rice.persistence
Interface Catalog

All Known Subinterfaces:

Cache, Storage, StorageManager

All Known Implementing Classes:

EmptyCache, LRUCache, MemoryStorage, PersistentStorage, StorageManagerImpl

public interface Catalog

This interface is the abstraction of something which holds objects which are available for lookup. This interface does not, however, specify how the objects are inserted, and makes NO guarantees as to whether objects available at a given point in time will be available at a later time. Implementations of the Catalog interface are designed to be interfaces which specify how objects are inserted and stored, and are designed to include a cache and persistent storage interface.

Version:

$Id: pretty.settings 2305 2005-03-11 20:22:33Z jeffh $

Author:

jeffh

Method Summary

boolean	exists(Id id) Returns whether or not an object is present in the location id .
void	flush(Continuation c) Method which is used to erase all data stored in the Catalog.
java.io.Serializable	getMetadata(Id id) Returns the metadata associated with the provided object, or null if no metadata exists.
void	getObject(Id id, Continuation c) Returns the object identified by the given id, or null if there is no cooresponding object (through receiveResult on c).
int	getSize() Returns the number of Ids currently stored in the catalog
long	getTotalSize() Returns the total size of the stored data in bytes.
void	rename(Id oldId, Id newId, Continuation c) Renames the given object to the new id.
IdSet	scan() Return all objects currently stored by this catalog NOTE: This method blocks so if the behavior of this method changes and no longer stored in memory, this method may be deprecated.
IdSet	scan(IdRange range) Return the objects identified by the given range of ids.
java.util.SortedMap	scanMetadata() Returns a map which contains keys mapping ids to the associated metadata.
java.util.SortedMap	scanMetadata(IdRange range) Returns a map which contains keys mapping ids to the associated metadata.
java.util.SortedMap	scanMetadataValuesHead(java.lang.Object value) Returns the submapping of ids which have metadata less than the provided value.
java.util.SortedMap	scanMetadataValuesNull() Returns the submapping of ids which have metadata null
void	setMetadata(Id id, java.io.Serializable metadata, Continuation command) Updates the metadata stored under the given key to be the provided value.

Method Detail

exists

public boolean exists(Id id)

Returns whether or not an object is present in the location id .

Parameters:

id - The id of the object in question.

Returns:

Whether or not an object is present at id.

getObject

public void getObject(Id id,
                      Continuation c)

Returns the object identified by the given id, or null if there is no cooresponding object (through receiveResult on c).

Parameters:

id - The id of the object in question.

c - The command to run once the operation is complete

getMetadata

public java.io.Serializable getMetadata(Id id)

Returns the metadata associated with the provided object, or null if no metadata exists. The metadata must be stored in memory, so this operation is guaranteed to be fast and non-blocking. The metadata returned from this method must *NOT* be mutated in any way, as the actual reference to the internal object is returned. Mutating this metadata may make the internal indices incorrect, resulting in undefined behavior. Changing the metadata should be done by creating a new metadata object and calling setMetadata().

Parameters:

id - The id for which the metadata is needed

Returns:

The metadata, or null if none exists

setMetadata

public void setMetadata(Id id,
                        java.io.Serializable metadata,
                        Continuation command)

Updates the metadata stored under the given key to be the provided value. As this may require a disk access, the requestor must also provide a continuation to return the result to.

Parameters:

id - The id for the metadata

metadata - The metadata to store

command - The new Metadata value

rename

public void rename(Id oldId,
                   Id newId,
                   Continuation c)

Renames the given object to the new id. This method is potentially faster than store/cache and unstore/uncache.

Parameters:

oldId - The id of the object in question.

newId - The new id of the object in question.

c - The command to run once the operation is complete

scan

public IdSet scan(IdRange range)

Return the objects identified by the given range of ids. The IdSet returned contains the Ids of the stored objects. The range is partially inclusive, the lower range is inclusive, and the upper exclusive. NOTE: This method blocks so if the behavior of this method changes and no longer stored in memory, this method may be deprecated.

Parameters:

range - The range to query

Returns:

The idset containg the keys

scan

public IdSet scan()

Return all objects currently stored by this catalog NOTE: This method blocks so if the behavior of this method changes and no longer stored in memory, this method may be deprecated.

Returns:

The idset containg the keys

scanMetadata

public java.util.SortedMap scanMetadata(IdRange range)

Returns a map which contains keys mapping ids to the associated metadata.

Parameters:

range - The range to query

Returns:

The map containg the keys

scanMetadata

public java.util.SortedMap scanMetadata()

Returns a map which contains keys mapping ids to the associated metadata.

Returns:

The treemap mapping ids to metadata

scanMetadataValuesHead

public java.util.SortedMap scanMetadataValuesHead(java.lang.Object value)

Returns the submapping of ids which have metadata less than the provided value.

Parameters:

value - The maximal metadata value

Returns:

The submapping

scanMetadataValuesNull

public java.util.SortedMap scanMetadataValuesNull()

Returns the submapping of ids which have metadata null

Returns:

The submapping

getSize

public int getSize()

Returns the number of Ids currently stored in the catalog

Returns:

The number of ids in the catalog

getTotalSize

public long getTotalSize()

Returns the total size of the stored data in bytes.

Returns:

The total storage size

flush

public void flush(Continuation c)

Method which is used to erase all data stored in the Catalog. Use this method with care!

Parameters:

c - The command to run once done