org.jboss.cache.loader
Class FileCacheLoader

java.lang.Object
  org.jboss.cache.loader.FileCacheLoader

All Implemented Interfaces:

CacheLoader, ExtendedCacheLoader, org.jboss.system.Service

Direct Known Subclasses:

FileExtendedCacheLoader

public class FileCacheLoader
extends java.lang.Object
implements ExtendedCacheLoader

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

Version:

$Id: FileCacheLoader.java,v 1.15 2006/05/30 12:42:31 msurtani Exp $

Author:

Bela Ban

Field Summary

static java.lang.String	DATA TreeCache data file.
static java.lang.String	DIR_SUFFIX TreeCache directory suffix.

Constructor Summary

FileCacheLoader()

Method Summary

void	commit(java.lang.Object tx) Commits the transaction.
void	create()
void	destroy()
boolean	exists(Fqn fqn) Returns true if the CacheLoader has a node with a Fqn.
java.util.Map	get(Fqn fqn) Returns all keys and values from the persistent store, given a fully qualified name.
java.util.Set	getChildrenNames(Fqn fqn) Returns a set of children node names as Strings.
protected java.util.Map	loadAttributes(Fqn fqn)
byte[]	loadEntireState() Loads the entire state from the filesystem and returns it as a byte buffer.
byte[]	loadState(Fqn subtree) Fetch a portion of the state for this cache from secondary storage (disk, DB) and return 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) Prepares a list of modifications.
void	put(Fqn fqn, java.util.Map attributes) Puts all entries of the map into the existing map of the given node, overwriting existing keys, but not clearing the existing map before insertion.
void	put(Fqn fqn, java.util.Map attributes, boolean erase)
java.lang.Object	put(Fqn fqn, java.lang.Object key, java.lang.Object value) Puts a key and value into the attribute map of a given node.
void	put(java.util.List modifications) Applies all modifications to the backend store.
void	remove(Fqn fqn) Removes the given node and all its subnodes.
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 or any subnodes.
void	rollback(java.lang.Object tx) Rolls the transaction back.
void	setCache(TreeCache c) Sets the TreeCache that is maintaining this CacheLoader.
void	setConfig(java.util.Properties props) Sets the configuration.
void	setRegionManager(RegionManager manager) Sets the RegionManager this object should use to manage marshalling/unmarshalling of different regions using different classloaders.
void	start()
void	stop()
protected void	storeAttributes(Fqn fqn, java.util.Map attrs)
void	storeEntireState(byte[] state) Stores the state given as a byte buffer to the filesystem.
void	storeState(byte[] state, Fqn subtree) Store the given portion of the cache tree's state in secondary storage.

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

TreeCache data file.

See Also:

Constant Field Values

DIR_SUFFIX

public static final java.lang.String DIR_SUFFIX

TreeCache directory 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. This is called before Service.create() and Service.start().

Specified by:

setConfig in interface CacheLoader

Parameters:

props - a collection of configuration properties

setCache

public void setCache(TreeCache c)

Description copied from interface: CacheLoader

Sets the TreeCache that is maintaining this CacheLoader. This method allows this CacheLoader to invoke methods on TreeCache, including fetching additional configuration information. This method is called be called after the CacheLoader instance has been constructed.

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

Throws:

java.lang.Exception

start

public void start()
           throws java.lang.Exception

Specified by:

start in interface org.jboss.system.Service

Throws:

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 set of children node names as Strings. All names are relative to this parent Fqn. Returns null if the named node is not found or there are no children. The returned set must not be modifiable. Implementors can use Collections.unmodifiableSet(Set) to make the set unmodifiable.

Specified by:

getChildrenNames in interface CacheLoader

Parameters:

fqn - The FQN of the parent

Returns:

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

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. NOTE that the expected return value of this method has changed from JBossCache 1.2.x and before! This will affect cache loaders written prior to JBossCache 1.3.0 and such implementations should be checked for compliance with the behaviour expected.

Specified by:

get in interface CacheLoader

Returns:

Map keys and values for the given node. Returns null if the node is not found. If the node is found but has no attributes, this method returns an empty Map.

Throws:

java.lang.Exception

exists

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

Description copied from interface: CacheLoader

Returns true if the CacheLoader has a node with a Fqn.

Specified by:

exists in interface CacheLoader

Returns:

true if node exists, false otherwise

Throws:

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

Puts a key and value into the attribute map of a 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

Throws:

java.lang.Exception

put

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

Description copied from interface: CacheLoader

Puts all entries of the map into the existing map of the given node, overwriting existing keys, but not clearing the existing map before insertion. This is the same behavior as Map.putAll(java.util.Map). 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

Throws:

java.lang.Exception

put

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

Throws:

java.lang.Exception

put

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

Description copied from interface: CacheLoader

Applies all modifications to the backend store. Changes may be applied in a single operation.

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. Does nothing if the node doesn't exist Returns the removed value.

Specified by:

remove in interface CacheLoader

Throws:

java.lang.Exception

remove

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

Description copied from interface: CacheLoader

Removes the given node and all its subnodes.

Specified by:

remove in interface CacheLoader

Throws:

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 or any subnodes.

Specified by:

removeData in interface CacheLoader

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

Prepares a list of 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

Commits 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 - transaction to commit

Throws:

java.lang.Exception

rollback

public void rollback(java.lang.Object tx)

Description copied from interface: CacheLoader

Rolls 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 - transaction to roll back

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

loadState

public byte[] loadState(Fqn subtree)
                 throws java.lang.Exception

Description copied from interface: ExtendedCacheLoader

Fetch a portion of the state for this cache from secondary storage (disk, DB) and return it as a byte buffer. This is for activation of a portion of new cache from a remote cache. The new cache would then call ExtendedCacheLoader.storeState(byte[], Fqn).

Specified by:

loadState in interface ExtendedCacheLoader

Parameters:

subtree - Fqn naming the root (i.e. highest level parent) node of the subtree for which state is requested.

Throws:

java.lang.Exception

See Also:

TreeCache.activateRegion(String)

storeEntireState

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

Stores 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

storeState

public void storeState(byte[] state,
                       Fqn subtree)
                throws java.lang.Exception

Description copied from interface: ExtendedCacheLoader

Store the given portion of the cache tree's state in secondary storage. Overwrite whatever is currently in secondary storage. If the transferred state has Fqns equal to or children of parameter subtree, then no special behavior is required. Otherwise, ensure that the state is integrated under the given subtree. Typically in the latter case subtree would be the Fqn of the buddy backup region for a buddy group; e.g.

If the the transferred state had Fqns starting with "/a" and subtree was "/_BUDDY_BACKUP_/192.168.1.2:5555" then the state should be stored in the local persistent store under "/_BUDDY_BACKUP_/192.168.1.2:5555/a"

Specified by:

storeState in interface ExtendedCacheLoader

Parameters:

state - the state to store

subtree - Fqn naming the root (i.e. highest level parent) node of the subtree included in state. If the Fqns of the data included in state are not already children of subtree, then their Fqns should be altered to make them children of subtree before they are persisted.

Throws:

java.lang.Exception

setRegionManager

public void setRegionManager(RegionManager manager)

Description copied from interface: ExtendedCacheLoader

Sets the RegionManager this object should use to manage marshalling/unmarshalling of different regions using different classloaders.

NOTE: This method is only intended to be used by the TreeCache instance this cache loader is associated with.

Specified by:

setRegionManager in interface ExtendedCacheLoader

Parameters:

manager - the region manager to use, or null.

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

Throws:

java.lang.Exception

storeAttributes

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

Throws:

java.lang.Exception