Storm---DirectGroup(直接分组)

以单词分割计数为例实现Storm的DirectGroup分组：

1、Spout实现

Spout是Storm数据源头，使用DirectGroup方式将Spout数据发送指定的Bolt，需注意：

1)、Spout消费的Bolt的Task(Task应为Storm的Executor的编号)，在如下代码中Spout.open()初始化中拿到消费Task

2）、需使用SpoutOutputCollector.emitDirect()方法

3）、将Spout声明为直接流，即在Spout.declareOutputFields()声明

/**
 * Fixed Cycle Spout
 *
 * @author hanhan.zhang
 * */
public class FixedCycleSpout implements IRichSpout {

    private String _fieldName;

    private boolean _direct;

    // stream mark
    private String _streamId;

    private int _index;

    // key = msgId, value = sending tuple
    private Map<String, List<Object>> _pendingTuple;

    // send tuple
    private List<Object> [] _sendTuple;

    private SpoutOutputCollector _collector;
    private CountMetric _sendMetric;
    private CountMetric _failMetric;

    // consume task set
    private List<Integer> _consumeTaskIdList;

    public FixedCycleSpout(String _streamId, String _fieldName, boolean _direct, List<Object> ... _sendTuple) {
        this._streamId = _streamId;
        this._fieldName = _fieldName;
        this._direct = _direct;
        this._sendTuple = _sendTuple;
    }

    @Override
    public void open(Map conf, TopologyContext context, SpoutOutputCollector collector) {
        this._index = 0;
        _pendingTuple = Maps.newHashMap();

        // register metric
        this._sendMetric = context.registerMetric("cycle.spout.send.tuple.metric", new CountMetric(), 60);
        this._failMetric = context.registerMetric("cycle.spout.fail.tuple.metric", new CountMetric(), 60);
        this._collector = collector;

        // get consume task id
        if (this._direct) {
            this._consumeTaskIdList = Lists.newLinkedList();
            Map<String, Map<String, Grouping>> consumeTargets = context.getThisTargets();
            if (consumeTargets != null && !consumeTargets.isEmpty()) {
                // streamId = this._streamId
                consumeTargets.forEach((streamId, target) -> {
                    if (target != null && !target.isEmpty()) {
                        // componentId = consume target component Id
                        target.forEach((componentId, group) -> {
                            if (group.is_set_direct()) {
                                this._consumeTaskIdList.addAll(context.getComponentTasks(componentId));
                            }
                        });
                    }
                });
            }
        }
    }

    @Override
    public void close() {

    }

    @Override
    public void activate() {

    }

    @Override
    public void deactivate() {

    }

    @Override
    public void nextTuple() {
        this._sendMetric.incr();
        if (this._index == _sendTuple.length) {
            this._index = 0;
        }
        String msgId = UUID.randomUUID().toString();
        List<Object> tuple = this._sendTuple[this._index++];
        sendTuple(msgId, tuple);
    }

    @Override
    public void ack(Object msgId) {
        String msgIdStr = (String) msgId;
        System.out.println("ack tuple with msgId " + msgIdStr);
        this._pendingTuple.remove(msgIdStr);
    }

    @Override
    public void fail(Object msgId) {
        this._failMetric.incr();
        String msgIdStr = (String) msgId;
        System.out.println("fail tuple with msgId " + msgIdStr);
        sendTuple(msgIdStr, this._pendingTuple.get(msgIdStr));
    }

    @Override
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        declarer.declareStream(this._streamId, this._direct, new Fields(_fieldName));
    }

    @Override
    public Map<String, Object> getComponentConfiguration() {
        return null;
    }

    protected void sendTuple(String msgId, List<Object> tuple) {
        this._pendingTuple.put(msgId, tuple);
        if (this._direct) {
            if (this._consumeTaskIdList == null || this._consumeTaskIdList.isEmpty()) {
                throw new IllegalStateException("direct task is empty !");
            }
            this._consumeTaskIdList.forEach(taskId ->
                    this._collector.emitDirect(taskId, this._streamId, tuple, msgId));
        } else {
            this._collector.emit(tuple, msgId);
        }
    }
}

2、Bolt实现

/**
 * Sentence Split Bolt
 *
 * @author hanhan.zhang
 * */
public class SentenceSplitBolt implements IRichBolt {

    private OutputCollector _collector;

    private CountMetric _ackMetric;

    private CountMetric _failMetric;

    private String _separator;

    private int _taskId;

    private boolean _direct;

    private String _streamId;

    public SentenceSplitBolt(String _streamId, boolean _direct) {
        this._streamId = _streamId;
        this._direct = _direct;
    }

    /**
     * @param context
     *          1: Register Metric
     *          2: Next Bolt Message
     * @param collector (thread-safe)
     *          1: Emit Tuple
     *          2: Ack/Fail Tuple
     * */
    public void prepare(Map stormConf, TopologyContext context, OutputCollector collector) {
        this._collector = collector;
        // register metric for monitor
        this._ackMetric = context.registerMetric("sentence.split.ack.metric", new CountMetric(), 60);
        this._failMetric = context.registerMetric("sentence.split.fail.metric", new CountMetric(), 60);
        this._taskId = context.getThisTaskId();

        this._separator = (String) stormConf.get(Const.SEPARATOR);
    }

    @Override
    public void execute(Tuple input) {
        try {
            String sentence = input.getString(0);
            if (Strings.isNullOrEmpty(sentence)) {
                return;
            }
            String []fields = sentence.split(_separator);
            for (String field : fields) {
                if (this._direct) {
                    this._collector.emitDirect(this._taskId, _streamId, input, new Values(field, 1));
                } else {
                    this._collector.emit(this._streamId, input, new Values(field, 1));
                }
            }
            this._collector.ack(input);
            this._ackMetric.incr();
        } catch (Exception e) {
            this._collector.fail(input);
            this._failMetric.incr();
        }
    }

    @Override
    public void cleanup() {

    }

    @Override
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        declarer.declareStream(this._streamId, this._direct, new Fields("word", "count"));
    }

    @Override
    public Map<String, Object> getComponentConfiguration() {
        return null;
    }
}

/**
 * Word Sum Bolt
 *
 * @author hanhan.zhang
 * */
public class WordSumBolt extends BaseRichBolt {

    private OutputCollector _collector;

    private int _taskId;

    private Cache<String, AtomicInteger> _wordCache;

    @Override
    public void prepare(Map stormConf, TopologyContext context, OutputCollector collector) {
        this._collector = collector;
        this._taskId = context.getThisTaskId();
        this._wordCache = CacheBuilder.newBuilder()
                                        .maximumSize(1024)
                                        .expireAfterWrite(3, TimeUnit.SECONDS)
                                        .removalListener((removalNotification) -> {
                                            String key = (String) removalNotification.getKey();
                                            AtomicInteger sum = (AtomicInteger) removalNotification.getValue();
                                            System.out.println("word sum result : [" + key + "," + sum.get() + "]");
                                        })
                                        .build();
    }

    @Override
    public void execute(Tuple input) {
        try {
            String word = input.getString(0);
            int count = input.getInteger(1);
            if (Strings.isEmpty(word)) {
                return;
            }
            AtomicInteger counter = this._wordCache.getIfPresent(word);
            if (counter == null) {
                this._wordCache.put(word, new AtomicInteger(count));
            } else {
                counter.addAndGet(count);
            }
            this._collector.ack(input);
        } catch (Exception e) {
            this._collector.fail(input);
        }
    }

    @Override
    public void declareOutputFields(OutputFieldsDeclarer declarer) {

    }
}

3、Storm运行

/**
 * Tuple Split-Flow Topology
 *
 * @author hanhan.zhang
 * */
public class FlowTopology {

    public static void main(String[] args) {

        // send tuple
        List<Object> []tuple = new List[] {new Values("the cow jumped over the moon"),
                                            new Values("the man went to the store and bought some candy"),
                                            new Values("four score and seven years ago"),
                                            new Values("how many apples can you eat")};

        //stream name
        String spoutStreamId = "topology.flow.cycle.spout.stream";
        String splitStreamId = "topology.flow.split.bolt.stream";

        // spout
        FixedCycleSpout cycleSpout = new FixedCycleSpout(spoutStreamId, "sentence", true, tuple);

        // bolt
        SentenceSplitBolt splitBolt = new SentenceSplitBolt(splitStreamId, false);
        WordSumBolt sumBolt = new WordSumBolt();

        TopologyBuilder topologyBuilder = new TopologyBuilder();
        topologyBuilder.setSpout ("sentence.cycle.spout", cycleSpout, 1);

        topologyBuilder.setBolt("sentence.split.bolt", splitBolt, 1)
                        .directGrouping("sentence.cycle.spout", spoutStreamId);

        topologyBuilder.setBolt("word.sum.bolt", sumBolt, 3)
                        .fieldsGrouping("sentence.split.bolt", splitStreamId, new Fields("word"));

        Config config = new Config();
        config.put(Const.SEPARATOR, " ");

        LocalCluster localCluster = new LocalCluster();
        localCluster.submitTopology("flowTopology", config, topologyBuilder.createTopology());

    }

}