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From huitseeker <...@git.apache.org>
Subject [GitHub] spark pull request: [SPARK-2629][STREAMING] Basic implementation o...
Date Fri, 06 Nov 2015 21:28:48 GMT
Github user huitseeker commented on a diff in the pull request:

    https://github.com/apache/spark/pull/9256#discussion_r44189624
  
    --- Diff: streaming/src/main/scala/org/apache/spark/streaming/util/StateMap.scala ---
    @@ -0,0 +1,304 @@
    +/*
    + * 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.util
    +
    +import java.io.{ObjectInputStream, ObjectOutputStream}
    +
    +import scala.reflect.ClassTag
    +
    +import org.apache.spark.SparkConf
    +import org.apache.spark.streaming.util.OpenHashMapBasedStateMap._
    +import org.apache.spark.util.collection.OpenHashMap
    +
    +/** Internal interface for defining the map that keeps track of sessions. */
    +private[streaming] abstract class StateMap[K: ClassTag, S: ClassTag] extends Serializable
{
    +
    +  /** Get the state for a key if it exists */
    +  def get(key: K): Option[S]
    +
    +  /** Get all the keys and states whose updated time is older than the given threshold
time */
    +  def getByTime(threshUpdatedTime: Long): Iterator[(K, S, Long)]
    +
    +  /** Get all the keys and states in this map. */
    +  def getAll(): Iterator[(K, S, Long)]
    +
    +  /** Add or update state */
    +  def put(key: K, state: S, updatedTime: Long): Unit
    +
    +  /** Remove a key */
    +  def remove(key: K): Unit
    +
    +  /**
    +   * Shallow copy `this` map to create a new state map.
    +   * Updates to the new map should not mutate `this` map.
    +   */
    +  def copy(): StateMap[K, S]
    +
    +  def toDebugString(): String = toString()
    +}
    +
    +/** Companion object for [[StateMap]], with utility methods */
    +private[streaming] object StateMap {
    +  def empty[K: ClassTag, S: ClassTag]: StateMap[K, S] = new EmptyStateMap[K, S]
    +
    +  def create[K: ClassTag, S: ClassTag](conf: SparkConf): StateMap[K, S] = {
    +    val deltaChainThreshold = conf.getInt("spark.streaming.sessionByKey.deltaChainThreshold",
    +      DELTA_CHAIN_LENGTH_THRESHOLD)
    +    new OpenHashMapBasedStateMap[K, S](64, deltaChainThreshold)
    +  }
    +}
    +
    +/** Specific implementation of SessionStore interface representing an empty map */
    +private[streaming] class EmptyStateMap[K: ClassTag, S: ClassTag] extends StateMap[K,
S] {
    +  override def put(key: K, session: S, updateTime: Long): Unit = {
    +    throw new NotImplementedError("put() should not be called on an EmptyStateMap")
    +  }
    +  override def get(key: K): Option[S] = None
    +  override def getByTime(threshUpdatedTime: Long): Iterator[(K, S, Long)] = Iterator.empty
    +  override def getAll(): Iterator[(K, S, Long)] = Iterator.empty
    +  override def copy(): StateMap[K, S] = new EmptyStateMap[K, S]
    +  override def remove(key: K): Unit = { }
    +  override def toDebugString(): String = ""
    +}
    +
    +
    +
    +/** Implementation of StateMap based on Spark's OpenHashMap */
    +private[streaming] class OpenHashMapBasedStateMap[K: ClassTag, S: ClassTag](
    +    @transient @volatile var parentStateMap: StateMap[K, S],
    +    initialCapacity: Int = 64,
    +    deltaChainThreshold: Int = DELTA_CHAIN_LENGTH_THRESHOLD
    +  ) extends StateMap[K, S] { self =>
    +
    +  def this(initialCapacity: Int, deltaChainThreshold: Int) = this(
    +    new EmptyStateMap[K, S],
    +    initialCapacity = initialCapacity,
    +    deltaChainThreshold = deltaChainThreshold)
    +
    +  def this(deltaChainThreshold: Int) = this(
    +    initialCapacity = 64, deltaChainThreshold = deltaChainThreshold)
    +
    +  def this() = this(DELTA_CHAIN_LENGTH_THRESHOLD)
    +
    +  @transient @volatile private var deltaMap =
    +    new OpenHashMap[K, StateInfo[S]](initialCapacity)
    +
    +  /** Get the session data if it exists */
    +  override def get(key: K): Option[S] = {
    +    val stateInfo = deltaMap(key)
    +    if (stateInfo != null) {
    +      if (!stateInfo.deleted) {
    +        Some(stateInfo.data)
    +      } else {
    +        None
    +      }
    +    } else {
    +      parentStateMap.get(key)
    +    }
    +  }
    +
    +  /** Get all the keys and states whose updated time is older than the give threshold
time */
    +  override def getByTime(threshUpdatedTime: Long): Iterator[(K, S, Long)] = {
    +    val oldStates = parentStateMap.getByTime(threshUpdatedTime).filter { case (key, value,
_) =>
    +      !deltaMap.contains(key)
    +    }
    +
    +    val updatedStates = deltaMap.iterator.flatMap { case (key, stateInfo) =>
    --- End diff --
    
    It makes it harder to not exhaust the iterator (IIUC what you suggest).


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