[SPARK-5155] [PYSPARK] [STREAMING] Mqtt streaming support in Python

This PR is based on #4229, thanks prabeesh.

Closes #4229

Author: Prabeesh K <prabsmails@gmail.com>
Author: zsxwing <zsxwing@gmail.com>
Author: prabs <prabsmails@gmail.com>
Author: Prabeesh K <prabeesh.k@namshi.com>

Closes #7833 from zsxwing/pr4229 and squashes the following commits:

9570bec [zsxwing] Fix the variable name and check null in finally
4a9c79e [zsxwing] Fix pom.xml indentation
abf5f18 [zsxwing] Merge branch 'master' into pr4229
935615c [zsxwing] Fix the flaky MQTT tests
47278c5 [zsxwing] Include the project class files
478f844 [zsxwing] Add unpack
5f8a1d4 [zsxwing] Make the maven build generate the test jar for Python MQTT tests
734db99 [zsxwing] Merge branch 'master' into pr4229
126608a [Prabeesh K] address the comments
b90b709 [Prabeesh K] Merge pull request #1 from zsxwing/pr4229
d07f454 [zsxwing] Register StreamingListerner before starting StreamingContext; Revert unncessary changes; fix the python unit test
a6747cb [Prabeesh K] wait for starting the receiver before publishing data
87fc677 [Prabeesh K] address the comments:
97244ec [zsxwing] Make sbt build the assembly test jar for streaming mqtt
80474d1 [Prabeesh K] fix
1f0cfe9 [Prabeesh K] python style fix
e1ee016 [Prabeesh K] scala style fix
a5a8f9f [Prabeesh K] added Python test
9767d82 [Prabeesh K] implemented Python-friendly class
a11968b [Prabeesh K] fixed python style
795ec27 [Prabeesh K] address comments
ee387ae [Prabeesh K] Fix assembly jar location of mqtt-assembly
3f4df12 [Prabeesh K] updated version
b34c3c1 [prabs] adress comments
3aa7fff [prabs] Added Python streaming mqtt word count example
b7d42ff [prabs] Mqtt streaming support in Python

5 files changed, 214 insertions, 103 deletions

diff --git a/external/mqtt/pom.xml b/external/mqtt/pom.xml
index 0e41e57817..69b309876a 100644
--- a/external/mqtt/pom.xml
+++ b/external/mqtt/pom.xml
@@ -78,5 +78,33 @@
   <build>
     <outputDirectory>target/scala-${scala.binary.version}/classes</outputDirectory>
     <testOutputDirectory>target/scala-${scala.binary.version}/test-classes</testOutputDirectory>
+
+    <plugins>
+      <!-- Assemble a jar with test dependencies for Python tests -->
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-assembly-plugin</artifactId>
+        <executions>
+          <execution>
+            <id>test-jar-with-dependencies</id>
+            <phase>package</phase>
+            <goals>
+              <goal>single</goal>
+            </goals>
+            <configuration>
+              <!-- Make sure the file path is same as the sbt build -->
+              <finalName>spark-streaming-mqtt-test-${project.version}</finalName>
+              <outputDirectory>${project.build.directory}/scala-${scala.binary.version}/</outputDirectory>
+              <appendAssemblyId>false</appendAssemblyId>
+              <!-- Don't publish it since it's only for Python tests -->
+              <attach>false</attach>
+              <descriptors>
+                <descriptor>src/main/assembly/assembly.xml</descriptor>
+              </descriptors>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
   </build>
 </project>
diff --git a/external/mqtt/src/main/assembly/assembly.xml b/external/mqtt/src/main/assembly/assembly.xml
new file mode 100644
index 0000000000..ecab5b360e
--- /dev/null
+++ b/external/mqtt/src/main/assembly/assembly.xml
@@ -0,0 +1,44 @@
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one or more
+  ~ contributor license agreements.  See the NOTICE file distributed with
+  ~ this work for additional information regarding copyright ownership.
+  ~ The ASF licenses this file to You under the Apache License, Version 2.0
+  ~ (the "License"); you may not use this file except in compliance with
+  ~ the License.  You may obtain a copy of the License at
+  ~
+  ~    http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<assembly>
+  <id>test-jar-with-dependencies</id>
+  <formats>
+    <format>jar</format>
+  </formats>
+  <includeBaseDirectory>false</includeBaseDirectory>
+
+  <fileSets>
+    <fileSet>
+      <directory>${project.build.directory}/scala-${scala.binary.version}/test-classes</directory>
+      <outputDirectory>/</outputDirectory>
+    </fileSet>
+  </fileSets>
+
+  <dependencySets>
+    <dependencySet>
+      <useTransitiveDependencies>true</useTransitiveDependencies>
+      <scope>test</scope>
+      <unpack>true</unpack>
+      <excludes>
+        <exclude>org.apache.hadoop:*:jar</exclude>
+        <exclude>org.apache.zookeeper:*:jar</exclude>
+        <exclude>org.apache.avro:*:jar</exclude>
+      </excludes>
+    </dependencySet>
+  </dependencySets>
+
+</assembly>
diff --git a/external/mqtt/src/main/scala/org/apache/spark/streaming/mqtt/MQTTUtils.scala b/external/mqtt/src/main/scala/org/apache/spark/streaming/mqtt/MQTTUtils.scala
index 1142d0f56b..38a1114863 100644
--- a/external/mqtt/src/main/scala/org/apache/spark/streaming/mqtt/MQTTUtils.scala
+++ b/external/mqtt/src/main/scala/org/apache/spark/streaming/mqtt/MQTTUtils.scala
@@ -74,3 +74,19 @@ object MQTTUtils {
     createStream(jssc.ssc, brokerUrl, topic, storageLevel)
   }
 }
+
+/**
+ * This is a helper class that wraps the methods in MQTTUtils into more Python-friendly class and
+ * function so that it can be easily instantiated and called from Python's MQTTUtils.
+ */
+private class MQTTUtilsPythonHelper {
+
+  def createStream(
+      jssc: JavaStreamingContext,
+      brokerUrl: String,
+      topic: String,
+      storageLevel: StorageLevel
+    ): JavaDStream[String] = {
+    MQTTUtils.createStream(jssc, brokerUrl, topic, storageLevel)
+  }
+}
diff --git a/external/mqtt/src/test/scala/org/apache/spark/streaming/mqtt/MQTTStreamSuite.scala b/external/mqtt/src/test/scala/org/apache/spark/streaming/mqtt/MQTTStreamSuite.scala
index c4bf5aa786..a6a9249db8 100644
--- a/external/mqtt/src/test/scala/org/apache/spark/streaming/mqtt/MQTTStreamSuite.scala
+++ b/external/mqtt/src/test/scala/org/apache/spark/streaming/mqtt/MQTTStreamSuite.scala
@@ -17,46 +17,30 @@
 
 package org.apache.spark.streaming.mqtt
 
-import java.net.{URI, ServerSocket}
-import java.util.concurrent.CountDownLatch
-import java.util.concurrent.TimeUnit
-
 import scala.concurrent.duration._
 import scala.language.postfixOps
 
-import org.apache.activemq.broker.{TransportConnector, BrokerService}
-import org.apache.commons.lang3.RandomUtils
-import org.eclipse.paho.client.mqttv3._
-import org.eclipse.paho.client.mqttv3.persist.MqttDefaultFilePersistence
-
 import org.scalatest.BeforeAndAfter
 import org.scalatest.concurrent.Eventually
 
-import org.apache.spark.streaming.{Milliseconds, StreamingContext}
-import org.apache.spark.storage.StorageLevel
-import org.apache.spark.streaming.dstream.ReceiverInputDStream
-import org.apache.spark.streaming.scheduler.StreamingListener
-import org.apache.spark.streaming.scheduler.StreamingListenerReceiverStarted
 import org.apache.spark.{SparkConf, SparkFunSuite}
-import org.apache.spark.util.Utils
+import org.apache.spark.storage.StorageLevel
+import org.apache.spark.streaming.{Milliseconds, StreamingContext}
 
 class MQTTStreamSuite extends SparkFunSuite with Eventually with BeforeAndAfter {
 
   private val batchDuration = Milliseconds(500)
   private val master = "local[2]"
   private val framework = this.getClass.getSimpleName
-  private val freePort = findFreePort()
-  private val brokerUri = "//localhost:" + freePort
   private val topic = "def"
-  private val persistenceDir = Utils.createTempDir()
 
   private var ssc: StreamingContext = _
-  private var broker: BrokerService = _
-  private var connector: TransportConnector = _
+  private var mqttTestUtils: MQTTTestUtils = _
 
   before {
     ssc = new StreamingContext(master, framework, batchDuration)
-    setupMQTT()
+    mqttTestUtils = new MQTTTestUtils
+    mqttTestUtils.setup()
   }
 
   after {
@@ -64,14 +48,17 @@ class MQTTStreamSuite extends SparkFunSuite with Eventually with BeforeAndAfter
       ssc.stop()
       ssc = null
     }
-    Utils.deleteRecursively(persistenceDir)
-    tearDownMQTT()
+    if (mqttTestUtils != null) {
+      mqttTestUtils.teardown()
+      mqttTestUtils = null
+    }
   }
 
   test("mqtt input stream") {
     val sendMessage = "MQTT demo for spark streaming"
-    val receiveStream =
-      MQTTUtils.createStream(ssc, "tcp:" + brokerUri, topic, StorageLevel.MEMORY_ONLY)
+    val receiveStream = MQTTUtils.createStream(ssc, "tcp://" + mqttTestUtils.brokerUri, topic,
+      StorageLevel.MEMORY_ONLY)
+
     @volatile var receiveMessage: List[String] = List()
     receiveStream.foreachRDD { rdd =>
       if (rdd.collect.length > 0) {
@@ -79,89 +66,14 @@ class MQTTStreamSuite extends SparkFunSuite with Eventually with BeforeAndAfter
         receiveMessage
       }
     }
-    ssc.start()
 
-    // wait for the receiver to start before publishing data, or we risk failing
-    // the test nondeterministically. See SPARK-4631
-    waitForReceiverToStart()
+    ssc.start()
 
-    publishData(sendMessage)
+    // Retry it because we don't know when the receiver will start.
     eventually(timeout(10000 milliseconds), interval(100 milliseconds)) {
+      mqttTestUtils.publishData(topic, sendMessage)
       assert(sendMessage.equals(receiveMessage(0)))
     }
     ssc.stop()
   }
-
-  private def setupMQTT() {
-    broker = new BrokerService()
-    broker.setDataDirectoryFile(Utils.createTempDir())
-    connector = new TransportConnector()
-    connector.setName("mqtt")
-    connector.setUri(new URI("mqtt:" + brokerUri))
-    broker.addConnector(connector)
-    broker.start()
-  }
-
-  private def tearDownMQTT() {
-    if (broker != null) {
-      broker.stop()
-      broker = null
-    }
-    if (connector != null) {
-      connector.stop()
-      connector = null
-    }
-  }
-
-  private def findFreePort(): Int = {
-    val candidatePort = RandomUtils.nextInt(1024, 65536)
-    Utils.startServiceOnPort(candidatePort, (trialPort: Int) => {
-      val socket = new ServerSocket(trialPort)
-      socket.close()
-      (null, trialPort)
-    }, new SparkConf())._2
-  }
-
-  def publishData(data: String): Unit = {
-    var client: MqttClient = null
-    try {
-      val persistence = new MqttDefaultFilePersistence(persistenceDir.getAbsolutePath)
-      client = new MqttClient("tcp:" + brokerUri, MqttClient.generateClientId(), persistence)
-      client.connect()
-      if (client.isConnected) {
-        val msgTopic = client.getTopic(topic)
-        val message = new MqttMessage(data.getBytes("utf-8"))
-        message.setQos(1)
-        message.setRetained(true)
-
-        for (i <- 0 to 10) {
-          try {
-            msgTopic.publish(message)
-          } catch {
-            case e: MqttException if e.getReasonCode == MqttException.REASON_CODE_MAX_INFLIGHT =>
-              // wait for Spark streaming to consume something from the message queue
-              Thread.sleep(50)
-          }
-        }
-      }
-    } finally {
-      client.disconnect()
-      client.close()
-      client = null
-    }
-  }
-
-  /**
-   * Block until at least one receiver has started or timeout occurs.
-   */
-  private def waitForReceiverToStart() = {
-    val latch = new CountDownLatch(1)
-    ssc.addStreamingListener(new StreamingListener {
-      override def onReceiverStarted(receiverStarted: StreamingListenerReceiverStarted) {
-        latch.countDown()
-      }
-    })
-
-    assert(latch.await(10, TimeUnit.SECONDS), "Timeout waiting for receiver to start.")
-  }
 }
diff --git a/external/mqtt/src/test/scala/org/apache/spark/streaming/mqtt/MQTTTestUtils.scala b/external/mqtt/src/test/scala/org/apache/spark/streaming/mqtt/MQTTTestUtils.scala
new file mode 100644
index 0000000000..1a371b7008
--- /dev/null
+++ b/external/mqtt/src/test/scala/org/apache/spark/streaming/mqtt/MQTTTestUtils.scala
@@ -0,0 +1,111 @@
+/*
+ * 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.mqtt
+
+import java.net.{ServerSocket, URI}
+
+import scala.language.postfixOps
+
+import com.google.common.base.Charsets.UTF_8
+import org.apache.activemq.broker.{BrokerService, TransportConnector}
+import org.apache.commons.lang3.RandomUtils
+import org.eclipse.paho.client.mqttv3._
+import org.eclipse.paho.client.mqttv3.persist.MqttDefaultFilePersistence
+
+import org.apache.spark.util.Utils
+import org.apache.spark.{Logging, SparkConf}
+
+/**
+ * Share codes for Scala and Python unit tests
+ */
+private class MQTTTestUtils extends Logging {
+
+  private val persistenceDir = Utils.createTempDir()
+  private val brokerHost = "localhost"
+  private val brokerPort = findFreePort()
+
+  private var broker: BrokerService = _
+  private var connector: TransportConnector = _
+
+  def brokerUri: String = {
+    s"$brokerHost:$brokerPort"
+  }
+
+  def setup(): Unit = {
+    broker = new BrokerService()
+    broker.setDataDirectoryFile(Utils.createTempDir())
+    connector = new TransportConnector()
+    connector.setName("mqtt")
+    connector.setUri(new URI("mqtt://" + brokerUri))
+    broker.addConnector(connector)
+    broker.start()
+  }
+
+  def teardown(): Unit = {
+    if (broker != null) {
+      broker.stop()
+      broker = null
+    }
+    if (connector != null) {
+      connector.stop()
+      connector = null
+    }
+    Utils.deleteRecursively(persistenceDir)
+  }
+
+  private def findFreePort(): Int = {
+    val candidatePort = RandomUtils.nextInt(1024, 65536)
+    Utils.startServiceOnPort(candidatePort, (trialPort: Int) => {
+      val socket = new ServerSocket(trialPort)
+      socket.close()
+      (null, trialPort)
+    }, new SparkConf())._2
+  }
+
+  def publishData(topic: String, data: String): Unit = {
+    var client: MqttClient = null
+    try {
+      val persistence = new MqttDefaultFilePersistence(persistenceDir.getAbsolutePath)
+      client = new MqttClient("tcp://" + brokerUri, MqttClient.generateClientId(), persistence)
+      client.connect()
+      if (client.isConnected) {
+        val msgTopic = client.getTopic(topic)
+        val message = new MqttMessage(data.getBytes(UTF_8))
+        message.setQos(1)
+        message.setRetained(true)
+
+        for (i <- 0 to 10) {
+          try {
+            msgTopic.publish(message)
+          } catch {
+            case e: MqttException if e.getReasonCode == MqttException.REASON_CODE_MAX_INFLIGHT =>
+              // wait for Spark streaming to consume something from the message queue
+              Thread.sleep(50)
+          }
+        }
+      }
+    } finally {
+      if (client != null) {
+        client.disconnect()
+        client.close()
+        client = null
+      }
+    }
+  }
+
+}