Add UserVarEvent

[heehehe]

Resolve #25

• user가 정의한 변수 사용 시 발생하는 UserVarEvent 구현
  • https://mariadb.com/kb/en/user_var_event
  • https://dev.mysql.com/doc/dev/mysql-server/latest/classbinary__log_1_1User__var__event.html

Overview

This PR addresses the implementation of the UserVarEvent class to handle MySQL/MariaDB binlog events related to user variables. Additionally, I've added a new test class TestStatementConnectionSetting to verify the functionality with statement-based logging.

Description

UserVarEvent Class Implementation: Developed based on MariaDB and MySQL's official documentation, this class provides robust handling for different user variable event types like STRING_RESULT, REAL_RESULT, INT_RESULT, ROW_RESULT(not in use), and DECIMAL_RESULT.

Statement-based Logging Test (TestStatementConnectionSetting): A new test class was added to cater specifically to the testing requirements of UserVarEvent under statement-based logging.

Key Features and Implementation Details

Type-specific Value Parsing

• Various functions handle the value parsing for each user variable type.(STRING_RESULT, REAL_RESULT, INT_RESULT, ROW_RESULT, DECIMAL_RESULT)
• DECIMAL Type : Created a novel bit-parsing function for this type.
• INT Type: Employed flags to distinguish between signed and unsigned integers.
  • Tested extreme cases, including:
  • Unsigned max(18446744073709551615)
  • Signed max( 9223372036854775807)
  • Signed min(-9223372036854775808)
  • Near zero(-1) ;

Method: _set_value_from_temp_buffer

• This function sets the appropriate value from the temporary buffer based on the event's type code. A dictionary mapping enables the correlation of each event type to its specific parsing method.

Reference

• MySQL UserVarEvent
• MariaDB UserVarEvent

[mjs1995]

@dongwook-chan 리뷰 부탁드리겠습니다!!

[dongwook-chan]

매번 어려운 과제 하시느라 고생이 많으십니다! 3조가 모든 조 통틀어서 특히 팀웤이 매우 좋으시고 그 결과로 인해 커밋이 늘어나는 점은 매우 긍정적이라고 볼 수 있습니다. 단, 그 개수가 너무 많으면 히스토리 관리의 순기능이 퇴색되는 단점도 있습니다. 따라서 협업하실 때는 커밋 마음껏 만들어주시고 PR 리뷰 받는 시점에는 몇 개의 의미있는 커밋으로 squash 부탁드리겠습니다. 최종적으로 몇 개의 커밋을 남겨야하는지 고민되신다면 연락주세요 :) 함께 고민해보면 좋을 것 같습니다!!

[heehehe]

julien-duponchelle#466 반영 완료 🎉