/*
* 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 com.facebook.presto.jdbc.internal.type.block;
import com.facebook.presto.jdbc.internal.type.type.TypeManager;
import com.facebook.presto.jdbc.internal.airlift.slice.Slice;
import com.facebook.presto.jdbc.internal.airlift.slice.SliceInput;
import com.facebook.presto.jdbc.internal.airlift.slice.SliceOutput;
import static com.facebook.presto.jdbc.internal.type.block.EncoderUtil.decodeNullBits;
import static com.facebook.presto.jdbc.internal.type.block.EncoderUtil.encodeNullsAsBits;
public class VariableWidthBlockEncoding
implements BlockEncoding
{
public static final BlockEncodingFactory<VariableWidthBlockEncoding> FACTORY = new VariableWidthBlockEncodingFactory();
private static final String NAME = "VARIABLE_WIDTH";
@Override
public String getName()
{
return NAME;
}
@Override
public void writeBlock(SliceOutput sliceOutput, Block block)
{
// The down casts here are safe because it is the block itself the provides this encoding implementation.
AbstractVariableWidthBlock variableWidthBlock = (AbstractVariableWidthBlock) block;
int positionCount = variableWidthBlock.getPositionCount();
sliceOutput.appendInt(positionCount);
// offsets
int totalLength = 0;
for (int position = 0; position < positionCount; position++) {
int length = variableWidthBlock.getLength(position);
sliceOutput.appendInt(length);
totalLength += length;
}
encodeNullsAsBits(sliceOutput, variableWidthBlock);
// write last null bits
if ((positionCount & 0b111) > 0) {
byte value = 0;
int mask = 0b1000_0000;
for (int position = positionCount & ~0b111; position < positionCount; position++) {
value |= variableWidthBlock.isNull(position) ? mask : 0;
mask >>>= 1;
}
sliceOutput.appendByte(value);
}
sliceOutput
.appendInt(totalLength)
.writeBytes(variableWidthBlock.getRawSlice(0), variableWidthBlock.getPositionOffset(0), totalLength);
}
@Override
public Block readBlock(SliceInput sliceInput)
{
int positionCount = sliceInput.readInt();
// offsets
int[] offsets = new int[positionCount + 1];
int offset = 0;
for (int position = 0; position < positionCount; position++) {
offset += sliceInput.readInt();
offsets[position + 1] = offset;
}
boolean[] valueIsNull = decodeNullBits(sliceInput, positionCount);
int blockSize = sliceInput.readInt();
Slice slice = sliceInput.readSlice(blockSize);
return new VariableWidthBlock(positionCount, slice, offsets, valueIsNull);
}
public static class VariableWidthBlockEncodingFactory
implements BlockEncodingFactory<VariableWidthBlockEncoding>
{
@Override
public String getName()
{
return NAME;
}
@Override
public VariableWidthBlockEncoding readEncoding(TypeManager manager, BlockEncodingSerde serde, SliceInput input)
{
return new VariableWidthBlockEncoding();
}
@Override
public void writeEncoding(BlockEncodingSerde serde, SliceOutput output, VariableWidthBlockEncoding blockEncoding)
{
}
}
}