ClickHouse/dbms/src/DataStreams/BlockIO.h

#pragma once

#include <DataStreams/IBlockStream_fwd.h>

#include <functional>

#include <Processors/QueryPipeline.h>


namespace DB
{

class ProcessListEntry;

struct BlockIO
{
    BlockIO() = default;
    BlockIO(const BlockIO &) = default;
    ~BlockIO() = default;

    /** process_list_entry should be destroyed after in and after out,
      *  since in and out contain pointer to objects inside process_list_entry (query-level MemoryTracker for example),
      *  which could be used before destroying of in and out.
      */
    std::shared_ptr<ProcessListEntry> process_list_entry;

    BlockOutputStreamPtr out;
    BlockInputStreamPtr in;

    QueryPipeline pipeline;

    /// Callbacks for query logging could be set here.
    std::function<void(IBlockInputStream *, IBlockOutputStream *)>    finish_callback;
    std::function<void()>                                             exception_callback;

    /// When it is true, don't bother sending any non-empty blocks to the out stream
    bool null_format = false;

    /// Call these functions if you want to log the request.
    void onFinish()
    {
        if (finish_callback)
            finish_callback(in.get(), out.get());
    }

    void onException()
    {
        if (exception_callback)
            exception_callback();
    }

    BlockIO & operator= (const BlockIO & rhs)
    {
        if (this == &rhs)
            return *this;

        out.reset();
        in.reset();
        process_list_entry.reset();

        process_list_entry      = rhs.process_list_entry;
        in                      = rhs.in;
        out                     = rhs.out;
        pipeline                = rhs.pipeline;

        finish_callback         = rhs.finish_callback;
        exception_callback      = rhs.exception_callback;

        return *this;
    }
};

}