PrestoThriftHyperLogLog.java

/*
 * 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.thrift.api.datatypes;

import com.facebook.drift.annotations.ThriftConstructor;
import com.facebook.drift.annotations.ThriftField;
import com.facebook.drift.annotations.ThriftStruct;
import com.facebook.presto.common.block.Block;
import com.facebook.presto.common.type.Type;

import javax.annotation.Nullable;

import java.util.Objects;

import static com.facebook.drift.annotations.ThriftField.Requiredness.OPTIONAL;
import static com.facebook.presto.common.type.HyperLogLogType.HYPER_LOG_LOG;
import static com.facebook.presto.thrift.api.datatypes.PrestoThriftBlock.hyperLogLogData;
import static com.facebook.presto.thrift.api.datatypes.SliceData.fromSliceBasedBlock;
import static com.google.common.base.MoreObjects.toStringHelper;
import static com.google.common.base.Preconditions.checkArgument;

/**
 * Elements of {@code nulls} array determine if a value for a corresponding row is null.
 * Each elements of {@code sizes} array contains the length in bytes for the corresponding element.
 * If row is null then the corresponding element in {@code sizes} is ignored.
 * {@code bytes} array contains encoded byte values for HyperLogLog representation as defined in
 * Airlift specification: href="https://github.com/airlift/airlift/blob/master/stats/docs/hll.md
 * Values for all rows are written to {@code bytes} array one after another.
 * The total number of bytes must be equal to the sum of all sizes.
 */
@ThriftStruct
public final class PrestoThriftHyperLogLog
        implements PrestoThriftColumnData
{
    private final SliceData sliceType;

    @ThriftConstructor
    public PrestoThriftHyperLogLog(
            @ThriftField(name = "nulls") @Nullable boolean[] nulls,
            @ThriftField(name = "sizes") @Nullable int[] sizes,
            @ThriftField(name = "bytes") @Nullable byte[] bytes)
    {
        this.sliceType = new SliceData(nulls, sizes, bytes);
    }

    @Nullable
    @ThriftField(value = 1, requiredness = OPTIONAL)
    public boolean[] getNulls()
    {
        return sliceType.getNulls();
    }

    @Nullable
    @ThriftField(value = 2, requiredness = OPTIONAL)
    public int[] getSizes()
    {
        return sliceType.getSizes();
    }

    @Nullable
    @ThriftField(value = 3, requiredness = OPTIONAL)
    public byte[] getBytes()
    {
        return sliceType.getBytes();
    }

    @Override
    public Block toBlock(Type desiredType)
    {
        checkArgument(HYPER_LOG_LOG.equals(desiredType), "type doesn't match: %s", desiredType);
        return sliceType.toBlock(desiredType);
    }

    @Override
    public int numberOfRecords()
    {
        return sliceType.numberOfRecords();
    }

    @Override
    public boolean equals(Object obj)
    {
        if (this == obj) {
            return true;
        }
        if (obj == null || getClass() != obj.getClass()) {
            return false;
        }
        PrestoThriftHyperLogLog other = (PrestoThriftHyperLogLog) obj;
        return Objects.equals(this.sliceType, other.sliceType);
    }

    @Override
    public int hashCode()
    {
        return sliceType.hashCode();
    }

    @Override
    public String toString()
    {
        return toStringHelper(this)
                .add("numberOfRecords", numberOfRecords())
                .toString();
    }

    public static PrestoThriftBlock fromBlock(Block block)
    {
        return fromSliceBasedBlock(block, HYPER_LOG_LOG, (nulls, sizes, bytes) -> hyperLogLogData(new PrestoThriftHyperLogLog(nulls, sizes, bytes)));
    }
}