ClickHouse/dbms/src/Processors/Transforms/AggregatingTransform.h

#pragma once
#include <Processors/IAccumulatingTransform.h>
#include <Interpreters/Aggregator.h>
#include <IO/ReadBufferFromFile.h>
#include <Compression/CompressedReadBuffer.h>
#include <Common/Stopwatch.h>

namespace DB
{

class AggregatedChunkInfo : public ChunkInfo
{
public:
    bool is_overflows = false;
    Int32 bucket_num = -1;
};

class IBlockInputStream;
using BlockInputStreamPtr = std::shared_ptr<IBlockInputStream>;

struct AggregatingTransformParams
{
    Aggregator::Params params;
    Aggregator aggregator;
    bool final;

    AggregatingTransformParams(const Aggregator::Params & params_, bool final_)
        : params(params_), aggregator(params), final(final_) {}

    Block getHeader() const { return aggregator.getHeader(final); }
};

struct ManyAggregatedData
{
    ManyAggregatedDataVariants variants;
    std::atomic<UInt32> num_finished = 0;

    explicit ManyAggregatedData(size_t num_threads = 0) : variants(num_threads)
    {
        for (auto & elem : variants)
            elem = std::make_shared<AggregatedDataVariants>();
    }
};

using AggregatingTransformParamsPtr = std::shared_ptr<AggregatingTransformParams>;
using ManyAggregatedDataPtr = std::shared_ptr<ManyAggregatedData>;

class AggregatingTransform : public IProcessor
{
public:
    AggregatingTransform(Block header, AggregatingTransformParamsPtr params_);

    /// For Parallel aggregating.
    AggregatingTransform(Block header, AggregatingTransformParamsPtr params_,
                         ManyAggregatedDataPtr many_data, size_t current_variant,
                         size_t temporary_data_merge_threads, size_t max_threads);
    ~AggregatingTransform() override;

    String getName() const override { return "AggregatingTransform"; }
    Status prepare() override;
    void work() override;
    Processors expandPipeline() override;

protected:
    void consume(Chunk chunk);

private:
    /// To read the data that was flushed into the temporary data file.
    Processors processors;

    AggregatingTransformParamsPtr params;
    Logger * log = &Logger::get("AggregatingTransform");

    ColumnRawPtrs key_columns;
    Aggregator::AggregateColumns aggregate_columns;
    bool no_more_keys = false;

    ManyAggregatedDataPtr many_data;
    AggregatedDataVariants & variants;
    size_t max_threads = 1;
    size_t temporary_data_merge_threads = 1;

    /// TODO: calculate time only for aggregation.
    Stopwatch watch;

    UInt64 src_rows = 0;
    UInt64 src_bytes = 0;

    bool is_generate_initialized = false;
    bool is_consume_finished = false;
    bool is_pipeline_created = false;

    Chunk current_chunk;
    bool read_current_chunk = false;

    bool is_consume_started = false;

    void initGenerate();
};

}