jstorm源码之PartitionedTridentSpoutExecutor

一、作用
    Partition Spout对应的executor
二、源码分析
package storm.trident.spout;

import backtype.storm.task.TopologyContext;
import backtype.storm.tuple.Fields;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import storm.trident.operation.TridentCollector;
import storm.trident.topology.TransactionAttempt;
import storm.trident.topology.state.RotatingTransactionalState;
import storm.trident.topology.state.TransactionalState;

// PartitionedTridentSpout的执行器
public class PartitionedTridentSpoutExecutor implements ITridentSpout<Integer> {
     // 内置一个spout对象 
    IPartitionedTridentSpout _spout;

    public PartitionedTridentSpoutExecutor(IPartitionedTridentSpout spout) {
        _spout = spout;
    }

    public IPartitionedTridentSpout getPartitionedSpout() {
        return _spout;
    }

    // 
    class Coordinator implements ITridentSpout.BatchCoordinator<Object> {
       // 协调器
        private IPartitionedTridentSpout.Coordinator _coordinator;

        public Coordinator(Map conf, TopologyContext context) {
            _coordinator = _spout.getCoordinator(conf, context);
        }

        //  若是当前的metadata为空则直接返回batch的partitions
        // 否则返回当前的metadata
        @Override
        public Object initializeTransaction(long txid, Object prevMetadata, Object currMetadata) {
            if (currMetadata != null) {
                return currMetadata;
            } else {
                return _coordinator.getPartitionsForBatch();
            }
        }

        // 关闭协调器
        @Override
        public void close() {
            _coordinator.close();
        }
        //  协调成功操作
        @Override
        public void success(long txid) {
        }
         //  指定的事务是否准备ok
        @Override
        public boolean isReady(long txid) {
            return _coordinator.isReady(txid);
        }
    }
     // 静态内部类 emit的状态类
    static class EmitterPartitionState {
        // transaction state
        public RotatingTransactionalState rotatingState;
        //  spout partiton
        public ISpoutPartition partition;

        public EmitterPartitionState(RotatingTransactionalState s, ISpoutPartition p) {
            rotatingState = s;
            partition = p;
        }
    }
   // emit的操作
    class Emitter implements ITridentSpout.Emitter<Object> {
         // emit
        private IPartitionedTridentSpout.Emitter _emitter;
         // 事务
        private TransactionalState _state;
        // partition transaction state
        private Map<String, EmitterPartitionState> _partitionStates = new HashMap<String, EmitterPartitionState>();
        // emit索引
        private int _index;
        //  task 的总数
        private int _numTasks;

        public Emitter(String txStateId, Map conf, TopologyContext context) {
            _emitter = _spout.getEmitter(conf, context);
            _state = TransactionalState.newUserState(conf, txStateId);
            _index = context.getThisTaskIndex();
            _numTasks = context.getComponentTasks(context.getThisComponentId()).size();
        }
        //  记录coordinator的meta data
        Object _savedCoordinatorMeta = null;

         //  若是本地缓存的coordinator的meta数据为空或者和指定coordinatorMeta不同 则直接重新获取partitions
         //  同时清空原有的partition state
         //  根据原有的索引 遍历partitions  ： 1、本地缓存  2、refresh partitions 3、更新本地coordinator
        @Override
        public void emitBatch(final TransactionAttempt tx, final Object coordinatorMeta, final TridentCollector collector) {
            if (_savedCoordinatorMeta == null || !_savedCoordinatorMeta.equals(coordinatorMeta)) {
                List<ISpoutPartition> partitions = _emitter.getOrderedPartitions(coordinatorMeta);
                _partitionStates.clear();
                List<ISpoutPartition> myPartitions = new ArrayList();
                for (int i = _index; i < partitions.size(); i += _numTasks) {
                    ISpoutPartition p = partitions.get(i);
                    String id = p.getId();
                    myPartitions.add(p);
                    _partitionStates.put(id, new EmitterPartitionState(new RotatingTransactionalState(_state, id), p));
                }
                _emitter.refreshPartitions(myPartitions);
                _savedCoordinatorMeta = coordinatorMeta;
            }
            for (EmitterPartitionState s : _partitionStates.values()) {
                RotatingTransactionalState state = s.rotatingState;
                final ISpoutPartition partition = s.partition;
                Object meta = state.getStateOrCreate(tx.getTransactionId(), new RotatingTransactionalState.StateInitializer() {
                    @Override
                    public Object init(long txid, Object lastState) {
                        return _emitter.emitPartitionBatchNew(tx, collector, partition, lastState);
                    }
                });
                // it's null if one of:
                // a) a later transaction batch was emitted before this, so we should skip this batch
                // b) if didn't exist and was created (in which case the StateInitializer was invoked and
                // it was emitted
                if (meta != null) {
                    _emitter.emitPartitionBatch(tx, collector, partition, meta);
                }
            }
        }
        //  提供成功的操作
        @Override
        public void success(TransactionAttempt tx) {
            for (EmitterPartitionState state : _partitionStates.values()) {
                state.rotatingState.cleanupBefore(tx.getTransactionId());
            }
        }
         //  关闭state 和 emit
        @Override
        public void close() {
            _state.close();
            _emitter.close();
        }
    }

    @Override
    public ITridentSpout.BatchCoordinator getCoordinator(String txStateId, Map conf, TopologyContext context) {
        return new Coordinator(conf, context);
    }

    @Override
    public ITridentSpout.Emitter getEmitter(String txStateId, Map conf, TopologyContext context) {
        return new Emitter(txStateId, conf, context);
    }

    @Override
    public Map<String, Object> getComponentConfiguration() {
        return _spout.getComponentConfiguration();
    }

    @Override
    public Fields getOutputFields() {
        return _spout.getOutputFields();
    }
}