[GitHub] [spark] rangadi commented on a diff in pull request #41752: [SPARK-44201][CONNECT][SS]Add support for Streaming Listener in Scala for Spark Connect

["rangadi (via GitHub)" <gi...@apache.org>]

rangadi commented on code in PR #41752:
URL: https://github.com/apache/spark/pull/41752#discussion_r1260122470


##########
connector/connect/common/src/main/scala/org/apache/spark/sql/connect/common/StreamingListenerPacket.scala:
##########
@@ -0,0 +1,20 @@
+/*
+ * 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.sql.connect.common
+
+case class StreamingListenerPacket(id: String, listener: AnyRef) extends Serializable

Review Comment:
   Can you add documentation? What is the second arg?



##########
connector/connect/server/src/main/scala/org/apache/spark/sql/connect/service/SessionHolder.scala:
##########
@@ -47,6 +48,9 @@ case class SessionHolder(userId: String, sessionId: String, session: SparkSessio
   // foreachBatch() in Streaming. Lazy since most sessions don't need it.
   private lazy val dataFrameCache: ConcurrentMap[String, DataFrame] = new ConcurrentHashMap()
 
+  private lazy val listenerCache: ConcurrentMap[String, StreamingQueryListener] =

Review Comment:
   Should this be part of the StreamingQuery itself? It does not need to be part of the session.
   Also, when is this removed? 



##########
connector/connect/server/src/main/scala/org/apache/spark/sql/connect/service/SessionHolder.scala:
##########
@@ -152,6 +156,26 @@ case class SessionHolder(userId: String, sessionId: String, session: SparkSessio
   private[connect] def removeCachedDataFrame(dfId: String): DataFrame = {
     dataFrameCache.remove(dfId)
   }
+
+  /**
+   * Caches given StreamingQueryListener with the ID.
+   */
+  private[connect] def cacheListenerById(id: String, listener: StreamingQueryListener): Unit = {
+    if (listenerCache.putIfAbsent(id, listener) != null) {
+      SparkException.internalError(s"A listener is already associated with id $id")
+    }
+  }
+
+  /**
+   * Returns [[StreamingQueryListener]] cached for Listener ID `id`. If it is not found, throw
+   * [[InvalidPlanInput]].
+   */
+  private[connect] def getListenerOrThrow(id: String): StreamingQueryListener = {

Review Comment:
   There does not seem to be 'remove()' method. When are these entries removed? 



##########
connector/connect/client/jvm/src/test/scala/org/apache/spark/sql/streaming/StreamingQuerySuite.scala:
##########
@@ -292,3 +331,31 @@ class TestForeachWriter[T] extends ForeachWriter[T] {
 case class TestClass(value: Int) {
   override def toString: String = value.toString
 }
+
+class EventCollector extends StreamingQueryListener {
+  @volatile var startEvent: QueryStartedEvent = null
+  @volatile var terminationEvent: QueryTerminatedEvent = null
+  @volatile var idleEvent: QueryIdleEvent = null
+
+  private val _progressEvents = new mutable.Queue[StreamingQueryProgress]
+
+  def progressEvents: Seq[StreamingQueryProgress] = _progressEvents.synchronized {
+    _progressEvents.clone().toSeq
+  }
+
+  override def onQueryStarted(event: StreamingQueryListener.QueryStartedEvent): Unit = {
+    startEvent = event
+  }
+
+  override def onQueryProgress(event: StreamingQueryListener.QueryProgressEvent): Unit = {
+    _progressEvents += event.progress

Review Comment:
   Could you update this to do a spark operation? Like spark.write() or spark.read()? 



##########
connector/connect/server/src/main/scala/org/apache/spark/sql/connect/planner/SparkConnectPlanner.scala:
##########
@@ -2909,6 +2918,36 @@ class SparkConnectPlanner(val sessionHolder: SessionHolder) extends Logging {
         session.streams.resetTerminated()
         respBuilder.setResetTerminated(true)
 
+      case StreamingQueryManagerCommand.CommandCase.ADD_LISTENER =>
+        val listenerPacket = Utils
+          .deserialize[StreamingListenerPacket](
+            command.getAddListener.getListenerPayload.toByteArray,
+            Utils.getContextOrSparkClassLoader)
+        val listener: StreamingQueryListener = listenerPacket.listener
+          .asInstanceOf[StreamingQueryListener]
+        val id: String = listenerPacket.id
+        sessionHolder.cacheListenerById(id, listener)
+        session.streams.addListener(listener)

Review Comment:
   So, from this point on this listener is treated as legacy StreamingListener. I.e. it is not a Connect streaming listener. Is that fine? Wondering what happens if user tries to run a spark command inside the listener (added a comment about this in unit test).
   For the first version here it might be fine, but I think we should have clearly defined TODO for this improvement. cc: @WweiL 



##########
sql/core/src/main/scala/org/apache/spark/sql/streaming/StreamingQueryListener.scala:
##########
@@ -34,7 +34,7 @@ import org.apache.spark.scheduler.SparkListenerEvent
  * @since 2.0.0
  */
 @Evolving
-abstract class StreamingQueryListener {
+abstract class StreamingQueryListener extends Serializable {

Review Comment:
   Client side class is different from server side, right? 



##########
connector/connect/client/jvm/src/test/scala/org/apache/spark/sql/streaming/StreamingQuerySuite.scala:
##########
@@ -292,3 +331,31 @@ class TestForeachWriter[T] extends ForeachWriter[T] {
 case class TestClass(value: Int) {
   override def toString: String = value.toString
 }
+
+class EventCollector extends StreamingQueryListener {
+  @volatile var startEvent: QueryStartedEvent = null
+  @volatile var terminationEvent: QueryTerminatedEvent = null
+  @volatile var idleEvent: QueryIdleEvent = null
+
+  private val _progressEvents = new mutable.Queue[StreamingQueryProgress]
+
+  def progressEvents: Seq[StreamingQueryProgress] = _progressEvents.synchronized {
+    _progressEvents.clone().toSeq
+  }
+
+  override def onQueryStarted(event: StreamingQueryListener.QueryStartedEvent): Unit = {
+    startEvent = event
+  }
+
+  override def onQueryProgress(event: StreamingQueryListener.QueryProgressEvent): Unit = {
+    _progressEvents += event.progress

Review Comment:
   If this not feasible now, we could do that a follow up to this PR with a TODO. 



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