spark streaming fileStream

Question

I'm programming with spark streaming but have some trouble with scala. I'm trying to use the function StreamingContext.fileStream

The definition of this function is like this:

def fileStream[K, V, F <: InputFormat[K, V]](directory: String)(implicit arg0: ClassManifest[K], arg1: ClassManifest[V], arg2: ClassManifest[F]): DStream[(K, V)]

Create a input stream that monitors a Hadoop-compatible filesystem for new files and reads them using the given key-value types and input format. File names starting with . are ignored. K Key type for reading HDFS file V Value type for reading HDFS file F Input format for reading HDFS file directory HDFS directory to monitor for new file

I don't know how to pass the type of Key and Value. My Code in spark streaming:

val ssc = new StreamingContext(args(0), "StreamingReceiver", Seconds(1),
  System.getenv("SPARK_HOME"), Seq("/home/mesos/StreamingReceiver.jar"))

// Create a NetworkInputDStream on target ip:port and count the
val lines = ssc.fileStream("/home/sequenceFile")

Java code to write the hadoop file:

public class MyDriver {

private static final String[] DATA = { "One, two, buckle my shoe",
        "Three, four, shut the door", "Five, six, pick up sticks",
        "Seven, eight, lay them straight", "Nine, ten, a big fat hen" };

public static void main(String[] args) throws IOException {
    String uri = args[0];
    Configuration conf = new Configuration();
    FileSystem fs = FileSystem.get(URI.create(uri), conf);
    Path path = new Path(uri);
    IntWritable key = new IntWritable();
    Text value = new Text();
    SequenceFile.Writer writer = null;
    try {
        writer = SequenceFile.createWriter(fs, conf, path, key.getClass(),
                value.getClass());
        for (int i = 0; i < 100; i++) {
            key.set(100 - i);
            value.set(DATA[i % DATA.length]);
            System.out.printf("[%s]\t%s\t%s\n", writer.getLength(), key,
                    value);
            writer.append(key, value);
        }
    } finally {
        IOUtils.closeStream(writer);
    }
}

}

Answer 1

If you want to use fileStream , you're going to have to supply all 3 type params to it when calling it. You need to know what your Key , Value and InputFormat types are before calling it. If your types were LongWritable , Text and TextInputFormat , you would call fileStream like so:

val lines = ssc.fileStream[LongWritable, Text, TextInputFormat]("/home/sequenceFile")

If those 3 types do happen to be your types, then you might want to use textFileStream instead as it does not require any type params and delegates to fileStream using those 3 types I mentioned. Using that would look like this:

val lines = ssc.textFileStream("/home/sequenceFile")

Answer 2

val filterF = new Function[Path, Boolean] {
    def apply(x: Path): Boolean = {
      val flag = if(x.toString.split("/").last.split("_").last.toLong < System.currentTimeMillis) true else false
      return flag
    }
}

val streamed_rdd = ssc.fileStream[LongWritable, Text, TextInputFormat]("/user/hdpprod/temp/spark_streaming_input",filterF,false).map(_._2.toString).map(u => u.split('\t'))