storm的可靠性

消息确认机制：

在数据发送的过程中可能会数据丢失导致没能接收到，spout有个超时时间（默认是30S），如果30S过去了还是没有接收到数据，也认为是处理失败。

运行结果都是处理成功

参考代码StormTopologyAcker.java

package yehua.storm;

import java.util.Map;

import org.apache.storm.Config;
import org.apache.storm.LocalCluster;
import org.apache.storm.StormSubmitter;
import org.apache.storm.generated.AlreadyAliveException;
import org.apache.storm.generated.AuthorizationException;
import org.apache.storm.generated.InvalidTopologyException;
import org.apache.storm.spout.SpoutOutputCollector;
import org.apache.storm.task.OutputCollector;
import org.apache.storm.task.TopologyContext;
import org.apache.storm.topology.OutputFieldsDeclarer;
import org.apache.storm.topology.TopologyBuilder;
import org.apache.storm.topology.base.BaseRichBolt;
import org.apache.storm.topology.base.BaseRichSpout;
import org.apache.storm.tuple.Fields;
import org.apache.storm.tuple.Tuple;
import org.apache.storm.tuple.Values;
import org.apache.storm.utils.Utils;

public class StormTopologyAcker {

    public static class MySpout extends BaseRichSpout{
        private Map conf;
        private TopologyContext context;
        private SpoutOutputCollector collector;
        @Override
        public void open(Map conf, TopologyContext context,
                SpoutOutputCollector collector) {
            this.conf = conf;
            this.collector = collector;
            this.context = context;
        }

        int num = 0;
        @Override
        public void nextTuple() {
            num++;
            System.out.println("spout:"+num);
            int messageid = num;
            //开启消息确认机制，就是在发送数据的时候发送一个messageid，一般情况下，messageid可以理解为mysql数据里面的主键id字段
            //要保证messageid和tuple之间有一个唯一的对应关系，这个关系需要程序员自己维护
            this.collector.emit(new Values(num),messageid);
            Utils.sleep(1000);
        }

        @Override
        public void declareOutputFields(OutputFieldsDeclarer declarer) {
            declarer.declare(new Fields("num"));
        }

        @Override
        public void ack(Object msgId) {
            System.out.println("处理成功！"+msgId);
        }

        @Override
        public void fail(Object msgId) {
            System.out.println("处理失败！"+msgId);
            //TODO  可以吧这个数据单独记录下来
        }

    }

    public static class MyBolt extends BaseRichBolt{

        private Map stormConf;
        private TopologyContext context;
        private OutputCollector collector;
        @Override
        public void prepare(Map stormConf, TopologyContext context,
                OutputCollector collector) {
            this.stormConf = stormConf;
            this.context = context;
            this.collector = collector;
        }

        int sum = 0;
        @Override
        public void execute(Tuple input) {
            try{
                Integer num = input.getIntegerByField("num");
                sum += num;
                System.out.println("sum="+sum);
                this.collector.ack(input);
            }catch(Exception e){
                this.collector.fail(input);
            }
        }

        @Override
        public void declareOutputFields(OutputFieldsDeclarer declarer) {

        }

    }

    public static void main(String[] args) {
        TopologyBuilder topologyBuilder = new TopologyBuilder();
        String spout_id = MySpout.class.getSimpleName();
        String bolt_id = MyBolt.class.getSimpleName();

        topologyBuilder.setSpout(spout_id, new MySpout());
        topologyBuilder.setBolt(bolt_id, new MyBolt()).shuffleGrouping(spout_id);

        Config config = new Config();
        config.setMaxSpoutPending(1000);//如果设置了这个参数，必须要保证开启了acker机制才有效
        String topology_name = StormTopologyAcker.class.getSimpleName();
        if(args.length==0){
            //在本地运行
            LocalCluster localCluster = new LocalCluster();
            localCluster.submitTopology(topology_name, config, topologyBuilder.createTopology());
        }else{
            //在集群运行
            try {
                StormSubmitter.submitTopology(topology_name, config, topologyBuilder.createTopology());
            } catch (AlreadyAliveException e) {
                e.printStackTrace();
            } catch (InvalidTopologyException e) {
                e.printStackTrace();
            } catch (AuthorizationException e) {
                e.printStackTrace();
            }
        }

    }

}