Class CacheableConglomerate
java.lang.Object
org.apache.derby.impl.store.access.CacheableConglomerate
- All Implemented Interfaces:
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
implementations: (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.
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate final RAMAccessManager
private Conglomerate
private Long
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
clean
(boolean forRemove) Clean the object.void
Put the object into the No Identity state.createIdentity
(Object key, Object createParameter) Create a new item and set the identity of the object to represent it.protected Conglomerate
Get the identity of this object.boolean
isDirty()
Returns true if the object is dirty.setIdentity
(Object key) Set the identity of the object to represent an item that already exists, e.g. an existing container.
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Field Details
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accessManager
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conglomid
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conglom
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Constructor Details
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CacheableConglomerate
CacheableConglomerate(RAMAccessManager parent)
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Method Details
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getConglom
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setIdentity
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 by cache manager and the cache manager will guarantee only one thread can be calling it.- Specified by:
setIdentity
in interfaceCacheable
- Returns:
- an object reference if the object can take on the identity, null otherwise.
- Throws:
StandardException
- Standard Derby Policy- See Also:
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createIdentity
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 interfaceCacheable
- 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:
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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 interfaceCacheable
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getIdentity
Get the identity of this object.
MT - thread safe.- Specified by:
getIdentity
in interfaceCacheable
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isDirty
public boolean isDirty()Returns true if the object is dirty. Will only be called when the object is unkept.
MT - thread safe -
clean
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 explicit 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 interfaceCacheable
- Throws:
StandardException
- Standard Derby error policy.
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