storm-client/src/jvm/org/apache/storm/trident/planner/processor/PartitionPersistProcessor.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.trident.planner.processor;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.apache.storm.task.TopologyContext;
import org.apache.storm.trident.operation.TridentOperationContext;
import org.apache.storm.trident.planner.ProcessorContext;
import org.apache.storm.trident.planner.TridentProcessor;
import org.apache.storm.trident.state.State;
import org.apache.storm.trident.state.StateUpdater;
import org.apache.storm.trident.topology.TransactionAttempt;
import org.apache.storm.trident.tuple.TridentTuple;
import org.apache.storm.trident.tuple.TridentTuple.Factory;
import org.apache.storm.trident.tuple.TridentTupleView.ProjectionFactory;
import org.apache.storm.tuple.Fields;


public class PartitionPersistProcessor implements TridentProcessor {
    StateUpdater updater;
    State state;
    String stateId;
    TridentContext context;
    Fields inputFields;
    ProjectionFactory projection;
    FreshCollector collector;

    public PartitionPersistProcessor(String stateId, Fields inputFields, StateUpdater updater) {
        this.updater = updater;
        this.stateId = stateId;
        this.inputFields = inputFields;
    }

    @Override
    public void prepare(Map<String, Object> conf, TopologyContext context, TridentContext tridentContext) {
        List<Factory> parents = tridentContext.getParentTupleFactories();
        if (parents.size() != 1) {
            throw new RuntimeException("Partition persist operation can only have one parent");
        }
        this.context = tridentContext;
        state = (State) context.getTaskData(stateId);
        projection = new ProjectionFactory(parents.get(0), inputFields);
        collector = new FreshCollector(tridentContext);
        updater.prepare(conf, new TridentOperationContext(context, projection));
    }

    @Override
    public void cleanup() {
        updater.cleanup();
    }

    @Override
    public void startBatch(ProcessorContext processorContext) {
        processorContext.state[context.getStateIndex()] = new ArrayList<TridentTuple>();
    }

    @Override
    public void execute(ProcessorContext processorContext, String streamId, TridentTuple tuple) {
        ((List) processorContext.state[context.getStateIndex()]).add(projection.create(tuple));
    }

    @Override
    public void flush() {
        // NO-OP
    }

    @Override
    public void finishBatch(ProcessorContext processorContext) {
        collector.setContext(processorContext);
        Object batchId = processorContext.batchId;
        // since this processor type is a committer, this occurs in the commit phase
        List<TridentTuple> buffer = (List) processorContext.state[context.getStateIndex()];

        // don't update unless there are tuples
        // this helps out with things like global partition persist, where multiple tasks may still
        // exist for this processor. Only want the global one to do anything
        // this is also a helpful optimization that state implementations don't need to manually do
        if (buffer.size() > 0) {
            Long txid = null;
            // this is to support things like persisting off of drpc stream, which is inherently unreliable
            // and won't have a tx attempt
            if (batchId instanceof TransactionAttempt) {
                txid = ((TransactionAttempt) batchId).getTransactionId();
            }
            state.beginCommit(txid);
            updater.updateState(state, buffer, collector);
            state.commit(txid);
        }
    }

    @Override
    public Factory getOutputFactory() {
        return collector.getOutputFactory();
    }
}