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sealed abstract class StateSpec[KeyType, ValueType, StateType, MappedType] extends Serializable

:: Experimental :: Abstract class representing all the specifications of the DStream transformation mapWithState operation of a pair DStream (Scala) or a JavaPairDStream (Java). Use org.apache.spark.streaming.StateSpec.function() factory methods to create instances of this class.

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));
KeyType

Class of the state key

ValueType

Class of the state value

StateType

Class of the state data

MappedType

Class of the mapped elements

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@Experimental()
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Abstract Value Members

  1. abstract def initialState(javaPairRDD: JavaPairRDD[KeyType, StateType]): StateSpec.this.type

    Set the RDD containing the initial states that will be used by mapWithState

  2. abstract def initialState(rdd: RDD[(KeyType, StateType)]): StateSpec.this.type

    Set the RDD containing the initial states that will be used by mapWithState

  3. abstract def numPartitions(numPartitions: Int): StateSpec.this.type

    Set the number of partitions by which the state RDDs generated by mapWithState will be partitioned.

    Set the number of partitions by which the state RDDs generated by mapWithState will be partitioned. Hash partitioning will be used.

  4. abstract def partitioner(partitioner: Partitioner): StateSpec.this.type

    Set the partitioner by which the state RDDs generated by mapWithState will be partitioned.

  5. abstract def timeout(idleDuration: Duration): StateSpec.this.type

    Set the duration after which the state of an idle key will be removed.

    Set the duration after which the state of an idle key will be removed. A key and its state is considered idle if it has not received any data for at least the given duration. The mapping function will be called one final time on the idle states that are going to be removed; State.isTimingOut() set to true in that call.

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