org.apache.storm.topology

## Class PersistentWindowedBoltExecutor<T extends State>

- java.lang.Object
- - org.apache.storm.topology.WindowedBoltExecutor
  - - org.apache.storm.topology.PersistentWindowedBoltExecutor<T>

- All Implemented Interfaces:
    Serializable, IBolt, IComponent, IRichBolt, IStatefulBolt<T>, IStatefulComponent<T>

      public class PersistentWindowedBoltExecutor<T extends State>
      extends WindowedBoltExecutor
      implements IStatefulBolt<T>

  Wraps a `IStatefulWindowedBolt` and handles the execution. Uses state and the underlying checkpointing mechanisms to save the tuples in window to state. The tuples are also kept in-memory by transparently caching the window partitions and checkpointing them as needed.

  See Also:
    Serialized Form

- - ### Field Summary

    - ### Fields inherited from class org.apache.storm.topology.WindowedBoltExecutor

      `LATE_TUPLE_FIELD`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `PersistentWindowedBoltExecutor(IStatefulWindowedBolt<T> bolt)`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `execute(Tuple input)` Process a single tuple of input.
    `void` | `initState(T state)` This method is invoked by the framework with the previously saved state of the component.
    `protected WindowLifecycleListener<Tuple>` | `newWindowLifecycleListener()`
    `void` | `preCommit(long txid)` This is a hook for the component to perform some actions just before the framework commits its state.
    `void` | `prepare(Map<String,Object> topoConf, TopologyContext context, OutputCollector collector)` Called when a task for this component is initialized within a worker on the cluster.
    `void` | `prePrepare(long txid)` This is a hook for the component to perform some actions just before the framework prepares its state.
    `void` | `preRollback()` This is a hook for the component to perform some actions just before the framework rolls back the prepared state.
    `protected void` | `start()` Start the trigger policy and waterMarkEventGenerator if set.
    `protected void` | `validate(Map<String,Object> topoConf, BaseWindowedBolt.Count windowLengthCount, BaseWindowedBolt.Duration windowLengthDuration, BaseWindowedBolt.Count slidingIntervalCount, BaseWindowedBolt.Duration slidingIntervalDuration)`

    - ### Methods inherited from class org.apache.storm.topology.WindowedBoltExecutor

      `boltExecute, boltExecute, cleanup, declareOutputFields, doPrepare, getComponentConfiguration, getState, getTopologyTimeoutMillis, restoreState`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

    - ### Methods inherited from interface org.apache.storm.topology.IStatefulBolt

      `cleanup`

    - ### Methods inherited from interface org.apache.storm.topology.IComponent

      `declareOutputFields, getComponentConfiguration`

- - ### Constructor Detail

    - #### PersistentWindowedBoltExecutor

          public PersistentWindowedBoltExecutor(IStatefulWindowedBolt<T> bolt)

  - ### Method Detail

    - #### prepare

          public void prepare(Map<String,Object> topoConf,
                              TopologyContext context,
                              OutputCollector collector)

      Description copied from interface: `IBolt`

      Called when a task for this component is initialized within a worker on the cluster. It provides the bolt with the environment in which the bolt executes.

      This includes the:

      Specified by:
        `prepare` in interface `IBolt`
      Specified by:
        `prepare` in interface `IStatefulBolt<T extends State>`
      Overrides:
        `prepare` in class `WindowedBoltExecutor`
      Parameters:
        `topoConf` - The Storm configuration for this bolt. This is the configuration provided to the topology merged in with cluster configuration on this machine.
        `context` - This object can be used to get information about this task’s place within the topology, including the task id and component id of this task, input and output information, etc.
        `collector` - The collector is used to emit tuples from this bolt. Tuples can be emitted at any time, including the prepare and cleanup methods. The collector is thread-safe and should be saved as an instance variable of this bolt object.
      See Also:
        `IBolt.prepare(Map, TopologyContext, OutputCollector)`

    - #### validate

          protected void validate(Map<String,Object> topoConf,
                                  BaseWindowedBolt.Count windowLengthCount,
                                  BaseWindowedBolt.Duration windowLengthDuration,
                                  BaseWindowedBolt.Count slidingIntervalCount,
                                  BaseWindowedBolt.Duration slidingIntervalDuration)

      Overrides:
        `validate` in class `WindowedBoltExecutor`

    - #### start

          protected void start()

      Description copied from class: `WindowedBoltExecutor`

      Start the trigger policy and waterMarkEventGenerator if set.

      Overrides:
        `start` in class `WindowedBoltExecutor`

    - #### execute

          public void execute(Tuple input)

      Description copied from interface: `IBolt`

      Process a single tuple of input. The Tuple object contains metadata on it about which component/stream/task it came from. The values of the Tuple can be accessed using Tuple#getValue. The IBolt does not have to process the Tuple immediately. It is perfectly fine to hang onto a tuple and process it later (for instance, to do an aggregation or join).

      Tuples should be emitted using the OutputCollector provided through the prepare method. It is required that all input tuples are acked or failed at some point using the OutputCollector. Otherwise, Storm will be unable to determine when tuples coming off the spouts have been completed.

      For the common case of acking an input tuple at the end of the execute method, see IBasicBolt which automates this.

      Specified by:
        `execute` in interface `IBolt`
      Specified by:
        `execute` in interface `IStatefulBolt<T extends State>`
      Overrides:
        `execute` in class `WindowedBoltExecutor`
      Parameters:
        `input` - The input tuple to be processed.
      See Also:
        `IBolt.execute(Tuple)`

    - #### initState

          public void initState(T state)

      Description copied from interface: `IStatefulComponent`

      This method is invoked by the framework with the previously saved state of the component. This is invoked after prepare but before the component starts processing tuples.

      Specified by:
        `initState` in interface `IStatefulComponent<T extends State>`
      Parameters:
        `state` - the previously saved state of the component.

    - #### prePrepare

          public void prePrepare(long txid)

      Description copied from interface: `IStatefulComponent`

      This is a hook for the component to perform some actions just before the framework prepares its state.

      Specified by:
        `prePrepare` in interface `IStatefulComponent<T extends State>`

    - #### preCommit

          public void preCommit(long txid)

      Description copied from interface: `IStatefulComponent`

      This is a hook for the component to perform some actions just before the framework commits its state.

      Specified by:
        `preCommit` in interface `IStatefulComponent<T extends State>`

    - #### preRollback

          public void preRollback()

      Description copied from interface: `IStatefulComponent`

      This is a hook for the component to perform some actions just before the framework rolls back the prepared state.

      Specified by:
        `preRollback` in interface `IStatefulComponent<T extends State>`

    - #### newWindowLifecycleListener

          protected WindowLifecycleListener<Tuple> newWindowLifecycleListener()

      Overrides:
        `newWindowLifecycleListener` in class `WindowedBoltExecutor`

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