wait for starting the receiver before publishing data

Author: prabeesh

external/mqtt/src/main/scala/org/apache/spark/streaming/mqtt/MQTTUtils.scala

@@ -19,7 +19,6 @@ package org.apache.spark.streaming.mqtt
 
 import scala.reflect.ClassTag
 
-import org.apache.spark.api.java.function.Function
 import org.apache.spark.storage.StorageLevel
 import org.apache.spark.streaming.StreamingContext
 import org.apache.spark.streaming.api.java.{JavaReceiverInputDStream, JavaStreamingContext, JavaDStream}

external/mqtt/src/test/scala/org/apache/spark/streaming/mqtt/MQTTTestUtils.scala

@@ -28,6 +28,7 @@ import org.eclipse.paho.client.mqttv3._
 import org.eclipse.paho.client.mqttv3.persist.MqttDefaultFilePersistence
 
 import org.apache.spark.streaming.StreamingContext
+import org.apache.spark.streaming.api.java.JavaStreamingContext
 import org.apache.spark.streaming.scheduler.StreamingListener
 import org.apache.spark.streaming.scheduler.StreamingListenerReceiverStarted
 import org.apache.spark.util.Utils
@@ -121,4 +122,15 @@ private class MQTTTestUtils extends Logging {
 
     assert(latch.await(10, TimeUnit.SECONDS), "Timeout waiting for receiver to start.")
   }
+
+  def waitForReceiverToStart(jssc: JavaStreamingContext) : Unit = {
+    val latch = new CountDownLatch(1)
+    jssc.addStreamingListener(new StreamingListener {
+      override def onReceiverStarted(receiverStarted: StreamingListenerReceiverStarted) {
+        latch.countDown()
+      }
+    })
+
+    assert(latch.await(10, TimeUnit.SECONDS), "Timeout waiting for receiver to start.")
+  }
 }

python/pyspark/streaming/tests.py

@@ -884,6 +884,7 @@ def test_mqtt_stream(self):
         sendData = "MQTT demo for spark streaming"
         topic = self._randomTopic()
         result = self._startContext(topic)
+        self._MQTTTestUtils.waitForReceiverToStart(self.ssc._jssc)
         self._publishData(topic, sendData)
         self.wait_for(result, len(sendData))
         self._validateStreamResult(sendData, result)