org.apache.hadoop.mapred
Class InputFormatBase

java.lang.Object
  org.apache.hadoop.mapred.InputFormatBase

All Implemented Interfaces:

InputFormat

Direct Known Subclasses:

MergerInputFormat, SequenceFileInputFormat, StreamInputFormat, TextInputFormat, TupleInputFormat

public abstract class InputFormatBase
extends Object
implements InputFormat

A base class for InputFormat.

Field Summary

static org.apache.commons.logging.Log

LOG

Constructor Summary

InputFormatBase()

Method Summary

abstract RecordReader	getRecordReader(InputSplit split, JobConf job, Reporter reporter) Construct a RecordReader for a FileSplit.
InputSplit[]	getSplits(JobConf job, int numSplits) Splits files returned by listPaths(JobConf) when they're too big.
protected boolean	isSplitable(FileSystem fs, Path filename) Is the given filename splitable? Usually, true, but if the file is stream compressed, it will not be.
protected Path[]	listPaths(JobConf job) List input directories.
protected void	setMinSplitSize(long minSplitSize)
void	validateInput(JobConf job) Are the input directories valid? This method is used to test the input directories when a job is submitted so that the framework can fail early with a useful error message when the input directory does not exist.

Methods inherited from class java.lang.Object

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

Field Detail

LOG

public static final org.apache.commons.logging.Log LOG

Constructor Detail

InputFormatBase

public InputFormatBase()

Method Detail

setMinSplitSize

protected void setMinSplitSize(long minSplitSize)

isSplitable

protected boolean isSplitable(FileSystem fs,
                              Path filename)

Is the given filename splitable? Usually, true, but if the file is stream compressed, it will not be.

Parameters:

fs - the file system that the file is on

filename - the file name to check

Returns:

is this file splitable?

getRecordReader

public abstract RecordReader getRecordReader(InputSplit split,
                                             JobConf job,
                                             Reporter reporter)
                                      throws IOException

Description copied from interface: InputFormat

Construct a RecordReader for a FileSplit.

Specified by:

getRecordReader in interface InputFormat

Parameters:

split - the InputSplit

job - the job that this split belongs to

Returns:

a RecordReader

Throws:

IOException

listPaths

protected Path[] listPaths(JobConf job)
                    throws IOException

List input directories. Subclasses may override to, e.g., select only files matching a regular expression.

Parameters:

job - the job to list input paths for

Returns:

array of Path objects

Throws:

IOException - if zero items.

validateInput

public void validateInput(JobConf job)
                   throws IOException

Description copied from interface: InputFormat

Are the input directories valid? This method is used to test the input directories when a job is submitted so that the framework can fail early with a useful error message when the input directory does not exist.

Specified by:

validateInput in interface InputFormat

Parameters:

job - the job to check

Throws:

InvalidInputException - if the job does not have valid input

IOException

getSplits

public InputSplit[] getSplits(JobConf job,
                              int numSplits)
                       throws IOException

Splits files returned by listPaths(JobConf) when they're too big.

Specified by:

getSplits in interface InputFormat

Parameters:

job - the job whose input files are to be split

numSplits - the desired number of splits

Returns:

the splits

Throws:

IOException