ds.granules.dataset

Class FileDatasetImpl

java.lang.Object

ds.granules.dataset.FileDatasetImpl

All Implemented Interfaces:

FormatMarshaller, Dataset, FileDataset

public class FileDatasetImpl
extends java.lang.Object
implements FileDataset

An implementation of the FileAccess dataset interface.

Author:

Shrideep Pallickara

Nested Class Summary

Nested classes/interfaces inherited from interface ds.granules.dataset.Dataset

Dataset.DatasetType

Constructor Summary

Constructors

Constructor and Description
FileDatasetImpl(FormatReader mFormat)
FileDatasetImpl(java.lang.String datasetIdentifier, java.lang.String datasetDescription)

Method Summary

Modifier and Type	Method and Description
void	addFile(java.lang.String fileName, java.lang.String mode) Adds a file with the specified permission "r", "w" or "rw" to this dataset.
boolean	close() Close access to this dataset.
DataAvailabilityNotifier	getDataAvailabilityNotifier() Retrieve the data availability notifier for this dataset.
Dataset.DatasetType	getDatasetType() Retrieve the type of the data set
java.lang.String	getDescription() Retrieve a description of the dataset
java.util.Collection<java.lang.String>	getFiles() Retrieves the list of files in this dataset.
java.lang.String	getIdentifier() Retrieve the identifier for this dataset.
long	getLastModificationTime() Retrieve the last update to this dataset
long	getPosition(java.lang.String fileName) Retrieves the position of filePointer for the given dataset
long	getSize(java.lang.String fileName) Returns the current size of the file in question
boolean	hasFile(java.lang.String fileName) Checks to see if the file is part of a given dataset
boolean	initializeDataset() Invokes the initialization of the dataset.
boolean	isAvailable() A check to see if the dataset is available
boolean	isDataAvailable() This polls the dataset to see if data is available for consumption.
boolean	isInitialized() Check to see if the dataset has been initialized
void	marshall(FormatWriter mFormat)
int	read(java.lang.String filename, byte[] bytesToRead) Attempts to read a set of bytes from the underlying file.
int	read(java.lang.String fileName, java.nio.ByteBuffer readBuffer) Attempts to read a set of bytes from the underlying file.
void	removeFile(java.lang.String fileName) Removes a file from this dataset.
void	setPosition(java.lang.String fileName, long newPosition) Sets the position of filePointer for one of the file in the given dataset.
boolean	supportsDataAvailabilityNotifications() Indicates whether this dataset supports dynamic data availability notifications
int	write(java.lang.String fileName, byte[] bytesToWrite) Writes a byte[] to a give file.
int	write(java.lang.String fileName, java.nio.ByteBuffer writeBuffer) Write the specified Buffer to the file corresponding to the specified file.

Methods inherited from class java.lang.Object

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

Constructor Detail

FileDatasetImpl

public FileDatasetImpl(java.lang.String datasetIdentifier,
                       java.lang.String datasetDescription)

FileDatasetImpl

public FileDatasetImpl(FormatReader mFormat)
                throws java.io.IOException,
                       DatasetException

Throws:

java.io.IOException

DatasetException

Method Detail

marshall

public void marshall(FormatWriter mFormat)

Specified by:

marshall in interface FormatMarshaller

Parameters:

mFormat - - The format writer to write to

getDatasetType

public Dataset.DatasetType getDatasetType()

Description copied from interface: Dataset

Retrieve the type of the data set

Specified by:

getDatasetType in interface Dataset

Returns:

type of the dataset

getDescription

public java.lang.String getDescription()

Description copied from interface: Dataset

Retrieve a description of the dataset

Specified by:

getDescription in interface Dataset

Returns:

A description of the dataset.

getIdentifier

public java.lang.String getIdentifier()

Description copied from interface: Dataset

Retrieve the identifier for this dataset. This would typically be a UUID which uniquely identifies the dataset in question.

Specified by:

getIdentifier in interface Dataset

Returns:

The unique identifier for this dataset.

isInitialized

public boolean isInitialized()

Description copied from interface: Dataset

Check to see if the dataset has been initialized

Specified by:

isInitialized in interface Dataset

Returns:

true if the dataset is initialized; false otherwise.

initializeDataset

public boolean initializeDataset()
                          throws DatasetException

Description copied from interface: Dataset

Invokes the initialization of the dataset. This is invoked only when the node is ready to execute the operation that will operate on this dataset.

Specified by:

initializeDataset in interface Dataset

Returns:

true if the dataset has been initialized; false otherwise.

Throws:

DatasetException

isAvailable

public boolean isAvailable()

Description copied from interface: Dataset

A check to see if the dataset is available

Specified by:

isAvailable in interface Dataset

Returns:

true if the dataset is available; false otherwise.

isDataAvailable

public boolean isDataAvailable()

Description copied from interface: Dataset

This polls the dataset to see if data is available for consumption.

Specified by:

isDataAvailable in interface Dataset

Returns:

true if data is available on this dataset; false otherwise.

getLastModificationTime

public long getLastModificationTime()

Description copied from interface: Dataset

Retrieve the last update to this dataset

Specified by:

getLastModificationTime in interface Dataset

Returns:

The time at which this dataset was last updated. The time is returned in milliseconds.

supportsDataAvailabilityNotifications

public boolean supportsDataAvailabilityNotifications()

Description copied from interface: Dataset

Indicates whether this dataset supports dynamic data availability notifications

Specified by:

supportsDataAvailabilityNotifications in interface Dataset

Returns:

true if this dataset supports data availability notifications;false otherwise.

getDataAvailabilityNotifier

public DataAvailabilityNotifier getDataAvailabilityNotifier()

Description copied from interface: Dataset

Retrieve the data availability notifier for this dataset. This method will return a NULL if the underlying dataset does not support availability notifications.

Specified by:

getDataAvailabilityNotifier in interface Dataset

Returns:

The data availability notifier for this dataset.

getSize

public long getSize(java.lang.String fileName)
             throws DatasetException

Description copied from interface: FileDataset

Returns the current size of the file in question

Specified by:

getSize in interface FileDataset

Parameters:

fileName - The name of the file

Returns:

The current size of the file

Throws:

DatasetException - If there are problems retrieving the FileChannel corresponding to the file

getPosition

public long getPosition(java.lang.String fileName)
                 throws DatasetException

Description copied from interface: FileDataset

Retrieves the position of filePointer for the given dataset

Specified by:

getPosition in interface FileDataset

Parameters:

fileName - The name of the file.

Returns:

The position of filePointer for the given dataset

Throws:

DatasetException - If there are problems retrieving the FileChannel corresponding to the file

setPosition

public void setPosition(java.lang.String fileName,
                        long newPosition)
                 throws DatasetException

Description copied from interface: FileDataset

Sets the position of filePointer for one of the file in the given dataset.

Specified by:

setPosition in interface FileDataset

Parameters:

fileName - The file

newPosition - The new position for the pointer

Throws:

DatasetException - If there are problems retrieving the FileChannel corresponding to the file

read

public int read(java.lang.String filename,
                byte[] bytesToRead)
         throws DatasetException

Description copied from interface: FileDataset

Attempts to read a set of bytes from the underlying file.

Specified by:

read in interface FileDataset

Parameters:

filename - The file to be read

bytesToRead - The byte[] to be read into

Returns:

The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream

Throws:

DatasetException - If there are problems retrieving the FileChannel corresponding to the file

read

public int read(java.lang.String fileName,
                java.nio.ByteBuffer readBuffer)
         throws DatasetException

Description copied from interface: FileDataset

Attempts to read a set of bytes from the underlying file.

Specified by:

read in interface FileDataset

Parameters:

fileName - The file to be read

readBuffer - The buffer to be read into

Returns:

The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream

Throws:

DatasetException - If there are problems retrieving the FileChannel corresponding to the file

write

public int write(java.lang.String fileName,
                 byte[] bytesToWrite)
          throws DatasetException

Description copied from interface: FileDataset

Writes a byte[] to a give file.

Specified by:

write in interface FileDataset

Parameters:

fileName - The file to be written to

bytesToWrite - The byte[] to be written.

Returns:

The number of bytes written, possibly zero

Throws:

DatasetException - If there are problems retrieving the FileChannel corresponding to the file

write

public int write(java.lang.String fileName,
                 java.nio.ByteBuffer writeBuffer)
          throws DatasetException

Description copied from interface: FileDataset

Write the specified Buffer to the file corresponding to the specified file.

Specified by:

write in interface FileDataset

Parameters:

fileName - The file to be written to

writeBuffer - The buffer holding the bytes to be written

Returns:

The number of bytes written, possibly zero

Throws:

DatasetException - If there are problems retrieving the FileChannel corresponding to the file

addFile

public void addFile(java.lang.String fileName,
                    java.lang.String mode)
             throws DatasetException

Description copied from interface: FileDataset

Adds a file with the specified permission "r", "w" or "rw" to this dataset.

Specified by:

addFile in interface FileDataset

Parameters:

fileName - The name of the file

mode - The permissions associated with this file

Throws:

DatasetException - If there are problems adding this file

removeFile

public void removeFile(java.lang.String fileName)
                throws DatasetException

Description copied from interface: FileDataset

Removes a file from this dataset.

Specified by:

removeFile in interface FileDataset

Parameters:

fileName - The name of the file

Throws:

DatasetException - If there are problems removing this file

hasFile

public boolean hasFile(java.lang.String fileName)

Description copied from interface: FileDataset

Checks to see if the file is part of a given dataset

Specified by:

hasFile in interface FileDataset

Parameters:

fileName - The name of the file

Returns:

true if the file is a part of the dataset; false otherwise.

getFiles

public java.util.Collection<java.lang.String> getFiles()

Description copied from interface: FileDataset

Retrieves the list of files in this dataset.

Specified by:

getFiles in interface FileDataset

Returns:

An collection of the files in this dataset.

close

public boolean close()
              throws DatasetException

Description copied from interface: Dataset

Close access to this dataset. This method returns true if a graceful closure of the dataset was possible. This method will try its best to close the dataset. If it fails to close the dataset an exception, outlining the problems that were encountered will, be thrown.

Specified by:

close in interface Dataset

Returns:

true if a graceful closure of this dataset was performed;false otherwise.

Throws:

DatasetException