cascading.tap.hadoop

Class Hfs

java.lang.Object

cascading.tap.Tap<Configuration,RecordReader,OutputCollector>

cascading.tap.hadoop.Hfs

All Implemented Interfaces:

FlowElement, ScopedElement, FileType<Configuration>, TapWith<Configuration,RecordReader,OutputCollector>, Traceable, java.io.Serializable

Direct Known Subclasses:

Dfs, Lfs, TempHfs

public class Hfs
extends Tap<Configuration,RecordReader,OutputCollector>
implements FileType<Configuration>, TapWith<Configuration,RecordReader,OutputCollector>

Class Hfs is the base class for all Hadoop file system access. Hfs may only be used with the Hadoop FlowConnector sub-classes when creating Hadoop executable Flow instances.

Paths typically should point to a directory, where in turn all the "part" files immediately in that directory will be included. This is the practice Hadoop expects. Sub-directories are not included and typically result in a failure.

To include sub-directories, Hadoop supports "globing". Globing is a frustrating feature and is supported more robustly by GlobHfs and less so by Hfs.

Hfs will accept /* (wildcard) paths, but not all convenience methods like jobConf.getSize will behave properly or reliably. Nor can the Hfs instance with a wildcard path be used as a sink to write data.

In those cases use GlobHfs since it is a sub-class of MultiSourceTap.

Optionally use Dfs or Lfs for resources specific to Hadoop Distributed file system or the Local file system, respectively. Using Hfs is the best practice when possible, Lfs and Dfs are conveniences.

Use the Hfs class if the 'kind' of resource is unknown at design time. To use, prefix a scheme to the 'stringPath'. Where hdfs://... will denote Dfs, and file://... will denote Lfs.

Call HfsProps.setTemporaryDirectory(java.util.Map, String) to use a different temporary file directory path other than the current Hadoop default path.

By default Cascading on Hadoop will assume any source or sink Tap using the file:// URI scheme intends to read files from the local client filesystem (for example when using the Lfs Tap) where the Hadoop job jar is started. Subsequently Cascading will force any MapReduce jobs reading or writing to file:// resources to run in Hadoop "standalone mode" so that the file can be read.

To change this behavior, HfsProps.setLocalModeScheme(java.util.Map, String) to set a different scheme value, or to "none" to disable entirely for the case the file to be read is available on every Hadoop processing node in the exact same path.

When using a MapReduce planner, Hfs can optionally combine multiple small files (or a series of small "blocks") into larger "splits". This reduces the number of resulting map tasks created by Hadoop and can improve application performance.

This is enabled by calling HfsProps.setUseCombinedInput(boolean) to true. By default, merging or combining splits into large ones is disabled.

Apache Tez planner does not require this setting, it is supported by default and enabled by the application manager.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.String	stringPath Field stringPath

Fields inherited from interface cascading.tap.type.FileType

CASCADING_SOURCE_PATH

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Hfs()
protected	Hfs(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme)
	Hfs(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme, Path path) Constructor Hfs creates a new Hfs instance.
	Hfs(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme, Path path, SinkMode sinkMode) Constructor Hfs creates a new Hfs instance.
	Hfs(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme, java.lang.String stringPath) Constructor Hfs creates a new Hfs instance.
	Hfs(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme, java.lang.String stringPath, SinkMode sinkMode) Constructor Hfs creates a new Hfs instance.

Method Summary

Modifier and Type	Method and Description
protected void	applySourceConfInitIdentifiers(FlowProcess<? extends Configuration> process, Configuration conf, java.lang.String... fullIdentifiers)
protected TapWith<Configuration,RecordReader,OutputCollector>	create(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme, Path path, SinkMode sinkMode)
boolean	createResource(Configuration conf)
boolean	deleteChildResource(Configuration conf, java.lang.String childIdentifier)
boolean	deleteChildResource(FlowProcess<? extends Configuration> flowProcess, java.lang.String childIdentifier)
boolean	deleteResource(Configuration conf)
long	getBlockSize(Configuration conf) Method getBlockSize returns the blocksize specified by the underlying file system for this resource.
long	getBlockSize(FlowProcess<? extends Configuration> flowProcess) Method getBlockSize returns the blocksize specified by the underlying file system for this resource.
java.lang.String[]	getChildIdentifiers(Configuration conf)
java.lang.String[]	getChildIdentifiers(Configuration conf, int depth, boolean fullyQualified)
java.lang.String[]	getChildIdentifiers(FlowProcess<? extends Configuration> flowProcess)
java.lang.String[]	getChildIdentifiers(FlowProcess<? extends Configuration> flowProcess, int depth, boolean fullyQualified)
protected static boolean	getCombinedInputSafeMode(Configuration conf)
protected FileSystem	getDefaultFileSystem(Configuration configuration)
java.net.URI	getDefaultFileSystemURIScheme(Configuration configuration) Method getDefaultFileSystemURIScheme returns the URI scheme for the default Hadoop FileSystem.
FileStatus	getFileStatus(Configuration conf)
protected FileSystem	getFileSystem(Configuration configuration)
java.lang.String	getFullIdentifier(Configuration conf)
java.lang.String	getIdentifier()
protected static java.lang.String	getLocalModeScheme(Configuration conf, java.lang.String defaultValue)
long	getModifiedTime(Configuration conf)
Path	getPath()
int	getReplication(Configuration conf) Method getReplication returns the replication specified by the underlying file system for this resource.
int	getReplication(FlowProcess<? extends Configuration> flowProcess) Method getReplication returns the replication specified by the underlying file system for this resource.
long	getSize(Configuration conf)
long	getSize(FlowProcess<? extends Configuration> flowProcess)
static Path	getTempPath(Configuration conf)
java.net.URI	getURIScheme(Configuration jobConf)
protected static boolean	getUseCombinedInput(Configuration conf)
boolean	isDirectory(Configuration conf)
boolean	isDirectory(FlowProcess<? extends Configuration> flowProcess)
protected java.lang.String	makeTemporaryPathDirString(java.lang.String name)
protected java.net.URI	makeURIScheme(Configuration configuration)
TupleEntryIterator	openForRead(FlowProcess<? extends Configuration> flowProcess, RecordReader input)
TupleEntryCollector	openForWrite(FlowProcess<? extends Configuration> flowProcess, OutputCollector output)
void	resetFileStatuses() Method resetFileStatuses removes the status cache, if any.
boolean	resourceExists(Configuration conf)
protected void	setStringPath(java.lang.String stringPath)
protected void	setUriScheme(java.net.URI uriScheme)
void	sinkConfInit(FlowProcess<? extends Configuration> process, Configuration conf)
void	sourceConfInit(FlowProcess<? extends Configuration> process, Configuration conf)
protected void	sourceConfInitAddInputPath(Configuration conf, Path qualifiedPath) Deprecated.
protected void	sourceConfInitAddInputPaths(Configuration conf, java.lang.Iterable<Path> qualifiedPaths)
protected void	sourceConfInitComplete(FlowProcess<? extends Configuration> process, Configuration conf)
protected static void	verifyNoDuplicates(Configuration conf)
TapWith<Configuration,RecordReader,OutputCollector>	withChildIdentifier(java.lang.String identifier)
TapWith<Configuration,RecordReader,OutputCollector>	withScheme(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme)
TapWith<Configuration,RecordReader,OutputCollector>	withSinkMode(SinkMode sinkMode)

Methods inherited from class cascading.tap.Tap

commitResource, createResource, deleteResource, entryStream, entryStream, entryStreamCopy, entryStreamCopy, equals, flowConfInit, getConfigDef, getFullIdentifier, getModifiedTime, getNodeConfigDef, getScheme, getSinkFields, getSinkMode, getSourceFields, getStepConfigDef, getTrace, hasConfigDef, hashCode, hasNodeConfigDef, hasStepConfigDef, id, isKeep, isReplace, isSink, isSource, isTemporary, isUpdate, openForRead, openForReadUnchecked, openForWrite, outgoingScopeFor, prepareResourceForRead, prepareResourceForWrite, presentSinkFields, presentSourceFields, resolveIncomingOperationArgumentFields, resolveIncomingOperationPassThroughFields, resourceExists, retrieveSinkFields, retrieveSourceFields, rollbackResource, setScheme, spliterator, splititerator, taps, toString, tupleStream, tupleStream, tupleStreamCopy, tupleStreamCopy

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface cascading.tap.type.TapWith

asTap

Field Detail

stringPath

protected java.lang.String stringPath

Field stringPath

Constructor Detail

Hfs

protected Hfs()

Hfs

@ConstructorProperties(value="scheme")
protected Hfs(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme)

Hfs

@ConstructorProperties(value={"scheme","stringPath"})
public Hfs(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme,
                                                                 java.lang.String stringPath)

Constructor Hfs creates a new Hfs instance.

Parameters:

scheme - of type Scheme

stringPath - of type String

Hfs

@ConstructorProperties(value={"scheme","stringPath","sinkMode"})
public Hfs(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme,
                                                                            java.lang.String stringPath,
                                                                            SinkMode sinkMode)

Constructor Hfs creates a new Hfs instance.

Parameters:

scheme - of type Scheme

stringPath - of type String

sinkMode - of type SinkMode

Hfs

@ConstructorProperties(value={"scheme","path"})
public Hfs(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme,
                                                           Path path)

Constructor Hfs creates a new Hfs instance.

Parameters:

scheme - of type Scheme

path - of type Path

Hfs

@ConstructorProperties(value={"scheme","path","sinkMode"})
public Hfs(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme,
                                                                      Path path,
                                                                      SinkMode sinkMode)

Constructor Hfs creates a new Hfs instance.

Parameters:

scheme - of type Scheme

path - of type Path

sinkMode - of type SinkMode

Method Detail

getLocalModeScheme

protected static java.lang.String getLocalModeScheme(Configuration conf,
                                                     java.lang.String defaultValue)

getUseCombinedInput

protected static boolean getUseCombinedInput(Configuration conf)

getCombinedInputSafeMode

protected static boolean getCombinedInputSafeMode(Configuration conf)

withChildIdentifier

public TapWith<Configuration,RecordReader,OutputCollector> withChildIdentifier(java.lang.String identifier)

Specified by:

withChildIdentifier in interface TapWith<Configuration,RecordReader,OutputCollector>

withScheme

public TapWith<Configuration,RecordReader,OutputCollector> withScheme(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme)

Specified by:

withScheme in interface TapWith<Configuration,RecordReader,OutputCollector>

withSinkMode

public TapWith<Configuration,RecordReader,OutputCollector> withSinkMode(SinkMode sinkMode)

Specified by:

withSinkMode in interface TapWith<Configuration,RecordReader,OutputCollector>

create

protected TapWith<Configuration,RecordReader,OutputCollector> create(Scheme<Configuration,RecordReader,OutputCollector,?,?> scheme,
                                                                     Path path,
                                                                     SinkMode sinkMode)

setStringPath

protected void setStringPath(java.lang.String stringPath)

setUriScheme

protected void setUriScheme(java.net.URI uriScheme)

getURIScheme

public java.net.URI getURIScheme(Configuration jobConf)

makeURIScheme

protected java.net.URI makeURIScheme(Configuration configuration)

getDefaultFileSystemURIScheme

public java.net.URI getDefaultFileSystemURIScheme(Configuration configuration)

Method getDefaultFileSystemURIScheme returns the URI scheme for the default Hadoop FileSystem.

Parameters:

configuration - of type JobConf

Returns:

URI

getDefaultFileSystem

protected FileSystem getDefaultFileSystem(Configuration configuration)

getFileSystem

protected FileSystem getFileSystem(Configuration configuration)

getIdentifier

public java.lang.String getIdentifier()

Specified by:

getIdentifier in class Tap<Configuration,RecordReader,OutputCollector>

getPath

public Path getPath()

getFullIdentifier

public java.lang.String getFullIdentifier(Configuration conf)

Overrides:

getFullIdentifier in class Tap<Configuration,RecordReader,OutputCollector>

sourceConfInit

public void sourceConfInit(FlowProcess<? extends Configuration> process,
                           Configuration conf)

Overrides:

sourceConfInit in class Tap<Configuration,RecordReader,OutputCollector>

verifyNoDuplicates

protected static void verifyNoDuplicates(Configuration conf)

applySourceConfInitIdentifiers

protected void applySourceConfInitIdentifiers(FlowProcess<? extends Configuration> process,
                                              Configuration conf,
                                              java.lang.String... fullIdentifiers)

sourceConfInitAddInputPaths

protected void sourceConfInitAddInputPaths(Configuration conf,
                                           java.lang.Iterable<Path> qualifiedPaths)

sourceConfInitAddInputPath

@Deprecated
protected void sourceConfInitAddInputPath(Configuration conf,
                                                      Path qualifiedPath)

Deprecated.

sourceConfInitComplete

protected void sourceConfInitComplete(FlowProcess<? extends Configuration> process,
                                      Configuration conf)

sinkConfInit

public void sinkConfInit(FlowProcess<? extends Configuration> process,
                         Configuration conf)

Overrides:

sinkConfInit in class Tap<Configuration,RecordReader,OutputCollector>

openForRead

public TupleEntryIterator openForRead(FlowProcess<? extends Configuration> flowProcess,
                                      RecordReader input)
                               throws java.io.IOException

Specified by:

openForRead in class Tap<Configuration,RecordReader,OutputCollector>

Throws:

java.io.IOException

openForWrite

public TupleEntryCollector openForWrite(FlowProcess<? extends Configuration> flowProcess,
                                        OutputCollector output)
                                 throws java.io.IOException

Specified by:

openForWrite in class Tap<Configuration,RecordReader,OutputCollector>

Throws:

java.io.IOException

createResource

public boolean createResource(Configuration conf)
                       throws java.io.IOException

Specified by:

createResource in class Tap<Configuration,RecordReader,OutputCollector>

Throws:

java.io.IOException

deleteResource

public boolean deleteResource(Configuration conf)
                       throws java.io.IOException

Specified by:

deleteResource in class Tap<Configuration,RecordReader,OutputCollector>

Throws:

java.io.IOException

deleteChildResource

public boolean deleteChildResource(FlowProcess<? extends Configuration> flowProcess,
                                   java.lang.String childIdentifier)
                            throws java.io.IOException

Throws:

java.io.IOException

deleteChildResource

public boolean deleteChildResource(Configuration conf,
                                   java.lang.String childIdentifier)
                            throws java.io.IOException

Throws:

java.io.IOException

resourceExists

public boolean resourceExists(Configuration conf)
                       throws java.io.IOException

Specified by:

resourceExists in class Tap<Configuration,RecordReader,OutputCollector>

Throws:

java.io.IOException

isDirectory

public boolean isDirectory(FlowProcess<? extends Configuration> flowProcess)
                    throws java.io.IOException

Specified by:

isDirectory in interface FileType<Configuration>

Throws:

java.io.IOException

isDirectory

public boolean isDirectory(Configuration conf)
                    throws java.io.IOException

Specified by:

isDirectory in interface FileType<Configuration>

Throws:

java.io.IOException

getSize

public long getSize(FlowProcess<? extends Configuration> flowProcess)
             throws java.io.IOException

Specified by:

getSize in interface FileType<Configuration>

Throws:

java.io.IOException

getSize

public long getSize(Configuration conf)
             throws java.io.IOException

Specified by:

getSize in interface FileType<Configuration>

Throws:

java.io.IOException

getBlockSize

public long getBlockSize(FlowProcess<? extends Configuration> flowProcess)
                  throws java.io.IOException

Method getBlockSize returns the blocksize specified by the underlying file system for this resource.

Parameters:

flowProcess -

Returns:

long

Throws:

java.io.IOException - when

getBlockSize

public long getBlockSize(Configuration conf)
                  throws java.io.IOException

Method getBlockSize returns the blocksize specified by the underlying file system for this resource.

Parameters:

conf - of JobConf

Returns:

long

Throws:

java.io.IOException - when

getReplication

public int getReplication(FlowProcess<? extends Configuration> flowProcess)
                   throws java.io.IOException

Method getReplication returns the replication specified by the underlying file system for this resource.

Parameters:

flowProcess -

Returns:

int

Throws:

java.io.IOException - when

getReplication

public int getReplication(Configuration conf)
                   throws java.io.IOException

Method getReplication returns the replication specified by the underlying file system for this resource.

Parameters:

conf - of JobConf

Returns:

int

Throws:

java.io.IOException - when

getChildIdentifiers

public java.lang.String[] getChildIdentifiers(FlowProcess<? extends Configuration> flowProcess)
                                       throws java.io.IOException

Specified by:

getChildIdentifiers in interface FileType<Configuration>

Throws:

java.io.IOException

getChildIdentifiers

public java.lang.String[] getChildIdentifiers(Configuration conf)
                                       throws java.io.IOException

Specified by:

getChildIdentifiers in interface FileType<Configuration>

Throws:

java.io.IOException

getChildIdentifiers

public java.lang.String[] getChildIdentifiers(FlowProcess<? extends Configuration> flowProcess,
                                              int depth,
                                              boolean fullyQualified)
                                       throws java.io.IOException

Specified by:

getChildIdentifiers in interface FileType<Configuration>

Throws:

java.io.IOException

getChildIdentifiers

public java.lang.String[] getChildIdentifiers(Configuration conf,
                                              int depth,
                                              boolean fullyQualified)
                                       throws java.io.IOException

Specified by:

getChildIdentifiers in interface FileType<Configuration>

Throws:

java.io.IOException

getModifiedTime

public long getModifiedTime(Configuration conf)
                     throws java.io.IOException

Specified by:

getModifiedTime in class Tap<Configuration,RecordReader,OutputCollector>

Throws:

java.io.IOException

getFileStatus

public FileStatus getFileStatus(Configuration conf)
                         throws java.io.IOException

Throws:

java.io.IOException

getTempPath

public static Path getTempPath(Configuration conf)

makeTemporaryPathDirString

protected java.lang.String makeTemporaryPathDirString(java.lang.String name)

resetFileStatuses

public void resetFileStatuses()

Method resetFileStatuses removes the status cache, if any.