/*
* 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.spi.block;
import com.facebook.presto.spi.type.Type;
import com.facebook.presto.spi.type.TypeManager;
import com.facebook.presto.spi.type.VariableWidthType;
import io.airlift.slice.Slice;
import io.airlift.slice.SliceInput;
import io.airlift.slice.SliceOutput;
import static java.util.Objects.requireNonNull;
public class VariableWidthBlockEncoding
implements BlockEncoding
{
private final VariableWidthType type;
public VariableWidthBlockEncoding(Type type)
{
this.type = (VariableWidthType) requireNonNull(type, "type is null");
}
@Override
public String getName()
{
return type.getName();
}
@Override
public Type getType()
{
return type;
}
@Override
public void writeBlock(SliceOutput sliceOutput, Block block)
{
if (!block.getType().equals(type)) {
throw new IllegalArgumentException("Invalid 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.getPositionLength(position);
sliceOutput.appendInt(length);
totalLength += length;
}
// write null bits 8 at a time
for (int position = 0; position < (positionCount & ~0b111); position += 8) {
byte value = 0;
value |= variableWidthBlock.isNull(position) ? 0b1000_0000 : 0;
value |= variableWidthBlock.isNull(position + 1) ? 0b0100_0000 : 0;
value |= variableWidthBlock.isNull(position + 2) ? 0b0010_0000 : 0;
value |= variableWidthBlock.isNull(position + 3) ? 0b0001_0000 : 0;
value |= variableWidthBlock.isNull(position + 4) ? 0b0000_1000 : 0;
value |= variableWidthBlock.isNull(position + 5) ? 0b0000_0100 : 0;
value |= variableWidthBlock.isNull(position + 6) ? 0b0000_0010 : 0;
value |= variableWidthBlock.isNull(position + 7) ? 0b0000_0001 : 0;
sliceOutput.appendByte(value);
}
// 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(), 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;
}
// read null bits 8 at a time
boolean[] valueIsNull = new boolean[positionCount];
for (int position = 0; position < (positionCount & ~0b111); position += 8) {
byte value = sliceInput.readByte();
valueIsNull[position ] = ((value & 0b1000_0000) != 0);
valueIsNull[position + 1] = ((value & 0b0100_0000) != 0);
valueIsNull[position + 2] = ((value & 0b0010_0000) != 0);
valueIsNull[position + 3] = ((value & 0b0001_0000) != 0);
valueIsNull[position + 4] = ((value & 0b0000_1000) != 0);
valueIsNull[position + 5] = ((value & 0b0000_0100) != 0);
valueIsNull[position + 6] = ((value & 0b0000_0010) != 0);
valueIsNull[position + 7] = ((value & 0b0000_0001) != 0);
}
// read last null bits
if ((positionCount & 0b111) > 0) {
byte value = sliceInput.readByte();
int mask = 0b1000_0000;
for (int position = positionCount & ~0b111; position < positionCount; position++) {
valueIsNull[position] = ((value & mask) != 0);
mask >>>= 1;
}
}
int blockSize = sliceInput.readInt();
Slice slice = sliceInput.readSlice(blockSize);
return new VariableWidthBlock(type, positionCount, slice, offsets, valueIsNull);
}
public static class VariableWidthBlockEncodingFactory
implements BlockEncodingFactory<VariableWidthBlockEncoding>
{
private final Type type;
public VariableWidthBlockEncodingFactory(Type type)
{
this.type = requireNonNull(type, "type is null");
}
@Override
public String getName()
{
return type.getName();
}
@Override
public VariableWidthBlockEncoding readEncoding(TypeManager manager, BlockEncodingSerde serde, SliceInput input)
{
return new VariableWidthBlockEncoding(type);
}
@Override
public void writeEncoding(BlockEncodingSerde serde, SliceOutput output, VariableWidthBlockEncoding blockEncoding)
{
}
}
}