spark JavaMapWithStateDStream 源码
spark JavaMapWithStateDStream 代码
文件路径：/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaMapWithStateDStream.scala
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.spark.streaming.api.java
import org.apache.spark.api.java.JavaSparkContext
import org.apache.spark.streaming.dstream.MapWithStateDStream
/**
* DStream representing the stream of data generated by `mapWithState` operation on a
* [[JavaPairDStream]]. Additionally, it also gives access to the
* stream of state snapshots, that is, the state data of all keys after a batch has updated them.
*
* @tparam KeyType Class of the keys
* @tparam ValueType Class of the values
* @tparam StateType Class of the state data
* @tparam MappedType Class of the mapped data
*/
class JavaMapWithStateDStream[KeyType, ValueType, StateType, MappedType] private[streaming](
dstream: MapWithStateDStream[KeyType, ValueType, StateType, MappedType])
extends JavaDStream[MappedType](dstream)(JavaSparkContext.fakeClassTag) {
def stateSnapshots(): JavaPairDStream[KeyType, StateType] =
new JavaPairDStream(dstream.stateSnapshots())(
JavaSparkContext.fakeClassTag,
JavaSparkContext.fakeClassTag)
}
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