org.apache.druid.segment.data.IntermediateColumnarLongsSerializer.java Source code

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Here is the source code for org.apache.druid.segment.data.IntermediateColumnarLongsSerializer.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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 org.apache.druid.segment.data;

import com.google.common.math.LongMath;
import it.unimi.dsi.fastutil.longs.Long2IntMap;
import it.unimi.dsi.fastutil.longs.Long2IntOpenHashMap;
import it.unimi.dsi.fastutil.longs.LongArrayList;
import it.unimi.dsi.fastutil.longs.LongList;
import org.apache.druid.java.util.common.io.smoosh.FileSmoosher;
import org.apache.druid.segment.writeout.SegmentWriteOutMedium;

import java.io.IOException;
import java.nio.ByteOrder;
import java.nio.channels.WritableByteChannel;

/**
 * Serializer that chooses optimal {@link ColumnarLongs} format dymamically, based on the values being written.
 *
 * Unsafe for concurrent use from multiple threads.
 */
public class IntermediateColumnarLongsSerializer implements ColumnarLongsSerializer {
    private final SegmentWriteOutMedium segmentWriteOutMedium;
    private final String filenameBase;
    private final ByteOrder order;
    private final CompressionStrategy compression;
    private LongList tempOut = null;

    private int numInserted = 0;

    private final Long2IntMap uniqueValues = new Long2IntOpenHashMap();
    private final LongList valuesAddedInOrder = new LongArrayList();

    private long maxVal = Long.MIN_VALUE;
    private long minVal = Long.MAX_VALUE;

    private ColumnarLongsSerializer delegate;

    IntermediateColumnarLongsSerializer(SegmentWriteOutMedium segmentWriteOutMedium, String filenameBase,
            ByteOrder order, CompressionStrategy compression) {
        this.segmentWriteOutMedium = segmentWriteOutMedium;
        this.filenameBase = filenameBase;
        this.order = order;
        this.compression = compression;
    }

    @Override
    public void open() {
        tempOut = new LongArrayList();
    }

    @Override
    public int size() {
        return numInserted;
    }

    @Override
    public void add(long value) {
        //noinspection VariableNotUsedInsideIf
        if (delegate != null) {
            throw new IllegalStateException("written out already");
        }
        tempOut.add(value);
        ++numInserted;
        if (uniqueValues.size() <= CompressionFactory.MAX_TABLE_SIZE && !uniqueValues.containsKey(value)) {
            uniqueValues.put(value, uniqueValues.size());
            valuesAddedInOrder.add(value);
        }
        if (value > maxVal) {
            maxVal = value;
        }
        if (value < minVal) {
            minVal = value;
        }
    }

    private void makeDelegate() throws IOException {
        //noinspection VariableNotUsedInsideIf
        if (delegate != null) {
            return;
        }
        CompressionFactory.LongEncodingWriter writer;
        long delta;
        try {
            delta = LongMath.checkedSubtract(maxVal, minVal);
        } catch (ArithmeticException e) {
            delta = -1;
        }
        if (uniqueValues.size() <= CompressionFactory.MAX_TABLE_SIZE) {
            writer = new TableLongEncodingWriter(uniqueValues, valuesAddedInOrder);
        } else if (delta != -1 && delta != Long.MAX_VALUE) {
            writer = new DeltaLongEncodingWriter(minVal, delta);
        } else {
            writer = new LongsLongEncodingWriter(order);
        }

        if (compression == CompressionStrategy.NONE) {
            delegate = new EntireLayoutColumnarLongsSerializer(segmentWriteOutMedium, writer);
        } else {
            delegate = new BlockLayoutColumnarLongsSerializer(segmentWriteOutMedium, filenameBase, order, writer,
                    compression);
        }

        delegate.open();
        for (int i = 0; i < tempOut.size(); i++) {
            delegate.add(tempOut.getLong(i));
        }
    }

    @Override
    public long getSerializedSize() throws IOException {
        makeDelegate();
        return delegate.getSerializedSize();
    }

    @Override
    public void writeTo(WritableByteChannel channel, FileSmoosher smoosher) throws IOException {
        makeDelegate();
        delegate.writeTo(channel, smoosher);
    }
}