Class TDCacheable
- java.lang.Object
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- org.apache.derby.impl.sql.catalog.TDCacheable
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- All Implemented Interfaces:
Cacheable
- Direct Known Subclasses:
NameTDCacheable
,OIDTDCacheable
abstract class TDCacheable extends java.lang.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.
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Field Summary
Fields Modifier and Type Field Description protected DataDictionaryImpl
dd
protected TableDescriptor
td
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Constructor Summary
Constructors Constructor Description TDCacheable(DataDictionaryImpl dd)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected boolean
checkConsistency(TableDescriptor uncachedTD, 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.TableDescriptor
getTableDescriptor()
Get the table descriptor that is associated with this Cacheableboolean
isDirty()
Returns true of the object is dirty.-
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Methods inherited from interface org.apache.derby.iapi.services.cache.Cacheable
clearIdentity, createIdentity, getIdentity, setIdentity
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Field Detail
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td
protected TableDescriptor td
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dd
protected final DataDictionaryImpl dd
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Constructor Detail
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TDCacheable
TDCacheable(DataDictionaryImpl dd)
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Method Detail
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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 interfaceCacheable
- See Also:
Cacheable.clean(boolean)
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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 interfaceCacheable
- See Also:
Cacheable.isDirty()
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getTableDescriptor
public TableDescriptor getTableDescriptor()
Get the table descriptor that is associated with this Cacheable
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checkConsistency
protected boolean checkConsistency(TableDescriptor uncachedTD, 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:
uncachedTD
- The uncached descriptor to compare toidentity
- The identity of the table descriptorreportInconsistent
- A HeaderPrintWriter to send complaints to- Returns:
- true if the descriptors are the same, false if they're different
- Throws:
StandardException
- Thrown on error
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