org.jboss.cache.loader
Class ReadOnlyDelegatingCacheLoader

java.lang.Object
  extended by org.jboss.cache.loader.AbstractCacheLoader
      extended by org.jboss.cache.loader.AbstractDelegatingCacheLoader
          extended by org.jboss.cache.loader.ReadOnlyDelegatingCacheLoader
All Implemented Interfaces:
Lifecycle, CacheLoader

public class ReadOnlyDelegatingCacheLoader
extends AbstractDelegatingCacheLoader

Provides ignoreModifications features to all cache loaders.

Since:
2.1.0
Author:
Manik Surtani

Field Summary
 
Fields inherited from class org.jboss.cache.loader.AbstractCacheLoader
buddyFqnTransformer, cache, regionManager, transactions
 
Constructor Summary
ReadOnlyDelegatingCacheLoader(CacheLoader cl)
           
 
Method Summary
 void commit(Object tx)
          Commits the transaction.
 void prepare(Object tx, List<Modification> modifications, boolean one_phase)
          Prepares a list of modifications.
 void put(Fqn name, 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.
 Object put(Fqn name, Object key, Object value)
          Puts a key and value into the attribute map of a given node.
 void put(List<Modification> modifications)
          Applies all modifications to the backend store.
 void remove(Fqn fqn)
          Removes the given node and all its subnodes, does nothing if the node does not exist.
 Object remove(Fqn fqn, 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(Object tx)
          Rolls the transaction back.
 void storeEntireState(ObjectInputStream is)
          Stores the entire state for this cache by reading it from a provided ObjectInputStream.
 void storeState(Fqn subtree, ObjectInputStream is)
          Stores the given portion of the cache tree's state in secondary storage.
 
Methods inherited from class org.jboss.cache.loader.AbstractDelegatingCacheLoader
create, destroy, exists, get, getCacheLoader, getChildrenNames, getConfig, loadEntireState, loadState, setCache, setCacheLoader, setConfig, setRegionManager, start, stop
 
Methods inherited from class org.jboss.cache.loader.AbstractCacheLoader
doMarshall, doUnmarshall, getMarshaller, getNodeDataList, loadStateHelper, move, put, regionAwareMarshall, regionAwareUnmarshall, storeStateHelper
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ReadOnlyDelegatingCacheLoader

public ReadOnlyDelegatingCacheLoader(CacheLoader cl)
Method Detail

put

public Object put(Fqn name,
                  Object key,
                  Object value)
           throws 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
Overrides:
put in class AbstractDelegatingCacheLoader
Throws:
Exception

put

public void put(Fqn name,
                Map attributes)
         throws 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

Note since 3.0, as an optimization, this method will require a definitive attribute map and not just a subset. This will allow cache loader implementations to overwrite rather than merge, if that is deemed more efficient. This will not break backward compatibility since performing a merge will not cause any loss of data even though it is an unnecessary step.

Specified by:
put in interface CacheLoader
Overrides:
put in class AbstractDelegatingCacheLoader
Parameters:
name - The fully qualified name of the node
attributes - A Map of attributes. Can be null
Throws:
Exception

put

public void put(List<Modification> modifications)
         throws 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
Overrides:
put in class AbstractDelegatingCacheLoader
Parameters:
modifications - A List of modifications
Throws:
Exception

remove

public Object remove(Fqn fqn,
                     Object key)
              throws 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
Overrides:
remove in class AbstractDelegatingCacheLoader
Throws:
Exception

remove

public void remove(Fqn fqn)
            throws Exception
Description copied from interface: CacheLoader
Removes the given node and all its subnodes, does nothing if the node does not exist.

Specified by:
remove in interface CacheLoader
Overrides:
remove in class AbstractDelegatingCacheLoader
Parameters:
fqn - the Fqn of the node
Throws:
Exception

removeData

public void removeData(Fqn fqn)
                throws 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
Overrides:
removeData in class AbstractDelegatingCacheLoader
Parameters:
fqn - the Fqn of the node
Throws:
Exception

prepare

public void prepare(Object tx,
                    List<Modification> modifications,
                    boolean one_phase)
             throws 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 corresponding SQL statements against the DB (statements derived from modifications)
For non-transactional CacheLoader (e.g. file-based), the implementation could attempt to implement its own transactional logic, attempting to write data to a temp location (or memory) and writing it to the proper location upon commit.

Specified by:
prepare in interface CacheLoader
Overrides:
prepare in class AbstractDelegatingCacheLoader
Parameters:
tx - The transaction, indended to be used by implementations as an identifier of the transaction (and not necessarily a JTA Transaction object)
modifications - A List containing Modifications, for 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:
Exception

commit

public void commit(Object tx)
            throws 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
Overrides:
commit in class AbstractDelegatingCacheLoader
Parameters:
tx - transaction to commit
Throws:
Exception

rollback

public void rollback(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
Overrides:
rollback in class AbstractDelegatingCacheLoader
Parameters:
tx - transaction to roll back

storeEntireState

public void storeEntireState(ObjectInputStream is)
                      throws Exception
Description copied from interface: CacheLoader
Stores the entire state for this cache by reading it from a provided ObjectInputStream. The state was provided to this cache by calling CacheLoader.loadEntireState(ObjectOutputStream)} on some other cache instance. State currently in storage gets overwritten.

Implementations of this method should not catch any exception or close the given ObjectInputStream parameter. In order to ensure cacheloader interoperability contents of the cache are read from the ObjectInputStream as a sequence of NodeData objects.

Default implementation is provided by AbstractCacheLoader and ensures cacheloader interoperability. Implementors are encouraged to consider extending AbstractCacheLoader prior to implementing completely custom cacheloader.

Specified by:
storeEntireState in interface CacheLoader
Overrides:
storeEntireState in class AbstractDelegatingCacheLoader
Parameters:
is - ObjectInputStream to read state
Throws:
Exception
See Also:
AbstractCacheLoader.storeEntireState(ObjectInputStream), NodeData

storeState

public void storeState(Fqn subtree,
                       ObjectInputStream is)
                throws Exception
Description copied from interface: CacheLoader
Stores 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"

Implementations of this method should not catch any exception or close the given ObjectInputStream parameter. In order to ensure cacheloader interoperability contents of the cache are read from the ObjectInputStream as a sequence of NodeData objects.

Default implementation is provided by AbstractCacheLoader and ensures cacheloader interoperability. Implementors are encouraged to consider extending AbstractCacheLoader prior to implementing completely custom cacheloader.

Specified by:
storeState in interface CacheLoader
Overrides:
storeState in class AbstractDelegatingCacheLoader
Parameters:
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.
is - ObjectInputStream to read state
Throws:
Exception
See Also:
AbstractCacheLoader.storeState(Fqn,ObjectInputStream), NodeData


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