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 Details

  • Constructor Details

  • 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:
    • 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:
    • 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