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

#pragma once

#include <DB/Storages/StorageReplicatedMergeTree.h>
#include <DB/Storages/MergeTree/AbandonableLockInZooKeeper.h>
#include <Yandex/time2str.h>


namespace DB
{

class ReplicatedMergeTreeBlockOutputStream : public IBlockOutputStream
{
public:
	ReplicatedMergeTreeBlockOutputStream(StorageReplicatedMergeTree & storage_, const String & insert_id_)
		: storage(storage_), insert_id(insert_id_), block_index(0),
		log(&Logger::get(storage.data.getLogName() + " (Replicated OutputStream)")) {}

	void write(const Block & block) override
	{
		auto part_blocks = storage.writer.splitBlockIntoParts(block);
		for (auto & current_block : part_blocks)
		{
			storage.data.delayInsertIfNeeded();

			++block_index;
			String block_id = insert_id.empty() ? "" : insert_id + "__" + toString(block_index);
			time_t min_date_time = DateLUT::instance().fromDayNum(DayNum_t(current_block.min_date));
			String month_name = toString(Date2OrderedIdentifier(min_date_time) / 100);

			storage.zookeeper->createIfNotExists(storage.zookeeper_path + "/block_numbers/" + month_name, "");

			AbandonableLockInZooKeeper block_number_lock(
				storage.zookeeper_path + "/block_numbers/" + month_name + "/block-",
				storage.zookeeper_path + "/temp", *storage.zookeeper);

			UInt64 part_number = block_number_lock.getNumber();

			MergeTreeData::MutableDataPartPtr part = storage.writer.writeTempPart(current_block, part_number);

			/// Если в запросе не указан ID, возьмем в качестве ID хеш от данных. То есть, не вставляем одинаковые данные дважды.
			/// NOTE: Если такая дедупликация не нужна, можно вместо этого оставлять block_id пустым.
			///       Можно для этого сделать настройку или синтаксис в запросе (например, ID=null).
			if (block_id.empty())
				block_id = part->checksums.summaryDataChecksum();

			LOG_DEBUG(log, "Wrote block " << part_number << " with ID " << block_id << ", " << current_block.block.rows() << " rows");

			MergeTreeData::Transaction transaction; /// Если не получится добавить кусок в ZK, снова уберем его из рабочего набора.
			storage.data.renameTempPartAndAdd(part, nullptr, &transaction);

			StorageReplicatedMergeTree::LogEntry log_entry;
			log_entry.type = StorageReplicatedMergeTree::LogEntry::GET_PART;
			log_entry.source_replica = storage.replica_name;
			log_entry.new_part_name = part->name;

			/// Одновременно добавим информацию о куске во все нужные места в ZooKeeper и снимем block_number_lock.
			zkutil::Ops ops;
			if (!block_id.empty())
			{
				ops.push_back(new zkutil::Op::Create(
					storage.zookeeper_path + "/blocks/" + block_id,
					"",
					storage.zookeeper->getDefaultACL(),
					zkutil::CreateMode::Persistent));
				ops.push_back(new zkutil::Op::Create(
					storage.zookeeper_path + "/blocks/" + block_id + "/columns",
					part->columns.toString(),
					storage.zookeeper->getDefaultACL(),
					zkutil::CreateMode::Persistent));
				ops.push_back(new zkutil::Op::Create(
					storage.zookeeper_path + "/blocks/" + block_id + "/checksums",
					part->checksums.toString(),
					storage.zookeeper->getDefaultACL(),
					zkutil::CreateMode::Persistent));
				ops.push_back(new zkutil::Op::Create(
					storage.zookeeper_path + "/blocks/" + block_id + "/number",
					toString(part_number),
					storage.zookeeper->getDefaultACL(),
					zkutil::CreateMode::Persistent));
			}
			storage.checkPartAndAddToZooKeeper(part, ops);
			ops.push_back(new zkutil::Op::Create(
				storage.replica_path + "/log/log-",
				log_entry.toString(),
				storage.zookeeper->getDefaultACL(),
				zkutil::CreateMode::PersistentSequential));
			block_number_lock.getUnlockOps(ops);

			auto code = storage.zookeeper->tryMulti(ops);
			if (code == ZOK)
			{
				transaction.commit();
				storage.merge_selecting_event.set();
			}
			else if (code == ZNODEEXISTS)
			{
				/// Если блок с таким ID уже есть в таблице, откатим его вставку.
				String expected_checksums_str;
				if (!block_id.empty() && storage.zookeeper->tryGet(
					storage.zookeeper_path + "/blocks/" + block_id + "/checksums", expected_checksums_str))
				{
					LOG_INFO(log, "Block with ID " << block_id << " already exists; ignoring it (removing part " << part->name << ")");

					auto expected_checksums = MergeTreeData::DataPart::Checksums::parse(expected_checksums_str);

					/// Если данные отличались от тех, что были вставлены ранее с тем же ID, бросим исключение.
					expected_checksums.checkEqual(part->checksums, true);
				}
				else
				{
					throw Exception("Unexpected ZNODEEXISTS while adding block " + toString(part_number) + " with ID " + block_id + ": "
						+ zkutil::ZooKeeper::error2string(code), ErrorCodes::UNEXPECTED_ZOOKEEPER_ERROR);
				}
			}
			else
			{
				throw Exception("Unexpected error while adding block " + toString(part_number) + " with ID " + block_id + ": "
					+ zkutil::ZooKeeper::error2string(code), ErrorCodes::UNEXPECTED_ZOOKEEPER_ERROR);
			}
		}
	}

private:
	StorageReplicatedMergeTree & storage;
	String insert_id;
	size_t block_index;

	Logger * log;
};

}