/**************************************************************************************
* Copyright (C) 2008 EsperTech, Inc. All rights reserved. *
* http://esper.codehaus.org *
* http://www.espertech.com *
* ---------------------------------------------------------------------------------- *
* The software in this package is published under the terms of the GPL license *
* a copy of which has been included with this distribution in the license.txt file. *
**************************************************************************************/
package com.espertech.esper.epl.join.base;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.client.EventType;
import com.espertech.esper.epl.expression.ExprEvaluator;
import com.espertech.esper.epl.expression.ExprEvaluatorContext;
import com.espertech.esper.epl.join.plan.QueryGraphValueEntryHashKeyed;
import com.espertech.esper.epl.join.table.EventTable;
import com.espertech.esper.epl.join.table.PropertyIndexedEventTableSingle;
import java.util.Iterator;
import java.util.Set;
/**
* Index lookup strategy into a poll-based cache result.
*/
public class HistoricalIndexLookupStrategyIndexSingle implements HistoricalIndexLookupStrategy
{
private final EventBean[] eventsPerStream;
private final ExprEvaluator evaluator;
private final int lookupStream;
/**
* Ctor.
*/
public HistoricalIndexLookupStrategyIndexSingle(int lookupStream, QueryGraphValueEntryHashKeyed hashKey)
{
this.eventsPerStream = new EventBean[lookupStream + 1];
this.evaluator = hashKey.getKeyExpr().getExprEvaluator();
this.lookupStream = lookupStream;
}
public Iterator<EventBean> lookup(EventBean lookupEvent, EventTable indexTable, ExprEvaluatorContext exprEvaluatorContext)
{
// The table may not be indexed as the cache may not actively cache, in which case indexing doesn't makes sense
if (indexTable instanceof PropertyIndexedEventTableSingle)
{
PropertyIndexedEventTableSingle index = (PropertyIndexedEventTableSingle) indexTable;
eventsPerStream[lookupStream] = lookupEvent;
Object key = evaluator.evaluate(eventsPerStream, true, exprEvaluatorContext);
Set<EventBean> events = index.lookup(key);
if (events != null)
{
return events.iterator();
}
return null;
}
return indexTable.iterator();
}
public String toQueryPlan() {
return this.getClass().getSimpleName() + " evaluator " + evaluator.getClass().getSimpleName();
}
}