[SPARK-3054][STREAMING] Add unit tests for Spark Sink.

This patch adds unit tests for Spark Sink.

It also removes the private[flume] for Spark Sink,
since the sink is instantiated from Flume configuration (looks like this is ignored by reflection which is used by
Flume, but we should still remove it anyway).

external/flume-sink/pom.xml

@@ -72,6 +72,13 @@
       <groupId>org.scalatest</groupId>
       <artifactId>scalatest_${scala.binary.version}</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.apache.spark</groupId>
+      <artifactId>spark-streaming_${scala.binary.version}</artifactId>
+      <version>${project.version}</version>
+      <type>test-jar</type>
+      <scope>test</scope> <!-- Need it only for tests, don't package it -->
+    </dependency>
   </dependencies>
   <build>
     <outputDirectory>target/scala-${scala.binary.version}/classes</outputDirectory>

external/flume-sink/src/main/scala/org/apache/spark/streaming/flume/sink/SparkSink.scala

@@ -53,7 +53,6 @@ import org.apache.flume.sink.AbstractSink
  *
  */
 
-private[flume]
 class SparkSink extends AbstractSink with Logging with Configurable {
 
   // Size of the pool to use for holding transaction processors.
@@ -131,6 +130,14 @@ class SparkSink extends AbstractSink with Logging with Configurable {
     blockingLatch.await()
     Status.BACKOFF
   }
+
+  private[flume] def getPort(): Int = {
+    serverOpt
+      .map(_.getPort)
+      .getOrElse(
+        throw new RuntimeException("Server was not started!")
+      )
+  }
 }
 
 /**

external/flume-sink/src/test/scala/org/apache/spark/streaming/flume/sink/SparkSinkSuite.scala

@@ -0,0 +1,211 @@
+package org.apache.spark.streaming.flume.sink
+
+import java.net.InetSocketAddress
+import java.util.concurrent.atomic.AtomicInteger
+import java.util.concurrent.{CountDownLatch, Executors}
+
+import scala.collection.JavaConversions._
+import scala.concurrent.{Promise, Future}
+import scala.util.{Failure, Success, Try}
+
+import com.google.common.util.concurrent.ThreadFactoryBuilder
+import org.apache.avro.ipc.NettyTransceiver
+import org.apache.avro.ipc.specific.SpecificRequestor
+import org.apache.flume.Context
+import org.apache.flume.channel.MemoryChannel
+import org.apache.flume.event.EventBuilder
+import org.apache.spark.streaming.TestSuiteBase
+import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory
+
+
+/*
+ * 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.
+ */
+class SparkSinkSuite extends TestSuiteBase {
+  val batchCount = 5
+  val eventsPerBatch = 100
+  val totalEventsPerChannel = batchCount * eventsPerBatch
+  val channelCapacity = 5000
+  val maxAttempts = 5
+
+  test("Success test") {
+    val (channel, sink) = initializeChannelAndSink(None)
+    channel.start()
+    sink.start()
+
+    putEvents(channel, 1000)
+
+    val port = sink.getPort
+    val address = new InetSocketAddress("0.0.0.0", port)
+
+    val (transceiver, client) = getTransceiverAndClient(address, 1)(0)
+    val events = client.getEventBatch(1000)
+    client.ack(events.getSequenceNumber)
+    assert(events.getEvents.size() === 1000)
+    assertChannelIsEmpty(channel)
+    sink.stop()
+    channel.stop()
+    transceiver.close()
+  }
+
+  test("Nack") {
+    val (channel, sink) = initializeChannelAndSink(None)
+    channel.start()
+    sink.start()
+    putEvents(channel, 1000)
+
+    val port = sink.getPort
+    val address = new InetSocketAddress("0.0.0.0", port)
+
+    val (transceiver, client) = getTransceiverAndClient(address, 1)(0)
+    val events = client.getEventBatch(1000)
+    assert(events.getEvents.size() === 1000)
+    client.nack(events.getSequenceNumber)
+    assert(availableChannelSlots(channel) === 4000)
+    sink.stop()
+    channel.stop()
+    transceiver.close()
+  }
+
+  test("Timeout") {
+    val (channel, sink) = initializeChannelAndSink(Option(Map(SparkSinkConfig
+      .CONF_TRANSACTION_TIMEOUT -> 1.toString)))
+    channel.start()
+    sink.start()
+    putEvents(channel, 1000)
+    val port = sink.getPort
+    val address = new InetSocketAddress("0.0.0.0", port)
+
+    val (transceiver, client) = getTransceiverAndClient(address, 1)(0)
+    val events = client.getEventBatch(1000)
+    assert(events.getEvents.size() === 1000)
+    Thread.sleep(1000)
+    assert(availableChannelSlots(channel) === 4000)
+    sink.stop()
+    channel.stop()
+    transceiver.close()
+  }
+
+  test("Multiple consumers") {
+    multipleClients(failSome = false)
+  }
+
+  test("Multiple consumers With Some Failures") {
+    multipleClients(failSome = true)
+  }
+
+  def multipleClients(failSome: Boolean): Unit = {
+    import scala.concurrent.ExecutionContext.Implicits.global
+    val (channel, sink) = initializeChannelAndSink(None)
+    channel.start()
+    sink.start()
+    (1 to 5).map(_ =>putEvents(channel, 1000))
+    val port = sink.getPort
+    val address = new InetSocketAddress("0.0.0.0", port)
+
+    val transAndClient = getTransceiverAndClient(address, 5)
+    val batchCounter = new CountDownLatch(5)
+    val counter = new AtomicInteger(0)
+    transAndClient.foreach(x => {
+      val promise = Promise[EventBatch]()
+      val future = promise.future
+      Future {
+        val client = x._2
+        var events: EventBatch = null
+        Try {
+          events = client.getEventBatch(1000)
+          if(!failSome || counter.incrementAndGet() % 2 == 0) {
+            client.ack(events.getSequenceNumber)
+          } else {
+            client.nack(events.getSequenceNumber)
+          }
+        }.map(_ => promise.success(events)).recover({
+          case e => promise.failure(e)
+        })
+      }
+      future.onComplete {
+        case Success(events) => assert(events.getEvents.size() === 1000)
+          batchCounter.countDown()
+        case Failure(t) =>
+          batchCounter.countDown()
+          throw t
+      }
+    })
+    batchCounter.await()
+    if(failSome) {
+      assert(availableChannelSlots(channel) === 2000)
+    } else {
+      assertChannelIsEmpty(channel)
+    }
+    sink.stop()
+    channel.stop()
+    transAndClient.foreach(x => x._1.close())
+  }
+
+  def initializeChannelAndSink(overrides: Option[Map[String, String]]):
+  (MemoryChannel, SparkSink) = {
+    val channel = new MemoryChannel()
+    val channelContext = new Context()
+
+    channelContext.put("capacity", channelCapacity.toString)
+    channelContext.put("transactionCapacity", 1000.toString)
+    channelContext.put("keep-alive", 0.toString)
+    overrides.foreach(channelContext.putAll(_))
+    channel.configure(channelContext)
+
+    val sink = new SparkSink()
+    val sinkContext = new Context()
+    sinkContext.put(SparkSinkConfig.CONF_HOSTNAME, "0.0.0.0")
+    sinkContext.put(SparkSinkConfig.CONF_PORT, 0.toString)
+    sink.setChannel(channel)
+    (channel, sink)
+  }
+
+  private def putEvents(ch: MemoryChannel, count: Int): Unit = {
+    val tx = ch.getTransaction
+    tx.begin()
+    (1 to count).map(x => ch.put(EventBuilder.withBody(x.toString.getBytes)))
+    tx.commit()
+    tx.close()
+  }
+
+  private def getTransceiverAndClient(address: InetSocketAddress, count: Int):
+  Seq[(NettyTransceiver, SparkFlumeProtocol.Callback)] = {
+
+    (1 to count).map(_ => {
+      lazy val channelFactoryExecutor =
+        Executors.newCachedThreadPool(new ThreadFactoryBuilder().setDaemon(true).
+          setNameFormat("Flume Receiver Channel Thread - %d").build())
+      lazy val channelFactory =
+        new NioClientSocketChannelFactory(channelFactoryExecutor, channelFactoryExecutor)
+      val transceiver = new NettyTransceiver(address, channelFactory)
+      val client = SpecificRequestor.getClient(classOf[SparkFlumeProtocol.Callback], transceiver)
+      (transceiver, client)
+    })
+  }
+
+  private def assertChannelIsEmpty(channel: MemoryChannel) = {
+    assert(availableChannelSlots(channel) === 5000)
+  }
+
+  private def availableChannelSlots(channel: MemoryChannel): Int = {
+    val queueRemaining = channel.getClass.getDeclaredField("queueRemaining")
+    queueRemaining.setAccessible(true)
+    val m = queueRemaining.get(channel).getClass.getDeclaredMethod("availablePermits")
+    m.invoke(queueRemaining.get(channel)).asInstanceOf[Int]
+  }
+
+}

external/flume/src/test/scala/org/apache/spark/streaming/flume/FlumePollingStreamSuite.scala

@@ -201,7 +201,7 @@ class FlumePollingStreamSuite extends TestSuiteBase {
   }
 
   def assertChannelIsEmpty(channel: MemoryChannel) = {
-    val queueRemaining = channel.getClass.getDeclaredField("queueRemaining");
+    val queueRemaining = channel.getClass.getDeclaredField("queueRemaining")
     queueRemaining.setAccessible(true)
     val m = queueRemaining.get(channel).getClass.getDeclaredMethod("availablePermits")
     assert(m.invoke(queueRemaining.get(channel)).asInstanceOf[Int] === 5000)