org.apache.derby.impl.sql.catalog
Class SPSNameCacheable

java.lang.Object
  extended byorg.apache.derby.impl.sql.catalog.SPSNameCacheable
All Implemented Interfaces:
Cacheable

class SPSNameCacheable
extends java.lang.Object
implements Cacheable

This class implements a Cacheable for a DataDictionary cache of sps descriptors, with the lookup key being the name/schema of the sps. Assumes client passes in a string that includes the schema name.

The cache ensures that the class of the target sps is loaded if the sps is found in cache. This is ensured by calling loadGeneratedClass() on the sps when it is added to the cache. Each subsequent user of the sps cache will do its own load/unload on the class. Because the class manager/loader maintains reference counts on the classes it is handling, the user load/unload will just increment/decrement the use count. Only when the sps is uncached will it be unloaded.


Field Summary
private  DataDictionaryImpl dd
           
private  TableKey identity
           
private  SPSDescriptor spsd
           
 
Constructor Summary
(package private) SPSNameCacheable(DataDictionaryImpl dd)
           
 
Method Summary
private  boolean checkConsistency(SPSDescriptor uncachedSpsd, java.lang.Object identity, HeaderPrintWriter reportInconsistent)
          Check the consistency of the table descriptor held by this TDCacheable versus an uncached table descriptor.
 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.
 java.lang.Object getIdentity()
          Get the identity of this object.
 SPSDescriptor getSPSDescriptor()
          Get the sps descriptor that is associated with this Cacheable
 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

identity

private TableKey identity

spsd

private SPSDescriptor spsd

dd

private final DataDictionaryImpl dd
Constructor Detail

SPSNameCacheable

SPSNameCacheable(DataDictionaryImpl dd)
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 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)
                      throws StandardException
Description copied from interface: Cacheable
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 - Thrown on error
See Also:
Cacheable.setIdentity(java.lang.Object)

clean

public void clean(boolean forRemove)
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()

getSPSDescriptor

public SPSDescriptor getSPSDescriptor()
Get the sps descriptor that is associated with this Cacheable


checkConsistency

private boolean checkConsistency(SPSDescriptor uncachedSpsd,
                                 java.lang.Object identity,
                                 HeaderPrintWriter reportInconsistent)
                          throws StandardException
Check the consistency of the table descriptor held by this TDCacheable versus an uncached table descriptor.

Parameters:
uncachedSpsd - The uncached descriptor to compare to
identity - The identity of the table descriptor
reportInconsistent - A HeaderPrintWriter to send complaints to
Returns:
true if the descriptors are the same, false if they're different
Throws:
StandardException - Thrown on error


Apache Derby V10.0 Engine Documentation - Copyright © 1997,2004 The Apache Software Foundation or its licensors, as applicable.