jstorm-core/src/main/java/backtype/storm/task/TopologyContext.java - storm - Git at Google

 /**
  * 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 backtype.storm.task;

 import backtype.storm.generated.GlobalStreamId;
 import backtype.storm.generated.Grouping;
 import backtype.storm.generated.StormTopology;
 import backtype.storm.hooks.ITaskHook;
 import backtype.storm.metric.api.*;
 import backtype.storm.state.ISubscribedState;
 import backtype.storm.tuple.Fields;
 import backtype.storm.utils.Utils;
 import com.alibaba.jstorm.cluster.StormClusterState;
 import org.apache.commons.lang.NotImplementedException;
 import org.json.simple.JSONValue;

 import java.util.*;

 /**
  * 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.
  *
  * <p>
  * The TopologyContext is also used to declare ISubscribedState objects to synchronize state with StateSpouts this object is subscribed to.
  * </p>
  */
 public class TopologyContext extends WorkerTopologyContext implements IMetricsContext {
     private Integer _taskId;
     private Map<String, Object> _taskData = new HashMap<String, Object>();
     private List<ITaskHook> _hooks = new ArrayList<ITaskHook>();
     private Map<String, Object> _executorData;
     private Map<Integer, Map<Integer, Map<String, IMetric>>> _registeredMetrics;
     private clojure.lang.Atom _openOrPrepareWasCalled;
     private StormClusterState _zkCluster;

     public TopologyContext(StormTopology topology, Map stormConf, Map<Integer, String> taskToComponent, Map<String, List<Integer>> componentToSortedTasks,
             Map<String, Map<String, Fields>> componentToStreamToFields, String stormId, String codeDir, String pidDir, Integer taskId, Integer workerPort,
             List<Integer> workerTasks, Map<String, Object> defaultResources, Map<String, Object> userResources, Map<String, Object> executorData,
             Map registeredMetrics, clojure.lang.Atom openOrPrepareWasCalled, StormClusterState zkCluster) {
         super(topology, stormConf, taskToComponent, componentToSortedTasks, componentToStreamToFields, stormId, codeDir, pidDir, workerPort, workerTasks,
                 defaultResources, userResources);
         _taskId = taskId;
         _executorData = executorData;
         _registeredMetrics = registeredMetrics;
         _openOrPrepareWasCalled = openOrPrepareWasCalled;
         _zkCluster = zkCluster;
     }

     /**
      * All state from all subscribed state spouts streams will be synced with the provided object.
      *
      * <p>
      * 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:
      * </p>
      *
      * <p>
      * _myState = context.setAllSubscribedState(new MyState());
      * </p>
      *
      * @param obj Provided ISubscribedState implementation
      * @return Returns the ISubscribedState object provided
      */
     public <T extends ISubscribedState> T setAllSubscribedState(T obj) {
         // check that only subscribed to one component/stream for statespout
         // setsubscribedstate appropriately
         throw new NotImplementedException();
     }

     /**
      * Synchronizes the default stream from the specified state spout component id with the provided ISubscribedState object.
      *
      * <p>
      * The recommended usage of this method is as follows:
      * </p>
      * <p>
      * _myState = context.setSubscribedState(componentId, new MyState());
      * </p>
      *
      * @param componentId the id of the StateSpout component to subscribe to
      * @param obj Provided ISubscribedState implementation
      * @return Returns the ISubscribedState object provided
      */
     public <T extends ISubscribedState> T setSubscribedState(String componentId, T obj) {
         return setSubscribedState(componentId, Utils.DEFAULT_STREAM_ID, obj);
     }

     /**
      * Synchronizes the specified stream from the specified state spout component id with the provided ISubscribedState object.
      *
      * <p>
      * The recommended usage of this method is as follows:
      * </p>
      * <p>
      * _myState = context.setSubscribedState(componentId, streamId, new MyState());
      * </p>
      *
      * @param componentId the id of the StateSpout component to subscribe to
      * @param streamId the stream to subscribe to
      * @param obj Provided ISubscribedState implementation
      * @return Returns the ISubscribedState object provided
      */
     public <T extends ISubscribedState> T setSubscribedState(String componentId, String streamId, T obj) {
         throw new NotImplementedException();
     }

     /**
      * Gets the task id of this task.
      *
      * @return the task id
      */
     public int getThisTaskId() {
         return _taskId;
     }

     /**
      * Gets the component id for this task. The component id maps to a component id specified for a Spout or Bolt in the topology definition.
      *
      * @return
      */
     public String getThisComponentId() {
         return getComponentId(_taskId);
     }

     /**
      * Gets the declared output fields for the specified stream id for the component this task is a part of.
      */
     public Fields getThisOutputFields(String streamId) {
         return getComponentOutputFields(getThisComponentId(), streamId);
     }

     /**
      * Gets the declared output fields for the specified stream id for the component this task is a part of.
      */
     public Map<String, List<String>> getThisOutputFieldsForStreams() {
         Map<String, List<String>> streamToFields = new HashMap<String, List<String>>();
         for (String stream : this.getThisStreams()) {
             streamToFields.put(stream, this.getThisOutputFields(stream).toList());
         }
         return streamToFields;
     }

     /**
      * Gets the set of streams declared for the component of this task.
      */
     public Set<String> getThisStreams() {
         return getComponentStreams(getThisComponentId());
     }

     /**
      * 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.
      */
     public int getThisTaskIndex() {
         List<Integer> tasks = new ArrayList<Integer>(getComponentTasks(getThisComponentId()));
         Collections.sort(tasks);
         for (int i = 0; i < tasks.size(); i++) {
             if (tasks.get(i) == getThisTaskId()) {
                 return i;
             }
         }
         throw new RuntimeException("Fatal: could not find this task id in this component");
     }

     /**
      * Gets the declared inputs to this component.
      *
      * @return A map from subscribed component/stream to the grouping subscribed with.
      */
     public Map<GlobalStreamId, Grouping> getThisSources() {
         return getSources(getThisComponentId());
     }

     /**
      * Gets information about who is consuming the outputs of this component, and how.
      *
      * @return Map from stream id to component id to the Grouping used.
      */
     public Map<String, Map<String, Grouping>> getThisTargets() {
         return getTargets(getThisComponentId());
     }

     public void setTaskData(String name, Object data) {
         _taskData.put(name, data);
     }

     public Object getTaskData(String name) {
         return _taskData.get(name);
     }

     public void setExecutorData(String name, Object data) {
         _executorData.put(name, data);
     }

     public Object getExecutorData(String name) {
         return _executorData.get(name);
     }

     public void addTaskHook(ITaskHook hook) {
         hook.prepare(_stormConf, this);
         _hooks.add(hook);
     }

     public Collection<ITaskHook> getHooks() {
         return _hooks;
     }

     private static Map<String, Object> groupingToJSONableMap(Grouping grouping) {
         Map groupingMap = new HashMap<String, Object>();
         groupingMap.put("type", grouping.getSetField().toString());
         if (grouping.is_set_fields()) {
             groupingMap.put("fields", grouping.get_fields());
         }
         return groupingMap;
     }

     @Override
     public String toJSONString() {
         Map obj = new HashMap();
         obj.put("task->component", this.getTaskToComponent());
         obj.put("taskid", this.getThisTaskId());
         obj.put("componentid", this.getThisComponentId());
         List<String> streamList = new ArrayList<String>();
         streamList.addAll(this.getThisStreams());
         obj.put("streams", streamList);
         obj.put("stream->outputfields", this.getThisOutputFieldsForStreams());
         // Convert targets to a JSON serializable format
         Map<String, Map> stringTargets = new HashMap<String, Map>();
         for (Map.Entry<String, Map<String, Grouping>> entry : this.getThisTargets().entrySet()) {
             Map stringTargetMap = new HashMap<String, Object>();
             for (Map.Entry<String, Grouping> innerEntry : entry.getValue().entrySet()) {
                 stringTargetMap.put(innerEntry.getKey(), groupingToJSONableMap(innerEntry.getValue()));
             }
             stringTargets.put(entry.getKey(), stringTargetMap);
         }
         obj.put("stream->target->grouping", stringTargets);
         // Convert sources to a JSON serializable format
         Map<String, Map<String, Object>> stringSources = new HashMap<String, Map<String, Object>>();
         for (Map.Entry<GlobalStreamId, Grouping> entry : this.getThisSources().entrySet()) {
             GlobalStreamId gid = entry.getKey();
             Map<String, Object> stringSourceMap = stringSources.get(gid.get_componentId());
             if (stringSourceMap == null) {
                 stringSourceMap = new HashMap<String, Object>();
                 stringSources.put(gid.get_componentId(), stringSourceMap);
             }
             stringSourceMap.put(gid.get_streamId(), groupingToJSONableMap(entry.getValue()));
         }
         obj.put("source->stream->grouping", stringSources);
         return JSONValue.toJSONString(obj);
     }

     /*
      * Register a IMetric instance. Storm will then call getValueAndReset on the metric every timeBucketSizeInSecs and the returned value is sent to all metrics
      * consumers. You must call this during IBolt::prepare or ISpout::open.
      *
      * @return The IMetric argument unchanged.
      */
     public <T extends IMetric> T registerMetric(String name, T metric, int timeBucketSizeInSecs) {
         if ((Boolean) _openOrPrepareWasCalled.deref() == true) {
             throw new RuntimeException("TopologyContext.registerMetric can only be called from within overridden "
                     + "IBolt::prepare() or ISpout::open() method.");
         }

         if (metric == null) {
             throw new IllegalArgumentException("Cannot register a null metric");
         }

         if (timeBucketSizeInSecs <= 0) {
             throw new IllegalArgumentException("TopologyContext.registerMetric can only be called with timeBucketSizeInSecs "
                     + "greater than or equal to 1 second.");
         }

         if (getRegisteredMetricByName(name) != null) {
             throw new RuntimeException("The same metric name `" + name + "` was registered twice.");
         }

         Map m1 = _registeredMetrics;
         if (!m1.containsKey(timeBucketSizeInSecs)) {
             m1.put(timeBucketSizeInSecs, new HashMap());
         }

         Map m2 = (Map) m1.get(timeBucketSizeInSecs);
         if (!m2.containsKey(_taskId)) {
             m2.put(_taskId, new HashMap());
         }

         Map m3 = (Map) m2.get(_taskId);
         if (m3.containsKey(name)) {
             throw new RuntimeException("The same metric name `" + name + "` was registered twice.");
         } else {
             m3.put(name, metric);
         }

         return metric;
     }

     /**
      * 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.
      */
     public IMetric getRegisteredMetricByName(String name) {
         IMetric metric = null;

         for (Map<Integer, Map<String, IMetric>> taskIdToNameToMetric : _registeredMetrics.values()) {
             Map<String, IMetric> nameToMetric = taskIdToNameToMetric.get(_taskId);
             if (nameToMetric != null) {
                 metric = nameToMetric.get(name);
                 if (metric != null) {
                     // we just return the first metric we meet
                     break;
                 }
             }
         }

         return metric;
     }

     /*
      * Convinience method for registering ReducedMetric.
      */
     public ReducedMetric registerMetric(String name, IReducer reducer, int timeBucketSizeInSecs) {
         return registerMetric(name, new ReducedMetric(reducer), timeBucketSizeInSecs);
     }

     /*
      * Convinience method for registering CombinedMetric.
      */
     public CombinedMetric registerMetric(String name, ICombiner combiner, int timeBucketSizeInSecs) {
         return registerMetric(name, new CombinedMetric(combiner), timeBucketSizeInSecs);
     }

     public StormClusterState getZkCluster() {
         return _zkCluster;
     }
     /*
     * Task error report callback
     * */
     public void reportError(String errorMsg) throws Exception{
             _zkCluster.report_task_error(getTopologyId(), _taskId, errorMsg, null);
     }
 }
	/**
	* 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 backtype.storm.task;

	import backtype.storm.generated.GlobalStreamId;
	import backtype.storm.generated.Grouping;
	import backtype.storm.generated.StormTopology;
	import backtype.storm.hooks.ITaskHook;
	import backtype.storm.metric.api.*;
	import backtype.storm.state.ISubscribedState;
	import backtype.storm.tuple.Fields;
	import backtype.storm.utils.Utils;
	import com.alibaba.jstorm.cluster.StormClusterState;
	import org.apache.commons.lang.NotImplementedException;
	import org.json.simple.JSONValue;

	import java.util.*;

	/**
	* 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.
	*
	* <p>
	* The TopologyContext is also used to declare ISubscribedState objects to synchronize state with StateSpouts this object is subscribed to.
	* </p>
	*/
	public class TopologyContext extends WorkerTopologyContext implements IMetricsContext {
	private Integer _taskId;
	private Map<String, Object> _taskData = new HashMap<String, Object>();
	private List<ITaskHook> _hooks = new ArrayList<ITaskHook>();
	private Map<String, Object> _executorData;
	private Map<Integer, Map<Integer, Map<String, IMetric>>> _registeredMetrics;
	private clojure.lang.Atom _openOrPrepareWasCalled;
	private StormClusterState _zkCluster;

	public TopologyContext(StormTopology topology, Map stormConf, Map<Integer, String> taskToComponent, Map<String, List<Integer>> componentToSortedTasks,
	Map<String, Map<String, Fields>> componentToStreamToFields, String stormId, String codeDir, String pidDir, Integer taskId, Integer workerPort,
	List<Integer> workerTasks, Map<String, Object> defaultResources, Map<String, Object> userResources, Map<String, Object> executorData,
	Map registeredMetrics, clojure.lang.Atom openOrPrepareWasCalled, StormClusterState zkCluster) {
	super(topology, stormConf, taskToComponent, componentToSortedTasks, componentToStreamToFields, stormId, codeDir, pidDir, workerPort, workerTasks,
	defaultResources, userResources);
	_taskId = taskId;
	_executorData = executorData;
	_registeredMetrics = registeredMetrics;
	_openOrPrepareWasCalled = openOrPrepareWasCalled;
	_zkCluster = zkCluster;
	}

	/**
	* All state from all subscribed state spouts streams will be synced with the provided object.
	*
	* <p>
	* 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:
	* </p>
	*
	* <p>
	* _myState = context.setAllSubscribedState(new MyState());
	* </p>
	*
	* @param obj Provided ISubscribedState implementation
	* @return Returns the ISubscribedState object provided
	*/
	public <T extends ISubscribedState> T setAllSubscribedState(T obj) {
	// check that only subscribed to one component/stream for statespout
	// setsubscribedstate appropriately
	throw new NotImplementedException();
	}

	/**
	* Synchronizes the default stream from the specified state spout component id with the provided ISubscribedState object.
	*
	* <p>
	* The recommended usage of this method is as follows:
	* </p>
	* <p>
	* _myState = context.setSubscribedState(componentId, new MyState());
	* </p>
	*
	* @param componentId the id of the StateSpout component to subscribe to
	* @param obj Provided ISubscribedState implementation
	* @return Returns the ISubscribedState object provided
	*/
	public <T extends ISubscribedState> T setSubscribedState(String componentId, T obj) {
	return setSubscribedState(componentId, Utils.DEFAULT_STREAM_ID, obj);
	}

	/**
	* Synchronizes the specified stream from the specified state spout component id with the provided ISubscribedState object.
	*
	* <p>
	* The recommended usage of this method is as follows:
	* </p>
	* <p>
	* _myState = context.setSubscribedState(componentId, streamId, new MyState());
	* </p>
	*
	* @param componentId the id of the StateSpout component to subscribe to
	* @param streamId the stream to subscribe to
	* @param obj Provided ISubscribedState implementation
	* @return Returns the ISubscribedState object provided
	*/
	public <T extends ISubscribedState> T setSubscribedState(String componentId, String streamId, T obj) {
	throw new NotImplementedException();
	}

	/**
	* Gets the task id of this task.
	*
	* @return the task id
	*/
	public int getThisTaskId() {
	return _taskId;
	}

	/**
	* Gets the component id for this task. The component id maps to a component id specified for a Spout or Bolt in the topology definition.
	*
	* @return
	*/
	public String getThisComponentId() {
	return getComponentId(_taskId);
	}

	/**
	* Gets the declared output fields for the specified stream id for the component this task is a part of.
	*/
	public Fields getThisOutputFields(String streamId) {
	return getComponentOutputFields(getThisComponentId(), streamId);
	}

	/**
	* Gets the declared output fields for the specified stream id for the component this task is a part of.
	*/
	public Map<String, List<String>> getThisOutputFieldsForStreams() {
	Map<String, List<String>> streamToFields = new HashMap<String, List<String>>();
	for (String stream : this.getThisStreams()) {
	streamToFields.put(stream, this.getThisOutputFields(stream).toList());
	}
	return streamToFields;
	}

	/**
	* Gets the set of streams declared for the component of this task.
	*/
	public Set<String> getThisStreams() {
	return getComponentStreams(getThisComponentId());
	}

	/**
	* 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.
	*/
	public int getThisTaskIndex() {
	List<Integer> tasks = new ArrayList<Integer>(getComponentTasks(getThisComponentId()));
	Collections.sort(tasks);
	for (int i = 0; i < tasks.size(); i++) {
	if (tasks.get(i) == getThisTaskId()) {
	return i;
	}
	}
	throw new RuntimeException("Fatal: could not find this task id in this component");
	}

	/**
	* Gets the declared inputs to this component.
	*
	* @return A map from subscribed component/stream to the grouping subscribed with.
	*/
	public Map<GlobalStreamId, Grouping> getThisSources() {
	return getSources(getThisComponentId());
	}

	/**
	* Gets information about who is consuming the outputs of this component, and how.
	*
	* @return Map from stream id to component id to the Grouping used.
	*/
	public Map<String, Map<String, Grouping>> getThisTargets() {
	return getTargets(getThisComponentId());
	}

	public void setTaskData(String name, Object data) {
	_taskData.put(name, data);
	}

	public Object getTaskData(String name) {
	return _taskData.get(name);
	}

	public void setExecutorData(String name, Object data) {
	_executorData.put(name, data);
	}

	public Object getExecutorData(String name) {
	return _executorData.get(name);
	}

	public void addTaskHook(ITaskHook hook) {
	hook.prepare(_stormConf, this);
	_hooks.add(hook);
	}

	public Collection<ITaskHook> getHooks() {
	return _hooks;
	}

	private static Map<String, Object> groupingToJSONableMap(Grouping grouping) {
	Map groupingMap = new HashMap<String, Object>();
	groupingMap.put("type", grouping.getSetField().toString());
	if (grouping.is_set_fields()) {
	groupingMap.put("fields", grouping.get_fields());
	}
	return groupingMap;
	}

	@Override
	public String toJSONString() {
	Map obj = new HashMap();
	obj.put("task->component", this.getTaskToComponent());
	obj.put("taskid", this.getThisTaskId());
	obj.put("componentid", this.getThisComponentId());
	List<String> streamList = new ArrayList<String>();
	streamList.addAll(this.getThisStreams());
	obj.put("streams", streamList);
	obj.put("stream->outputfields", this.getThisOutputFieldsForStreams());
	// Convert targets to a JSON serializable format
	Map<String, Map> stringTargets = new HashMap<String, Map>();
	for (Map.Entry<String, Map<String, Grouping>> entry : this.getThisTargets().entrySet()) {
	Map stringTargetMap = new HashMap<String, Object>();
	for (Map.Entry<String, Grouping> innerEntry : entry.getValue().entrySet()) {
	stringTargetMap.put(innerEntry.getKey(), groupingToJSONableMap(innerEntry.getValue()));
	}
	stringTargets.put(entry.getKey(), stringTargetMap);
	}
	obj.put("stream->target->grouping", stringTargets);
	// Convert sources to a JSON serializable format
	Map<String, Map<String, Object>> stringSources = new HashMap<String, Map<String, Object>>();
	for (Map.Entry<GlobalStreamId, Grouping> entry : this.getThisSources().entrySet()) {
	GlobalStreamId gid = entry.getKey();
	Map<String, Object> stringSourceMap = stringSources.get(gid.get_componentId());
	if (stringSourceMap == null) {
	stringSourceMap = new HashMap<String, Object>();
	stringSources.put(gid.get_componentId(), stringSourceMap);
	}
	stringSourceMap.put(gid.get_streamId(), groupingToJSONableMap(entry.getValue()));
	}
	obj.put("source->stream->grouping", stringSources);
	return JSONValue.toJSONString(obj);
	}

	/*
	* Register a IMetric instance. Storm will then call getValueAndReset on the metric every timeBucketSizeInSecs and the returned value is sent to all metrics
	* consumers. You must call this during IBolt::prepare or ISpout::open.
	*
	* @return The IMetric argument unchanged.
	*/
	public <T extends IMetric> T registerMetric(String name, T metric, int timeBucketSizeInSecs) {
	if ((Boolean) _openOrPrepareWasCalled.deref() == true) {
	throw new RuntimeException("TopologyContext.registerMetric can only be called from within overridden "
	+ "IBolt::prepare() or ISpout::open() method.");
	}

	if (metric == null) {
	throw new IllegalArgumentException("Cannot register a null metric");
	}

	if (timeBucketSizeInSecs <= 0) {
	throw new IllegalArgumentException("TopologyContext.registerMetric can only be called with timeBucketSizeInSecs "
	+ "greater than or equal to 1 second.");
	}

	if (getRegisteredMetricByName(name) != null) {
	throw new RuntimeException("The same metric name `" + name + "` was registered twice.");
	}

	Map m1 = _registeredMetrics;
	if (!m1.containsKey(timeBucketSizeInSecs)) {
	m1.put(timeBucketSizeInSecs, new HashMap());
	}

	Map m2 = (Map) m1.get(timeBucketSizeInSecs);
	if (!m2.containsKey(_taskId)) {
	m2.put(_taskId, new HashMap());
	}

	Map m3 = (Map) m2.get(_taskId);
	if (m3.containsKey(name)) {
	throw new RuntimeException("The same metric name `" + name + "` was registered twice.");
	} else {
	m3.put(name, metric);
	}

	return metric;
	}

	/**
	* 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.
	*/
	public IMetric getRegisteredMetricByName(String name) {
	IMetric metric = null;

	for (Map<Integer, Map<String, IMetric>> taskIdToNameToMetric : _registeredMetrics.values()) {
	Map<String, IMetric> nameToMetric = taskIdToNameToMetric.get(_taskId);
	if (nameToMetric != null) {
	metric = nameToMetric.get(name);
	if (metric != null) {
	// we just return the first metric we meet
	break;
	}
	}
	}

	return metric;
	}

	/*
	* Convinience method for registering ReducedMetric.
	*/
	public ReducedMetric registerMetric(String name, IReducer reducer, int timeBucketSizeInSecs) {
	return registerMetric(name, new ReducedMetric(reducer), timeBucketSizeInSecs);
	}

	/*
	* Convinience method for registering CombinedMetric.
	*/
	public CombinedMetric registerMetric(String name, ICombiner combiner, int timeBucketSizeInSecs) {
	return registerMetric(name, new CombinedMetric(combiner), timeBucketSizeInSecs);
	}

	public StormClusterState getZkCluster() {
	return _zkCluster;
	}
	/*
	* Task error report callback
	* */
	public void reportError(String errorMsg) throws Exception{
	_zkCluster.report_task_error(getTopologyId(), _taskId, errorMsg, null);
	}
	}