[jira] [Created] (THRIFT-5483) Support customized comparator in Java

["Tian Jiang (Jira)" <ji...@apache.org>]

Tian Jiang created THRIFT-5483:
----------------------------------

             Summary: Support customized comparator in Java
                 Key: THRIFT-5483
                 URL: https://issues.apache.org/jira/browse/THRIFT-5483
             Project: Thrift
          Issue Type: Improvement
            Reporter: Tian Jiang


The generated comparator (and hash code) of Thrift Structs compares two objects by all of their fields, which may cause trouble when used in hash structures.

For example, I defined a struct like:


{code:thrift}
struct Person{
  1: required i64 id
  2: required string phoneNumber
}
{code}


The id of a Person is final, while its phoneNumber can be changed.

Then I use it as a key in a map to record a Person's supervisors:

{code:java}
Map<Person, Person> supervisorMap;
{code}

Apparently, as the generated comparator of Person will use both id and phoneNumber for comparison and hash so if I change the phoneNumber of a Person, I can no longer get it from the map as its hash value changes and it will be distributed to another hash slot.

Therefore, I wish I could specify the fields that are to be used in comparator and hash code generation. One preferable grammar may be like:

{code:thrift}
struct Person{
  1: required comparable i64 id
  2: required string phoneNumber
}
{code}

Then the generated comparator and hash code will only use fields marked with `comparable`, and if no fields are marked with comparable, Java's default comparison and hashcode (using object address) will be used. 




--
This message was sent by Atlassian Jira
(v8.20.1#820001)