com.facebook.presto.jdbc.internal.common.block.RunLengthBlockEncoding Maven / Gradle / Ivy

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/*
 * 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.common.block;

import com.facebook.presto.jdbc.internal.io.airlift.slice.SliceInput;
import com.facebook.presto.jdbc.internal.io.airlift.slice.SliceOutput;

public class RunLengthBlockEncoding
        implements BlockEncoding
{
    public static final String NAME = "RLE";

    @Override
    public String getName()
    {
        return NAME;
    }

    @Override
    public void writeBlock(BlockEncodingSerde blockEncodingSerde, SliceOutput sliceOutput, Block block)
    {
        RunLengthEncodedBlock rleBlock = (RunLengthEncodedBlock) block;

        // write the run length
        sliceOutput.writeInt(rleBlock.getPositionCount());

        // write the value
        blockEncodingSerde.writeBlock(sliceOutput, rleBlock.getValue());
    }

    @Override
    public RunLengthEncodedBlock readBlock(BlockEncodingSerde blockEncodingSerde, SliceInput sliceInput)
    {
        // read the run length
        int positionCount = sliceInput.readInt();

        // read the value
        Block value = blockEncodingSerde.readBlock(sliceInput);

        return new RunLengthEncodedBlock(value, positionCount);
    }
}