org.apache.derby.impl.services.bytecode
Class VMTypeIdCacheable

java.lang.Object
  extended byorg.apache.derby.impl.services.bytecode.VMTypeIdCacheable
All Implemented Interfaces:
Cacheable

class VMTypeIdCacheable
extends java.lang.Object
implements Cacheable

This class implements a Cacheable for a Byte code generator cache of VMTypeIds. It maps a Java class or type name to a VM type ID.


Field Summary
private  java.lang.Object descriptor
           
private  java.lang.Object key
           
 
Constructor Summary
(package private) VMTypeIdCacheable()
           
 
Method Summary
 void clean(boolean remove)
          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.
(package private)  java.lang.Object descriptor()
          Get the VM Type name (java/lang/Object) that is associated with this Cacheable
 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.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

descriptor

private java.lang.Object descriptor

key

private java.lang.Object key
Constructor Detail

VMTypeIdCacheable

VMTypeIdCacheable()
Method Detail

clearIdentity

public void clearIdentity()
Description copied from interface: Cacheable
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
See Also:
Cacheable.clearIdentity()

getIdentity

public java.lang.Object getIdentity()
Description copied from interface: Cacheable
Get the identity of this object.
MT - thread safe.

Specified by:
getIdentity in interface Cacheable
See Also:
Cacheable.getIdentity()

createIdentity

public Cacheable createIdentity(java.lang.Object key,
                                java.lang.Object createParameter)
Description copied from interface: Cacheable
Create a new item.

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 if the key is not immutable. 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.
See Also:
Cacheable.createIdentity(java.lang.Object, java.lang.Object)

setIdentity

public Cacheable setIdentity(java.lang.Object key)
Description copied from interface: Cacheable
Set the identity of the object.

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.
See Also:
Cacheable.setIdentity(java.lang.Object)

clean

public void clean(boolean remove)
Description copied from interface: Cacheable
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
See Also:
Cacheable.clean(boolean)

isDirty

public boolean isDirty()
Description copied from interface: Cacheable
Returns true of the object is dirty. May be called when the object is kept or unkept.
MT - thread safe

Specified by:
isDirty in interface Cacheable
See Also:
Cacheable.isDirty()

descriptor

java.lang.Object descriptor()
Get the VM Type name (java/lang/Object) that is associated with this Cacheable


Built on Tue 2006-10-10 19:23:47+0200, from revision exported

Apache Derby V10.1 Engine Documentation - Copyright © 1997,2005 The Apache Software Foundation or its licensors, as applicable.