AVRO-2123: Duration logical type Java conversion

[robvadai]

Implementation of http://avro.apache.org/docs/current/spec.html#Duration

Can be used to serialize/deserialize to/from Java POJOs and Generic Fixed type.

Make sure you have checked all steps below.

Jira

• My PR addresses the following Avro Jira issues and references them in the PR title. For example, "AVRO-1234: My Avro PR"
  • https://issues.apache.org/jira/browse/AVRO-2123

Tests

• My PR adds the following unit tests:
• lang/java/avro/src/test/java/org/apache/avro/TestDurationConversion.java

Commits

• My commits all reference Jira issues in their subject lines. In addition, my commits follow the guidelines from "How to write a good git commit message"

Documentation

• In case of new functionality, my PR adds documentation that describes how to use it.
  • All the public functions and the classes in the PR contain Javadoc that explain what it does: existing conversaion don't have Javadoc so I didn't add one. This is considered an internal API IMHO.

[adiroy05]

assign to me

[opwvhk]

A month has 28, 29, 30 or 31 days. Hardcoding a single value (31 days/month occurs more often) is basically a bug. Note that this cannot be fixed if we choose to support all possible duration values (see the conversation comments for more info).

[opwvhk]

A Java Duration is a fixed amount of time, and cannot compensate for the varying number of days per month. A Java Period can, but cannot consider fractions of a day.

To "fix" the underlying incompatibility between an Avro duration and the Java Duration/Period classes, and also to avoid bugs with respect to leap seconds (avoided by Java because it doesn't mix days & day fractions), the conversion must disallow the combination of non-zero milliseconds with any other non-zero field. This means that either the milliseconds field must be 0, or all other fields must be 0.

Also, the conversion should accept both java.time.Duration and java.time.Period to convert to an Avro duration, and return the most appropriate one converting back (throwing an exception when both the milliseconds field and one of the other fields is non-zero).

[snuyanzin]

Hi @robvadai
i'm looking forward to have that feature in Avro, could you please tell us whether you are going to continue work on it or not?

[opwvhk]

As an alternative to this PR, I've opened #2520. This implements a new Java Time class TimePeriod, that combines functionality of java.time.Period and java.time.Duration. Other than that, the PR is equivalent.

[opwvhk]

Closing, as there is now an alternative implementation.