ReachTopology 1
/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.sxt.storm.drpc; import java.util.Arrays; 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.LocalCluster; import backtype.storm.LocalDRPC; import backtype.storm.StormSubmitter; import backtype.storm.coordination.BatchOutputCollector; import backtype.storm.drpc.LinearDRPCTopologyBuilder; import backtype.storm.task.TopologyContext; import backtype.storm.topology.BasicOutputCollector; import backtype.storm.topology.OutputFieldsDeclarer; import backtype.storm.topology.base.BaseBasicBolt; import backtype.storm.topology.base.BaseBatchBolt; import backtype.storm.tuple.Fields; import backtype.storm.tuple.Tuple; import backtype.storm.tuple.Values; /** * This is a good example of doing complex Distributed RPC on top of Storm. This * program creates a topology that can compute the reach for any URL on Twitter * in realtime by parallelizing the whole computation. * <p/> * Reach is the number of unique people exposed to a URL on Twitter. To compute * reach, you have to get all the people who tweeted the URL, get all the * followers of all those people, unique that set of followers, and then count * the unique set. It's an intense computation that can involve thousands of * database calls and tens of millions of follower records. * <p/> * This Storm topology does every piece of that computation in parallel, turning * what would be a computation that takes minutes on a single machine into one * that takes just a couple seconds. * <p/> * For the purposes of demonstration, this topology replaces the use of actual * DBs with in-memory hashmaps. * <p/> * See https://github.com/nathanmarz/storm/wiki/Distributed-RPC for more * information on Distributed RPC. */ public class ReachTopology { public static Map<String, List<String>> TWEETERS_DB = new HashMap<String, List<String>>() { { put("foo.com/blog/1", Arrays.asList("sally", "bob", "tim", "george", "nathan")); put("engineering.twitter.com/blog/5", Arrays.asList("adam", "david", "sally", "nathan")); put("tech.backtype.com/blog/123", Arrays.asList("tim", "mike", "john")); } }; public static Map<String, List<String>> FOLLOWERS_DB = new HashMap<String, List<String>>() { { put("sally", Arrays.asList("bob", "tim", "alice", "adam", "jim", "chris", "jai")); put("bob", Arrays.asList("sally", "nathan", "jim", "mary", "david", "vivian")); put("tim", Arrays.asList("alex")); put("nathan", Arrays.asList("sally", "bob", "adam", "harry", "chris", "vivian", "emily", "jordan")); put("adam", Arrays.asList("david", "carissa")); put("mike", Arrays.asList("john", "bob")); put("john", Arrays.asList("alice", "nathan", "jim", "mike", "bob")); } }; public static class GetTweeters extends BaseBasicBolt { @Override public void execute(Tuple tuple, BasicOutputCollector collector) { Object id = tuple.getValue(0); String url = tuple.getString(1); List<String> tweeters = TWEETERS_DB.get(url); if (tweeters != null) { for (String tweeter : tweeters) { collector.emit(new Values(id, tweeter)); } } } @Override public void declareOutputFields(OutputFieldsDeclarer declarer) { declarer.declare(new Fields("id", "tweeter")); } } public static class GetFollowers extends BaseBasicBolt { @Override public void execute(Tuple tuple, BasicOutputCollector collector) { Object id = tuple.getValue(0); String tweeter = tuple.getString(1); List<String> followers = FOLLOWERS_DB.get(tweeter); if (followers != null) { for (String follower : followers) { collector.emit(new Values(id, follower)); } } } @Override public void declareOutputFields(OutputFieldsDeclarer declarer) { declarer.declare(new Fields("id", "follower")); } } public static class PartialUniquer extends BaseBatchBolt { BatchOutputCollector _collector; Object _id; Set<String> _followers = new HashSet<String>(); @Override public void prepare(Map conf, TopologyContext context, BatchOutputCollector collector, Object id) { _collector = collector; _id = id; } @Override public void execute(Tuple tuple) { _followers.add(tuple.getString(1)); } @Override public void finishBatch() { _collector.emit(new Values(_id, _followers.size())); } @Override public void declareOutputFields(OutputFieldsDeclarer declarer) { declarer.declare(new Fields("id", "partial-count")); } } public static class CountAggregator extends BaseBatchBolt { BatchOutputCollector _collector; Object _id; int _count = 0; @Override public void prepare(Map conf, TopologyContext context, BatchOutputCollector collector, Object id) { _collector = collector; _id = id; } @Override public void execute(Tuple tuple) { _count += tuple.getInteger(1); } @Override public void finishBatch() { _collector.emit(new Values(_id, _count)); } @Override public void declareOutputFields(OutputFieldsDeclarer declarer) { declarer.declare(new Fields("id", "reach")); } } public static LinearDRPCTopologyBuilder construct() { LinearDRPCTopologyBuilder builder = new LinearDRPCTopologyBuilder("reach"); builder.addBolt(new GetTweeters(), 4); builder.addBolt(new GetFollowers(), 12).shuffleGrouping(); builder.addBolt(new PartialUniquer(), 6).fieldsGrouping(new Fields("id", "follower")); builder.addBolt(new CountAggregator(), 3).fieldsGrouping(new Fields("id")); return builder; } public static void main(String[] args) throws Exception { LinearDRPCTopologyBuilder builder = construct(); Config conf = new Config(); if (args == null || args.length == 0) { conf.setMaxTaskParallelism(3); LocalDRPC drpc = new LocalDRPC(); LocalCluster cluster = new LocalCluster(); cluster. ("reach-drpc", conf, builder.createLocalTopology(drpc)); String[] urlsToTry = new String[] { "foo.com/blog/1", "engineering.twitter.com/blog/5", "notaurl.com" }; for (String url : urlsToTry) { System.err.println("Reach of " + url + ": " + drpc.execute("reach", url)); } cluster.shutdown(); drpc.shutdown(); } else { conf.setNumWorkers(6); StormSubmitter.submitTopologyWithProgressBar(args[0], conf, builder.createRemoteTopology()); } } }