Storm处理Stream Join的简单实例

package com.wxt.storm.SingleJoinExample.bolt;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import backtype.storm.Config;
import backtype.storm.generated.GlobalStreamId;
import backtype.storm.task.OutputCollector;
import backtype.storm.task.TopologyContext;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.topology.base.BaseRichBolt;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Tuple;
import backtype.storm.utils.TimeCacheMap;
public class SimpleJoinBolt extends BaseRichBolt {
private OutputCollector _collector;
private Fields _outFields;
private Fields _idFields;
int _numSources;
Map<String,GlobalStreamId> _fieldLocations;
//在内存中保留近期活跃的对象
//由于bolt在接收两个数据源的流数据时，同一id两个数据流很可能不会再一个时间点同时发出，因此需要对数据流先进行缓存，直到所有
//id相同的数据源都被后被聚合处理，做完聚合处理后再将对应的tuple信息从缓存中删除。在
TimeCacheMap<List<Object>,Map<GlobalStreamId,Tuple>> _pending;
//传进的Fields是聚合后将被输出的字段
public SimpleJoinBolt(Fields outFields){
this._outFields=outFields;
}
public void execute(Tuple tuple) {
// TODO Auto-generated method stub
//从tuple中获取_idFields字段，如果不存在于等待被处理的队列_pending中，则加入一行
List<Object> id=tuple.select(_idFields);
GlobalStreamId streamId=new GlobalStreamId(tuple.getSourceComponent(),tuple.getSourceStreamId());
//打印当前处理元组的来源Spout
System.out.println("元组来源："+tuple.getSourceComponent());
//打印当前元组
System.out.println("接收的元组："+tuple.getFields().get(0)+" = "+tuple.getValues().get(0)+" , "+tuple.getFields().get(1)+" = "+tuple.getValues().get(1));
//如果当前pending中还不存在join key为此id的元组，则将该条记录加入
if(!_pending.containsKey(id)){
_pending.put(id, new HashMap<GlobalStreamId,Tuple>());
}
//从_pending队列中获取当前GlobalStreamId对应的HashMap对象
Map<GlobalStreamId,Tuple> parts=_pending.get(id);
//如果streamId已经包含其中，则抛出异常，接收到同一个spout中的两条一样id的tuple，否则将该streamId加入parts中
if(parts.containsKey(streamId)){
throw new RuntimeException("Received same side of single join twice");
}
parts.put(streamId, tuple);
//如果parts中已经包含了聚合数据源的个数，则从_pending队列中移除这条记录
if(parts.size()==_numSources){
_pending.remove(id);
List<Object> joinResult=new ArrayList<Object>();
for(String outField:_outFields){
GlobalStreamId loc=_fieldLocations.get(outField);
joinResult.add(parts.get(loc).getValueByField(outField));
}
//输出聚合结果
System.out.print("两条关系流中id值为"+id.get(0)+"的元组均已收到，聚合结果为：");
for(Object obj:joinResult){
System.out.print(obj+" ");
}
System.out.println();
//多锚定
_collector.emit(new ArrayList<Tuple>(parts.values()),joinResult);
for (Tuple part : parts.values()) {
_collector.ack(part);
}
}else{
System.out.println("只从一个关系流中收取到id值为"+id+"的元组，不可进行join操作");
}
}
public void prepare(Map conf, TopologyContext context, OutputCollector collector) {
// TODO Auto-generated method stub
_fieldLocations = new HashMap<String, GlobalStreamId>();
this._collector=collector;
//创建TimeCacheMap对象，设置超时回调接口，用于tuple处理失败时fail消息
int timeout=((Number)conf.get(Config.TOPOLOGY_MESSAGE_TIMEOUT_SECS)).intValue();
_pending=new TimeCacheMap<List<Object>,Map<GlobalStreamId,Tuple>>(timeout,new ExpireCallback());
//记录数据源的数据个数
_numSources=context.getThisSources().size();
Set<String> idFields=null;
//遍历TopologyContext中不同的数据源:genderSpout和ageSpout
System.out.println(context.getThisSources().keySet());
for(GlobalStreamId source:context.getThisSources().keySet()){
//得到公共的Fields字段id,保存到_idFields中
Fields fields=context.getComponentOutputFields(source.get_componentId(),source.get_streamId());
//fields:[id,gender],[id,age]
Set<String> setFields=new HashSet<String>(fields.toList());
if(idFields==null){
idFields=setFields;
}else{
//求交集
idFields.retainAll(setFields);
System.out.println(idFields);
}
//同时将_outFields中字段所在数据源记录下来，保存到一张HashMap _fieldLocations中，以便聚合后获取对应的字段值
for(String outfield:_outFields){
for(String sourcefield:fields){
if(outfield.equals(sourcefield)){
_fieldLocations.put(outfield, source);
}
}
}
//打印结果:gender=GlobalStreamId(componentId=gender-spout,streamId=default)
//age=GlobalStreamId(componentId=age-spout,streamId=default)
System.out.println(_fieldLocations);
}
_idFields=new Fields(new ArrayList<String>(idFields));
if(_fieldLocations.size()!=_outFields.size()){
throw new RuntimeException("Cannot find all outfields among sources");
}
}
public void declareOutputFields(OutputFieldsDeclarer declarer) {
// TODO Auto-generated method stub
declarer.declare(_outFields);
}
private class ExpireCallback implements TimeCacheMap.ExpiredCallback<List<Object>, Map<GlobalStreamId,Tuple>>{
public void expire(List<Object> key, Map<GlobalStreamId, Tuple> tuples) {
// TODO Auto-generated method stub
for(Tuple tuple:tuples.values()){
_collector.fail(tuple);
}
}
}
}

package com.wxt.storm.SingleJoinExample;
import com.wxt.storm.SingleJoinExample.bolt.SimpleJoinBolt;
import backtype.storm.Config;
import backtype.storm.LocalCluster;
import backtype.storm.testing.FeederSpout;
import backtype.storm.topology.TopologyBuilder;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Values;
import backtype.storm.utils.Utils;
public class SingleJoinExample {
public static void main(String[] args) {
FeederSpout genderSpout = new FeederSpout(new Fields("id", "gender"));
FeederSpout ageSpout = new FeederSpout(new Fields("id", "age"));
TopologyBuilder builder = new TopologyBuilder();
builder.setSpout(CommonKeys.GENDER_SPOUT, genderSpout);
builder.setSpout(CommonKeys.AGE_SPOUT, ageSpout);
builder.setBolt(CommonKeys.JOIN_BOLT, new SimpleJoinBolt(new Fields("gender", "age"))).fieldsGrouping(CommonKeys.GENDER_SPOUT, new Fields("id"))
.fieldsGrouping(CommonKeys.AGE_SPOUT, new Fields("id"));
Config conf = new Config();
conf.setDebug(true);
LocalCluster cluster = new LocalCluster();
cluster.submitTopology(CommonKeys.JOIN_TOPOLOGY, conf, builder.createTopology());
for (int i = 0; i < 10; i++) {
String gender;
if (i % 2 == 0) {
gender = "male";
}
else {
gender = "female";
}
genderSpout.feed(new Values(i, gender));
}
for (int i = 9; i >= 0; i--) {
ageSpout.feed(new Values(i, i + 20));
}
Utils.sleep(2000);
cluster.shutdown();
}
}