/*
***************************************************************************************
* Copyright (C) 2006 EsperTech, Inc. All rights reserved. *
* http://www.espertech.com/esper *
* 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.epl.expression.core.ExprEvaluator;
import com.espertech.esper.epl.expression.core.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;
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[0] instanceof PropertyIndexedEventTableSingle) {
PropertyIndexedEventTableSingle index = (PropertyIndexedEventTableSingle) indexTable[0];
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[0].iterator();
}
public String toQueryPlan() {
return this.getClass().getSimpleName() + " evaluator " + evaluator.getClass().getSimpleName();
}
}