Class CacheableConglomerate
- java.lang.Object
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- org.apache.derby.impl.store.access.CacheableConglomerate
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- 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 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
Fields Modifier and Type Field Description private RAMAccessManager
accessManager
private Conglomerate
conglom
private java.lang.Long
conglomid
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Constructor Summary
Constructors Constructor Description CacheableConglomerate(RAMAccessManager parent)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method 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 if 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.
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Field Detail
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accessManager
private final RAMAccessManager accessManager
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conglomid
private java.lang.Long conglomid
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conglom
private Conglomerate conglom
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Constructor Detail
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CacheableConglomerate
CacheableConglomerate(RAMAccessManager parent)
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Method Detail
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getConglom
protected Conglomerate getConglom()
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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 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:
CacheManager.find(java.lang.Object)
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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 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:
CacheManager.create(java.lang.Object, java.lang.Object)
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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
public java.lang.Object 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
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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 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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