|
||||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Objectorg.apache.hadoop.mapred.lib.DelegatingMapper<K1,V1,K2,V2>
@InterfaceAudience.Private @InterfaceStability.Unstable public class DelegatingMapper<K1,V1,K2,V2>
An Mapper
that delegates behaviour of paths to multiple other
mappers.
MultipleInputs.addInputPath(JobConf, Path, Class, Class)
Constructor Summary | |
---|---|
DelegatingMapper()
|
Method Summary | |
---|---|
void |
close()
|
void |
configure(JobConf conf)
Initializes a new instance from a JobConf . |
void |
map(K1 key,
V1 value,
OutputCollector<K2,V2> outputCollector,
Reporter reporter)
Maps a single input key/value pair into an intermediate key/value pair. |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
---|
public DelegatingMapper()
Method Detail |
---|
public void map(K1 key, V1 value, OutputCollector<K2,V2> outputCollector, Reporter reporter) throws IOException
Mapper
Output pairs need not be of the same types as input pairs. A given
input pair may map to zero or many output pairs. Output pairs are
collected with calls to
OutputCollector.collect(Object,Object)
.
Applications can use the Reporter
provided to report progress
or just indicate that they are alive. In scenarios where the application
takes significant amount of time to process individual key/value
pairs, this is crucial since the framework might assume that the task has
timed-out and kill that task. The other way of avoiding this is to set
mapreduce.task.timeout to a high-enough value (or even zero for no
time-outs).
map
in interface Mapper<K1,V1,K2,V2>
key
- the input key.value
- the input value.outputCollector
- collects mapped keys and values.reporter
- facility to report progress.
IOException
public void configure(JobConf conf)
JobConfigurable
JobConf
.
configure
in interface JobConfigurable
conf
- the configurationpublic void close() throws IOException
close
in interface Closeable
IOException
|
||||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |