org.egothor.repository
Class BlobRepository

java.lang.Object
  org.egothor.repository.BlobRepository

All Implemented Interfaces:

DataRepository

public class BlobRepository
extends java.lang.Object
implements DataRepository

BLOB repository stores huge data objects which cannot be effectively stored within other repository types. This special repository assumes:

• no record of historic changes, it means, no XDeltas or patches are stored, but the previous original copies are saved as-is
• data objects come as a ready-to-use files on a disk store, or as streams

Storage method: Data objects are saved in separate files, one for each object, within a given directory. To bypass the file system limits, a directory structure is constructed to contain up to 16^{MAX_DIR_ENTRIES_HEX} files or directories.

Author:

galambos

Nested Class Summary

Nested classes/interfaces inherited from interface org.egothor.repository.DataRepository

DataRepository.TupleSequence

Constructor Summary

BlobRepository(java.lang.String root, boolean useGzip)

Method Summary

int	acceptInto(long key, File blob)
int	addItem(long key, byte[] document, int length) Adds another document into the repository.
int	addItem(long key, DataInput in)
void	close() Closes the repository.
void	destroy() Destroy the repository.
DataInputStream	elementAt(long key, int revision) Retrieves a data block.
DataRepository.TupleSequence	elements() The tuples are [long:uid;int:rev;Object:DataInputStream].
void	flush()

Methods inherited from class java.lang.Object

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

Constructor Detail

BlobRepository

public BlobRepository(java.lang.String root,
                      boolean useGzip)

Method Detail

acceptInto

public int acceptInto(long key,
                      File blob)

addItem

public int addItem(long key,
                   DataInput in)

addItem

public int addItem(long key,
                   byte[] document,
                   int length)

Description copied from interface: DataRepository

Adds another document into the repository. If the implementation is able to recognize whether the incoming data block is still the same (as the existing in the repository), it would discard the insertion request and return 0 as the signal of no-op.

Specified by:

addItem in interface DataRepository

Returns:

revision number (0 iff unchanged) or -1 when fails

elementAt

public DataInputStream elementAt(long key,
                                 int revision)

Description copied from interface: DataRepository

Retrieves a data block.

Specified by:

elementAt in interface DataRepository

Parameters:

key - the key of the block

revision - revision number of the block, 0 is used for the latest (current) revision

Returns:

null if the revision is not available (or the key is unknown)

elements

public DataRepository.TupleSequence elements()

Description copied from interface: DataRepository

The tuples are [long:uid;int:rev;Object:DataInputStream].

Specified by:

elements in interface DataRepository

flush

public void flush()

Specified by:

flush in interface DataRepository

close

public void close()

Description copied from interface: DataRepository

Closes the repository.

Specified by:

close in interface DataRepository

destroy

public void destroy()

Description copied from interface: DataRepository

Destroy the repository.

Specified by:

destroy in interface DataRepository