examples/storm-hdfs-examples/src/main/java/org/apache/storm/hdfs/trident/FixedBatchSpout.java

/*
 * 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.storm.hdfs.trident;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.storm.Config;
import org.apache.storm.task.TopologyContext;
import org.apache.storm.trident.operation.TridentCollector;
import org.apache.storm.trident.spout.IBatchSpout;
import org.apache.storm.tuple.Fields;

public class FixedBatchSpout implements IBatchSpout {

    Fields fields;
    List<Object>[] outputs;
    int maxBatchSize;
    HashMap<Long, List<List<Object>>> batches = new HashMap<Long, List<List<Object>>>();
    int index = 0;
    boolean cycle = false;

    public FixedBatchSpout(Fields fields, int maxBatchSize, List<Object>... outputs) {
        this.fields = fields;
        this.outputs = outputs;
        this.maxBatchSize = maxBatchSize;
    }

    public void setCycle(boolean cycle) {
        this.cycle = cycle;
    }

    @Override
    public void open(Map<String, Object> conf, TopologyContext context) {
        index = 0;
    }

    @Override
    public void emitBatch(long batchId, TridentCollector collector) {
        List<List<Object>> batch = this.batches.get(batchId);
        if (batch == null) {
            batch = new ArrayList<List<Object>>();
            if (index >= outputs.length && cycle) {
                index = 0;
            }
            for (int i = 0; i < maxBatchSize; index++, i++) {
                if (index == outputs.length) {
                    index = 0;
                }
                batch.add(outputs[index]);
            }
            this.batches.put(batchId, batch);
        }
        for (List<Object> list : batch) {
            collector.emit(list);
        }
    }

    @Override
    public void ack(long batchId) {
        this.batches.remove(batchId);
    }

    @Override
    public void close() {
    }

    @Override
    public Map<String, Object> getComponentConfiguration() {
        Config conf = new Config();
        conf.setMaxTaskParallelism(1);
        return conf;
    }

    @Override
    public Fields getOutputFields() {
        return fields;
    }
}