org.jboss.cache.loader
Class AdjListJDBCCacheLoader

java.lang.Object
  org.jboss.cache.loader.AbstractCacheLoader
      org.jboss.cache.loader.AdjListJDBCCacheLoader

All Implemented Interfaces:

CacheLoader

Direct Known Subclasses:

JDBCCacheLoader, JDBCCacheLoaderOld

@ThreadSafe
public abstract class AdjListJDBCCacheLoader
extends AbstractCacheLoader

Adjacency List Model is the model of persisting trees in which each children holds a reference to its parent. An alternative model is the Nested Set Model (a.k.a. Modified Preorder Model) - this approach adds some additional indexing information to each persisted node. This indexing info is further used for optimizing operations like subtree loading, deleting etc. The indexes are update for each insertion.

Adjacency List Model proved more performance-effective for the following reason: the entire path is persisted rather than only a reference to parent. Looking up nodes heavily relies on that, and the performance is similar as in the case of Modified Preorder Model. Even more there is no costly update indexes operation.

Version:

1.0

Author:

Mircea.Markus@iquestint.com, Galder Zamarreno

Field Summary

protected ConnectionFactory	cf
protected String	driverName
protected StripedLock	lock
protected static Map<Object,Object>	NULL_NODE_IN_ROW

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

buddyFqnTransformer, cache, regionManager, transactions

Constructor Summary

AdjListJDBCCacheLoader()

Method Summary

void	commit(Object tx) Commits a transaction.
boolean	exists(Fqn name) Checks that there is a row for the fqn in the database.
Map<Object,Object>	get(Fqn name) Returns a map representing a node.
protected String	getDriverName(Connection con)
Set<String>	getChildrenNames(Fqn fqn) Fetches child node names (not pathes).
protected abstract org.apache.commons.logging.Log	getLogger()
protected void	insertNode(Fqn name, Map dataMap, boolean rowMayExist) Inserts a node into the database
protected Map<Object,Object>	loadNode(Fqn name) Loads a node from the database.
protected ByteBuffer	marshall(Object obj)
protected void	populatePreparedStatementForInsert(Fqn name, Map dataMap, PreparedStatement ps) Expects a PreparedStatement binded to AdjListJDBCCacheLoaderConfig.getInsertNodeSql()
void	prepare(Object tx, List<Modification> modifications, boolean one_phase) First phase in transaction commit process.
protected abstract AdjListJDBCCacheLoaderConfig	processConfig(CacheLoaderConfig.IndividualCacheLoaderConfig base)
Object	remove(Fqn name, Object key) Removes attribute's value for a key.
void	removeData(Fqn name) Nullifies the node.
protected void	reportAndRethrowError(String message, Exception cause)
void	rollback(Object tx) Rolls back a transaction.
protected void	safeClose(InputStream is)
protected void	safeClose(ResultSet rs)
protected void	safeClose(Statement st)
void	setConfig(CacheLoaderConfig.IndividualCacheLoaderConfig base) Sets the configuration.
void	start() Lifecycle method, called when the cache loader is started.
void	stop() Lifecycle method, called when the cache loader is stopped.
protected boolean	tableExists(String tableName, Connection con)
protected Object	unmarshall(InputStream from)
protected void	updateNode(Fqn name, Map<Object,Object> node) Updates a node in the database.

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

create, destroy, doMarshall, doUnmarshall, getMarshaller, getNodeDataList, loadEntireState, loadState, loadStateHelper, move, put, put, regionAwareMarshall, regionAwareUnmarshall, setCache, setRegionManager, storeEntireState, storeState, storeStateHelper

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.jboss.cache.loader.CacheLoader

getConfig, put, put, remove

Field Detail

cf

protected ConnectionFactory cf

driverName

protected String driverName

lock

protected StripedLock lock

NULL_NODE_IN_ROW

protected static final Map<Object,Object> NULL_NODE_IN_ROW

Constructor Detail

AdjListJDBCCacheLoader

public AdjListJDBCCacheLoader()

Method Detail

setConfig

public void setConfig(CacheLoaderConfig.IndividualCacheLoaderConfig base)

Description copied from interface: CacheLoader

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

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<Object,Object> get(Fqn name)
                       throws Exception

Returns a map representing a node.

Parameters:

name - node's fqn

Returns:

node

Throws:

Exception

getChildrenNames

public Set<String> getChildrenNames(Fqn fqn)
                             throws Exception

Fetches child node names (not pathes).

Parameters:

fqn - parent fqn

Returns:

a set of child node names or null if there are not children found for the fqn

Throws:

Exception

removeData

public void removeData(Fqn name)
                throws Exception

Nullifies the node.

Parameters:

name - node's fqn

Throws:

Exception

prepare

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

First phase in transaction commit process. The changes are committed if only one phase if requested. All the modifications are committed using the same connection.

Specified by:

prepare in interface CacheLoader

Overrides:

prepare in class AbstractCacheLoader

Parameters:

tx - something representing transaction

modifications - a list of modifications

one_phase - indicates whether it's one or two phase commit transaction

Throws:

Exception

commit

public void commit(Object tx)
            throws Exception

Commits a transaction.

Specified by:

commit in interface CacheLoader

Overrides:

commit in class AbstractCacheLoader

Parameters:

tx - the tx to commit

Throws:

Exception

rollback

public void rollback(Object tx)

Rolls back a transaction.

Specified by:

rollback in interface CacheLoader

Overrides:

rollback in class AbstractCacheLoader

Parameters:

tx - the tx to rollback

start

public void start()
           throws Exception

Description copied from interface: CacheLoader

Lifecycle method, called when the cache loader is started.

Specified by:

start in interface CacheLoader

Overrides:

start in class AbstractCacheLoader

Throws:

Exception

stop

public void stop()

Description copied from interface: CacheLoader

Lifecycle method, called when the cache loader is stopped.

Specified by:

stop in interface CacheLoader

Overrides:

stop in class AbstractCacheLoader

exists

public boolean exists(Fqn name)
               throws Exception

Checks that there is a row for the fqn in the database.

Parameters:

name - node's fqn

Returns:

true if there is a row in the database for the given fqn even if the node column is null.

Throws:

Exception

remove

public Object remove(Fqn name,
                     Object key)
              throws Exception

Removes attribute's value for a key. If after removal the node contains no attributes, the node is nullified.

Parameters:

name - node's name

key - attribute's key

Returns:

removed value or null if there was no value for the passed in key

Throws:

Exception

loadNode

protected Map<Object,Object> loadNode(Fqn name)

Loads a node from the database.

Parameters:

name - the fqn

Returns:

non-null Map representing the node, null if there is no row with the fqn in the table, NULL_NODE_IN_ROW if there is a row in the table with the fqn but the node column contains null.

insertNode

protected void insertNode(Fqn name,
                          Map dataMap,
                          boolean rowMayExist)

Inserts a node into the database

Parameters:

name - the fqn

dataMap - the node

rowMayExist - if true, then this method will not be strict in testing for 1 row being inserted, since 0 may be inserted if the row already exists.

populatePreparedStatementForInsert

protected void populatePreparedStatementForInsert(Fqn name,
                                                  Map dataMap,
                                                  PreparedStatement ps)
                                           throws Exception

Expects a PreparedStatement binded to AdjListJDBCCacheLoaderConfig.getInsertNodeSql()

Throws:

Exception

updateNode

protected void updateNode(Fqn name,
                          Map<Object,Object> node)

Updates a node in the database.

Parameters:

name - the fqn

node - new node value

getDriverName

protected String getDriverName(Connection con)

tableExists

protected boolean tableExists(String tableName,
                              Connection con)

getLogger

protected abstract org.apache.commons.logging.Log getLogger()

processConfig

protected abstract AdjListJDBCCacheLoaderConfig processConfig(CacheLoaderConfig.IndividualCacheLoaderConfig base)

reportAndRethrowError

protected void reportAndRethrowError(String message,
                                     Exception cause)
                              throws IllegalStateException

Throws:

IllegalStateException

safeClose

protected void safeClose(InputStream is)

safeClose

protected void safeClose(Statement st)

safeClose

protected void safeClose(ResultSet rs)

unmarshall

protected Object unmarshall(InputStream from)
                     throws Exception

Throws:

Exception

marshall

protected ByteBuffer marshall(Object obj)
                       throws Exception

Throws:

Exception