org.apache.derby.impl.store.access

Class CacheableConglomerate

java.lang.Object

org.apache.derby.impl.store.access.CacheableConglomerate

All Implemented Interfaces:

Cacheable

 class CacheableConglomerate
extends java.lang.Object
implements Cacheable

The CacheableConglomerate implements a single item in the cache used by the Conglomerate directory to cache Conglomerates. It is simply a wrapper object for the conglomid and Conglomerate object that is read from the Conglomerate Conglomerate. It is a wrapper rather than extending the conglomerate implementations because we want to cache all conglomerate implementatations: (ie. Heap, B2I, ...). References to the Conglomerate objects cached by this wrapper will be handed out to callers. When this this object goes out of cache callers may still have references to the Conglomerate objects, which we are counting on java to garbage collect. The Conglomerate Objects never change after they are created.

Field Summary

Fields

Modifier and Type	Field and Description
private RAMAccessManager	accessManager
private Conglomerate	conglom
private java.lang.Long	conglomid

Constructor Summary

Constructors

Constructor and Description
CacheableConglomerate(RAMAccessManager parent)

Method Summary

Methods

Modifier and Type	Method and Description
void	clean(boolean forRemove) Clean the object.
void	clearIdentity() Put the object into the No Identity state.
Cacheable	createIdentity(java.lang.Object key, java.lang.Object createParameter) Create a new item and set the identity of the object to represent it.
protected Conglomerate	getConglom()
java.lang.Object	getIdentity() Get the identity of this object.
boolean	isDirty() Returns true of the object is dirty.
Cacheable	setIdentity(java.lang.Object key) Set the identity of the object to represent an item that already exists, e.g. an existing container.

Methods inherited from class java.lang.Object

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

Field Detail

accessManager

private final RAMAccessManager accessManager

conglomid

private java.lang.Long conglomid

conglom

private Conglomerate conglom

Constructor Detail

CacheableConglomerate

CacheableConglomerate(RAMAccessManager parent)

Method Detail

getConglom

protected Conglomerate getConglom()

setIdentity

public Cacheable setIdentity(java.lang.Object key)
                      throws StandardException

Set the identity of the object to represent an item that already exists, e.g. an existing container. The object will be in the No Identity state, ie. it will have just been created or clearIdentity() was just called.
The object must copy the information out of key, not just store a reference to key. After this call the expression getIdentity().equals(key) must return true.
If the class of the object needs to change (e.g. to support a different format) then the object should create a new object, call its initParameter() with the parameters the original object was called with, set its identity and return a reference to it. The cache manager will discard the reference to the old object.
If an exception is thrown the object must be left in the no-identity state.
MT - single thread required - Method must only be called be cache manager and the cache manager will guarantee only one thread can be calling it.

Specified by:

setIdentity in interface Cacheable

Returns:

an object reference if the object can take on the identity, null otherwise.

Throws:

StandardException - Standard Derby Policy

See Also:

CacheManager.find(java.lang.Object)

createIdentity

public Cacheable createIdentity(java.lang.Object key,
                       java.lang.Object createParameter)
                         throws StandardException

Create a new item and set the identity of the object to represent it. The object will be in the No Identity state, ie. it will have just been created or clearIdentity() was just called.
The object must copy the information out of key, not just store a reference to key. After this call the expression getIdentity().equals(key) must return true.
If the class of the object needs to change (e.g. to support a different format) then the object should create a new object, call its initParameter() with the parameters the original object was called with, set its identity and return a reference to it. The cache manager will discard the reference to the old object.
If an exception is thrown the object must be left in the no-identity state.
MT - single thread required - Method must only be called be cache manager and the cache manager will guarantee only one thread can be calling it.

Specified by:

createIdentity in interface Cacheable

Returns:

an object reference if the object can take on the identity, null otherwise.

Throws:

StandardException - If forCreate is true and the object cannot be created.

See Also:

CacheManager.create(java.lang.Object, java.lang.Object)

clearIdentity

public void clearIdentity()

Put the object into the No Identity state.
MT - single thread required - Method must only be called be cache manager and the cache manager will guarantee only one thread can be calling it.

Specified by:

clearIdentity in interface Cacheable

getIdentity

public java.lang.Object getIdentity()

Get the identity of this object.
MT - thread safe.

Specified by:

getIdentity in interface Cacheable

isDirty

public boolean isDirty()

Returns true of the object is dirty. Will only be called when the object is unkept.
MT - thread safe

Specified by:

isDirty in interface Cacheable

clean

public void clean(boolean forRemove)
           throws StandardException

Clean the object. It is up to the object to ensure synchronization of the isDirty() and clean() method calls.
If forRemove is true then the object is being removed due to an explict remove request, in this case the cache manager will have called this method regardless of the state of the isDirty()
If an exception is thrown the object must be left in the clean state.
MT - thread safe - Can be called at any time by the cache manager, it is the responsibility of the object implementing Cacheable to ensure any users of the object do not conflict with the clean call.

Specified by:

clean in interface Cacheable

Throws:

StandardException - Standard Derby error policy.