public class NullScheme<Config,Input,Output,SourceContext,SinkContext> extends Scheme<Config,Input,Output,SourceContext,SinkContext>
Scheme
that neither reads or writes any values.
It is typically used as a placeholder where a Scheme instance is needed but generally ignored.Constructor and Description |
---|
NullScheme() |
NullScheme(Fields sourceFields,
Fields sinkFields) |
Modifier and Type | Method and Description |
---|---|
void |
sink(FlowProcess<? extends Config> flowProcess,
SinkCall<SinkContext,Output> sinkCall)
Method sink writes out the given
Tuple found on SinkCall.getOutgoingEntry() to
the SinkCall.getOutput() . |
void |
sinkConfInit(FlowProcess<? extends Config> flowProcess,
Tap<Config,Input,Output> tap,
Config conf)
Method sinkInit initializes this instance as a sink.
|
boolean |
source(FlowProcess<? extends Config> flowProcess,
SourceCall<SourceContext,Input> sourceCall)
Method source will read a new "record" or value from
SourceCall.getInput() and populate
the available Tuple via SourceCall.getIncomingEntry() and return true
on success or false if no more values available. |
void |
sourceConfInit(FlowProcess<? extends Config> flowProcess,
Tap<Config,Input,Output> tap,
Config conf)
Method sourceInit initializes this instance as a source.
|
java.lang.String |
toString() |
equals, getNumSinkParts, getSinkFields, getSourceFields, getTrace, hashCode, isSink, isSource, isSymmetrical, presentSinkFields, presentSinkFieldsInternal, presentSourceFields, presentSourceFieldsInternal, retrieveSinkFields, retrieveSourceFields, setNumSinkParts, setSinkFields, setSourceFields, sinkCleanup, sinkPrepare, sourceCleanup, sourcePrepare, sourceRePrepare
public NullScheme()
public NullScheme(Fields sourceFields, Fields sinkFields)
public void sourceConfInit(FlowProcess<? extends Config> flowProcess, Tap<Config,Input,Output> tap, Config conf)
Scheme
Scheme.sourcePrepare(cascading.flow.FlowProcess, SourceCall)
if resources much be initialized
before use. And Scheme.sourceCleanup(cascading.flow.FlowProcess, SourceCall)
if resources must be
destroyed after use.sourceConfInit
in class Scheme<Config,Input,Output,SourceContext,SinkContext>
flowProcess
- of type FlowProcesstap
- of type Tapconf
- of type Configpublic void sinkConfInit(FlowProcess<? extends Config> flowProcess, Tap<Config,Input,Output> tap, Config conf)
Scheme
Scheme.sinkPrepare(cascading.flow.FlowProcess, SinkCall)
if resources much be initialized
before use. And Scheme.sinkCleanup(cascading.flow.FlowProcess, SinkCall)
if resources must be
destroyed after use.sinkConfInit
in class Scheme<Config,Input,Output,SourceContext,SinkContext>
flowProcess
- of type FlowProcesstap
- of type Tapconf
- of type Configpublic boolean source(FlowProcess<? extends Config> flowProcess, SourceCall<SourceContext,Input> sourceCall) throws java.io.IOException
Scheme
SourceCall.getInput()
and populate
the available Tuple
via SourceCall.getIncomingEntry()
and return true
on success or false
if no more values available.
It's ok to set a new Tuple instance on the incomingEntry
TupleEntry
, or
to simply re-use the existing instance.
Note this is only time it is safe to modify a Tuple instance handed over via a method call.
This method may optionally throw a TapException
if it cannot process a particular
instance of data. If the payload Tuple is set on the TapException, that Tuple will be written to
any applicable failure trap Tap.source
in class Scheme<Config,Input,Output,SourceContext,SinkContext>
flowProcess
- of type FlowProcesssourceCall
- of SourceCalltrue
when a Tuple was successfully readjava.io.IOException
public void sink(FlowProcess<? extends Config> flowProcess, SinkCall<SinkContext,Output> sinkCall) throws java.io.IOException
Scheme
Tuple
found on SinkCall.getOutgoingEntry()
to
the SinkCall.getOutput()
.
This method may optionally throw a TapException
if it cannot process a particular
instance of data. If the payload Tuple is set on the TapException, that Tuple will be written to
any applicable failure trap Tap. If not set, the incoming Tuple will be written instead.sink
in class Scheme<Config,Input,Output,SourceContext,SinkContext>
flowProcess
- of ProcesssinkCall
- of SinkCalljava.io.IOException
public java.lang.String toString()
toString
in class Scheme<Config,Input,Output,SourceContext,SinkContext>
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