dbms: development [#CONV-2944].

dbms/include/DB/DataStreams/AddingDefaultBlockInputStream.h

@@ -26,6 +26,11 @@ public:
 		children.push_back(input);
 	}
 
+	String getName() const { return "AddingDefaultBlockInputStream"; }
+
+	BlockInputStreamPtr clone() { return new AddingDefaultBlockInputStream(input, required_columns); }
+
+protected:
 	Block readImpl()
 	{
 		Block res = input->read();
@@ -43,15 +48,11 @@ public:
 					res.rows(), it->second->getDefault())).convertToFullColumn();
 				res.insert(col);
 			}
-		}				
-		
+		}
+
 		return res;
 	}
 
-	String getName() const { return "AddingDefaultBlockInputStream"; }
-
-	BlockInputStreamPtr clone() { return new AddingDefaultBlockInputStream(input, required_columns); }
-
 private:
 	BlockInputStreamPtr input;
 	NamesAndTypesListPtr required_columns;

dbms/include/DB/DataStreams/AggregatingBlockInputStream.h

@@ -31,12 +31,13 @@ public:
 	  */
 	AggregatingBlockInputStream(BlockInputStreamPtr input_, ExpressionPtr expression);
 
-	Block readImpl();
-
 	String getName() const { return "AggregatingBlockInputStream"; }
 
 	BlockInputStreamPtr clone() { return new AggregatingBlockInputStream(*this); }
 
+protected:
+	Block readImpl();
+
 private:
 	AggregatingBlockInputStream(const AggregatingBlockInputStream & src)
 		: input(src.input), aggregator(src.aggregator), has_been_read(src.has_been_read) {}

dbms/include/DB/DataStreams/ArrayJoiningBlockInputStream.h

@@ -48,6 +48,11 @@ public:
 		children.push_back(input);
 	}
 	
+	String getName() const { return "ArrayJoiningBlockInputStream"; }
+
+	BlockInputStreamPtr clone() { return new ArrayJoiningBlockInputStream(input, array_column); }
+
+protected:
 	Block readImpl()
 	{
 		Block block = input->read();
@@ -67,7 +72,7 @@ public:
 		for (size_t i = 0; i < columns; ++i)
 		{
 			ColumnWithNameAndType & current = block.getByPosition(i);
-			
+
 			if (static_cast<ssize_t>(i) == array_column)
 			{
 				ColumnWithNameAndType result;
@@ -85,10 +90,6 @@ public:
 		return block;
 	}
 
-	String getName() const { return "ArrayJoiningBlockInputStream"; }
-
-	BlockInputStreamPtr clone() { return new ArrayJoiningBlockInputStream(input, array_column); }
-
 private:
 	BlockInputStreamPtr input;
 	ssize_t array_column;

dbms/include/DB/DataStreams/AsynchronousBlockInputStream.h

@@ -1,6 +1,8 @@
 #pragma once
 
-#include <statdaemons/threadpool.hpp>
+#include <Poco/Mutex.h>
+#include <Poco/Thread.h>
+#include <Poco/Runnable.h>
 
 #include <DB/DataStreams/IProfilingBlockInputStream.h>
 
@@ -8,83 +10,185 @@
 namespace DB
 {
 
-/** Выполняет другой BlockInputStream в отдельном потоке, используя двойную буферизацию.
+/** thread-safe очередь из одного элемента,
+  * рассчитанная на одного producer-а и одного consumer-а.
+  */
+template <typename T>
+class OneElementQueue
+{
+private:
+	T data;
+	Poco::FastMutex mutex_fill;		/// Захвачен, когда данные есть.
+	Poco::FastMutex mutex_empty;	/// Захвачен, когда данных нет.
+
+public:
+	OneElementQueue()
+	{
+		mutex_empty.lock();
+	}
+
+	/// Вызывается единственным producer-ом.
+	void push(const T & x)
+	{
+		mutex_fill.lock();
+ 		data = x;
+		mutex_empty.unlock();
+	}
+
+	/// Вызывается единственным consumer-ом.
+	void pop(T & x)
+	{
+		mutex_empty.lock();
+		x = data;
+		mutex_fill.unlock();
+	}
+
+	/// Позволяет ждать элемента не дольше заданного таймаута. Вызывается единственным consumer-ом.
+	bool poll(UInt64 milliseconds)
+	{
+		if (mutex_empty.tryLock(milliseconds))
+		{
+			mutex_empty.unlock();
+			return true;
+		}
+
+		return false;
+	}
+};
+
+
+/** Выполняет другой BlockInputStream в отдельном потоке.
+  * Это служит для двух целей:
+  * 1. Позволяет сделать так, чтобы разные стадии конвеьера выполнения запроса работали параллельно.
+  * 2. Позволяет не ждать до того, как данные будут готовы, а периодически проверять их готовность без блокировки.
+  *    Это нужно, например, чтобы можно было во время ожидания проверить, не пришёл ли по сети пакет с просьбой прервать выполнение запроса.
+  *    Также это позволяет выполнить несколько запросов одновременно.
   */
 class AsynchronousBlockInputStream : public IProfilingBlockInputStream
 {
 public:
-	AsynchronousBlockInputStream(BlockInputStreamPtr in_) : in(in_), pool(1), started(false)
+	AsynchronousBlockInputStream(BlockInputStreamPtr in_) : in(in_), started(false), runnable(*this)
 	{
 		children.push_back(in);
 	}
 
-	Block readImpl()
+
+	/** Ждать готовность данных не более заданного таймаута. Запустить получение данных, если нужно.
+	  * Если функция вернула true - данные готовы и можно делать read().
+	  */
+	bool poll(UInt64 milliseconds)
 	{
-		/// Если вычислений ещё не было - вычислим первый блок синхронно
-		if (!started)
-		{
-			calculate();
-			started = true;
-		}
-		else	/// Если вычисления уже идут - подождём результата
-			pool.wait();
-
-		if (exception)
-			exception->rethrow();
-
-		Block res = block;
-		if (!res)
-			return res;
-
-		/// Запустим вычисления следующего блока
-		block = Block();
-		pool.schedule(boost::bind(&AsynchronousBlockInputStream::calculate, this));
-
-		return res;
+		startIfNeed();
+		return output_queue.poll(milliseconds);
 	}
+	
 
 	String getName() const { return "AsynchronousBlockInputStream"; }
 
 	BlockInputStreamPtr clone() { return new AsynchronousBlockInputStream(in); }
+	
 
     ~AsynchronousBlockInputStream()
 	{
 		if (started)
-			pool.wait();
+			thread->join();
 	}
 
 protected:
-	BlockInputStreamPtr in;
-	boost::threadpool::pool pool;
-	bool started;
-
-	Block block;
-	ExceptionPtr exception;
-
-	/// Вычисления, которые могут выполняться в отдельном потоке
-	void calculate()
+	Block readImpl()
 	{
-		try
+		OutputData res;
+
+		startIfNeed();
+
+		/// Будем ждать, пока будет готов следующий блок или будет выкинуто исключение.
+		output_queue.pop(res);
+
+		if (res.exception)
+			res.exception->rethrow();
+
+		return res.block;
+	}
+	
+	
+	void startIfNeed()
+	{
+		if (!started)
 		{
-			block = in->read();
-		}
-		catch (const Exception & e)
-		{
-			exception = e.clone();
-		}
-		catch (const Poco::Exception & e)
-		{
-			exception = e.clone();
-		}
-		catch (const std::exception & e)
-		{
-			exception = new Exception(e.what(), ErrorCodes::STD_EXCEPTION);
-		}
-		catch (...)
-		{
-			exception = new Exception("Unknown exception", ErrorCodes::UNKNOWN_EXCEPTION);
+			thread = new Poco::Thread;
+			thread->start(runnable);
 		}
 	}
+
+
+	/// Вычисления, которые могут выполняться в отдельном потоке
+	class Thread : public Poco::Runnable
+	{
+	public:
+		Thread(AsynchronousBlockInputStream & parent_) : parent(parent_) {}
+
+		void run()
+		{
+			ExceptionPtr exception;
+
+			try
+			{
+				loop();
+			}
+			catch (const Exception & e)
+			{
+				exception = e.clone();
+			}
+			catch (const Poco::Exception & e)
+			{
+				exception = e.clone();
+			}
+			catch (const std::exception & e)
+			{
+				exception = new Exception(e.what(), ErrorCodes::STD_EXCEPTION);
+			}
+			catch (...)
+			{
+				exception = new Exception("Unknown exception", ErrorCodes::UNKNOWN_EXCEPTION);
+			}
+
+			if (exception)
+			{
+				parent.cancel();
+
+				/// Отдаём эксепшен в основной поток.
+				parent.output_queue.push(exception);
+			}
+		}
+
+		void loop()
+		{
+			while (Block res = parent.in->read())
+				parent.output_queue.push(res);
+		}
+
+	private:
+		AsynchronousBlockInputStream & parent;
+	};
+
+
+	BlockInputStreamPtr in;
+	bool started;
+
+	struct OutputData
+	{
+		Block block;
+		ExceptionPtr exception;
+
+		OutputData() {}
+		OutputData(Block & block_) : block(block_) {}
+		OutputData(ExceptionPtr & exception_) : exception(exception_) {}
+	};
+
+	OneElementQueue<OutputData> output_queue;
+
+	Thread runnable;
+	SharedPtr<Poco::Thread> thread;
 };
 
 }

dbms/include/DB/DataStreams/BlockInputStreamFromRowInputStream.h

@@ -20,7 +20,6 @@ public:
 		const Block & sample_,
 		size_t max_block_size_ = DEFAULT_BLOCK_SIZE);
 
-	Block readImpl();
 	void readPrefix() { row_input->readPrefix(); }
 	void readSuffix() { row_input->readSuffix(); }
 
@@ -28,6 +27,9 @@ public:
 
 	BlockInputStreamPtr clone() { return new BlockInputStreamFromRowInputStream(row_input, sample, max_block_size); }
 
+protected:
+	Block readImpl();
+
 private:
 	RowInputStreamPtr row_input;
 	const Block sample;

dbms/include/DB/DataStreams/CollapsingSortedBlockInputStream.h

@@ -32,13 +32,14 @@ public:
 	{
 	}
 
-	/// Может возвращаться на 1 больше записей, чем max_block_size.
-	Block readImpl();
-
 	String getName() const { return "CollapsingSortedBlockInputStream"; }
 
 	BlockInputStreamPtr clone() { return new CollapsingSortedBlockInputStream(inputs, description, sign_column, max_block_size); }
 
+protected:
+	/// Может возвращаться на 1 больше записей, чем max_block_size.
+	Block readImpl();
+
 private:
 	String sign_column;
 	size_t sign_column_number;

dbms/include/DB/DataStreams/ConcatBlockInputStream.h

@@ -22,6 +22,11 @@ public:
 		current_stream = children.begin();
 	}
 
+	String getName() const { return "ConcatBlockInputStream"; }
+
+	BlockInputStreamPtr clone() { return new ConcatBlockInputStream(children); }
+
+protected:
 	Block readImpl()
 	{
 		Block res;
@@ -39,10 +44,6 @@ public:
 		return res;
 	}
 
-	String getName() const { return "ConcatBlockInputStream"; }
-
-	BlockInputStreamPtr clone() { return new ConcatBlockInputStream(children); }
-
 private:
 	BlockInputStreams::iterator current_stream;
 };

dbms/include/DB/DataStreams/ExpressionBlockInputStream.h

@@ -28,6 +28,11 @@ public:
 		children.push_back(input);
 	}
 
+	String getName() const { return "ExpressionBlockInputStream"; }
+
+	BlockInputStreamPtr clone() { return new ExpressionBlockInputStream(input, expression, part_id); }
+
+protected:
 	Block readImpl()
 	{
 		Block res = input->read();
@@ -38,10 +43,6 @@ public:
 		return res;
 	}
 
-	String getName() const { return "ExpressionBlockInputStream"; }
-
-	BlockInputStreamPtr clone() { return new ExpressionBlockInputStream(input, expression, part_id); }
-
 private:
 	BlockInputStreamPtr input;
 	ExpressionPtr expression;

dbms/include/DB/DataStreams/FilterBlockInputStream.h

@@ -21,12 +21,14 @@ public:
 	/// filter_column_ - номер столбца с условиями фильтрации.
 	FilterBlockInputStream(BlockInputStreamPtr input_, ssize_t filter_column_);
 	FilterBlockInputStream(BlockInputStreamPtr input_, const String & filter_column_name_);
-	Block readImpl();
 
 	String getName() const { return "FilterBlockInputStream"; }
 
 	BlockInputStreamPtr clone() { return new FilterBlockInputStream(input, filter_column); }
 
+protected:
+	Block readImpl();
+
 private:
 	BlockInputStreamPtr input;
 	ssize_t filter_column;

dbms/include/DB/DataStreams/FinalizingAggregatedBlockInputStream.h

@@ -22,6 +22,11 @@ public:
 		children.push_back(input);
 	}
 
+	String getName() const { return "FinalizingAggregatedBlockInputStream"; }
+
+	BlockInputStreamPtr clone() { return new FinalizingAggregatedBlockInputStream(input); }
+
+protected:
 	Block readImpl()
 	{
 		Block res = input->read();
@@ -42,7 +47,7 @@ public:
 
 				for (size_t j = 0; j < rows; ++j)
 					finalized_column->insert(data[j]->getResult());
-				
+
 				column.column = finalized_column;
 			}
 		}
@@ -50,10 +55,6 @@ public:
 		return res;
 	}
 
-	String getName() const { return "FinalizingAggregatedBlockInputStream"; }
-
-	BlockInputStreamPtr clone() { return new FinalizingAggregatedBlockInputStream(input); }
-
 private:
 	BlockInputStreamPtr input;
 };

dbms/include/DB/DataStreams/IProfilingBlockInputStream.h

@@ -49,9 +49,6 @@ public:
 	
 	Block read();
 
-	/// Наследники должны реализовать эту функцию.
-	virtual Block readImpl() = 0;
-
 	/// Получить информацию о скорости выполнения.
 	const BlockStreamProfileInfo & getInfo() const;
 
@@ -96,6 +93,9 @@ protected:
 	volatile bool is_cancelled;
 	IsCancelledCallback is_cancelled_callback;
 	ProgressCallback progress_callback;
+
+	/// Наследники должны реализовать эту функцию.
+	virtual Block readImpl() = 0;
 };
 
 }

dbms/include/DB/DataStreams/LimitBlockInputStream.h

@@ -17,12 +17,14 @@ class LimitBlockInputStream : public IProfilingBlockInputStream
 {
 public:
 	LimitBlockInputStream(BlockInputStreamPtr input_, size_t limit_, size_t offset_ = 0);
-	Block readImpl();
-
+	
 	String getName() const { return "LimitBlockInputStream"; }
 
 	BlockInputStreamPtr clone() { return new LimitBlockInputStream(input, limit, offset); }
 
+protected:
+	Block readImpl();
+
 private:
 	BlockInputStreamPtr input;
 	size_t limit;

dbms/include/DB/DataStreams/MaterializingBlockInputStream.h

@@ -19,6 +19,11 @@ public:
 		children.push_back(input);
 	}
 
+	String getName() const { return "MaterializingBlockInputStream"; }
+
+	BlockInputStreamPtr clone() { return new MaterializingBlockInputStream(input); }
+
+protected:
 	Block readImpl()
 	{
 		Block res = input->read();
@@ -37,10 +42,6 @@ public:
 		return res;
 	}
 
-	String getName() const { return "MaterializingBlockInputStream"; }
-
-	BlockInputStreamPtr clone() { return new MaterializingBlockInputStream(input); }
-
 private:
 	BlockInputStreamPtr input;
 };

dbms/include/DB/DataStreams/MergeSortingBlockInputStream.h

@@ -21,12 +21,13 @@ public:
 		children.push_back(input);
 	}
 
-	Block readImpl();
-
 	String getName() const { return "MergeSortingBlockInputStream"; }
 
 	BlockInputStreamPtr clone() { return new MergeSortingBlockInputStream(input, description); }
 
+protected:
+	Block readImpl();
+
 private:
 	BlockInputStreamPtr input;
 	SortDescription description;

dbms/include/DB/DataStreams/MergingAggregatedBlockInputStream.h

@@ -29,12 +29,13 @@ public:
 	  */
 	MergingAggregatedBlockInputStream(BlockInputStreamPtr input_, ExpressionPtr expression);
 
-	Block readImpl();
-
 	String getName() const { return "MergingAggregatedBlockInputStream"; }
 
 	BlockInputStreamPtr clone() { return new MergingAggregatedBlockInputStream(*this); }
 
+protected:
+	Block readImpl();
+
 private:
 	MergingAggregatedBlockInputStream(const MergingAggregatedBlockInputStream & src)
 		: input(src.input), aggregator(src.aggregator), has_been_read(src.has_been_read) {}

dbms/include/DB/DataStreams/MergingSortedBlockInputStream.h

@@ -24,7 +24,6 @@ public:
 		children.insert(children.end(), inputs.begin(), inputs.end());
 	}
 
-	Block readImpl();
 	void readSuffix();
 
 	String getName() const { return "MergingSortedBlockInputStream"; }
@@ -32,6 +31,8 @@ public:
 	BlockInputStreamPtr clone() { return new MergingSortedBlockInputStream(inputs, description, max_block_size); }
 
 protected:
+	Block readImpl();
+	
 	/// Инициализирует очередь и следующий блок результата.
 	void init(Block & merged_block, ColumnPlainPtrs & merged_columns);
 	

dbms/include/DB/DataStreams/NativeBlockInputStream.h

@@ -16,15 +16,13 @@ public:
 	NativeBlockInputStream(ReadBuffer & istr_, const DataTypeFactory & data_type_factory_)
 		: istr(istr_), data_type_factory(data_type_factory_) {}
 	
-	/** Прочитать следующий блок.
-	  * Если блоков больше нет - вернуть пустой блок (для которого operator bool возвращает false).
-	  */
-	Block readImpl();
-
 	String getName() const { return "NativeBlockInputStream"; }
 
 	BlockInputStreamPtr clone() { return new NativeBlockInputStream(istr, data_type_factory); }
 
+protected:
+	Block readImpl();
+
 private:
 	ReadBuffer & istr;
 	const DataTypeFactory & data_type_factory;

dbms/include/DB/DataStreams/OneBlockInputStream.h

@@ -18,6 +18,11 @@ class OneBlockInputStream : public IProfilingBlockInputStream
 public:
 	OneBlockInputStream(Block & block_) : block(block_), has_been_read(false) {}
 
+	String getName() const { return "OneBlockInputStream"; }
+
+	BlockInputStreamPtr clone() { return new OneBlockInputStream(block); }
+
+protected:
 	Block readImpl()
 	{
 		if (has_been_read)
@@ -27,10 +32,6 @@ public:
 		return block;
 	}
 
-	String getName() const { return "OneBlockInputStream"; }
-
-	BlockInputStreamPtr clone() { return new OneBlockInputStream(block); }
-
 private:
 	Block block;
 	bool has_been_read;

dbms/include/DB/DataStreams/ParallelAggregatingBlockInputStream.h

@@ -42,6 +42,11 @@ public:
 		aggregator = new Aggregator(key_names, aggregates);
 	}
 
+	String getName() const { return "ParallelAggregatingBlockInputStream"; }
+
+	BlockInputStreamPtr clone() { return new ParallelAggregatingBlockInputStream(*this); }
+
+protected:
 	Block readImpl()
 	{
 		if (has_been_read)
@@ -51,7 +56,7 @@ public:
 
 		ManyAggregatedDataVariants many_data(inputs.size());
 		Exceptions exceptions(inputs.size());
-		
+
 		for (size_t i = 0, size = many_data.size(); i < size; ++i)
 		{
 			many_data[i] = new AggregatedDataVariants;
@@ -62,15 +67,11 @@ public:
 		for (size_t i = 0, size = exceptions.size(); i < size; ++i)
 			if (exceptions[i])
 				exceptions[i]->rethrow();
-		
+
 		AggregatedDataVariantsPtr res = aggregator->merge(many_data);
 		return aggregator->convertToBlock(*res);
 	}
 
-	String getName() const { return "ParallelAggregatingBlockInputStream"; }
-
-	BlockInputStreamPtr clone() { return new ParallelAggregatingBlockInputStream(*this); }
-
 private:
 	ParallelAggregatingBlockInputStream(const ParallelAggregatingBlockInputStream & src)
 		: inputs(src.inputs), aggregator(src.aggregator), has_been_read(src.has_been_read) {}

dbms/include/DB/DataStreams/PartialSortingBlockInputStream.h

@@ -20,12 +20,13 @@ public:
 		children.push_back(input);
 	}
 
-	Block readImpl();
-
 	String getName() const { return "PartialSortingBlockInputStream"; }
 
 	BlockInputStreamPtr clone() { return new PartialSortingBlockInputStream(input, description); }
 
+protected:
+	Block readImpl();
+
 private:
 	BlockInputStreamPtr input;
 	SortDescription description;

dbms/include/DB/DataStreams/ProjectionBlockInputStream.h

@@ -29,6 +29,11 @@ public:
 		children.push_back(input);
 	}
 
+	String getName() const { return "ProjectionBlockInputStream"; }
+
+	BlockInputStreamPtr clone() { return new ProjectionBlockInputStream(input, expression, without_duplicates_and_aliases, part_id, subtree); }
+
+protected:
 	Block readImpl()
 	{
 		Block res = input->read();
@@ -38,10 +43,6 @@ public:
 		return expression->projectResult(res, without_duplicates_and_aliases, part_id, subtree);
 	}
 
-	String getName() const { return "ProjectionBlockInputStream"; }
-
-	BlockInputStreamPtr clone() { return new ProjectionBlockInputStream(input, expression, without_duplicates_and_aliases, part_id, subtree); }
-
 private:
 	BlockInputStreamPtr input;
 	ExpressionPtr expression;

dbms/include/DB/DataStreams/RemoteBlockInputStream.h

@@ -23,50 +23,6 @@ public:
 	}
 
 
-	Block readImpl()
-	{
-		if (!sent_query)
-		{
-			connection.sendQuery(query, 1, stage);
-			sent_query = true;
-		}
-		
-		while (true)
-		{
-			Connection::Packet packet = connection.receivePacket();
-
-			switch (packet.type)
-			{
-				case Protocol::Server::Data:
-					if (packet.block)
-						return packet.block;
-					break;	/// Если блок пустой - получим другие пакеты до EndOfStream.
-
-				case Protocol::Server::Exception:
-					got_exception_from_server = true;
-					packet.exception->rethrow();
-					break;
-
-				case Protocol::Server::EndOfStream:
-					finished = true;
-					return Block();
-
-				case Protocol::Server::Progress:
-					if (progress_callback)
-						progress_callback(packet.progress.rows, packet.progress.bytes);
-
-					if (!was_cancelled && !finished && isCancelled())
-						cancel();
-					
-					break;
-
-				default:
-					throw Exception("Unknown packet from server", ErrorCodes::UNKNOWN_PACKET_FROM_SERVER);
-			}
-		}
-	}
-
-
 	String getName() const { return "RemoteBlockInputStream"; }
 
 	BlockInputStreamPtr clone() { return new RemoteBlockInputStream(connection, query, stage); }
@@ -143,6 +99,50 @@ public:
 		}
 	}
 
+protected:
+	Block readImpl()
+	{
+		if (!sent_query)
+		{
+			connection.sendQuery(query, 1, stage);
+			sent_query = true;
+		}
+
+		while (true)
+		{
+			Connection::Packet packet = connection.receivePacket();
+
+			switch (packet.type)
+			{
+				case Protocol::Server::Data:
+					if (packet.block)
+						return packet.block;
+					break;	/// Если блок пустой - получим другие пакеты до EndOfStream.
+
+				case Protocol::Server::Exception:
+					got_exception_from_server = true;
+					packet.exception->rethrow();
+					break;
+
+				case Protocol::Server::EndOfStream:
+					finished = true;
+					return Block();
+
+				case Protocol::Server::Progress:
+					if (progress_callback)
+						progress_callback(packet.progress.rows, packet.progress.bytes);
+
+					if (!was_cancelled && !finished && isCancelled())
+						cancel();
+
+					break;
+
+				default:
+					throw Exception("Unknown packet from server", ErrorCodes::UNKNOWN_PACKET_FROM_SERVER);
+			}
+		}
+	}
+
 private:
 	Connection & connection;
 	const String query;

dbms/include/DB/DataStreams/UnionBlockInputStream.h

@@ -92,12 +92,30 @@ public:
 		}
 	}
 
+	String getName() const { return "UnionBlockInputStream"; }
+
+	BlockInputStreamPtr clone() { return new UnionBlockInputStream(children, max_threads); }
+
+	~UnionBlockInputStream()
+	{
+		LOG_TRACE(log, "Waiting for threads to finish");
+
+		finish = true;
+		cancel();
+		
+		for (ThreadsData::iterator it = threads_data.begin(); it != threads_data.end(); ++it)
+			it->thread->join();
+
+		LOG_TRACE(log, "Waited for threads to finish");
+	}
+
+protected:
 	Block readImpl()
 	{
 		OutputData res;
 		if (finish)
 			return res.block;
-		
+
 		/// Запускаем потоки, если это ещё не было сделано.
 		if (threads_data.empty())
 		{
@@ -119,23 +137,6 @@ public:
 		return res.block;
 	}
 
-	String getName() const { return "UnionBlockInputStream"; }
-
-	BlockInputStreamPtr clone() { return new UnionBlockInputStream(children, max_threads); }
-
-	~UnionBlockInputStream()
-	{
-		LOG_TRACE(log, "Waiting for threads to finish");
-
-		finish = true;
-		cancel();
-		
-		for (ThreadsData::iterator it = threads_data.begin(); it != threads_data.end(); ++it)
-			it->thread->join();
-
-		LOG_TRACE(log, "Waited for threads to finish");
-	}
-
 private:
 	/// Данные отдельного источника
 	struct InputData

dbms/include/DB/Storages/StorageLog.h

@@ -33,9 +33,10 @@ class LogBlockInputStream : public IProfilingBlockInputStream
 {
 public:
 	LogBlockInputStream(size_t block_size_, const Names & column_names_, StorageLog & storage_, size_t mark_number_, size_t rows_limit_);
-	Block readImpl();
 	String getName() const { return "LogBlockInputStream"; }
 	BlockInputStreamPtr clone() { return new LogBlockInputStream(block_size, column_names, storage, mark_number, rows_limit); }
+protected:
+	Block readImpl();
 private:
 	size_t block_size;
 	Names column_names;

dbms/include/DB/Storages/StorageMemory.h

@@ -14,9 +14,10 @@ class MemoryBlockInputStream : public IProfilingBlockInputStream
 {
 public:
 	MemoryBlockInputStream(const Names & column_names_, Blocks::iterator begin_, Blocks::iterator end_);
-	Block readImpl();
 	String getName() const { return "MemoryBlockInputStream"; }
 	BlockInputStreamPtr clone() { return new MemoryBlockInputStream(column_names, begin, end); }
+protected:
+	Block readImpl();
 private:
 	Names column_names;
 	Blocks::iterator begin;

dbms/include/DB/Storages/StorageSystemNumbers.h

@@ -16,9 +16,10 @@ class NumbersBlockInputStream : public IProfilingBlockInputStream
 {
 public:
 	NumbersBlockInputStream(size_t block_size_);
-	Block readImpl();
 	String getName() const { return "NumbersBlockInputStream"; }
 	BlockInputStreamPtr clone() { return new NumbersBlockInputStream(block_size); }
+protected:
+	Block readImpl();
 private:
 	size_t block_size;
 	UInt64 next;

dbms/include/DB/Storages/StorageTinyLog.h

@@ -21,9 +21,10 @@ class TinyLogBlockInputStream : public IProfilingBlockInputStream
 {
 public:
 	TinyLogBlockInputStream(size_t block_size_, const Names & column_names_, StorageTinyLog & storage_);
-	Block readImpl();
 	String getName() const { return "TinyLogBlockInputStream"; }
 	BlockInputStreamPtr clone() { return new TinyLogBlockInputStream(block_size, column_names, storage); }
+protected:
+	Block readImpl();
 private:
 	size_t block_size;
 	Names column_names;

dbms/src/Storages/StorageMergeTree.cpp

@@ -604,6 +604,14 @@ public:
 	{
 	}
 
+	String getName() const { return "MergeTreeBlockInputStream"; }
+	
+	BlockInputStreamPtr clone()
+	{
+		return new MergeTreeBlockInputStream(path, block_size, column_names, storage, owned_data_part, mark_number, rows_limit);
+	}
+
+protected:
 	Block readImpl()
 	{
 		Block res;
@@ -645,13 +653,6 @@ public:
 
 		return res;
 	}
-	
-	String getName() const { return "MergeTreeBlockInputStream"; }
-	
-	BlockInputStreamPtr clone()
-	{
-		return new MergeTreeBlockInputStream(path, block_size, column_names, storage, owned_data_part, mark_number, rows_limit);
-	}
 
 private:
 	const String path;