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https://issues.apache.org/jira/browse/FLINK-5982?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15938422#comment-15938422
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Till Rohrmann commented on FLINK-5982:
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Hi [~tonywei],
I think you should check in the {{AbstractInvokable}} that the passed
environment and state instances are not null.
1. If nowhere {{DummyInvokable.setEnvironment}} is called, then you can simply
pass a {{DummyEnvironment}} which does nothing in the {{DummyInvokable}}
constructor to the super class. For the state you can pass an empty state
object.
2. What exceptions are you referring to? If you don't change the behaviour of
the testing classes, then it should be ok.
3. What would the default behaviour be? Alternatively, we could think about
throwing an {{UnsupportedOperationException}} in the classes which don't
support the state methods. That way we are sure that they are not mistakenly
used with state.
> Refactor AbstractInvokable and StatefulTask
> -------------------------------------------
>
> Key: FLINK-5982
> URL: https://issues.apache.org/jira/browse/FLINK-5982
> Project: Flink
> Issue Type: Improvement
> Components: Distributed Coordination, State Backends, Checkpointing
> Affects Versions: 1.2.0
> Reporter: Wei-Che Wei
> Assignee: Wei-Che Wei
>
> Currently, running a invokable in {{Task}} needs to call
> {{setEnvironment(env)}} and {{invoke()}}. If the invokable is also a
> {{StatefulTask}}, it need to call {{setInitialState(state)}}. That makes the
> difficulty in doing the eager initialization on invokable during
> {{DEPLOYING}} state. One solution discussed in FLINK-4714 is to separate
> {{invoke()}} into {{open()}} and {{invoke()}}, but that makes the complexity
> for running it in {{Task}}.
> This task wants to refactor {{AbstractInvokable}} and {{StatefulTask}} to
> make it easier to construct and run an invokable.
> # Refactor abstract class to have one default constructor.
> #* Drop {{StatefulTask}} and assume all subclasses of {{AbstractInvokable}}
> are stateful.
> #* Remove {{setEnvironment(env)}} and {{setInitialState(state)}}. Make
> {{AbstractInvokable}} have a two argument constructor with {{Environment}}
> and {{TaskStateHandles}}.
> # Update all subclass
> #* Make all subclass of {{AbstractInvokable}} have a two argument constructor
> and call the constructor in {{AbstractInvokable}}.
> #* Throw an error in {{BatchTask}} if the initial state is not null. (This
> will be removed after {{BatchTask}} have been stateful.)
> # Change the creation of the invokable to call that constructor, update all
> the tests.
> Then, we can simplify the logic to run an invokable by using constructor and
> {{invoke()}}. The eager initialization can easily be placed in the
> constructor to fulfill the requirement such as FLINK-4714.
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