org.apache.hadoop.mapred

Class FileInputFormat<K,V>

java.lang.Object

org.apache.hadoop.mapred.FileInputFormat<K,V>

All Implemented Interfaces:

InputFormat<K,V>

Direct Known Subclasses:

FixedLengthInputFormat, KeyValueTextInputFormat, MultiFileInputFormat, NLineInputFormat, SequenceFileInputFormat, TextInputFormat

@InterfaceAudience.Public
@InterfaceStability.Stable
public abstract class FileInputFormat<K,V>
extends Object
implements InputFormat<K,V>

A base class for file-based InputFormat.

FileInputFormat is the base class for all file-based InputFormats. This provides a generic implementation of getSplits(JobConf, int). Implementations of FileInputFormat can also override the isSplitable(FileSystem, Path) method to prevent input files from being split-up in certain situations. Implementations that may deal with non-splittable files must override this method, since the default implementation assumes splitting is always possible.

Field Summary

Fields

Modifier and Type	Field and Description
static String	INPUT_DIR_RECURSIVE
static org.apache.commons.logging.Log	LOG
static String	NUM_INPUT_FILES

Constructor Summary

Constructors

Constructor and Description
FileInputFormat()

Method Summary

Methods

Modifier and Type	Method and Description
static void	addInputPath(JobConf conf, Path path) Add a Path to the list of inputs for the map-reduce job.
protected void	addInputPathRecursively(List<FileStatus> result, FileSystem fs, Path path, PathFilter inputFilter) Add files in the input path recursively into the results.
static void	addInputPaths(JobConf conf, String commaSeparatedPaths) Add the given comma separated paths to the list of inputs for the map-reduce job.
protected long	computeSplitSize(long goalSize, long minSize, long blockSize)
protected int	getBlockIndex(BlockLocation[] blkLocations, long offset)
static PathFilter	getInputPathFilter(JobConf conf) Get a PathFilter instance of the filter set for the input paths.
static Path[]	getInputPaths(JobConf conf) Get the list of input Paths for the map-reduce job.
abstract RecordReader<K,V>	getRecordReader(InputSplit split, JobConf job, Reporter reporter) Get the RecordReader for the given InputSplit.
protected String[]	getSplitHosts(BlockLocation[] blkLocations, long offset, long splitSize, org.apache.hadoop.net.NetworkTopology clusterMap) This function identifies and returns the hosts that contribute most for a given split.
InputSplit[]	getSplits(JobConf job, int numSplits) Splits files returned by listStatus(JobConf) when they're too big.
protected boolean	isSplitable(FileSystem fs, Path filename) Is the given filename splittable? Usually, true, but if the file is stream compressed, it will not be.
protected FileStatus[]	listStatus(JobConf job) List input directories.
protected FileSplit	makeSplit(Path file, long start, long length, String[] hosts) A factory that makes the split for this class.
protected FileSplit	makeSplit(Path file, long start, long length, String[] hosts, String[] inMemoryHosts) A factory that makes the split for this class.
static void	setInputPathFilter(JobConf conf, Class<? extends PathFilter> filter) Set a PathFilter to be applied to the input paths for the map-reduce job.
static void	setInputPaths(JobConf conf, Path... inputPaths) Set the array of Paths as the list of inputs for the map-reduce job.
static void	setInputPaths(JobConf conf, String commaSeparatedPaths) Sets the given comma separated paths as the list of inputs for the map-reduce job.
protected void	setMinSplitSize(long minSplitSize)

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

NUM_INPUT_FILES

public static final String NUM_INPUT_FILES

See Also:

Constant Field Values

INPUT_DIR_RECURSIVE

public static final String INPUT_DIR_RECURSIVE

See Also:

Constant Field Values

Constructor Detail

FileInputFormat

public FileInputFormat()

Method Detail

setMinSplitSize

protected void setMinSplitSize(long minSplitSize)

isSplitable

protected boolean isSplitable(FileSystem fs,
                  Path filename)

Is the given filename splittable? Usually, true, but if the file is stream compressed, it will not be. The default implementation in FileInputFormat always returns true. Implementations that may deal with non-splittable files must override this method. FileInputFormat implementations can override this and return false to ensure that individual input files are never split-up so that Mappers process entire files.

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<K,V> getRecordReader(InputSplit split,
                                JobConf job,
                                Reporter reporter)
                                           throws IOException

Description copied from interface: InputFormat

Get the RecordReader for the given InputSplit.

It is the responsibility of the RecordReader to respect record boundaries while processing the logical split to present a record-oriented view to the individual task.

Specified by:

getRecordReader in interface InputFormat<K,V>

Parameters:

split - the InputSplit

job - the job that this split belongs to

Returns:

a RecordReader

Throws:

IOException

setInputPathFilter

public static void setInputPathFilter(JobConf conf,
                      Class<? extends PathFilter> filter)

Set a PathFilter to be applied to the input paths for the map-reduce job.

Parameters:

filter - the PathFilter class use for filtering the input paths.

getInputPathFilter

public static PathFilter getInputPathFilter(JobConf conf)

Get a PathFilter instance of the filter set for the input paths.

Returns:

the PathFilter instance set for the job, NULL if none has been set.

addInputPathRecursively

protected void addInputPathRecursively(List<FileStatus> result,
                           FileSystem fs,
                           Path path,
                           PathFilter inputFilter)
                                throws IOException

Add files in the input path recursively into the results.

Parameters:

result - The List to store all files.

fs - The FileSystem.

path - The input path.

inputFilter - The input filter that can be used to filter files/dirs.

Throws:

IOException

listStatus

protected FileStatus[] listStatus(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 FileStatus objects

Throws:

IOException - if zero items.

makeSplit

protected FileSplit makeSplit(Path file,
                  long start,
                  long length,
                  String[] hosts)

A factory that makes the split for this class. It can be overridden by sub-classes to make sub-types

makeSplit

protected FileSplit makeSplit(Path file,
                  long start,
                  long length,
                  String[] hosts,
                  String[] inMemoryHosts)

A factory that makes the split for this class. It can be overridden by sub-classes to make sub-types

getSplits

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

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

Specified by:

getSplits in interface InputFormat<K,V>

Parameters:

job - job configuration.

numSplits - the desired number of splits, a hint.

Returns:

an array of InputSplits for the job.

Throws:

IOException

computeSplitSize

protected long computeSplitSize(long goalSize,
                    long minSize,
                    long blockSize)

getBlockIndex

protected int getBlockIndex(BlockLocation[] blkLocations,
                long offset)

setInputPaths

public static void setInputPaths(JobConf conf,
                 String commaSeparatedPaths)

Sets the given comma separated paths as the list of inputs for the map-reduce job.

Parameters:

conf - Configuration of the job

commaSeparatedPaths - Comma separated paths to be set as the list of inputs for the map-reduce job.

addInputPaths

public static void addInputPaths(JobConf conf,
                 String commaSeparatedPaths)

Add the given comma separated paths to the list of inputs for the map-reduce job.

Parameters:

conf - The configuration of the job

commaSeparatedPaths - Comma separated paths to be added to the list of inputs for the map-reduce job.

setInputPaths

public static void setInputPaths(JobConf conf,
                 Path... inputPaths)

Set the array of Paths as the list of inputs for the map-reduce job.

Parameters:

conf - Configuration of the job.

inputPaths - the Paths of the input directories/files for the map-reduce job.

addInputPath

public static void addInputPath(JobConf conf,
                Path path)

Add a Path to the list of inputs for the map-reduce job.

Parameters:

conf - The configuration of the job

path - Path to be added to the list of inputs for the map-reduce job.

getInputPaths

public static Path[] getInputPaths(JobConf conf)

Get the list of input Paths for the map-reduce job.

Parameters:

conf - The configuration of the job

Returns:

the list of input Paths for the map-reduce job.

getSplitHosts

protected String[] getSplitHosts(BlockLocation[] blkLocations,
                     long offset,
                     long splitSize,
                     org.apache.hadoop.net.NetworkTopology clusterMap)
                          throws IOException

This function identifies and returns the hosts that contribute most for a given split. For calculating the contribution, rack locality is treated on par with host locality, so hosts from racks that contribute the most are preferred over hosts on racks that contribute less

Parameters:

blkLocations - The list of block locations

offset -

splitSize -

Returns:

an array of hosts that contribute most to this split

Throws:

IOException