Package org.apache.storm.task

Class TopologyContext

  • All Implemented Interfaces:
    org.apache.storm.shade.net.minidev.json.JSONAware, IMetricsContext
    public class TopologyContext
extends WorkerTopologyContext
implements IMetricsContext
    A `TopologyContext` is given to bolts and spouts in their `prepare()` and `open()` methods, respectively. This object provides information about the component's place within the topology, such as task ids, inputs and outputs, etc.

    The `TopologyContext` is also used to declare `ISubscribedState` objects to synchronize state with StateSpouts this object is subscribed to.

    • Method Detail

      • setAllSubscribedState

        public <T extends ISubscribedState> T setAllSubscribedState​(T obj)
        All state from all subscribed state spouts streams will be synced with the provided object.

        It is recommended that your ISubscribedState object is kept as an instance variable of this object. The recommended usage of this method is as follows:

        ```java _myState = context.setAllSubscribedState(new MyState()); ```

        Parameters:
        obj - Provided ISubscribedState implementation
        Returns:
        Returns the ISubscribedState object provided

      • setSubscribedState

        public <T extends ISubscribedState> T setSubscribedState​(String componentId,
                                                         T obj)
        Synchronizes the default stream from the specified state spout component id with the provided ISubscribedState object.

        The recommended usage of this method is as follows:

        ```java _myState = context.setSubscribedState(componentId, new MyState()); ```

        Parameters:
        componentId - the id of the StateSpout component to subscribe to
        obj - Provided ISubscribedState implementation
        Returns:
        Returns the ISubscribedState object provided

      • setSubscribedState

        public <T extends ISubscribedState> T setSubscribedState​(String componentId,
                                                         String streamId,
                                                         T obj)
        Synchronizes the specified stream from the specified state spout component id with the provided ISubscribedState object.

        The recommended usage of this method is as follows:

        ```java _myState = context.setSubscribedState(componentId, streamId, new MyState()); ```

        Parameters:
        componentId - the id of the StateSpout component to subscribe to
        streamId - the stream to subscribe to
        obj - Provided ISubscribedState implementation
        Returns:
        Returns the ISubscribedState object provided

      • getBlobToLastKnownVersion

        public Map<String,​Long> getBlobToLastKnownVersion()

      • getThisTaskId

        public int getThisTaskId()
        Gets the task id of this task.
        Returns:
        the task id

      • getThisComponentId

        public String getThisComponentId()
        Get component id.
        Returns:
        the component id for this task. The component id maps to a component id specified for a Spout or Bolt in the topology definition.

      • getThisOutputFields

        public Fields getThisOutputFields​(String streamId)
        Gets the declared output fields for the specified stream id for the component this task is a part of.

      • getThisOutputFieldsForStreams

        public Map<String,​List<String>> getThisOutputFieldsForStreams()
        Gets the declared output fields for all streams for the component this task is a part of.

      • getThisStreams

        public Set<String> getThisStreams()
        Gets the set of streams declared for the component of this task.

      • getThisTaskIndex

        public int getThisTaskIndex()
        Gets the index of this task id in getComponentTasks(getThisComponentId()). An example use case for this method is determining which task accesses which resource in a distributed resource to ensure an even distribution.

      • getThisInputFields

        public Map<String,​Map<String,​List<String>>> getThisInputFields()
        Gets the declared input fields for this component.
        Returns:
        A map from sources to streams to fields.

      • getThisSources

        public Map<GlobalStreamId,​Grouping> getThisSources()
        Gets the declared inputs to this component.
        Returns:
        A map from subscribed component/stream to the grouping subscribed with.

      • getThisTargets

        public Map<String,​Map<String,​Grouping>> getThisTargets()
        Gets information about who is consuming the outputs of this component, and how.
        Returns:
        Map from stream id to component id to the Grouping used.

      • setTaskData

        public void setTaskData​(String name,
                        Object data)
        Sets the task-level data for the given name. This data is shared amongst the task and its corresponding task hooks.
        Parameters:
        name - name of the task-level data to be set
        data - task-level data

      • getTaskData

        public Object getTaskData​(String name)
        Fetches the task-level data for the given name. This data is shared amongst the task and its corresponding task hooks.
        Parameters:
        name - name of the task-level data to be fetched
        Returns:
        Associated task-level data

      • setExecutorData

        public void setExecutorData​(String name,
                            Object data)
        Sets the executor-level data for the given name. This data is shared amongst tasks and corresponding task hooks managed by the given executor.
        Parameters:
        name - name of the executor-level data to be set
        data - executor-level data

      • getExecutorData

        public Object getExecutorData​(String name)
        Fetches the executor-level data for the given name. This data is shared across tasks and corresponding task hook managed by the given executor.
        Parameters:
        name - name of the executor-level data to be fetched
        Returns:
        Associated executor-level data

      • addTaskHook

        public void addTaskHook​(ITaskHook hook)

      • getRegisteredMetricByName

        @Deprecated
public IMetric getRegisteredMetricByName​(String name)
        Deprecated.
        Get component's metric from registered metrics by name. Notice: Normally, one component can only register one metric name once. But now registerMetric has a bug(https://issues.apache.org/jira/browse/STORM-254) cause the same metric name can register twice. So we just return the first metric we meet.

      • registerGauge

        public <T> com.codahale.metrics.Gauge<T> registerGauge​(String name,
                                                       com.codahale.metrics.Gauge<T> gauge)
        Specified by:
        registerGauge in interface IMetricsContext