ClickHouse/dbms/include/DB/DataStreams/BlockIO.h

#pragma once

#include <DB/DataStreams/IBlockInputStream.h>
#include <DB/DataStreams/IBlockOutputStream.h>


namespace DB
{

class ProcessListEntry;

struct BlockIO
{
	/** process_list_entry should be destroyed after in and after out,
	  *  since in and out contain pointer to an object inside process_list_entry
	  *  (MemoryTracker * current_memory_tracker),
	  *  which could be used before destroying of in and out.
	  */
	std::shared_ptr<ProcessListEntry> process_list_entry;

	BlockInputStreamPtr in;
	BlockOutputStreamPtr out;

	Block in_sample;	/// Пример блока, который будет прочитан из in.
	Block out_sample;	/// Пример блока, которого нужно писать в out.

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

	/// Вызывайте эти функции, если нужно логгировать запрос.
	void onFinish()
	{
		if (finish_callback)
			finish_callback(in.get(), out.get());
	}

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

	BlockIO & operator= (const BlockIO & rhs)
	{
		/// Обеспечиваем правильный порядок уничтожения.
		out 				= nullptr;
		in 					= nullptr;
		process_list_entry 	= nullptr;

		process_list_entry 	= rhs.process_list_entry;
		in 					= rhs.in;
		out 				= rhs.out;
		in_sample 			= rhs.in_sample;
		out_sample 			= rhs.out_sample;

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

		return *this;
	}

	~BlockIO();
};

}