org.planx.xmlstore.io
Interface FileSystem

All Known Implementing Classes:

LocalFileSystem, MemoryFileSystem

public interface FileSystem

An abstraction of a FileSystem supporting operations needed by disk XMLStore implementations. Every FileSystem has a unique FileSystemIdentifier that can be used to identify it. All Locators returned by a FileSystem will contain this FileSystemIdentifier so that the origin of the Locator can be determined.

Author:

Thomas Ambus

Method Summary

LocalLocator	all() Returns a LocalLocator to all content currently in this FileSystem.
LocalLocator	allocate() Returns a LocalLocator to a free write position that can hold size number of bytes.
LocalLocator	allocate(int size)
LocalLocator	allocate(int size, FileSystemIdentifier fsi)
void	close() Closes the file system and releases all resources.
void	copy(FileSystem fs, LocalLocator fromLoc, LocalLocator toLoc) Copies the data at fromLoc in the specified FileSystem to toLoc in this FileSystem.
FileSystemIdentifier	currentIdentifier()
void	free(LocalLocator loc) Frees the space occupied by the specified LocalLocator.
DataInput	getInput(LocalLocator loc) Positions the input at the specified location and returns a DataInput for reading.
DataOutput	getOutput(LocalLocator loc) Positions the output at the specified location and returns a DataOutpu for writing.
boolean	isContained(LocalLocator loc) Returns true if the specified LocalLocator originates from this FileSystem.
long	size() Returns the size of the FileSystem.

Method Detail

copy

void copy(FileSystem fs,
          LocalLocator fromLoc,
          LocalLocator toLoc)
          throws IOException,
                 UnknownLocatorException

Copies the data at fromLoc in the specified FileSystem to toLoc in this FileSystem.

Throws:

IOException

UnknownLocatorException

getInput

DataInput getInput(LocalLocator loc)
                   throws IOException,
                          UnknownLocatorException

Positions the input at the specified location and returns a DataInput for reading. The DataInput is shared so if multiple threads operate on the same FileSystem concurrently, external synchronization should be used.

Throws:

IOException

UnknownLocatorException

getOutput

DataOutput getOutput(LocalLocator loc)
                     throws IOException,
                            UnknownLocatorException

Positions the output at the specified location and returns a DataOutpu for writing. Note, that this can overwrite existing data. The DataInput is shared so if multiple threads operate on the same FileSystem concurrently, external synchronization should be used. When writing new data allocate() should be called first.

Throws:

IOException

UnknownLocatorException

allocate

LocalLocator allocate()
                      throws IOException

Returns a LocalLocator to a free write position that can hold size number of bytes.

Throws:

IOException

allocate

LocalLocator allocate(int size)
                      throws IOException

Throws:

IOException

allocate

LocalLocator allocate(int size,
                      FileSystemIdentifier fsi)
                      throws IOException

Throws:

IOException

currentIdentifier

FileSystemIdentifier currentIdentifier()

isContained

boolean isContained(LocalLocator loc)

Returns true if the specified LocalLocator originates from this FileSystem.

all

LocalLocator all()
                 throws IOException

Returns a LocalLocator to all content currently in this FileSystem.

Throws:

IOException

free

void free(LocalLocator loc)
          throws IOException,
                 UnknownLocatorException

Frees the space occupied by the specified LocalLocator.

Throws:

IOException

UnknownLocatorException

size

long size()
          throws IOException

Returns the size of the FileSystem.

Throws:

IOException

close

void close()
           throws IOException

Closes the file system and releases all resources.

Throws:

IOException