org.rapidcontext.core.storage

Class Storage

java.lang.Object

org.rapidcontext.core.storage.StorableObject

org.rapidcontext.core.storage.Storage

All Implemented Interfaces:

java.lang.Comparable

Direct Known Subclasses:

DirStorage, MemoryStorage, RootStorage, WrappedStorage, ZipStorage

public abstract class Storage
extends StorableObject
implements java.lang.Comparable

The persistent data storage and retrieval class. This base class is extended by storage services to provide actual data lookup and storage.

Version:

1.0

Author:

Per Cederberg

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	KEY_MOUNT_OVERLAY_PATH The dictionary key for the mount overlay path.
static java.lang.String	KEY_MOUNT_OVERLAY_PRIO The dictionary key for the mount overlay priority.
static java.lang.String	KEY_MOUNT_PATH The dictionary key for the mount path.
static java.lang.String	KEY_MOUNT_TIME The dictionary key for the mount timestamp.
static java.lang.String	KEY_READWRITE The dictionary key for the read-write flag.
static Path	PATH_STORAGE The base storage path for mounting a storage to the root.
static Path	PATH_STORAGE_CACHE The base storage path for the storage caches.
static Path	PATH_STORAGEINFO The storage information path.

Fields inherited from class org.rapidcontext.core.storage.StorableObject

dict, KEY_CLASSNAME, KEY_ID, KEY_TYPE

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Storage(java.lang.String storageType, boolean readWrite) Creates a new storage.

Method Summary

Modifier and Type	Method and Description
int	compareTo(java.lang.Object obj) Compares this storage with another.
boolean	isReadWrite() Returns the read-write flag.
abstract java.lang.Object	load(Path path) Loads an object from the specified location.
java.lang.Object[]	loadAll(Path path) Loads all object from the specified location.
protected Path	localPath(Path path) Returns a local storage path by removing an optional base storage path.
abstract Metadata	lookup(Path path) Searches for an object at the specified location and returns metadata about the object if found.
Metadata[]	lookupAll(Path path) Searches for all objects at the specified location and returns metadata about the ones found.
Path	mountOverlayPath() Returns the mount overlay path.
int	mountOverlayPrio() Returns the mount overlay priority.
java.util.Date	mountTime() Returns the storage mount time.
Path	path() Returns the storage mount path.
abstract void	remove(Path path) Removes an object or an index at the specified location.
void	setMountInfo(Path path, boolean readWrite, Path overlay, int prio) Updates the mount information for this storage.
abstract void	store(Path path, java.lang.Object data) Stores an object at the specified location.

Methods inherited from class org.rapidcontext.core.storage.StorableObject

activate, destroy, id, init, isActive, isModified, passivate, serialize, toString, type

Methods inherited from class java.lang.Object

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

Field Detail

KEY_READWRITE

public static final java.lang.String KEY_READWRITE

The dictionary key for the read-write flag.

See Also:

Constant Field Values

KEY_MOUNT_PATH

public static final java.lang.String KEY_MOUNT_PATH

The dictionary key for the mount path. The value stored is a path object. If the storage is not mounted, this key is not set or has a null value.

See Also:

Constant Field Values

KEY_MOUNT_TIME

public static final java.lang.String KEY_MOUNT_TIME

The dictionary key for the mount timestamp. The value stored is a Date object, using the current system time as default.

See Also:

Constant Field Values

KEY_MOUNT_OVERLAY_PATH

public static final java.lang.String KEY_MOUNT_OVERLAY_PATH

The dictionary key for the mount overlay path. The value stored is a path object indicating if the storage is also mounted as a global overlay. If the storage has not been mounted at all, this key is not set.

See Also:

Constant Field Values

KEY_MOUNT_OVERLAY_PRIO

public static final java.lang.String KEY_MOUNT_OVERLAY_PRIO

The dictionary key for the mount overlay priority. The value stored is an integer indicating the mount overlay priority, higher numbers corresponding to higher priority. If the storage has not been mounted at all, this key is not set.

See Also:

Constant Field Values

PATH_STORAGE

public static final Path PATH_STORAGE

The base storage path for mounting a storage to the root.

PATH_STORAGE_CACHE

public static final Path PATH_STORAGE_CACHE

The base storage path for the storage caches.

PATH_STORAGEINFO

public static final Path PATH_STORAGEINFO

The storage information path. Each storage implementation should provide introspection abilities by returning it's own dictionary when queried for this path.

Constructor Detail

Storage

protected Storage(java.lang.String storageType,
                  boolean readWrite)

Creates a new storage.

Parameters:

storageType - the storage type name

readWrite - the read write flag

Method Detail

compareTo

public int compareTo(java.lang.Object obj)
              throws java.lang.ClassCastException

Compares this storage with another.

Specified by:

compareTo in interface java.lang.Comparable

Parameters:

obj - the object to compare with

Returns:

a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified one

Throws:

java.lang.ClassCastException - if the object wasn't comparable

path

public Path path()

Returns the storage mount path.

Overrides:

path in class StorableObject

Returns:

the storage mount path, or the root path if the storage isn't mounted

localPath

protected Path localPath(Path path)

Returns a local storage path by removing an optional base storage path. If the specified path does not have the base path prefix, it is returned unmodified.

Parameters:

path - the path to adjust

Returns:

the local storage path

isReadWrite

public boolean isReadWrite()

Returns the read-write flag.

Returns:

true if the storage is writable, or false otherwise

mountTime

public java.util.Date mountTime()

Returns the storage mount time.

Returns:

the storage mount time, or the current system time if not mounted

mountOverlayPath

public Path mountOverlayPath()

Returns the mount overlay path. This value is set if the storage has been mounted as a global overlay (to the path returned). If the storage has not been mounted at all, null will be returned.

Returns:

the storage mount overlay path, or null if no mount overlay is used

mountOverlayPrio

public int mountOverlayPrio()

Returns the mount overlay priority. Higher numbers correspond to higher priority.

Returns:

the mount overlay priority, or -1 if not mounted

setMountInfo

public void setMountInfo(Path path,
                         boolean readWrite,
                         Path overlay,
                         int prio)

Updates the mount information for this storage. This method will update the mount time to the current timestamp.

Parameters:

path - the mount path (or storage root path)

readWrite - the storage read-write flag

overlay - the mount overlay path

prio - the mount overlay priority

lookup

public abstract Metadata lookup(Path path)

Searches for an object at the specified location and returns metadata about the object if found. The path may locate either an index or a specific object.

Parameters:

path - the storage location

Returns:

the metadata for the object, or null if not found

lookupAll

public Metadata[] lookupAll(Path path)

Searches for all objects at the specified location and returns metadata about the ones found. The path may locate either an index or a specific object. Any indices found by this method will be traversed recursively instead of being returned.

Parameters:

path - the storage location

Returns:

the array of object metadata, or an empty array if no objects were found

load

public abstract java.lang.Object load(Path path)

Loads an object from the specified location. The path may locate either an index or a specific object. In case of an index, the data returned is an index dictionary listing of all objects in it.

Parameters:

path - the storage location

Returns:

the data read, or null if not found

loadAll

public java.lang.Object[] loadAll(Path path)

Loads all object from the specified location. The path may locate either an index or a specific object. Any indices found by this method will be traversed recursively instead of being returned.

Parameters:

path - the storage location

Returns:

the array of data read, or an empty array if no objects were found

store

public abstract void store(Path path,
                           java.lang.Object data)
                    throws StorageException

Stores an object at the specified location. The path must locate a particular object or file, since direct manipulation of indices is not supported. Any previous data at the specified path will be overwritten or removed.

Parameters:

path - the storage location

data - the data to store

Throws:

StorageException - if the data couldn't be written

remove

public abstract void remove(Path path)
                     throws StorageException

Removes an object or an index at the specified location. If the path refers to an index, all contained objects and indices will be removed recursively.

Parameters:

path - the storage location

Throws:

StorageException - if the data couldn't be removed