[FLINK-26738] Default value of StateDescriptor is valid when enable state ttl config

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.15.0
• Fix Version/s: 1.14.5, 1.15.0, 1.16.0
• Component/s: API / Core
• Labels: pull-request-available
• Assignee: Jianhui Dong
• Reporter: Jianhui Dong
• Created: 19/Mar/22 11:12
• Updated: 02/Apr/22 08:22
• Resolved: 02/Apr/22 08:22

Description

Suppose we declare a ValueState like following:

ValueStateDescriptor<Tuple2<Long, Long>> descriptor =
                new ValueStateDescriptor<>(
                        "average", // the state name
                        TypeInformation.of(new TypeHint<Tuple2<Long, Long>>() {}),  
                        Tuple2.of(0L, 0L)); 

and then we add state ttl config to the state:

descriptor.enableTimeToLive(StateTtlConfigUtil.createTtlConfig(60000));

the default value Tuple2.of(0L, 0L) will be invalid and may cause NPE.

I don't know if this is a bug cause I see @Deprecated in the comment of the ValueStateDescriptor constructor with argument defaultValue:

Use {@link #ValueStateDescriptor(String, TypeSerializer)} instead and manually
     *     manage the default value by checking whether the contents of the state is {@code null}.

and if we decide not to use the defaultValue field in the class StateDescriptor, should we add @Deprecated annotation to the field defaultValue?

Issue Links

• links to: GitHub Pull Request #19229