binary;
/**
* Write prefix lengths using delta encoding, followed by suffixes with Delta length byte arrays
* <pre>
* {@code
* delta-length-byte-array : prefix-length* suffixes*
* }
* </pre>
* @author Aniket Mokashi
*
*/
public class DeltaByteArrayWriter extends ValuesWriter{
private ValuesWriter prefixLengthWriter;
private ValuesWriter suffixWriter;
private byte[] previous;
public DeltaByteArrayWriter(int initialCapacity) {
this.prefixLengthWriter = new DeltaBinaryPackingValuesWriter(128, 4, initialCapacity);
this.suffixWriter = new DeltaLengthByteArrayValuesWriter(initialCapacity);
this.previous = new byte[0];
}
@Override
public long getBufferedSize() {
return prefixLengthWriter.getBufferedSize() + suffixWriter.getBufferedSize();
}
@Override
public BytesInput getBytes() {
return BytesInput.concat(prefixLengthWriter.getBytes(), suffixWriter.getBytes());
}
@Override
public Encoding getEncoding() {
return Encoding.DELTA_BYTE_ARRAY;
}
@Override
public void reset() {
prefixLengthWriter.reset();
suffixWriter.reset();
}
@Override
public long getAllocatedSize() {
return prefixLengthWriter.getAllocatedSize() + suffixWriter.getAllocatedSize();
}
@Override
public String memUsageString(String prefix) {
prefix = prefixLengthWriter.memUsageString(prefix);
return suffixWriter.memUsageString(prefix + " DELTA_STRINGS");
}
@Override
public void writeBytes(Binary v) {
int i = 0;
byte[] vb = v.getBytes();
int length = previous.length < vb.length ? previous.length : vb.length;
for(i = 0; (i < length) && (previous[i] == vb[i]); i++);
prefixLengthWriter.writeInteger(i);
suffixWriter.writeBytes(Binary.fromByteArray(vb, i, vb.length - i));
previous = vb;
}
}