com.aspc.DBObj

Class CacheLoadDataSource

java.lang.Object

com.aspc.DBObj.ReadOnlyDataSource

com.aspc.DBObj.CacheLoadDataSource

All Implemented Interfaces:

DataSource

public final class CacheLoadDataSource
extends ReadOnlyDataSource

Cache load data source is a special data source that will lock records fetch from this data source into memory. It is designed to be used by the "CACHE COMMAND command_text" command. All records fetched via this data source eventually are created by calling findRow( ). We have overloaded the findRow() method in the read only data source, each record that is loaded we get the associated DBData ( the actual data base raw information ) and mark it as "locked". When the MemoryManager calls clear memory because we are in a low memory situation only records that aren't "locked" will be released. If these records are needed again they will be loaded again via an SQL query. Being smart about what we lock into memory can greatly improve the system performance. THREAD MODE: MULTI-THREADED

Since:

8 March, 2003

Author:

Varun Mishra

Field Summary

Fields inherited from class com.aspc.DBObj.ReadOnlyDataSource

rootDS

Constructor Summary

Constructors

Constructor and Description
CacheLoadDataSource(DataSource ds) Creates a read only data source from another data source
CacheLoadDataSource(Login login) A valid login is required to create a ReadOnlyDataSource All database requests will be limited by the ACLs associated with Login's access group.
CacheLoadDataSource(Session session) Create a read only data source for a session

Method Summary

Modifier and Type	Method and Description
DBObject	findRow(long rowId, DBClassConcrete def, Hint hint) Finds a DBObject by it's rowId.
boolean	getForce() is the force objects to be locked into memory turned on ?
boolean	getLock() Is the data source set to lock objects in memory
void	setForce(boolean force) set on/off the force objects to be locked option
void	setLock(boolean lock) turn on/off locking of objects in memory

Methods inherited from class com.aspc.DBObj.ReadOnlyDataSource

clear, create, create, create, dispose, findDBClass, findDBClass, findDBClassAbstract, findDBClassAbstract, findKey, findKey, findKey, findKey, getAttribute, getCacheObject, getCurrentDataSource, getDataBase, getDataBaseReadOnly, getGlobalObject, getInwardLinkage, getLogin, getQueryHandler, getRealLogin, getSession, getTimeZone, getUser, hasChild, hasExcludedGroups, isDisposed, isExcludeFromGroup, makeQuery, nextNumber, nextNumber, resetReadChecks, setCacheObject, setTimeZone, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

CacheLoadDataSource

public CacheLoadDataSource(@Nonnull
                           Login login)

A valid login is required to create a ReadOnlyDataSource All database requests will be limited by the ACLs associated with Login's access group.

Parameters:

login - The user's login.

CacheLoadDataSource

public CacheLoadDataSource(@Nonnull
                           Session session)

Create a read only data source for a session

Parameters:

session - The session to use

CacheLoadDataSource

public CacheLoadDataSource(@Nonnull
                           DataSource ds)

Creates a read only data source from another data source

Parameters:

ds - The data source to use

Method Detail

findRow

@CheckReturnValue
 @Nonnull
public DBObject findRow(long rowId,
                                                    DBClassConcrete def,
                                                    Hint hint)
                                             throws NotFoundException

Finds a DBObject by it's rowId.
This is the method that is called to get ANY record for this data source no matter now this is done ie. query or findKey or getLinkedObject()

Specified by:

findRow in interface DataSource

Overrides:

findRow in class ReadOnlyDataSource

Parameters:

hint - The hint of other rows to be fetched

rowId - The row id

def - The DBClass

Returns:

The DBObject

Throws:

NotFoundException - The row wasn't found

setLock

public void setLock(boolean lock)

turn on/off locking of objects in memory

Parameters:

lock - TRUE to turn on

getLock

@CheckReturnValue
public boolean getLock()

Is the data source set to lock objects in memory

Returns:

TRUE if turned on

setForce

public void setForce(boolean force)

set on/off the force objects to be locked option

Parameters:

force - true to turn on

getForce

@CheckReturnValue
public boolean getForce()

is the force objects to be locked into memory turned on ?

Returns:

true if turned on.