[storm-user] Set spout Parallelism Hint for Trident topology

Hi Oleg,

I'm a total newbie when it comes to Trident, but the example below seems to
be doing what you ask for.
The line "Open MySpout instance" is printed 5 times whereas "Prepare Inc
instance" is printed 2 times, which means, I believe, that the 5 instances
of spout and 2 instances of bolt are created.

static class MySpout extends BaseRichSpout {
private SpoutOutputCollector collector;
@Override
public void declareOutputFields(OutputFieldsDeclarer
outputFieldsDeclarer) {
outputFieldsDeclarer.declare(new Fields("value"));
}

@Override
public void open(Map map, TopologyContext topologyContext,
SpoutOutputCollector spoutOutputCollector) {
this.collector = spoutOutputCollector;
System.out.println("Open MySpout instance");
}

@Override
public void nextTuple() {
Utils.sleep(1000);
collector.emit(new Values(1));
}
}

static class Inc implements Function {

@Override
public void execute(TridentTuple tuple, TridentCollector collector)
{
Integer x = tuple.getInteger(0);
collector.emit(new Values(x + 1));
}

@Override
public void prepare(Map map, TridentOperationContext
tridentOperationContext) {
System.out.println("Prepare Inc instance");
}

@Override
public void cleanup() {
}
}

public static void main(String[] args) {
TridentTopology topology = new TridentTopology();

topology.newStream("stream", new MySpout())
.parallelismHint(5)
.shuffle()
.each(new Fields("value"), new Inc(), new
Fields("incrementedValue"))
.parallelismHint(2);

LocalCluster cluster = new LocalCluster();
cluster.submitTopology("topology", new Config(), topology.build());

Utils.sleep(5000);
cluster.shutdown();
}

Thanks Gleb!
This approach works for me.

Yeah, Trident API quite poorly documented, so it's difficult sometimes
figure-out (without JavaDoc) how it should work.

------
Oleg M.