pingcap/tidb

Refactor currentTimeFunctionClass and utcTimeFunctionClass

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#27,760 opened on Sep 2, 2021

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help wantedtype/enhancement

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Description

Enhancement

currentTimeFunctionClass is very simlier to currentTimeFunctionClass. We can see from the MySQL's code:

class Item_func_curtime_local final : public Item_func_curtime {
 protected:
  Time_zone *time_zone() override;

 public:
  Item_func_curtime_local(const POS &pos, uint8 dec_arg)
      : Item_func_curtime(pos, dec_arg) {}
  const char *func_name() const override { return "curtime"; }
};

class Item_func_curtime_utc final : public Item_func_curtime {
 protected:
  Time_zone *time_zone() override;

 public:
  Item_func_curtime_utc(const POS &pos, uint8 dec_arg)
      : Item_func_curtime(pos, dec_arg) {}
  const char *func_name() const override { return "utc_time"; }
};

This means that we can reuse some codes. After investigation, I found that utcTimeFunctionClass's flen is more accurate than currentTimeFunctionClass. We can fix it by using utcTimeFunctionClass's logic.

Contributor guide

Research direction
Examine both currentTimeFunctionClass and utcTimeFunctionClass to identify common logic, then refactor by creating a shared base class or utility function. Focus on the flen difference mentioned; adopt utcTimeFunctionClass's more accurate calculation.
Tech stack
go
Domain
backend
Issue type
Refactor
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Gounderstanding of MySQL time functions
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50