org.vrspace.server.db
Class DBCache

java.lang.Object
  org.vrspace.server.DB
      org.vrspace.server.db.DBCache

public class DBCache

extends DB

In memory write-through cache. Holds reference to persisting DB class.

Field Summary

Fields inherited from class org.vrspace.server.DB

cache

Constructor Summary

DBCache(DB db)

Method Summary

void	commit() Commit.
void	connect(java.lang.String name) Connect to database.
java.lang.String	create(java.lang.String name) create a new database if does not exist
void	delete(java.lang.Object obj) From the table obj.getClass().getName() deletes the row having db_id == obj.db_id, from both cache and the underlying db.
void	disconnect() Disconnect
java.lang.Object	get(java.lang.Object obj) Get an object.
java.lang.Object	get(java.lang.String className, long id) Returns the object having id == obj.db_id
java.lang.Object	get(java.lang.String className, java.lang.String field, java.lang.Object value) Returns the object of className class having field == value
java.lang.Object[]	getAll(java.lang.String className) Returns all members of the class
java.lang.String[]	getClasses() Returns all VRObject Classes stored in the database.
java.lang.String	getClassName(java.lang.Object obj)
java.lang.Object[]	getRange(java.lang.Object o1, java.lang.Object o2) Returns Object[] between o1 and o2 Class must have comparator() method to be searchable.
java.lang.Object[]	getRange(java.lang.String className, java.lang.String field, java.lang.Object value) Returns Object[] of className class having field == value
void	put(java.lang.Object obj) Stores obj into database
boolean	tableExists(java.lang.String table) Does table exist?
void	update(Request r) This method updates object in cache and passes request to underlying database.

Methods inherited from class org.vrspace.server.DB

load, load, load

Methods inherited from class java.lang.Object

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

Constructor Detail

DBCache

public DBCache(DB db)

Method Detail

create

public java.lang.String create(java.lang.String name)
                        throws java.lang.Exception

Description copied from class: DB

create a new database if does not exist

Specified by:

create in class DB

Parameters:

name - Database name

Returns:

String to use as parameter to connect()

Throws:

java.lang.Exception

See Also:

DB.connect(java.lang.String)

connect

public void connect(java.lang.String name)
             throws java.lang.Exception

Connect to database. Calls underlying DB connect(). If underlying DB is SQLDB, loads all objects from DB into cache.

Specified by:

connect in class DB

Throws:

java.lang.Exception

disconnect

public void disconnect()

Disconnect

Specified by:

disconnect in class DB

commit

public void commit()

Commit. Just calls underlying commit

Specified by:

commit in class DB

get

public java.lang.Object get(java.lang.Object obj)
                     throws java.lang.Exception

Get an object.

Specified by:

get in class DB

Throws:

java.lang.Exception

delete

public void delete(java.lang.Object obj)
            throws java.lang.Exception

From the table obj.getClass().getName() deletes the row having db_id == obj.db_id, from both cache and the underlying db.

Specified by:

delete in class DB

Throws:

java.lang.Exception

get

public java.lang.Object get(java.lang.String className,
                            long id)
                     throws java.lang.Exception

Returns the object having id == obj.db_id

Specified by:

get in class DB

Throws:

java.lang.Exception

get

public java.lang.Object get(java.lang.String className,
                            java.lang.String field,
                            java.lang.Object value)
                     throws java.lang.Exception

Returns the object of className class having field == value

Specified by:

get in class DB

Throws:

java.lang.Exception

getAll

public java.lang.Object[] getAll(java.lang.String className)
                          throws java.lang.Exception

Returns all members of the class

Specified by:

getAll in class DB

Throws:

java.lang.Exception

getClasses

public java.lang.String[] getClasses()
                              throws java.lang.Exception

Returns all VRObject Classes stored in the database.

Specified by:

getClasses in class DB

Throws:

java.lang.Exception

getRange

public java.lang.Object[] getRange(java.lang.String className,
                                   java.lang.String field,
                                   java.lang.Object value)
                            throws java.lang.Exception

Returns Object[] of className class having field == value

Specified by:

getRange in class DB

Throws:

java.lang.Exception

getRange

public java.lang.Object[] getRange(java.lang.Object o1,
                                   java.lang.Object o2)
                            throws java.lang.Exception

Returns Object[] between o1 and o2 Class must have comparator() method to be searchable.

Specified by:

getRange in class DB

Throws:

java.lang.Exception

getClassName

public java.lang.String getClassName(java.lang.Object obj)

put

public void put(java.lang.Object obj)
         throws java.lang.Exception

Stores obj into database

Specified by:

put in class DB

Throws:

java.lang.Exception

update

public void update(Request r)
            throws java.lang.Exception

This method updates object in cache and passes request to underlying database.

Specified by:

update in class DB

Throws:

java.lang.Exception

tableExists

public boolean tableExists(java.lang.String table)

Does table exist?