text: # 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.
  
  import os
  
  from py4j.java_gateway import JavaGateway, GatewayClient
  from pyspark.conf import SparkConf
  from pyspark.context import SparkContext
  from pyspark.sql import SparkSession
  
  # use jvm gateway to create a java class instance by full-qualified class name
  def _getjvm_class(gateway, fullClassName):
      return gateway.jvm.java.lang.Thread.currentThread().getContextClassLoader().loadClass(fullClassName).newInstance()
  
  
  class Context(object):
  
      def __init__(self):
          from py4j.java_gateway import java_import
          """When running a Python script from Scala - this function is called
          by the script to initialize the connection to the Java Gateway and get the spark context.
          code is basically copied from: 
          https://github.com/apache/zeppelin/blob/master/spark/interpreter/src/main/resources/python/zeppelin_pyspark.py#L30
          """
  
          if os.environ.get("SPARK_EXECUTOR_URI"):
              SparkContext.setSystemProperty("spark.executor.uri", os.environ["SPARK_EXECUTOR_URI"])
  
          gateway = JavaGateway(GatewayClient(port=int(os.environ.get("PYSPARK_GATEWAY_PORT"))), auto_convert=True)
          java_import(gateway.jvm, "org.apache.spark.SparkEnv")
          java_import(gateway.jvm, "org.apache.spark.SparkConf")
          java_import(gateway.jvm, "org.apache.spark.api.java.*")
          java_import(gateway.jvm, "org.apache.spark.api.python.*")
          java_import(gateway.jvm, "org.apache.spark.mllib.api.python.*")
          java_import(gateway.jvm, "org.apache.spark.sql.*")
          java_import(gateway.jvm, "org.apache.spark.sql.hive.*")
  
          intp = gateway.entry_point
  
          jSparkSession = intp.pyGetSparkSession()
          jsc = intp.pyGetJSparkContext(jSparkSession)
          jconf = intp.pyGetSparkConf(jsc)
          conf = SparkConf(_jvm = gateway.jvm, _jconf = jconf)
          self.sc = SparkContext(jsc=jsc, gateway=gateway, conf=conf)
  
          # Spark 2
          self.sparkSession = SparkSession(self.sc, jSparkSession)
          self.sqlContext = self.sparkSession._wrapped
  
  ctx = None
  
  
  def get_contexts():
      global ctx
      if not ctx:
          ctx = Context()
  
      return ctx.sc, ctx.sqlContext, ctx.sparkSession
  