classic_query_sender.h

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/*
  Copyright (c) 2023, 2025, Oracle and/or its affiliates.
 
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License, version 2.0,
  as published by the Free Software Foundation.
 
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  permission to link the program and your derivative works with the
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  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
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  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/
 
#ifndef ROUTING_CLASSIC_QUERY_SENDER_INCLUDED
#define ROUTING_CLASSIC_QUERY_SENDER_INCLUDED
 
#include <system_error>
 
#include "processor.h"
#include "stmt_classifier.h"
 
class QuerySender : public Processor {
 public:
  using Processor::Processor;
 
  class Handler {
   public:
    virtual ~Handler() = default;
 
    virtual void on_column_count(uint64_t count) { (void)count; }
 
    virtual void on_column(
        const classic_protocol::message::server::ColumnMeta &column) {
      (void)column;
    }
    virtual void on_row(const classic_protocol::message::server::Row &row) {
      (void)row;
    }
    virtual void on_row_end(const classic_protocol::message::server::Eof &eof) {
      (void)eof;
    }
    virtual void on_ok(const classic_protocol::message::server::Ok &ok) {
      (void)ok;
    }
    virtual void on_error(const classic_protocol::message::server::Error &err) {
      (void)err;
    }
  };
 
  QuerySender(MysqlRoutingClassicConnectionBase *conn, std::string stmt)
      : Processor(conn), stmt_{std::move(stmt)} {}
 
  QuerySender(MysqlRoutingClassicConnectionBase *conn, std::string stmt,
              std::unique_ptr<Handler> handler)
      : Processor(conn), stmt_{std::move(stmt)}, handler_(std::move(handler)) {}
 
  enum class Stage {
    Command,
 
    Response,
    ColumnCount,
    Column,
    ColumnEnd,
    RowOrEnd,
    Row,
    RowEnd,
 
    LoadData,
    Data,
 
    Ok,
    Error,
 
    Done,
  };
 
  stdx::expected<Result, std::error_code> process() override;
 
  void stage(Stage stage) { stage_ = stage; }
  Stage stage() const { return stage_; }
 
 private:
  stdx::expected<Result, std::error_code> command();
  stdx::expected<Result, std::error_code> response();
  stdx::expected<Result, std::error_code> load_data();
  stdx::expected<Result, std::error_code> data();
 
  stdx::expected<Result, std::error_code> column_count();
  stdx::expected<Result, std::error_code> column();
  stdx::expected<Result, std::error_code> column_end();
  stdx::expected<Result, std::error_code> row_or_end();
  stdx::expected<Result, std::error_code> row();
  stdx::expected<Result, std::error_code> row_end();
 
  stdx::expected<Result, std::error_code> ok();
  stdx::expected<Result, std::error_code> error();
 
  stdx::expected<void, std::error_code> track_session_changes(
      net::const_buffer session_trackers,
      classic_protocol::capabilities::value_type caps);
 
  Stage stage_{Stage::Command};
 
  std::string stmt_;
  uint64_t columns_left_{0};
 
  std::unique_ptr<Handler> handler_;
};
 
#endif