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/**
  @file

  @brief Transaction boundary parser definitions. This includes code for
  parsing a stream of events identifying the transaction boundaries (like
  if the event is starting a transaction, is in the middle of a transaction
  or if the event is ending a transaction).
*/

#ifndef MYSQL_BINLOG_EVENT_TRX_BOUNDARY_PARSER_H
#define MYSQL_BINLOG_EVENT_TRX_BOUNDARY_PARSER_H

#include <stddef.h>

#include "mysql/binlog/event/control_events.h"

/// @addtogroup GroupLibsMysqlBinlogEvent
/// @{

namespace mysql::binlog::event {

/**
  @class Transaction_boundary_parser

  This is the base class for verifying transaction boundaries.
*/
class Transaction_boundary_parser {
 public:
  /**
    The context where the parser is used
  */
  enum enum_trx_boundary_parser_context {
    /* Parser used on a receiver, like an IO thread */
    TRX_BOUNDARY_PARSER_RECEIVER,
    /* Parser used in an applier parsing Relay Log files */
    TRX_BOUNDARY_PARSER_APPLIER
  };

  /**
     Constructor.
     @param context If this parser is used on a receiver or applier context
  */
  Transaction_boundary_parser(enum_trx_boundary_parser_context context)
      : current_parser_state(EVENT_PARSER_NONE),
        last_parser_state(EVENT_PARSER_NONE),
        m_current_boundary_state(EVENT_BOUNDARY_TYPE_ERROR),
        m_trx_boundary_parser_context(context) {}

  /**
    Destructor
  */
  virtual ~Transaction_boundary_parser();

  /**
     Reset the transaction boundary parser state.
  */
  void reset();

  /*
    In an event stream, an event is considered safe to be separated from the
    next if it is not inside a transaction.
    We need to know this in order to evaluate if we will let the relay log
    to be rotated or not.
  */

  /**
     State if the transaction boundary parser is inside a transaction.
     This "inside a transaction" means that the parser was fed with at least
     one event of a transaction, but the transaction wasn't completely fed yet.
     This also means that the last event fed depends on following event(s) to
     be correctly applied.

     @return  false if the boundary parser is not inside a transaction.
              true if the boundary parser is inside a transaction.
  */
  inline bool is_inside_transaction() {
    return (current_parser_state != EVENT_PARSER_ERROR &&
            current_parser_state != EVENT_PARSER_NONE);
  }

  /**
     State if the transaction boundary parser is not inside a transaction.
     This "not inside a transaction" means that the parser was fed with an
     event that doesn't depend on following events.

     @return  false if the boundary parser is inside a transaction.
              true if the boundary parser is not inside a transaction.
  */
  inline bool is_not_inside_transaction() {
    return (current_parser_state == EVENT_PARSER_NONE);
  }

  /**
     State if the transaction boundary parser was fed with a sequence of events
     that the parser wasn't able to parse correctly.

     @return  false if the boundary parser is not in the error state.
              true if the boundary parser is in the error state.
  */
  inline bool is_error() {
    return (current_parser_state == EVENT_PARSER_ERROR);
  }

  /**
   Feed the transaction boundary parser with a Log_event of any type
   in object type.

   @param log_event_info the event object
   @param throw_warnings If the function should throw warning messages while
                         updating the boundary parser state.
                         While initializing the Relay_log_info the
                         relay log is scanned backwards and this could
                         generate false errors. So, in this case, we
                         don't want to throw warnings.

   @return  false if the transaction boundary parser accepted the event.
            true if the transaction boundary parser didn't accepted the event.
  */
  bool feed_event(mysql::binlog::event::Log_event_basic_info log_event_info,
                  bool throw_warnings);

  /**
    Evaluate given the current info about boundary type, event type and
    parser state if the given event violates any restriction associated
    to row based only modes.

    @param event_info the event information: type, query, is it ignorable

    @return true if it violates any restrictions
            false if it passes all tests
  */
  bool check_row_logging_constraints(
      mysql::binlog::event::Log_event_basic_info event_info);

  /**
     Rolls back to the last parser state.

     This should be called in the case of a failed queued event.
  */
  void rollback() { current_parser_state = last_parser_state; }

  /**
    Internal error indentifiers for parser issues
  */
  enum enum_event_parser_error {
    /* Unexpected event that the parser can't ignore  */
    ER_TRX_BOUND_UNSUPPORTED_UNIGNORABLE_EVENT_IN_STREAM,
    /* Unexpected GTID event in the stream */
    ER_TRX_BOUND_GTID_LOG_EVENT_IN_STREAM,
    /* Unexpected BEGIN event in the stream */
    ER_TRX_BOUND_UNEXPECTED_BEGIN_IN_STREAM,
    /* Unexpected Commit event in the stream  */
    ER_TRX_BOUND_UNEXPECTED_COMMIT_ROLLBACK_OR_XID_LOG_EVENT_IN_STREAM,
    /* Unexpected XA Rollback event in the stream */
    ER_TRX_BOUND_UNEXPECTED_XA_ROLLBACK_IN_STREAM
  };

 private:
  enum enum_event_boundary_type {
    EVENT_BOUNDARY_TYPE_ERROR = -1,
    /* Gtid_log_event */
    EVENT_BOUNDARY_TYPE_GTID = 0,
    /* Query_log_event(BEGIN), Query_log_event(XA START) */
    EVENT_BOUNDARY_TYPE_BEGIN_TRX = 1,
    /* Xid, Query_log_event(COMMIT), Query_log_event(ROLLBACK),
       XA_Prepare_log_event */
    EVENT_BOUNDARY_TYPE_END_TRX = 2,
    /* Query_log_event(XA ROLLBACK) */
    EVENT_BOUNDARY_TYPE_END_XA_TRX = 3,
    /* User_var, Intvar and Rand */
    EVENT_BOUNDARY_TYPE_PRE_STATEMENT = 4,
    /*
      All other Query_log_events and all other DML events
      (Rows, Load_data, etc.)
    */
    EVENT_BOUNDARY_TYPE_STATEMENT = 5,
    /* Incident */
    EVENT_BOUNDARY_TYPE_INCIDENT = 6,
    /*
      All non DDL/DML events: Format_desc, Rotate,
      Previous_gtids, Stop, etc.
    */
    EVENT_BOUNDARY_TYPE_IGNORE = 7,
    /*
      Transaction payload boundary.
     */
    EVENT_BOUNDARY_TYPE_TRANSACTION_PAYLOAD = 8
  };

  /*
    Internal states for parsing a stream of events.

    DDL has the format:
      DDL-1: [GTID]
      DDL-2: [User] [Intvar] [Rand]
      DDL-3: Query

    DML has the format:
      DML-1: [GTID]
      DML-2: Query(BEGIN)
      DML-3: Statements
      DML-4: (Query(COMMIT) | Query([XA] ROLLBACK) | Xid | Xa_prepare)

    Compressed DML/DDL has the format:
      DDL-1: GTID
      RAW-1: Transaction_Payload
  */
  enum enum_event_parser_state {
    /* NONE is set after DDL-3 or DML-4 or RAW-1*/
    EVENT_PARSER_NONE,
    /* GTID is set after DDL-1 or DML-1 */
    EVENT_PARSER_GTID,
    /* DDL is set after DDL-2 */
    EVENT_PARSER_DDL,
    /* DML is set after DML-2 */
    EVENT_PARSER_DML,
    /* ERROR is set whenever the above pattern is not followed */
    EVENT_PARSER_ERROR
  };

  /**
     Current internal state of the event parser.
  */
  enum_event_parser_state current_parser_state;

  /**
     Last internal state of the event parser.

     This should be used if we had to roll back the last parsed event.
  */
  enum_event_parser_state last_parser_state;

  /**
    The last processed boundary event type
  */
  enum_event_boundary_type m_current_boundary_state;

  /**
    In which context of the boundary parser is used
  */
  enum_trx_boundary_parser_context m_trx_boundary_parser_context;

  /**
    Parses an raw event based on the event parser logic.

    @param event_info      Info about an event: type, query, is it ignorable
    @param throw_warnings  If the function should throw warning messages
                           while updating the boundary parser state.
    @return What is the boundary type associated to this event
  */
  enum_event_boundary_type get_event_boundary_type(
      mysql::binlog::event::Log_event_basic_info event_info,
      bool throw_warnings);

  /**
    Set the boundary parser state based on the event parser logic.

    @param event_boundary_type  the current event boundary type
    @param throw_warnings       If the function should throw warning messages
                                while updating the boundary parser state.

    @return true if there is an error while updating the state, like unexpected
            event order
  */
  bool update_state(enum_event_boundary_type event_boundary_type,
                    bool throw_warnings);

  /**
    Log warnings using some defined logging interface.

    @note: this method is empty by default. Extend it to add a logging routine.

    @param error the error number
    @param message the error message
  */
  virtual void log_server_warning(int error, const char *message);
};

}  // namespace mysql::binlog::event

/// @}

#endif  // MYSQL_BINLOG_EVENT_TRX_BOUNDARY_PARSER_H