org.apache.metron.bolt.JoinBolt.java Source code

Introduction

Here is the source code for org.apache.metron.bolt.JoinBolt.java

Source

/**
 * 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 org.apache.metron.bolt;

import backtype.storm.task.OutputCollector;
import backtype.storm.task.TopologyContext;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Tuple;
import backtype.storm.tuple.Values;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.Sets;
import org.json.simple.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

public abstract class JoinBolt<V> extends ConfiguredBolt {

    private static final Logger LOG = LoggerFactory.getLogger(JoinBolt.class);
    protected OutputCollector collector;

    protected transient CacheLoader<String, Map<String, V>> loader;
    protected transient LoadingCache<String, Map<String, V>> cache;
    protected Long maxCacheSize;
    protected Long maxTimeRetain;

    public JoinBolt(String zookeeperUrl) {
        super(zookeeperUrl);
    }

    public JoinBolt withMaxCacheSize(long maxCacheSize) {
        this.maxCacheSize = maxCacheSize;
        return this;
    }

    public JoinBolt withMaxTimeRetain(long maxTimeRetain) {
        this.maxTimeRetain = maxTimeRetain;
        return this;
    }

    @Override
    public void prepare(Map map, TopologyContext topologyContext, OutputCollector outputCollector) {
        super.prepare(map, topologyContext, outputCollector);
        this.collector = outputCollector;
        if (this.maxCacheSize == null)
            throw new IllegalStateException("maxCacheSize must be specified");
        if (this.maxTimeRetain == null)
            throw new IllegalStateException("maxTimeRetain must be specified");
        loader = new CacheLoader<String, Map<String, V>>() {
            public Map<String, V> load(String key) throws Exception {
                return new HashMap<>();
            }
        };
        cache = CacheBuilder.newBuilder().maximumSize(maxCacheSize)
                .expireAfterWrite(maxTimeRetain, TimeUnit.MINUTES).build(loader);
        prepare(map, topologyContext);
    }

    @SuppressWarnings("unchecked")
    @Override
    public void execute(Tuple tuple) {
        String streamId = tuple.getSourceStreamId();
        String key = (String) tuple.getValueByField("key");
        V message = (V) tuple.getValueByField("message");
        try {
            Map<String, V> streamMessageMap = cache.get(key);
            if (streamMessageMap.containsKey(streamId)) {
                LOG.warn(String.format("Received key %s twice for " + "stream %s", key, streamId));
            }
            streamMessageMap.put(streamId, message);
            Set<String> streamIds = getStreamIds(message);
            Set<String> streamMessageKeys = streamMessageMap.keySet();
            if (streamMessageKeys.size() == streamIds.size()
                    && Sets.symmetricDifference(streamMessageKeys, streamIds).isEmpty()) {
                collector.emit("message", tuple, new Values(key, joinMessages(streamMessageMap)));
                collector.ack(tuple);
                cache.invalidate(key);
            } else {
                cache.put(key, streamMessageMap);
            }
        } catch (ExecutionException e) {
            collector.reportError(e);
            LOG.error(e.getMessage(), e);
        }
    }

    @Override
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        declarer.declareStream("message", new Fields("key", "message"));
    }

    public abstract void prepare(Map map, TopologyContext topologyContext);

    public abstract Set<String> getStreamIds(V value);

    public abstract V joinMessages(Map<String, V> streamMessageMap);
}