io.cdap.cdap.api.mapreduce

Interface MapReduceTaskContext<KEYOUT,VALUEOUT>

Type Parameters:

KEYOUT - output key type

VALUEOUT - output value type

All Superinterfaces:

DatasetContext, FeatureFlagsProvider, PluginContext, RuntimeContext, SchedulableProgramContext, SecureStore, ServiceDiscoverer, TaskLocalizationContext

@Beta
public interface MapReduceTaskContext<KEYOUT,VALUEOUT>
extends SchedulableProgramContext, RuntimeContext, DatasetContext, ServiceDiscoverer, PluginContext, TaskLocalizationContext, SecureStore

MapReduce task execution context.

Method Summary

Modifier and Type	Method and Description
<T> T	getHadoopContext() Returns the Hadoop context object for the task.
InputContext	getInputContext() Returns an InputContext of the input configured for this task.
long	getLogicalStartTime() Returns the logical start time of this MapReduce job.
MapReduceSpecification	getSpecification()
WorkflowInfo	getWorkflowInfo()
WorkflowToken	getWorkflowToken()
void	write(KEYOUT key, VALUEOUT value) Write key and value to the Hadoop context.
<K,V> void	write(String namedOutput, K key, V value) Write key and value to the named output Dataset.

Methods inherited from interface io.cdap.cdap.api.SchedulableProgramContext

getTriggeringScheduleInfo

Methods inherited from interface io.cdap.cdap.api.RuntimeContext

getAdmin, getApplicationSpecification, getClusterName, getDataTracer, getNamespace, getRunId, getRuntimeArguments

Methods inherited from interface io.cdap.cdap.api.data.DatasetContext

discardDataset, getDataset, getDataset, getDataset, getDataset, releaseDataset

Methods inherited from interface io.cdap.cdap.api.ServiceDiscoverer

getServiceURL, getServiceURL, getServiceURL, openConnection

Methods inherited from interface io.cdap.cdap.api.plugin.PluginContext

getPluginProperties, getPluginProperties, loadPluginClass, newPluginInstance, newPluginInstance

Methods inherited from interface io.cdap.cdap.api.feature.FeatureFlagsProvider

isFeatureEnabled

Methods inherited from interface io.cdap.cdap.api.TaskLocalizationContext

getAllLocalFiles, getLocalFile

Methods inherited from interface io.cdap.cdap.api.security.store.SecureStore

get, list

Method Detail

write

<K,V> void write(String namedOutput,
                 K key,
                 V value)
          throws IOException,
                 InterruptedException

Write key and value to the named output Dataset. This method must only be used if the MapReduce writes to more than one output. If there is a single output, write(Object, Object) must be used, or the data may not be written correctly.

Parameters:

namedOutput - the name of the output Dataset

key - the key

value - the value

Throws:

IOException

InterruptedException

write

void write(KEYOUT key,
           VALUEOUT value)
    throws IOException,
           InterruptedException

Write key and value to the Hadoop context. This method must only be used if the MapReduce writes to a single output. If there is more than one output, write(String, Object, Object) must be used instead.

Parameters:

key - the key

value - the value

Throws:

IOException

InterruptedException

getSpecification

MapReduceSpecification getSpecification()

Returns:

The specification used to configure this MapReduce job instance.

getLogicalStartTime

long getLogicalStartTime()

Returns the logical start time of this MapReduce job. Logical start time is the time when this MapReduce job is supposed to start if this job is started by the scheduler. Otherwise, it is the current time when the job runs.

Returns:

Time in milliseconds since epoch time (00:00:00 January 1, 1970 UTC).

getHadoopContext

<T> T getHadoopContext()

Returns the Hadoop context object for the task.

getWorkflowToken

@Nullable
WorkflowToken getWorkflowToken()

Returns:

the WorkflowToken associated with the current Workflow, if the MapReduce program is executed as a part of the Workflow; returns null otherwise.

getWorkflowInfo

@Nullable
WorkflowInfo getWorkflowInfo()

Returns:

information about the enclosing Workflow run, if this MapReduce program is executed as a part of the Workflow; returns null otherwise.

getInputContext

InputContext getInputContext()

Returns an InputContext of the input configured for this task. The returned object will be a PartitionedFileSetInputContext if the input for this task was configured from the PartitionedFileSet APIs. Returns null, if this task is a Reducer or no inputs were configured through CDAP APIs.