TimeAccumViewFactory.java

/**************************************************************************************
 * 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.view.window;

import com.espertech.esper.client.EventType;
import com.espertech.esper.core.context.util.AgentInstanceViewFactoryChainContext;
import com.espertech.esper.core.service.StatementContext;
import com.espertech.esper.epl.expression.ExprNode;
import com.espertech.esper.util.JavaClassHelper;
import com.espertech.esper.view.*;

import java.util.List;

/**
 * Factory for {@link com.espertech.esper.view.window.TimeAccumView}.
 */
public class TimeAccumViewFactory implements DataWindowViewFactory, DataWindowViewWithPrevious
{
    private EventType eventType;

    /**
     * Number of msec of quiet time before results are flushed.
     */
    protected long millisecondsQuietTime;

    public void setViewParameters(ViewFactoryContext viewFactoryContext, List<ExprNode> expressionParameters) throws ViewParameterException
    {
        List<Object> viewParameters = ViewFactorySupport.validateAndEvaluate("Time accumulative batch view", viewFactoryContext.getStatementContext(), expressionParameters);
        String errorMessage = "Time accumulative batch view requires a single numeric parameter or time period parameter";
        if (viewParameters.size() != 1)
        {
            throw new ViewParameterException(errorMessage);
        }

        Object parameter = viewParameters.get(0);
        if (!(parameter instanceof Number))
        {
            throw new ViewParameterException(errorMessage);
        }
        else
        {
            Number param = (Number) parameter;
            if (JavaClassHelper.isFloatingPointNumber(param))
            {
                millisecondsQuietTime = Math.round(1000d * param.doubleValue());
            }
            else
            {
                millisecondsQuietTime = 1000 * param.longValue();
            }
        }

        if (millisecondsQuietTime < 1)
        {
            throw new ViewParameterException("Time accumulative batch view requires a size of at least 1 msec");
        }
    }

    public void attach(EventType parentEventType, StatementContext statementContext, ViewFactory optionalParentFactory, List<ViewFactory> parentViewFactories) throws ViewParameterException
    {
        this.eventType = parentEventType;
    }

    public Object makePreviousGetter() {
        return new RandomAccessByIndexGetter();
    }

    public View makeView(AgentInstanceViewFactoryChainContext agentInstanceViewFactoryContext)
    {
        IStreamRandomAccess randomAccess = ViewServiceHelper.getOptPreviousExprRandomAccess(agentInstanceViewFactoryContext);
        if (agentInstanceViewFactoryContext.isRemoveStream())
        {
            return new TimeAccumViewRStream(this, agentInstanceViewFactoryContext, millisecondsQuietTime);
        }
        else
        {
            return new TimeAccumView(this, agentInstanceViewFactoryContext, millisecondsQuietTime, randomAccess);
        }
    }

    public EventType getEventType()
    {
        return eventType;
    }

    public boolean canReuse(View view)
    {
        if (!(view instanceof TimeAccumView))
        {
            return false;
        }

        TimeAccumView myView = (TimeAccumView) view;
        if (myView.getMsecIntervalSize() != millisecondsQuietTime)
        {
            return false;
        }

        return myView.isEmpty();
    }
}