org.rapidcontext.core.storage

Class RootStorage

java.lang.Object

org.rapidcontext.core.storage.StorableObject

org.rapidcontext.core.storage.Storage

org.rapidcontext.core.storage.RootStorage

All Implemented Interfaces:

java.lang.Comparable

public class RootStorage
extends Storage

The root storage that provides a unified view of other storages. This class provides a number of unique storage services:

• Mounting -- Sub-storages can be mounted on a "storage/..." subpath, providing a global namespace for objects. Storage paths are automatically converted to local paths for all storage operations.
• Unification -- Mounted storages can also be overlaid or unified with the root path, providing a storage view where objects from all storages are mixed. The mount order defines which object names take priority, in case several objects have the same paths.
• Object Initialization -- Dictionary objects will be inspected upon retrieval from a mounted and unified path (i.e. not when retrieved directly from the storage). If a matching type handler or class can be located, the corresponding object will be created, initialized and cached for future references.

Version:

1.0

Author:

Per Cederberg

Field Summary

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

KEY_MOUNT_OVERLAY_PATH, KEY_MOUNT_OVERLAY_PRIO, KEY_MOUNT_PATH, KEY_MOUNT_TIME, KEY_READWRITE, PATH_STORAGE, PATH_STORAGE_CACHE, PATH_STORAGEINFO

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

dict, KEY_CLASSNAME, KEY_ID, KEY_TYPE

Constructor Summary

Constructors

Constructor and Description
RootStorage(boolean readWrite) Creates a new root storage.

Method Summary

Modifier and Type	Method and Description
void	cacheClean(boolean force) Destroys all cached objects.
java.lang.Object	load(Path path) Loads an object from the specified location.
Metadata	lookup(Path path) Searches for an object at the specified location and returns metadata about the object if found.
void	mount(Storage storage, Path path, boolean readWrite, Path overlay, int prio) Mounts a storage to a unique path.
void	remount(Path path, boolean readWrite, Path overlay, int prio) Remounts a storage for a unique path.
void	remove(Path path) Removes an object or an index at the specified location.
void	store(Path path, java.lang.Object data) Stores an object at the specified location.
void	unmount(Path path) Unmounts a storage from the specified path.
void	unmountAll() Unmounts and destroys all mounted storages.

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

compareTo, isReadWrite, loadAll, localPath, lookupAll, mountOverlayPath, mountOverlayPrio, mountTime, path, setMountInfo

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

Constructor Detail

RootStorage

public RootStorage(boolean readWrite)

Creates a new root storage.

Parameters:

readWrite - the read write flag

Method Detail

mount

public void mount(Storage storage,
                  Path path,
                  boolean readWrite,
                  Path overlay,
                  int prio)
           throws StorageException

Mounts a storage to a unique path. The path may not collide with a previously mounted storage, such that it would hide or be hidden by the other storage. Overlapping parent indices will be merged automatically. In addition to adding the storage to the specified path, it's contents may also be overlaid directly on the root path.

Parameters:

storage - the storage to mount

path - the mount path

readWrite - the read write flag

overlay - the root overlay path

prio - the root overlay search priority (higher numbers are searched before lower numbers)

Throws:

StorageException - if the storage couldn't be mounted

remount

public void remount(Path path,
                    boolean readWrite,
                    Path overlay,
                    int prio)
             throws StorageException

Remounts a storage for a unique path. The path or the storage are not modified, but only the mounting options.

Parameters:

path - the mount path

readWrite - the read write flag

overlay - the root overlay path

prio - the root overlay search priority (higher numbers are searched before lower numbers)

Throws:

StorageException - if the storage couldn't be remounted

unmount

public void unmount(Path path)
             throws StorageException

Unmounts a storage from the specified path. The path must have previously been used to mount a storage, which will also be destroyed by this operation.

Parameters:

path - the mount path

Throws:

StorageException - if the storage couldn't be unmounted

unmountAll

public void unmountAll()

Unmounts and destroys all mounted storages.

lookup

public 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.

Specified by:

lookup in class Storage

Parameters:

path - the storage location

Returns:

the metadata for the object, or null if not found

load

public 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.

Specified by:

load in class Storage

Parameters:

path - the storage location

Returns:

the data read, or null if not found

store

public 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.

Specified by:

store in class Storage

Parameters:

path - the storage location

data - the data to store

Throws:

StorageException - if the data couldn't be written

remove

public 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.

Specified by:

remove in class Storage

Parameters:

path - the storage location

Throws:

StorageException - if the data couldn't be removed

cacheClean

public void cacheClean(boolean force)

Destroys all cached objects. The objects will first be passivated and thereafter queried for their status. All modified objects will be stored persistently if possible, but errors will only be logged. If the force clean flag is set, all objects in the cache will be destroyed. Otherwise only inactive objects.

This method is called regularly from a background job in order to destroy inactive objects.

Parameters:

force - the forced clean flag