[GitHub] [flink] Myasuka opened a new pull request #9255: [FLINK-13034] Introduce isEmpty method for MapState

[GitBox <gi...@apache.org>]

Myasuka opened a new pull request #9255: [FLINK-13034] Introduce isEmpty method for MapState
URL: https://github.com/apache/flink/pull/9255
 
 
   ## What is the purpose of the change
   
   Introduce `#isEmpty()` method for `MapState`, this aims to improve the performance when we use `MapState.iterator().hasNext()` to judge whether the map is empty for RocksDB.
   
   
   ## Brief change log
   
     - Introduce `#isEmpty()` method for `MapState`.
     - Introduce `#isEmpty()` method for `MapView`.
     - Replace previous usage of `MapState.iterator().hasNext()` to `MapState.isEmpty()`.
   
   
   ## Verifying this change
   
   This change added tests and can be verified as follows:
   
     - Add test for `StateBackendTestBase#testMapState()`.
   
   ## Does this pull request potentially affect one of the following parts:
   
     - Dependencies (does it add or upgrade a dependency): **no**
     - The public API, i.e., is any changed class annotated with `@Public(Evolving)`: **yes**
     - The serializers: **no**
     - The runtime per-record code paths (performance sensitive): **yes, improve**
     - Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: ** no**
     - The S3 file system connector: **no**
   
   ## Documentation
   
     - Does this pull request introduce a new feature? **yes**
     - If yes, how is the feature documented? **JavaDocs**
   

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