feat ydb: upd topic docs

b15b7b6dccd22dea83a06e91e67adca86412e7ee

Author: kpavlov00

ydb/include/userver/ydb/topic.hpp

@@ -1,5 +1,8 @@
 #pragma once
 
+/// @file userver/ydb/topic.hpp
+/// @brief YDB Topic client
+
 #include <chrono>
 #include <memory>
 #include <string>
@@ -15,6 +18,14 @@ 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:
+///
+/// @snippet userver/samples/ydb_service/components/topic_reader.hpp  Sample
+/// Topic reader
 class TopicReadSession final {
  public:
   /// @cond
@@ -23,17 +34,32 @@ class TopicReadSession final {
       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
+  /// 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 = {});
 
+  /// @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
   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
@@ -44,14 +70,18 @@ class TopicClient final {
 
   ~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
   NYdb::NTopic::TTopicClient& GetNativeTopicClient();
 
  private: