topic.hpp

Go to the documentation of this file.

#pragma once
 
/// @file userver/ydb/topic.hpp
/// @brief YDB Topic client
 
#include <chrono>
#include <memory>
#include <string>
 
#include <ydb-cpp-sdk/client/topic/client.h>
 
USERVER_NAMESPACE_BEGIN
 
namespace ydb {
 
namespace impl {
class Driver;
struct TopicSettings;
}  // namespace impl
 
/// @brief Read session used to connect to one or more topics for reading
///
/// @see https://ydb.tech/docs/en/reference/ydb-sdk/topic#reading
///
/// ## Example usage:
///
/// @ref samples/ydb_service/components/topic_reader.hpp
/// @ref samples/ydb_service/components/topic_reader.cpp
///
/// @example samples/ydb_service/components/topic_reader.hpp
/// @example samples/ydb_service/components/topic_reader.cpp
class TopicReadSession final {
public:
    /// @cond
    // For internal use only.
    explicit TopicReadSession(std::shared_ptr<NYdb::NTopic::IReadSession> read_session);
    /// @endcond
 
    /// @brief Get read session events
    ///
    /// Waits until event occurs
    /// @param max_events_count maximum events count in batch
    /// @param max_size_bytes total size limit for data messages in batch
    /// if not specified, read session chooses event batch size automatically
    std::vector<NYdb::NTopic::TReadSessionEvent::TEvent> GetEvents(
        std::optional<std::size_t> max_events_count = {},
        size_t max_size_bytes = std::numeric_limits<size_t>::max()
    );
 
    /// @brief Close read session
    ///
    /// Waits for all commit acknowledgments to arrive.
    /// Force close after timeout
    bool Close(std::chrono::milliseconds timeout);
 
    /// Get native read session
    /// @warning Use with care! Facilities from
    /// `<core/include/userver/drivers/subscribable_futures.hpp>` can help with
    /// non-blocking wait operations.
    std::shared_ptr<NYdb::NTopic::IReadSession> GetNativeTopicReadSession();
 
private:
    std::shared_ptr<NYdb::NTopic::IReadSession> read_session_;
};
 
/// @ingroup userver_clients
///
/// @brief YDB Topic Client
///
/// @see https://ydb.tech/docs/en/concepts/topic
class TopicClient final {
public:
    /// @cond
    // For internal use only.
    TopicClient(std::shared_ptr<impl::Driver> driver, impl::TopicSettings settings);
    /// @endcond
 
    ~TopicClient();
 
    /// Alter topic
    void AlterTopic(const std::string& path, const NYdb::NTopic::TAlterTopicSettings& settings);
 
    /// Describe topic
    NYdb::NTopic::TDescribeTopicResult DescribeTopic(const std::string& path);
 
    /// Create read session
    TopicReadSession CreateReadSession(const NYdb::NTopic::TReadSessionSettings& settings);
 
    /// Get native topic client
    /// @warning Use with care! Facilities from
    /// `<core/include/userver/drivers/subscribable_futures.hpp>` can help with
    /// non-blocking wait operations.
    NYdb::NTopic::TTopicClient& GetNativeTopicClient();
 
private:
    std::shared_ptr<impl::Driver> driver_;
    NYdb::NTopic::TTopicClient topic_client_;
};
 
}  // namespace ydb
 
USERVER_NAMESPACE_END