org.apache.jena.hadoop.rdf.io.input.readers

Class AbstractBlockBasedNodeTupleReader<TValue,T extends AbstractNodeTupleWritable<TValue>>

java.lang.Object

org.apache.hadoop.mapreduce.RecordReader<org.apache.hadoop.io.LongWritable,T>

org.apache.jena.hadoop.rdf.io.input.readers.AbstractBlockBasedNodeTupleReader<TValue,T>

Type Parameters:

TValue - Value type

T - Tuple type

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

AbstractBlockBasedQuadReader, AbstractBlockBasedTripleReader

public abstract class AbstractBlockBasedNodeTupleReader<TValue,T extends AbstractNodeTupleWritable<TValue>>
extends org.apache.hadoop.mapreduce.RecordReader<org.apache.hadoop.io.LongWritable,T>

An abstract implementation for a record reader that reads records from blocks of files, this is a hybrid between AbstractLineBasedNodeTupleReader and AbstractWholeFileNodeTupleReader in that it can only be used by formats which can be split by lines but reduces the overhead by parsing the split as a whole rather than as individual lines.

The keys produced are the approximate position in the file at which a tuple was found and the values will be node tuples. Positions are approximate because they are recorded after the point at which the most recent tuple was parsed from the input thus they reflect the approximate position in the stream immediately after which the triple was found.

Constructor Summary

Constructors

Constructor and Description
AbstractBlockBasedNodeTupleReader()

Method Summary

Modifier and Type	Method and Description
void	close()
org.apache.hadoop.io.LongWritable	getCurrentKey()
T	getCurrentValue()
float	getProgress()
void	initialize(org.apache.hadoop.mapreduce.InputSplit genericSplit, org.apache.hadoop.mapreduce.TaskAttemptContext context)
boolean	nextKeyValue()

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractBlockBasedNodeTupleReader

public AbstractBlockBasedNodeTupleReader()

Method Detail

initialize

public void initialize(org.apache.hadoop.mapreduce.InputSplit genericSplit,
                       org.apache.hadoop.mapreduce.TaskAttemptContext context)
                throws IOException

Specified by:

initialize in class org.apache.hadoop.mapreduce.RecordReader<org.apache.hadoop.io.LongWritable,T extends AbstractNodeTupleWritable<TValue>>

Throws:

IOException

nextKeyValue

public boolean nextKeyValue()
                     throws IOException

Specified by:

nextKeyValue in class org.apache.hadoop.mapreduce.RecordReader<org.apache.hadoop.io.LongWritable,T extends AbstractNodeTupleWritable<TValue>>

Throws:

IOException

getCurrentKey

public org.apache.hadoop.io.LongWritable getCurrentKey()

Specified by:

getCurrentKey in class org.apache.hadoop.mapreduce.RecordReader<org.apache.hadoop.io.LongWritable,T extends AbstractNodeTupleWritable<TValue>>

getCurrentValue

public T getCurrentValue()

Specified by:

getCurrentValue in class org.apache.hadoop.mapreduce.RecordReader<org.apache.hadoop.io.LongWritable,T extends AbstractNodeTupleWritable<TValue>>

getProgress

public float getProgress()

Specified by:

getProgress in class org.apache.hadoop.mapreduce.RecordReader<org.apache.hadoop.io.LongWritable,T extends AbstractNodeTupleWritable<TValue>>

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in class org.apache.hadoop.mapreduce.RecordReader<org.apache.hadoop.io.LongWritable,T extends AbstractNodeTupleWritable<TValue>>

Throws:

IOException