/**************************************************************************************
* 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.pattern.guard;
import com.espertech.esper.client.EPException;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.epl.expression.ExprEvaluator;
import com.espertech.esper.pattern.MatchedEventConvertor;
import com.espertech.esper.pattern.MatchedEventMap;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Guard implementation that keeps a timer instance and quits when the timer expired,
* and also keeps a count of the number of matches so far, checking both count and timer,
* letting all {@link com.espertech.esper.pattern.MatchedEventMap} instances pass until then.
*/
public class ExpressionGuard implements Guard
{
private static Log log = LogFactory.getLog(ExpressionGuard.class);
private final Quitable quitable;
private final MatchedEventConvertor convertor;
private final ExprEvaluator expression;
/**
* Ctor.
* @param quitable - to use to indicate that the gaurd quitted
*/
public ExpressionGuard(MatchedEventConvertor convertor, ExprEvaluator expression, Quitable quitable) {
this.quitable = quitable;
this.convertor = convertor;
this.expression = expression;
}
public void startGuard() {
}
public boolean inspect(MatchedEventMap matchEvent) {
EventBean[] eventsPerStream = convertor.convert(matchEvent);
try
{
Object result = expression.evaluate(eventsPerStream, true, quitable.getContext().getAgentInstanceContext());
if (result == null) {
return false;
}
if (result.equals(Boolean.TRUE)) {
return true;
}
quitable.guardQuit();
return false;
}
catch (RuntimeException ex)
{
String message = "Failed to evaluate expression for pattern-guard for statement '" + quitable.getContext().getPatternContext().getStatementName() + "'";
if (ex.getMessage() != null)
{
message += ": " + ex.getMessage();
}
log.error(message, ex);
throw new EPException(message);
}
}
public void stopGuard() {
}
}