Class TDCacheable

java.lang.Object

org.apache.derby.impl.sql.catalog.TDCacheable

All Implemented Interfaces:

Cacheable

Direct Known Subclasses:

NameTDCacheable, OIDTDCacheable

abstract class TDCacheable
extends Object
implements Cacheable

This class implements a Cacheable for a DataDictionary cache of table descriptors. It is an abstract class - there is more than one cache of table descriptors per data dictionary, and this class provides the implementation that's common to all of them. The lookup key for the cache (the "identity" of the cache item) is provided by the subclass. Another design alternative was to make the table descriptors themselves the cacheable objects. This was rejected because: we would have only one way of caching table descriptors, and we need at least two (by UUID and by name); the contents of a table descriptor would have to be split out into a separate class, so it could be used as the createParameter to the createIdentity() method; the releasing of the Cacheable would have to be done when at the end of compilation by traversing the tree - by creating a separate Cacheable object, we can release the object within the getTableDescriptor() method after getting the table descriptor out of it.

Field Summary

Fields

Modifier and Type	Field	Description
protected final DataDictionaryImpl	dd
protected TableDescriptor	td

Constructor Summary

Constructors

Constructor	Description
TDCacheable(DataDictionaryImpl dd)

Method Summary

Modifier and Type	Method	Description
protected boolean	checkConsistency(TableDescriptor uncachedTD, 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.
TableDescriptor	getTableDescriptor()	Get the table descriptor that is associated with this Cacheable
boolean	isDirty()	Returns true of the object is dirty.

Methods inherited from class Object

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

Methods inherited from interface Cacheable

clearIdentity, createIdentity, getIdentity, setIdentity

Field Details

td

protected TableDescriptor td

dd

protected final DataDictionaryImpl dd

Constructor Details

TDCacheable

TDCacheable(DataDictionaryImpl dd)

Method Details

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()

getTableDescriptor

public TableDescriptor getTableDescriptor()

Get the table descriptor that is associated with this Cacheable

checkConsistency

protected boolean checkConsistency(TableDescriptor uncachedTD,
 Object identity,
 HeaderPrintWriter reportInconsistent)
                            throws StandardException

Check the consistency of the table descriptor held by this TDCacheable versus an uncached table descriptor.

Parameters:

uncachedTD - 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