ClickHouse/dbms/include/DB/Storages/MergeTree/MergeTreeThreadBlockInputStream.h

#pragma once

#include <DB/DataStreams/IProfilingBlockInputStream.h>
#include <DB/Storages/MergeTree/MergeTreeData.h>


namespace DB
{

class MergeTreeReader;
class MergeTreeReadPool;
struct MergeTreeReadTask;
class UncompressedCache;
class MarkCache;


/** Used in conjunction with MergeTreeReadPool, asking it for more work to do and performing whatever reads it is asked
  * to perform.
  */
class MergeTreeThreadBlockInputStream : public IProfilingBlockInputStream
{
    /// "thread" index (there are N threads and each thread is assigned index in interval [0..N-1])
    std::size_t thread;
public:
    MergeTreeThreadBlockInputStream(
        const std::size_t thread,
        const std::shared_ptr<MergeTreeReadPool> & pool, const std::size_t min_marks_to_read, const std::size_t block_size,
        MergeTreeData & storage, const bool use_uncompressed_cache, const ExpressionActionsPtr & prewhere_actions,
        const String & prewhere_column, const Settings & settings, const Names & virt_column_names);

    ~MergeTreeThreadBlockInputStream() override;

    String getName() const override { return "MergeTreeThread"; }

    String getID() const override;

protected:
    /// Будем вызывать progressImpl самостоятельно.
    void progress(const Progress & value) override {}

    Block readImpl() override;

private:
    /// Requests read task from MergeTreeReadPool and signals whether it got one
    bool getNewTask();
    Block readFromPart();

    void injectVirtualColumns(Block & block);

    std::shared_ptr<MergeTreeReadPool> pool;
    const std::size_t block_size_marks;
    const std::size_t min_marks_to_read;
    MergeTreeData & storage;
    const bool use_uncompressed_cache;
    ExpressionActionsPtr prewhere_actions;
    const String prewhere_column;
    const std::size_t min_bytes_to_use_direct_io;
    const std::size_t max_read_buffer_size;
    const Names virt_column_names;

    Logger * log;

    using MergeTreeReaderPtr = std::unique_ptr<MergeTreeReader>;

    std::shared_ptr<UncompressedCache> owned_uncompressed_cache;
    std::shared_ptr<MarkCache> owned_mark_cache;

    std::shared_ptr<MergeTreeReadTask> task;
    MergeTreeReaderPtr reader;
    MergeTreeReaderPtr pre_reader;
};


}