Package org.apache.hadoop.mapreduce

Interface Summary
Counter A named counter that tracks the progress of a map/reduce job.
CounterGroup A group of Counters that logically belong together.
JobContext A read-only view of the job that is provided to the tasks while they are running.
MapContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT> The context that is given to the Mapper.
ReduceContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT> The context passed to the Reducer.
TaskAttemptContext The context for task attempts.
TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT> A context object that allows input and output from the task.

Class Summary
Cluster Provides a way to access information about the map/reduce cluster.
ClusterMetrics Status information on the current state of the Map-Reduce cluster.
Counters Counters holds per job/task counters, defined either by the Map-Reduce framework or applications.
ID A general identifier, which internally stores the id as an integer.
InputFormat<K,V> InputFormat describes the input-specification for a Map-Reduce job.
InputSplit InputSplit represents the data to be processed by an individual Mapper.
Job The job submitter's view of the Job.
JobID JobID represents the immutable and unique identifier for the job.
JobStatus Describes the current status of a job.
Mapper<KEYIN,VALUEIN,KEYOUT,VALUEOUT> Maps input key/value pairs to a set of intermediate key/value pairs.
MarkableIterator<VALUE> MarkableIterator is a wrapper iterator class that implements the MarkableIteratorInterface.
OutputCommitter OutputCommitter describes the commit of task output for a Map-Reduce job.
OutputFormat<K,V> OutputFormat describes the output-specification for a Map-Reduce job.
Partitioner<KEY,VALUE> Partitions the key space.
QueueAclsInfo Class to encapsulate Queue ACLs for a particular user.
QueueInfo Class that contains the information regarding the Job Queues which are maintained by the Hadoop Map/Reduce framework.
RecordReader<KEYIN,VALUEIN> The record reader breaks the data into key/value pairs for input to the Mapper.
RecordWriter<K,V> RecordWriter writes the output <key, value> pairs to an output file.
Reducer<KEYIN,VALUEIN,KEYOUT,VALUEOUT> Reduces a set of intermediate values which share a key to a smaller set of values.
TaskAttemptID TaskAttemptID represents the immutable and unique identifier for a task attempt.
TaskCompletionEvent This is used to track task completion events on job tracker.
TaskID TaskID represents the immutable and unique identifier for a Map or Reduce Task.
TaskTrackerInfo Information about TaskTracker.

Enum Summary
JobPriority Used to describe the priority of the running job.
QueueState Enum representing queue state
TaskType Enum for map, reduce, job-setup, job-cleanup, task-cleanup task types.

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