com.github.sakserv.storm.bolt.MongoBolt.java Source code

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Here is the source code for com.github.sakserv.storm.bolt.MongoBolt.java

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/*
 *  Licensed 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.github.sakserv.storm.bolt;

import backtype.storm.task.OutputCollector;
import backtype.storm.task.TopologyContext;
import backtype.storm.topology.base.BaseRichBolt;
import backtype.storm.tuple.Tuple;
import com.mongodb.*;

import java.util.Map;

/**
 * A Bolt for recording input tuples to Mongo. Subclasses are expected to
 * provide the logic behind mapping input tuples to Mongo objects.
 *
 * @todo Provide optional batching of calls.
 *
 * @author Adrian Petrescu <apetresc@gmail.com>
 *
 */
public abstract class MongoBolt extends BaseRichBolt {
    private OutputCollector collector;
    private DB mongoDB;

    private final String mongoHost;
    private final int mongoPort;
    private final String mongoDbName;

    /**
     * @param mongoHost The host on which Mongo is running.
     * @param mongoPort The port on which Mongo is running.
     * @param mongoDbName The Mongo database containing all collections being
     * written to.
     */
    protected MongoBolt(String mongoHost, int mongoPort, String mongoDbName) {
        this.mongoHost = mongoHost;
        this.mongoPort = mongoPort;
        this.mongoDbName = mongoDbName;
    }

    @Override
    public void prepare(@SuppressWarnings("rawtypes") Map stormConf, TopologyContext context,
            OutputCollector collector) {

        this.collector = collector;
        try {
            this.mongoDB = new MongoClient(mongoHost, mongoPort).getDB(mongoDbName);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void execute(Tuple input) {
        if (shouldActOnInput(input)) {
            String collectionName = getMongoCollectionForInput(input);
            DBObject dbObject = getDBObjectForInput(input);
            if (dbObject != null) {
                try {
                    mongoDB.getCollection(collectionName).save(dbObject, new WriteConcern(1));
                    collector.ack(input);
                } catch (MongoException me) {
                    collector.fail(input);
                }
            }
        } else {
            collector.ack(input);
        }
    }

    /**
     * Decide whether or not this input tuple should trigger a Mongo write.
     *
     * @param input the input tuple under consideration
     * @return {@code true} iff this input tuple should trigger a Mongo write
     */
    public abstract boolean shouldActOnInput(Tuple input);

    /**
     * Returns the Mongo collection which the input tuple should be written to.
     *
     * @param input the input tuple under consideration
     * @return the Mongo collection which the input tuple should be written to
     */
    public abstract String getMongoCollectionForInput(Tuple input);

    /**
     * Returns the DBObject to store in Mongo for the specified input tuple.
     *
     * @param input the input tuple under consideration
     * @return the DBObject to be written to Mongo
     */
    public abstract DBObject getDBObjectForInput(Tuple input);

    @Override
    public void cleanup() {
        this.mongoDB.getMongo().close();
    }

}