[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

2 files changed, 176 insertions, 2 deletions

diff --git a/python/pyspark/streaming/mqtt.py b/python/pyspark/streaming/mqtt.py
new file mode 100644
index 0000000000..f06598971c
--- /dev/null
+++ b/python/pyspark/streaming/mqtt.py
@@ -0,0 +1,72 @@
+#
+# 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.
+#
+
+from py4j.java_gateway import Py4JJavaError
+
+from pyspark.storagelevel import StorageLevel
+from pyspark.serializers import UTF8Deserializer
+from pyspark.streaming import DStream
+
+__all__ = ['MQTTUtils']
+
+
+class MQTTUtils(object):
+
+    @staticmethod
+    def createStream(ssc, brokerUrl, topic,
+                     storageLevel=StorageLevel.MEMORY_AND_DISK_SER_2):
+        """
+        Create an input stream that pulls messages from a Mqtt Broker.
+        :param ssc:  StreamingContext object
+        :param brokerUrl:  Url of remote mqtt publisher
+        :param topic:  topic name to subscribe to
+        :param storageLevel:  RDD storage level.
+        :return: A DStream object
+        """
+        jlevel = ssc._sc._getJavaStorageLevel(storageLevel)
+
+        try:
+            helperClass = ssc._jvm.java.lang.Thread.currentThread().getContextClassLoader() \
+                .loadClass("org.apache.spark.streaming.mqtt.MQTTUtilsPythonHelper")
+            helper = helperClass.newInstance()
+            jstream = helper.createStream(ssc._jssc, brokerUrl, topic, jlevel)
+        except Py4JJavaError as e:
+            if 'ClassNotFoundException' in str(e.java_exception):
+                MQTTUtils._printErrorMsg(ssc.sparkContext)
+            raise e
+
+        return DStream(jstream, ssc, UTF8Deserializer())
+
+    @staticmethod
+    def _printErrorMsg(sc):
+        print("""
+________________________________________________________________________________________________
+
+  Spark Streaming's MQTT libraries not found in class path. Try one of the following.
+
+  1. Include the MQTT library and its dependencies with in the
+     spark-submit command as
+
+     $ bin/spark-submit --packages org.apache.spark:spark-streaming-mqtt:%s ...
+
+  2. Download the JAR of the artifact from Maven Central http://search.maven.org/,
+     Group Id = org.apache.spark, Artifact Id = spark-streaming-mqtt-assembly, Version = %s.
+     Then, include the jar in the spark-submit command as
+
+     $ bin/spark-submit --jars <spark-streaming-mqtt-assembly.jar> ...
+________________________________________________________________________________________________
+""" % (sc.version, sc.version))
diff --git a/python/pyspark/streaming/tests.py b/python/pyspark/streaming/tests.py
index 5cd544b214..66ae3345f4 100644
--- a/python/pyspark/streaming/tests.py
+++ b/python/pyspark/streaming/tests.py
@@ -40,6 +40,7 @@ from pyspark.storagelevel import StorageLevel
 from pyspark.streaming.context import StreamingContext
 from pyspark.streaming.kafka import Broker, KafkaUtils, OffsetRange, TopicAndPartition
 from pyspark.streaming.flume import FlumeUtils
+from pyspark.streaming.mqtt import MQTTUtils
 from pyspark.streaming.kinesis import KinesisUtils, InitialPositionInStream
 
 
@@ -893,6 +894,68 @@ class FlumePollingStreamTests(PySparkStreamingTestCase):
         self._testMultipleTimes(self._testFlumePollingMultipleHosts)
 
 
+class MQTTStreamTests(PySparkStreamingTestCase):
+    timeout = 20  # seconds
+    duration = 1
+
+    def setUp(self):
+        super(MQTTStreamTests, self).setUp()
+
+        MQTTTestUtilsClz = self.ssc._jvm.java.lang.Thread.currentThread().getContextClassLoader() \
+            .loadClass("org.apache.spark.streaming.mqtt.MQTTTestUtils")
+        self._MQTTTestUtils = MQTTTestUtilsClz.newInstance()
+        self._MQTTTestUtils.setup()
+
+    def tearDown(self):
+        if self._MQTTTestUtils is not None:
+            self._MQTTTestUtils.teardown()
+            self._MQTTTestUtils = None
+
+        super(MQTTStreamTests, self).tearDown()
+
+    def _randomTopic(self):
+        return "topic-%d" % random.randint(0, 10000)
+
+    def _startContext(self, topic):
+        # Start the StreamingContext and also collect the result
+        stream = MQTTUtils.createStream(self.ssc, "tcp://" + self._MQTTTestUtils.brokerUri(), topic)
+        result = []
+
+        def getOutput(_, rdd):
+            for data in rdd.collect():
+                result.append(data)
+
+        stream.foreachRDD(getOutput)
+        self.ssc.start()
+        return result
+
+    def test_mqtt_stream(self):
+        """Test the Python MQTT stream API."""
+        sendData = "MQTT demo for spark streaming"
+        topic = self._randomTopic()
+        result = self._startContext(topic)
+
+        def retry():
+            self._MQTTTestUtils.publishData(topic, sendData)
+            # Because "publishData" sends duplicate messages, here we should use > 0
+            self.assertTrue(len(result) > 0)
+            self.assertEqual(sendData, result[0])
+
+        # Retry it because we don't know when the receiver will start.
+        self._retry_or_timeout(retry)
+
+    def _retry_or_timeout(self, test_func):
+        start_time = time.time()
+        while True:
+            try:
+                test_func()
+                break
+            except:
+                if time.time() - start_time > self.timeout:
+                    raise
+                time.sleep(0.01)
+
+
 class KinesisStreamTests(PySparkStreamingTestCase):
 
     def test_kinesis_stream_api(self):
@@ -985,7 +1048,42 @@ def search_flume_assembly_jar():
             "'build/mvn package' before running this test")
     elif len(jars) > 1:
         raise Exception(("Found multiple Spark Streaming Flume assembly JARs in %s; please "
-                         "remove all but one") % flume_assembly_dir)
+                        "remove all but one") % flume_assembly_dir)
+    else:
+        return jars[0]
+
+
+def search_mqtt_assembly_jar():
+    SPARK_HOME = os.environ["SPARK_HOME"]
+    mqtt_assembly_dir = os.path.join(SPARK_HOME, "external/mqtt-assembly")
+    jars = glob.glob(
+        os.path.join(mqtt_assembly_dir, "target/scala-*/spark-streaming-mqtt-assembly-*.jar"))
+    if not jars:
+        raise Exception(
+            ("Failed to find Spark Streaming MQTT assembly jar in %s. " % mqtt_assembly_dir) +
+            "You need to build Spark with "
+            "'build/sbt assembly/assembly streaming-mqtt-assembly/assembly' or "
+            "'build/mvn package' before running this test")
+    elif len(jars) > 1:
+        raise Exception(("Found multiple Spark Streaming MQTT assembly JARs in %s; please "
+                         "remove all but one") % mqtt_assembly_dir)
+    else:
+        return jars[0]
+
+
+def search_mqtt_test_jar():
+    SPARK_HOME = os.environ["SPARK_HOME"]
+    mqtt_test_dir = os.path.join(SPARK_HOME, "external/mqtt")
+    jars = glob.glob(
+        os.path.join(mqtt_test_dir, "target/scala-*/spark-streaming-mqtt-test-*.jar"))
+    if not jars:
+        raise Exception(
+            ("Failed to find Spark Streaming MQTT test jar in %s. " % mqtt_test_dir) +
+            "You need to build Spark with "
+            "'build/sbt assembly/assembly streaming-mqtt/test:assembly'")
+    elif len(jars) > 1:
+        raise Exception(("Found multiple Spark Streaming MQTT test JARs in %s; please "
+                         "remove all but one") % mqtt_test_dir)
     else:
         return jars[0]
 
@@ -1012,8 +1110,12 @@ def search_kinesis_asl_assembly_jar():
 if __name__ == "__main__":
     kafka_assembly_jar = search_kafka_assembly_jar()
     flume_assembly_jar = search_flume_assembly_jar()
+    mqtt_assembly_jar = search_mqtt_assembly_jar()
+    mqtt_test_jar = search_mqtt_test_jar()
     kinesis_asl_assembly_jar = search_kinesis_asl_assembly_jar()
-    jars = "%s,%s,%s" % (kafka_assembly_jar, flume_assembly_jar, kinesis_asl_assembly_jar)
+
+    jars = "%s,%s,%s,%s,%s" % (kafka_assembly_jar, flume_assembly_jar, kinesis_asl_assembly_jar,
+                               mqtt_assembly_jar, mqtt_test_jar)
 
     os.environ["PYSPARK_SUBMIT_ARGS"] = "--jars %s pyspark-shell" % jars
     unittest.main()