Class DistCacheTap

  extended by cascading.tap.Tap<Config,Input,Output>
      extended by cascading.tap.DecoratorTap<Void,JobConf,RecordReader,OutputCollector>
          extended by cascading.tap.hadoop.DistCacheTap
All Implemented Interfaces:
FlowElement, Traceable, Serializable

public class DistCacheTap
extends DecoratorTap<Void,JobConf,RecordReader,OutputCollector>

Class DistCacheTap is a Tap decorator for Hfs and can be used to move a file to the DistributedCache on read when accessed cluster side.

This is useful for HashJoins.

The distributed cache is only used when the Tap is used as a source. If the DistCacheTap is used as a sink, it will delegate to the provided parent instance and not use the DistributedCache.

See Also:
Serialized Form

Field Summary
Fields inherited from class cascading.tap.DecoratorTap
metaInfo, original
Constructor Summary
DistCacheTap(Hfs parent)
          Constructs a new DistCacheTap instance with the given Hfs.
Method Summary
 TupleEntryIterator openForRead(FlowProcess<JobConf> flowProcess, RecordReader input)
 void sourceConfInit(FlowProcess<JobConf> process, JobConf conf)
Methods inherited from class cascading.tap.DecoratorTap
commitResource, createResource, createResource, deleteResource, deleteResource, flowConfInit, getConfigDef, getFullIdentifier, getFullIdentifier, getIdentifier, getMetaInfo, getModifiedTime, getModifiedTime, getOriginal, getScheme, getSinkFields, getSinkMode, getSourceFields, getStepConfigDef, getTrace, hasConfigDef, hasStepConfigDef, isEquivalentTo, isKeep, isReplace, isSink, isSource, isTemporary, isUpdate, openForRead, openForWrite, openForWrite, outgoingScopeFor, presentSinkFields, presentSourceFields, resolveIncomingOperationArgumentFields, resolveIncomingOperationPassThroughFields, resourceExists, resourceExists, retrieveSinkFields, retrieveSourceFields, rollbackResource, setMetaInfo, setOriginal, sinkConfInit, toString
Methods inherited from class cascading.tap.Tap
equals, hashCode, id, setScheme, taps
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail


public DistCacheTap(Hfs parent)
Constructs a new DistCacheTap instance with the given Hfs.

parent - an Hfs or GlobHfs instance representing a small file.
Method Detail


public void sourceConfInit(FlowProcess<JobConf> process,
                           JobConf conf)
sourceConfInit in class DecoratorTap<Void,JobConf,RecordReader,OutputCollector>


public TupleEntryIterator openForRead(FlowProcess<JobConf> flowProcess,
                                      RecordReader input)
                               throws IOException
openForRead in class DecoratorTap<Void,JobConf,RecordReader,OutputCollector>

Copyright © 2007-2014 Concurrent, Inc. All Rights Reserved.