com.google.appengine.tools.mapreduce

Class Input<I>

java.lang.Object

com.google.appengine.tools.mapreduce.Input<I>

Type Parameters:

I - type of values produced by this input

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

BlobstoreInput, ConsecutiveLongInput, DatastoreInput, DatastoreKeyInput, GoogleCloudStorageLevelDbInput, GoogleCloudStorageLineInput, GoogleCloudStorageMergeInput, GoogleCloudStorageReduceInput, GoogleCloudStorageSortInput, InMemoryInput, LogInput, NoInput, RandomLongInput, UnmarshallingInput

public abstract class Input<I>
extends Object
implements Serializable

Input is the data source specification for the job. Input simply defines data source, while InputReader handles reading itself.

This class is really an interface that might be evolving. In order to avoid breaking users when we change the interface, we made it an abstract class.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
Input()

Method Summary

Methods

Modifier and Type	Method and Description
abstract List<? extends InputReader<I>>	createReaders() Returns a list of readers for this input.
Context	getContext() Returns the current context, or null if none.

Methods inherited from class java.lang.Object

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

Constructor Detail

Input

public Input()

Method Detail

getContext

public Context getContext()

Returns the current context, or null if none.

createReaders

public abstract List<? extends InputReader<I>> createReaders()
                                                      throws IOException

Returns a list of readers for this input. It is the Input's responsibility to determine an appropriate number of readers to split into. This could be specified by the user or determined algorithmically. The number of input readers returned determines the number of map shards.

Throws:

IOException