org.jboss.cache.loader
Class FileCacheLoader

java.lang.Object
  |
  +--org.jboss.cache.loader.FileCacheLoader

All Implemented Interfaces:

CacheLoader, org.jboss.system.Service

Direct Known Subclasses:

FileExtendedCacheLoader

public class FileCacheLoader

extends java.lang.Object

implements CacheLoader

Simple file-based CacheLoader implementation. Nodes are directories, attributes of a node is a file in the directory

Version:

$Id: FileCacheLoader.java,v 1.3 2005/09/09 07:55:09 bstansberry Exp $

Author:

Bela Ban

Field Summary

static java.lang.String	DATA
static java.lang.String	DIR_SUFFIX

Constructor Summary

FileCacheLoader()

Method Summary

void	commit(java.lang.Object tx) Commit the transaction.
void	create()
void	destroy()
boolean	exists(Fqn fqn) Checks whether the CacheLoader has a node with Fqn
java.util.Map	get(Fqn fqn) Returns all keys and values from the persistent store, given a fully qualified name
java.lang.Object	get(Fqn fqn, java.lang.Object key) Returns the value for a given key.
java.util.Set	getChildrenNames(Fqn fqn) Returns a list of children names, all names are relative.
protected java.util.Map	loadAttributes(Fqn fqn)
byte[]	loadEntireState() Loads the entire state from the filesystem and returns it as a byte buffer.
protected void	loadStateFromFilessystem(Fqn fqn, java.io.ObjectOutputStream out) Do a preorder traversal: visit the node first, then the node's children
void	prepare(java.lang.Object tx, java.util.List modifications, boolean one_phase) Prepare the modifications.
void	put(Fqn fqn, java.util.Map attributes) Inserts all elements of attributes into the attributes hashmap of the given node, overwriting existing attributes, but not clearing the existing hashmap before insertion (making it a union of existing and new attributes) If the node does not exist, all parent nodes from the root down are created automatically
void	put(Fqn fqn, java.util.Map attributes, boolean erase)
java.lang.Object	put(Fqn fqn, java.lang.Object key, java.lang.Object value) Inserts key and value into the attributes hashmap of the given node.
void	put(java.util.List modifications) Inserts all modifications to the backend store.
void	remove(Fqn fqn) Removes the given node.
java.lang.Object	remove(Fqn fqn, java.lang.Object key) Removes the given key and value from the attributes of the given node.
void	removeData(Fqn fqn) Removes all attributes from a given node, but doesn't delete the node itself
void	rollback(java.lang.Object tx) Roll the transaction back.
void	setCache(TreeCache c) This method allows the CacheLoader to set the TreeCache, therefore allowing the CacheLoader to invoke methods of the TreeCache.
void	setConfig(java.util.Properties props) Sets the configuration.
void	start()
void	stop()
protected void	storeAttributes(Fqn fqn, java.util.Map attrs)
void	storeEntireState(byte[] state) Store the state given as a byte buffer to the filesystem.

Methods inherited from class java.lang.Object

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

Field Detail

DATA

public static final java.lang.String DATA

See Also:

Constant Field Values

DIR_SUFFIX

public static final java.lang.String DIR_SUFFIX

See Also:

Constant Field Values

Constructor Detail

FileCacheLoader

public FileCacheLoader()

Method Detail

setConfig

public void setConfig(java.util.Properties props)

Description copied from interface: CacheLoader

Sets the configuration. Will be called before Service.create() and Service.start()

Specified by:

setConfig in interface CacheLoader

Parameters:

props - A list of properties, defined in the XML file

setCache

public void setCache(TreeCache c)

Description copied from interface: CacheLoader

This method allows the CacheLoader to set the TreeCache, therefore allowing the CacheLoader to invoke methods of the TreeCache. It can also use the TreeCache to fetch configuration information. Alternatively, the CacheLoader could maintain its own configuration
This method will be called directly after the CacheLoader instance has been created

Specified by:

setCache in interface CacheLoader

Parameters:

c - The cache on which this loader works

create

public void create()
            throws java.lang.Exception

Specified by:

create in interface org.jboss.system.Service

java.lang.Exception

start

public void start()
           throws java.lang.Exception

Specified by:

start in interface org.jboss.system.Service

java.lang.Exception

stop

public void stop()

Specified by:

stop in interface org.jboss.system.Service

destroy

public void destroy()

Specified by:

destroy in interface org.jboss.system.Service

getChildrenNames

public java.util.Set getChildrenNames(Fqn fqn)
                               throws java.lang.Exception

Description copied from interface: CacheLoader

Returns a list of children names, all names are relative. Returns null if the parent node is not found. The returned set must not be modified, e.g. use Collections.unmodifiableSet(s) to return the result

Specified by:

getChildrenNames in interface CacheLoader

Parameters:

fqn - The FQN of the parent

Returns:

Set. A list of children. Returns null if no children nodes are present, or the parent is not present

java.lang.Exception

get

public java.lang.Object get(Fqn fqn,
                            java.lang.Object key)
                     throws java.lang.Exception

Description copied from interface: CacheLoader

Returns the value for a given key. Returns null if the node doesn't exist, or the value is not bound

Specified by:

get in interface CacheLoader

Parameters:

fqn -

Returns:

Throws:

java.lang.Exception

get

public java.util.Map get(Fqn fqn)
                  throws java.lang.Exception

Description copied from interface: CacheLoader

Returns all keys and values from the persistent store, given a fully qualified name

Specified by:

get in interface CacheLoader

Parameters:

fqn -

Returns:

Map of keys and values for the given node. Returns null if the node was not found, or if the node has no attributes

Throws:

java.lang.Exception

exists

public boolean exists(Fqn fqn)
               throws java.lang.Exception

Description copied from interface: CacheLoader

Checks whether the CacheLoader has a node with Fqn

Specified by:

exists in interface CacheLoader

Parameters:

fqn -

Returns:

True if node exists, false otherwise

java.lang.Exception

put

public java.lang.Object put(Fqn fqn,
                            java.lang.Object key,
                            java.lang.Object value)
                     throws java.lang.Exception

Description copied from interface: CacheLoader

Inserts key and value into the attributes hashmap of the given node. If the node does not exist, all parent nodes from the root down are created automatically. Returns the old value

Specified by:

put in interface CacheLoader

java.lang.Exception

put

public void put(Fqn fqn,
                java.util.Map attributes)
         throws java.lang.Exception

Description copied from interface: CacheLoader

Inserts all elements of attributes into the attributes hashmap of the given node, overwriting existing attributes, but not clearing the existing hashmap before insertion (making it a union of existing and new attributes) If the node does not exist, all parent nodes from the root down are created automatically

Specified by:

put in interface CacheLoader

Parameters:

fqn - The fully qualified name of the node

attributes - A Map of attributes. Can be null

java.lang.Exception

put

public void put(Fqn fqn,
                java.util.Map attributes,
                boolean erase)
         throws java.lang.Exception

java.lang.Exception

put

public void put(java.util.List modifications)
         throws java.lang.Exception

Description copied from interface: CacheLoader

Inserts all modifications to the backend store. Overwrite whatever is already in the datastore.

Specified by:

put in interface CacheLoader

Parameters:

modifications - List

Throws:

java.lang.Exception

remove

public java.lang.Object remove(Fqn fqn,
                               java.lang.Object key)
                        throws java.lang.Exception

Description copied from interface: CacheLoader

Removes the given key and value from the attributes of the given node. No-op if node doesn't exist

Specified by:

remove in interface CacheLoader

java.lang.Exception

remove

public void remove(Fqn fqn)
            throws java.lang.Exception

Description copied from interface: CacheLoader

Removes the given node. If the node is the root of a subtree, this will recursively remove all subnodes, depth-first

Specified by:

remove in interface CacheLoader

java.lang.Exception

removeData

public void removeData(Fqn fqn)
                throws java.lang.Exception

Description copied from interface: CacheLoader

Removes all attributes from a given node, but doesn't delete the node itself

Specified by:

removeData in interface CacheLoader

Parameters:

fqn -

Throws:

java.lang.Exception

prepare

public void prepare(java.lang.Object tx,
                    java.util.List modifications,
                    boolean one_phase)
             throws java.lang.Exception

Description copied from interface: CacheLoader

Prepare the modifications. For example, for a DB-based CacheLoader:

1. Create a local (JDBC) transaction
2. Associate the local transaction with tx (tx is the key)
3. Execute the coresponding SQL statements against the DB (statements derived from modifications)

For non-transactional CacheLoader (e.g. file-based), this could be a null operation

Specified by:

prepare in interface CacheLoader

Parameters:

tx - The transaction, just used as a hashmap key

modifications - List, a list of all modifications within the given transaction

one_phase - Persist immediately and (for example) commit the local JDBC transaction as well. When true, we won't get a CacheLoader.commit(Object) or CacheLoader.rollback(Object) method call later

Throws:

java.lang.Exception

commit

public void commit(java.lang.Object tx)
            throws java.lang.Exception

Description copied from interface: CacheLoader

Commit the transaction. A DB-based CacheLoader would look up the local JDBC transaction asociated with tx and commit that transaction
Non-transactional CacheLoaders could simply write the data that was previously saved transiently under the given tx key, to (for example) a file system (note this only holds if the previous prepare() did not define one_phase=true

Specified by:

commit in interface CacheLoader

Parameters:

tx -

java.lang.Exception

rollback

public void rollback(java.lang.Object tx)

Description copied from interface: CacheLoader

Roll the transaction back. A DB-based CacheLoader would look up the local JDBC transaction asociated with tx and roll back that transaction

Specified by:

rollback in interface CacheLoader

Parameters:

tx -

loadEntireState

public byte[] loadEntireState()
                       throws java.lang.Exception

Loads the entire state from the filesystem and returns it as a byte buffer. The format of the byte buffer must be a list of NodeData elements

Specified by:

loadEntireState in interface CacheLoader

Returns:

Throws:

java.lang.Exception

storeEntireState

public void storeEntireState(byte[] state)
                      throws java.lang.Exception

Store the state given as a byte buffer to the filesystem. The byte buffer contains a list of zero or more NodeData elements

Specified by:

storeEntireState in interface CacheLoader

Parameters:

state -

Throws:

java.lang.Exception

loadStateFromFilessystem

protected void loadStateFromFilessystem(Fqn fqn,
                                        java.io.ObjectOutputStream out)
                                 throws java.lang.Exception

Do a preorder traversal: visit the node first, then the node's children

Parameters:

fqn - Start node

out -

Throws:

java.lang.Exception

loadAttributes

protected java.util.Map loadAttributes(Fqn fqn)
                                throws java.lang.Exception

java.lang.Exception

storeAttributes

protected void storeAttributes(Fqn fqn,
                               java.util.Map attrs)
                        throws java.lang.Exception

java.lang.Exception