C++ StoragePtr::get方法代码示例

void InterpreterSystemQuery::syncReplica(ASTSystemQuery & query)
{
    String database_name = !query.target_database.empty() ? query.target_database : context.getCurrentDatabase();
    const String & table_name = query.target_table;

    StoragePtr table = context.getTable(database_name, table_name);

    auto table_replicated = dynamic_cast<StorageReplicatedMergeTree *>(table.get());
    if (!table_replicated)
        throw Exception("Table " + database_name + "." + table_name + " is not replicated", ErrorCodes::BAD_ARGUMENTS);

    table_replicated->waitForShrinkingQueueSize(0, context.getSettingsRef().receive_timeout.value.milliseconds());
}

StorageMerge::StorageListWithLocks StorageMerge::getSelectedTables(const ASTPtr & query, bool has_virtual_column, bool get_lock) const
{
    StorageListWithLocks selected_tables;
    DatabasePtr database = global_context.getDatabase(source_database);
    DatabaseIteratorPtr iterator = database->getIterator(global_context);

    auto virtual_column = ColumnString::create();

    while (iterator->isValid())
    {
        if (table_name_regexp.match(iterator->name()))
        {
            StoragePtr storage = iterator->table();

            if (query && typeid_cast<ASTSelectQuery *>(query.get())->prewhere_expression && !storage->supportsPrewhere())
                throw Exception("Storage " + storage->getName() + " doesn't support PREWHERE.", ErrorCodes::ILLEGAL_PREWHERE);

            if (storage.get() != this)
            {
                virtual_column->insert(storage->getTableName());
                selected_tables.emplace_back(storage, get_lock ? storage->lockStructure(false) : TableStructureReadLockPtr{});
            }
        }

        iterator->next();
    }

    if (has_virtual_column)
    {
        Block virtual_columns_block = Block{ColumnWithTypeAndName(std::move(virtual_column), std::make_shared<DataTypeString>(), "_table")};
        VirtualColumnUtils::filterBlockWithQuery(query, virtual_columns_block, global_context);
        auto values = VirtualColumnUtils::extractSingleValueFromBlock<String>(virtual_columns_block, "_table");

        /// Remove unused tables from the list
        selected_tables.remove_if([&] (const auto & elem) { return values.find(elem.first->getTableName()) == values.end(); });
    }

    return selected_tables;
}

BlockInputStreams StorageSystemColumns::read(
	const Names & column_names,
	ASTPtr query,
	const Context & context,
	const Settings & settings,
	QueryProcessingStage::Enum & processed_stage,
	const size_t max_block_size,
	const unsigned threads)
{
	check(column_names);
	processed_stage = QueryProcessingStage::FetchColumns;

	Block block;

	std::map<std::pair<std::string, std::string>, StoragePtr> storages;

	{
		Databases databases = context.getDatabases();

		/// Добавляем столбец database.
		ColumnPtr database_column = std::make_shared<ColumnString>();
		for (const auto & database : databases)
			database_column->insert(database.first);
		block.insert(ColumnWithTypeAndName(database_column, std::make_shared<DataTypeString>(), "database"));

		/// Отфильтруем блок со столбцом database.
		VirtualColumnUtils::filterBlockWithQuery(query, block, context);

		if (!block.rows())
			return BlockInputStreams();

		database_column = block.getByName("database").column;
		size_t rows = database_column->size();

		/// Добавляем столбец table.
		ColumnPtr table_column = std::make_shared<ColumnString>();
		IColumn::Offsets_t offsets(rows);
		for (size_t i = 0; i < rows; ++i)
		{
			const std::string database_name = (*database_column)[i].get<std::string>();
			const DatabasePtr database = databases.at(database_name);
			offsets[i] = i ? offsets[i - 1] : 0;

			for (auto iterator = database->getIterator(); iterator->isValid(); iterator->next())
			{
				const String & table_name = iterator->name();
				storages.emplace(std::piecewise_construct,
					std::forward_as_tuple(database_name, table_name),
					std::forward_as_tuple(iterator->table()));
				table_column->insert(table_name);
				offsets[i] += 1;
			}
		}

		for (size_t i = 0; i < block.columns(); ++i)
		{
			ColumnPtr & column = block.getByPosition(i).column;
			column = column->replicate(offsets);
		}

		block.insert(ColumnWithTypeAndName(table_column, std::make_shared<DataTypeString>(), "table"));
	}

	/// Отфильтруем блок со столбцами database и table.
	VirtualColumnUtils::filterBlockWithQuery(query, block, context);

	if (!block.rows())
		return BlockInputStreams();

	ColumnPtr filtered_database_column = block.getByName("database").column;
	ColumnPtr filtered_table_column = block.getByName("table").column;

	/// Составляем результат.
	ColumnPtr database_column = std::make_shared<ColumnString>();
	ColumnPtr table_column = std::make_shared<ColumnString>();
	ColumnPtr name_column = std::make_shared<ColumnString>();
	ColumnPtr type_column = std::make_shared<ColumnString>();
	ColumnPtr default_type_column = std::make_shared<ColumnString>();
	ColumnPtr default_expression_column = std::make_shared<ColumnString>();
	ColumnPtr bytes_column = std::make_shared<ColumnUInt64>();

	size_t rows = filtered_database_column->size();
	for (size_t i = 0; i < rows; ++i)
	{
		const std::string database_name = (*filtered_database_column)[i].get<std::string>();
		const std::string table_name = (*filtered_table_column)[i].get<std::string>();

		NamesAndTypesList columns;
		ColumnDefaults column_defaults;
		std::unordered_map<String, size_t> column_sizes;

		{
			StoragePtr storage = storages.at(std::make_pair(database_name, table_name));
			IStorage::TableStructureReadLockPtr table_lock;

			try
			{
				table_lock = storage->lockStructure(false);
			}
			catch (const Exception & e)
//.........这里部分代码省略.........

	void write(const Block & block)
	{
		if (!block)
			return;

		size_t rows = block.rowsInFirstColumn();
		if (!rows)
			return;

		StoragePtr destination;
		if (!storage.no_destination)
		{
			destination = storage.context.tryGetTable(storage.destination_database, storage.destination_table);

			if (destination)
			{
				if (destination.get() == &storage)
					throw Exception("Destination table is myself. Write will cause infinite loop.", ErrorCodes::INFINITE_LOOP);

				/// Проверяем структуру таблицы.
				try
				{
					destination->check(block, true);
				}
				catch (Exception & e)
				{
					e.addMessage("(when looking at destination table " + storage.destination_database + "." + storage.destination_table + ")");
					throw;
				}
			}
		}

		size_t bytes = block.bytes();

		/// Если блок уже превышает максимальные ограничения, то пишем минуя буфер.
		if (rows > storage.max_thresholds.rows || bytes > storage.max_thresholds.bytes)
		{
			if (!storage.no_destination)
			{
				LOG_TRACE(storage.log, "Writing block with " << rows << " rows, " << bytes << " bytes directly.");
				storage.writeBlockToDestination(block, destination);
 			}
			return;
		}

		/// Распределяем нагрузку по шардам по номеру потока.
		const auto start_shard_num = Poco::ThreadNumber::get() % storage.num_shards;

		/// Перебираем буферы по кругу, пытаясь заблокировать mutex. Не более одного круга.
		auto shard_num = start_shard_num;
		size_t try_no = 0;
		for (; try_no != storage.num_shards; ++try_no)
		{
			std::unique_lock<std::mutex> lock(storage.buffers[shard_num].mutex, std::try_to_lock_t());
			if (lock.owns_lock())
			{
				insertIntoBuffer(block, storage.buffers[shard_num], std::move(lock));
				break;
			}

			++shard_num;
			if (shard_num == storage.num_shards)
				shard_num = 0;
		}

		/// Если так и не удалось ничего сразу заблокировать, то будем ждать на mutex-е.
		if (try_no == storage.num_shards)
			insertIntoBuffer(block, storage.buffers[start_shard_num], std::unique_lock<std::mutex>(storage.buffers[start_shard_num].mutex));
	}

    void write(const Block & block) override
    {
        if (!block)
            return;

        size_t rows = block.rows();
        if (!rows)
            return;

        StoragePtr destination;
        if (!storage.no_destination)
        {
            destination = storage.context.tryGetTable(storage.destination_database, storage.destination_table);

            if (destination)
            {
                if (destination.get() == &storage)
                    throw Exception("Destination table is myself. Write will cause infinite loop.", ErrorCodes::INFINITE_LOOP);

                /// Check table structure.
                try
                {
                    destination->check(block, true);
                }
                catch (Exception & e)
                {
                    e.addMessage("(when looking at destination table " + storage.destination_database + "." + storage.destination_table + ")");
                    throw;
                }
            }
        }

        size_t bytes = block.bytes();

        /// If the block already exceeds the maximum limit, then we skip the buffer.
        if (rows > storage.max_thresholds.rows || bytes > storage.max_thresholds.bytes)
        {
            if (!storage.no_destination)
            {
                LOG_TRACE(storage.log, "Writing block with " << rows << " rows, " << bytes << " bytes directly.");
                storage.writeBlockToDestination(block, destination);
             }
            return;
        }

        /// We distribute the load on the shards by the stream number.
        const auto start_shard_num = Poco::ThreadNumber::get() % storage.num_shards;

        /// We loop through the buffers, trying to lock mutex. No more than one lap.
        auto shard_num = start_shard_num;

        StorageBuffer::Buffer * least_busy_buffer = nullptr;
        std::unique_lock<std::mutex> least_busy_lock;
        size_t least_busy_shard_rows = 0;

        for (size_t try_no = 0; try_no < storage.num_shards; ++try_no)
        {
            std::unique_lock<std::mutex> lock(storage.buffers[shard_num].mutex, std::try_to_lock_t());

            if (lock.owns_lock())
            {
                size_t num_rows = storage.buffers[shard_num].data.rows();
                if (!least_busy_buffer || num_rows < least_busy_shard_rows)
                {
                    least_busy_buffer = &storage.buffers[shard_num];
                    least_busy_lock = std::move(lock);
                    least_busy_shard_rows = num_rows;
                }
            }

            shard_num = (shard_num + 1) % storage.num_shards;
        }

        /// If you still can not lock anything at once, then we'll wait on mutex.
        if (!least_busy_buffer)
            insertIntoBuffer(block, storage.buffers[start_shard_num], std::unique_lock<std::mutex>(storage.buffers[start_shard_num].mutex));
        else
            insertIntoBuffer(block, *least_busy_buffer, std::move(least_busy_lock));
    }