org.apache.spark.streaming

StateSpec

object StateSpec extends Serializable

:: Experimental :: Builder object for creating instances of StateSpec that is used for specifying the parameters of the DStream transformation mapWithState that is used for specifying the parameters of the DStream transformation mapWithState operation of a pair DStream (Scala) or a JavaPairDStream (Java).

Example in Scala:

// A mapping function that maintains an integer state and return a String
def mappingFunction(key: String, value: Option[Int], state: State[Int]): Option[String] = {
  // Use state.exists(), state.get(), state.update() and state.remove()
  // to manage state, and return the necessary string
}

val spec = StateSpec.function(mappingFunction).numPartitions(10)

val mapWithStateDStream = keyValueDStream.mapWithState[StateType, MappedType](spec)

Example in Java:

// A mapping function that maintains an integer state and return a string
Function3<String, Optional<Integer>, State<Integer>, String> mappingFunction =
    new Function3<String, Optional<Integer>, State<Integer>, String>() {
        @Override
        public Optional<String> call(Optional<Integer> value, State<Integer> state) {
            // Use state.exists(), state.get(), state.update() and state.remove()
            // to manage state, and return the necessary string
        }
    };

 JavaMapWithStateDStream<String, Integer, Integer, String> mapWithStateDStream =
     keyValueDStream.mapWithState(StateSpec.function(mappingFunc));
Annotations
@Experimental()
Source
StateSpec.scala
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  11. def function[KeyType, ValueType, StateType, MappedType](mappingFunction: Function3[KeyType, Optional[ValueType], State[StateType], MappedType]): StateSpec[KeyType, ValueType, StateType, MappedType]

    Create a StateSpec for setting all the specifications of the mapWithState operation on a JavaPairDStream.

    Create a StateSpec for setting all the specifications of the mapWithState operation on a JavaPairDStream.

    ValueType

    Class of the values

    StateType

    Class of the states data

    MappedType

    Class of the mapped data

    mappingFunction

    The function applied on every data item to manage the associated state and generate the mapped data

  12. def function[KeyType, ValueType, StateType, MappedType](mappingFunction: Function4[Time, KeyType, Optional[ValueType], State[StateType], Optional[MappedType]]): StateSpec[KeyType, ValueType, StateType, MappedType]

    Create a StateSpec for setting all the specifications of the mapWithState operation on a JavaPairDStream.

    Create a StateSpec for setting all the specifications of the mapWithState operation on a JavaPairDStream.

    KeyType

    Class of the keys

    ValueType

    Class of the values

    StateType

    Class of the states data

    MappedType

    Class of the mapped data

    mappingFunction

    The function applied on every data item to manage the associated state and generate the mapped data

  13. def function[KeyType, ValueType, StateType, MappedType](mappingFunction: (KeyType, Option[ValueType], State[StateType]) ⇒ MappedType): StateSpec[KeyType, ValueType, StateType, MappedType]

    Create a StateSpec for setting all the specifications of the mapWithState operation on a pair DStream.

    Create a StateSpec for setting all the specifications of the mapWithState operation on a pair DStream.

    ValueType

    Class of the values

    StateType

    Class of the states data

    MappedType

    Class of the mapped data

    mappingFunction

    The function applied on every data item to manage the associated state and generate the mapped data

  14. def function[KeyType, ValueType, StateType, MappedType](mappingFunction: (Time, KeyType, Option[ValueType], State[StateType]) ⇒ Option[MappedType]): StateSpec[KeyType, ValueType, StateType, MappedType]

    Create a StateSpec for setting all the specifications of the mapWithState operation on a pair DStream.

    Create a StateSpec for setting all the specifications of the mapWithState operation on a pair DStream.

    KeyType

    Class of the keys

    ValueType

    Class of the values

    StateType

    Class of the states data

    MappedType

    Class of the mapped data

    mappingFunction

    The function applied on every data item to manage the associated state and generate the mapped data

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