org.jboss.cache.loader

Class AsyncCacheLoader

java.lang.Object

org.jboss.cache.loader.AbstractCacheLoader

org.jboss.cache.loader.AbstractDelegatingCacheLoader

org.jboss.cache.loader.AsyncCacheLoader

All Implemented Interfaces:

Lifecycle, CacheLoader

public class AsyncCacheLoader
extends AbstractDelegatingCacheLoader

The AsyncCacheLoader is a delegating cache loader that extends AbstractDelegatingCacheLoader overriding methods to that should not just delegate the operation to the underlying cache loader.

Read operations are done synchronously, while write (CRUD - Create, Remove, Update, Delete) operations are done asynchronously. There is no provision for exception handling at the moment for problems encountered with the underlying CacheLoader during a CRUD operation, and the exception is just logged.

When configuring the CacheLoader, use the following attribute:

<attribute name="CacheLoaderAsynchronous">true</attribute>

to define whether cache loader operations are to be asynchronous. If not specified, a cache loader operation is assumed synchronous.

The following additional parameters are available:

cache.async.batchSize

Number of modifications to commit in one transaction, default is 100. The minimum batch size is 1.

cache.async.pollWait

How long to wait before processing an incomplete batch, in milliseconds. Default is 100. Set this to 0 to not wait before processing available records.

cache.async.returnOld

If true, this loader returns the old values from put(org.jboss.cache.Fqn, java.lang.Object, java.lang.Object) and remove(org.jboss.cache.Fqn, java.lang.Object) methods. Otherwise, these methods always return null. Default is true. false improves the performance of these operations.

cache.async.queueSize

Maximum number of entries to enqueue for asynchronous processing. Lowering this size may help prevent out-of-memory conditions. It also may help to prevent less records lost in the case of JVM failure. Default is 10,000 operations.

cache.async.put

If set to false, all put(org.jboss.cache.Fqn, java.lang.Object, java.lang.Object) operations will be processed synchronously, and then only the remove(org.jboss.cache.Fqn, java.lang.Object) operations will be processed asynchronously. This mode may be useful for processing expiration of messages within a separate thread and keeping other operations synchronous for reliability.

cache.async.threadPoolSize

The size of the async processor thread pool. Defaults to 1. This property is new in JBoss Cache 3.0.

For increased performance for many smaller transactions, use higher values for cache.async.batchSize and cache.async.pollWait. For larger sized records, use a smaller value for cache.async.queueSize.

Author:

Manik Surtani (manik.surtani@jboss.com)

Field Summary

Fields inherited from class org.jboss.cache.loader.AbstractCacheLoader

buddyFqnTransformer, cache, regionManager, transactions

Constructor Summary

Constructors

Constructor and Description
AsyncCacheLoader()
AsyncCacheLoader(CacheLoader cacheLoader)

Method Summary

Methods

Modifier and Type	Method and Description
void	commit(Object tx) TODO this is the same as the AbstractCacheLoader.
Map	get(Fqn name) Returns all keys and values from the persistent store, given a Fqn
void	prepare(Object tx, List<Modification> modifications, boolean one_phase) TODO this is the same as the AbstractCacheLoader.
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 name) Removes the given node and all its subnodes, does nothing if the node does not exist.
Object	remove(Fqn name, Object key) Removes the given key and value from the attributes of the given node.
void	removeData(Fqn name) Removes all attributes from a given node, but doesn't delete the node itself or any subnodes.
void	rollback(Object tx) TODO this is the same as the AbstractCacheLoader.
void	setConfig(CacheLoaderConfig.IndividualCacheLoaderConfig base) Sets the configuration.
void	start()
void	stop()
String	toString()

Methods inherited from class org.jboss.cache.loader.AbstractDelegatingCacheLoader

create, destroy, exists, getCacheLoader, getChildrenNames, getConfig, loadEntireState, loadState, setCache, setCacheLoader, setRegionManager, storeEntireState, storeState

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, wait, wait, wait

Constructor Detail

AsyncCacheLoader

public AsyncCacheLoader()

AsyncCacheLoader

public AsyncCacheLoader(CacheLoader cacheLoader)

Method Detail

setConfig

public void setConfig(CacheLoaderConfig.IndividualCacheLoaderConfig base)

Description copied from interface: CacheLoader

Sets the configuration. This is called before Lifecycle.create() and Lifecycle.start().

Specified by:

setConfig in interface CacheLoader

Overrides:

setConfig in class AbstractDelegatingCacheLoader

Parameters:

base - May be an instance of the CacheLoaderConfig.IndividualCacheLoaderConfig base class, in which case the cache loader should use the PluggableConfigurationComponent.getProperties() method to find configuration information. Alternatively, may be a type-specific subclass of CacheLoaderConfig.IndividualCacheLoaderConfig, if there is one.

get

public Map get(Fqn name)
        throws Exception

Description copied from interface: CacheLoader

Returns all keys and values from the persistent store, given a Fqn

Specified by:

get in interface CacheLoader

Overrides:

get in class AbstractDelegatingCacheLoader

Parameters:

name - the Fqn to search for.

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:

Exception

prepare

public void prepare(Object tx,
           List<Modification> modifications,
           boolean one_phase)
             throws Exception

TODO this is the same as the AbstractCacheLoader.

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

TODO this is the same as the AbstractCacheLoader.

Specified by:

commit in interface CacheLoader

Overrides:

commit in class AbstractDelegatingCacheLoader

Parameters:

tx - transaction to commit

Throws:

Exception

rollback

public void rollback(Object tx)

TODO this is the same as the AbstractCacheLoader.

Specified by:

rollback in interface CacheLoader

Overrides:

rollback in class AbstractDelegatingCacheLoader

Parameters:

tx - transaction to roll back

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<? extends K, ? extends V>). 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 name,
            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 name)
            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:

name - the Fqn of the node

Throws:

Exception

removeData

public void removeData(Fqn name)
                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:

name - the Fqn of the node

Throws:

Exception

start

public void start()
           throws Exception

Specified by:

start in interface Lifecycle

Overrides:

start in class AbstractDelegatingCacheLoader

Throws:

Exception

stop

public void stop()

Specified by:

stop in interface Lifecycle

Overrides:

stop in class AbstractDelegatingCacheLoader

toString

public String toString()

Overrides:

toString in class Object