sealed abstract class StateSpec[KeyType, ValueType, StateType, MappedType] extends Serializable
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
- Annotations
- @Experimental()
- Source
- StateSpec.scala
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Abstract Value Members
-
abstract
def
initialState(javaPairRDD: JavaPairRDD[KeyType, StateType]): StateSpec.this.type
Set the RDD containing the initial states that will be used by
mapWithState
-
abstract
def
initialState(rdd: RDD[(KeyType, StateType)]): StateSpec.this.type
Set the RDD containing the initial states that will be used by
mapWithState
-
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. -
abstract
def
partitioner(partitioner: Partitioner): StateSpec.this.type
Set the partitioner by which the state RDDs generated by
mapWithState
will be partitioned. -
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.