io.druid.segment.data.DeltaLongEncodingWriter.java Source code

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Here is the source code for io.druid.segment.data.DeltaLongEncodingWriter.java

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/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Metamarkets licenses this file
 * to you 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 io.druid.segment.data;

import com.google.common.primitives.Ints;
import com.google.common.primitives.Longs;

import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;

public class DeltaLongEncodingWriter implements CompressionFactory.LongEncodingWriter {

    private final long base;
    private VSizeLongSerde.LongSerializer serializer;
    private int bitsPerValue;

    public DeltaLongEncodingWriter(long base, long delta) {
        this.base = base;
        this.bitsPerValue = VSizeLongSerde.getBitsForMax(delta + 1);
    }

    @Override
    public void setBuffer(ByteBuffer buffer) {
        serializer = VSizeLongSerde.getSerializer(bitsPerValue, buffer, buffer.position());
    }

    @Override
    public void setOutputStream(OutputStream output) {
        serializer = VSizeLongSerde.getSerializer(bitsPerValue, output);
    }

    @Override
    public void write(long value) throws IOException {
        serializer.write(value - base);
    }

    public void putMeta(OutputStream metaOut, CompressedObjectStrategy.CompressionStrategy strategy)
            throws IOException {
        metaOut.write(CompressionFactory.setEncodingFlag(strategy.getId()));
        metaOut.write(CompressionFactory.LongEncodingFormat.DELTA.getId());
        metaOut.write(CompressionFactory.DELTA_ENCODING_VERSION);
        metaOut.write(Longs.toByteArray(base));
        metaOut.write(Ints.toByteArray(bitsPerValue));
    }

    @Override
    public int getBlockSize(int bytesPerBlock) {
        return VSizeLongSerde.getNumValuesPerBlock(bitsPerValue, bytesPerBlock);
    }

    @Override
    public int getNumBytes(int values) {
        return VSizeLongSerde.getSerializedSize(bitsPerValue, values);
    }

    @Override
    public void flush() throws IOException {
        if (serializer != null) {
            serializer.close();
        }
    }
}