ca.uhn.cache.util
Class UnstationaryQueryProcessor

java.lang.Object
  ca.uhn.cache.util.QueryProcessor
      ca.uhn.cache.util.UnstationaryQueryProcessor

public class UnstationaryQueryProcessor

extends QueryProcessor

An extension of QueryProcessor to handle unstationary data. See IUnstationaryDataSource for discussion.

Version:

$Revision: 1.1 $ updated on $Date: 2005/01/24 22:51:49 $ by $Author: bryan_tripp $

Author:

Bryan Tripp

Constructor Summary

UnstationaryQueryProcessor(IQuery theQuery, ISemanticCache theCache, int theMaxGroups, EDU.oswego.cs.dl.util.concurrent.Executor theExecutor)

Method Summary

java.util.Date	getUpdateBoundary()
protected void	init() Does nothing (over-rides default of starting cache query ...
void	setUpdate(IQueryResult theUpdate) Must be called before getCombinedData().

Methods inherited from class ca.uhn.cache.util.QueryProcessor

declareException, getCombinedResult, getRemainderQueries, setCombinedResult, setSourceResult, thread

Methods inherited from class java.lang.Object

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

Constructor Detail

UnstationaryQueryProcessor

public UnstationaryQueryProcessor(IQuery theQuery,
                                  ISemanticCache theCache,
                                  int theMaxGroups,
                                  EDU.oswego.cs.dl.util.concurrent.Executor theExecutor)
                           throws CacheException

Parameters:

theQuery - the query to process

theCache - the cache against which to process it

theMaxGroups - maximum number of remainder queries

theExecutor - handler of concurrent tasks (defaults to DirectExecutor if null)

Throws:

CacheException - if there is a problem finding the query remainder

Method Detail

init

protected void init()

Does nothing (over-rides default of starting cache query ... this is deferred until setUpdate() is called).

Overrides:

init in class QueryProcessor

getUpdateBoundary

public java.util.Date getUpdateBoundary()
                                 throws CacheException

Returns:

the date since which updates are needed from the source system, for cached regions, in order to ensure cache consistency. Should be used in a source system query (for example against an IUnstationaryDataSource) and the results should be passed to setUpdate(...).

Throws:

CacheException - if unable to perform

setUpdate

public void setUpdate(IQueryResult theUpdate)
               throws CacheException

Must be called before getCombinedData(). The cache is not queried until it is updated via this call.

Parameters:

theUpdate - results of an update query against the original source data. The update query has the same scope as theQuery, except that it is limited to data that have been updated since corresponding cached data were cached. It is used to make cached regions current before performing the main query. An IUnstationaryDataSource can be used as a source. This is essential only for unstationary data, i.e. data that may move between semantic regions. Unstationary data, if not updated, may result in records missing from getCombinedResult().

Throws:

CacheException - if unable to perform