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## rice.persistence
Class MemoryStorage

    java.lang.Object
      rice.persistence.MemoryStorage

All Implemented Interfaces:
  Catalog, Storage

    public class MemoryStorage

extends java.lang.Object
implements Storage

This class is an implementation of Storage which provides in-memory storage. This class is specifically *NOT* designed to provide persistent storage, and simply functions as an enhanced hash table.

Constructor Summary
`MemoryStorage(IdFactory factory)` Builds a MemoryStorage object.

Method Summary
`boolean` | `exists(Id id)` Returns whether or not the provided id exists
`void` | `flush(Continuation c)` Method which is used to erase all data stored in the Storage.
`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.The result is returned via the receiveResult method on the provided Continuation with an Integer representing the size.
`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.
`void` | `store(Id id, java.io.Serializable metadata, java.io.Serializable obj, Continuation c)` Stores the object under the key `id`.
`void` | `unstore(Id id, Continuation c)` Removes the object from the list of stored objects.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### MemoryStorage

    public MemoryStorage(IdFactory factory)

  Builds a MemoryStorage object.

  Parameters:
    `factory` - The factory to build protocol-specific Ids from.

Method Detail

### flush

    public void flush(Continuation c)

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

  Specified by:
    `flush` in interface `Catalog`
  Parameters:
    `c` - The command to run once done

### 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.

  Specified by:
    `rename` in interface `Catalog`
  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

### store

    public void store(Id id,
                      java.io.Serializable metadata,
                      java.io.Serializable obj,
                      Continuation c)

  Stores the object under the key `id`. If there is already an object under `id`, that object is replaced. This method completes by calling recieveResult() of the provided continuation with the success or failure of the operation.

  Specified by:
    `store` in interface `Storage`
  Parameters:
    `obj` - The object to be made persistent.
    `id` - The object's id.
    `metadata` - The object's metadata
    `c` - The command to run once the operation is complete

### unstore

    public void unstore(Id id,
                        Continuation c)

  Removes the object from the list of stored objects. If the object was not in the cached list in the first place, nothing happens and `false` is returned. This method completes by calling recieveResult() of the provided continuation with the success or failure of the operation.

  Specified by:
    `unstore` in interface `Storage`
  Parameters:
    `id` - The object's persistence id
    `c` - The command to run once the operation is complete

### exists

    public boolean exists(Id id)

  Returns whether or not the provided id exists

  Specified by:
    `exists` in interface `Catalog`
  Parameters:
    `id` - The id to check
  Returns:
    Whether or not the given id is stored

### 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.

  Specified by:
    `getMetadata` in interface `Catalog`
  Parameters:
    `id` - The id for which the metadata is needed
  Returns:
    The metadata, or null of non 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.

  Specified by:
    `setMetadata` in interface `Catalog`
  Parameters:
    `id` - The id for the metadata
    `metadata` - The metadata to store
    `c` - The command to run once the operation is complete

### 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).

  Specified by:
    `getObject` in interface `Catalog`
  Parameters:
    `id` - The 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 the guys don't fit in memory, this method may be deprecated.

  Specified by:
    `scan` in interface `Catalog`
  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.

  Specified by:
    `scan` in interface `Catalog`
  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.

  Specified by:
    `scanMetadata` in interface `Catalog`
  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.

  Specified by:
    `scanMetadata` in interface `Catalog`
  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.

  Specified by:
    `scanMetadataValuesHead` in interface `Catalog`
  Parameters:
    `value` - The maximal metadata value
  Returns:
    The submapping

### scanMetadataValuesNull

    public java.util.SortedMap scanMetadataValuesNull()

  Returns the submapping of ids which have metadata null

  Specified by:
    `scanMetadataValuesNull` in interface `Catalog`
  Returns:
    The submapping

### getTotalSize

    public long getTotalSize()

  Returns the total size of the stored data in bytes.The result is returned via the receiveResult method on the provided Continuation with an Integer representing the size.

  Specified by:
    `getTotalSize` in interface `Catalog`
  Parameters:
    `c` - The command to run once the operation is complete
  Returns:
    The total storage size

### getSize

    public int getSize()

  Returns the number of Ids currently stored in the catalog

  Specified by:
    `getSize` in interface `Catalog`
  Returns:
    The number of ids in the catalog

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