com.espertech.esper.epl.core.MethodPollingExecStrategyBase.java Source code

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Here is the source code for com.espertech.esper.epl.core.MethodPollingExecStrategyBase.java

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/**************************************************************************************
 * Copyright (C) 2006-2015 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.core;

import com.espertech.esper.client.EPException;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.client.EventType;
import com.espertech.esper.epl.db.PollExecStrategy;
import com.espertech.esper.epl.expression.core.ExprEvaluatorContext;
import com.espertech.esper.epl.variable.VariableReader;
import com.espertech.esper.epl.variable.VariableService;
import com.espertech.esper.event.EventAdapterService;
import net.sf.cglib.reflect.FastMethod;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.lang.reflect.InvocationTargetException;
import java.util.List;

/**
 * Viewable providing historical data from a database.
 */
public abstract class MethodPollingExecStrategyBase implements PollExecStrategy {
    private static final Log log = LogFactory.getLog(MethodPollingExecStrategyBase.class);

    protected final EventAdapterService eventAdapterService;
    protected final FastMethod method;
    protected final EventType eventType;
    protected final Object invocationTarget;
    protected final MethodPollingExecStrategyEnum strategy;
    protected final VariableReader variableReader;
    protected final String variableName;
    protected final VariableService variableService;

    public MethodPollingExecStrategyBase(EventAdapterService eventAdapterService, FastMethod method,
            EventType eventType, Object invocationTarget, MethodPollingExecStrategyEnum strategy,
            VariableReader variableReader, String variableName, VariableService variableService) {
        this.eventAdapterService = eventAdapterService;
        this.method = method;
        this.eventType = eventType;
        this.invocationTarget = invocationTarget;
        this.strategy = strategy;
        this.variableReader = variableReader;
        this.variableName = variableName;
        this.variableService = variableService;
    }

    protected abstract List<EventBean> handleResult(Object invocationResult);

    protected boolean checkNonNullArrayValue(Object value) {
        if (value == null) {
            log.warn("Expected non-null return result from method '" + method.getName()
                    + "', but received null array element value");
            return false;
        }
        return true;
    }

    public void start() {
    }

    public void done() {
    }

    public void destroy() {
    }

    public List<EventBean> poll(Object[] lookupValues, ExprEvaluatorContext exprEvaluatorContext) {
        switch (strategy) {
        case TARGET_CONST:
            return invokeInternal(lookupValues, invocationTarget);
        case TARGET_VAR:
            return invokeInternalVariable(lookupValues, variableReader);
        case TARGET_VAR_CONTEXT:
            VariableReader reader = variableService.getReader(variableName,
                    exprEvaluatorContext.getAgentInstanceId());
            if (reader == null) {
                return null;
            }
            return invokeInternalVariable(lookupValues, reader);
        default:
            throw new UnsupportedOperationException("unrecognized strategy " + strategy);
        }
    }

    private List<EventBean> invokeInternalVariable(Object[] lookupValues, VariableReader variableReader) {
        Object target = variableReader.getValue();
        if (target == null) {
            return null;
        }
        if (target instanceof EventBean) {
            target = ((EventBean) target).getUnderlying();
        }
        return invokeInternal(lookupValues, target);
    }

    private List<EventBean> invokeInternal(Object[] lookupValues, Object invocationTarget) {
        try {
            Object invocationResult = method.invoke(invocationTarget, lookupValues);
            if (invocationResult != null) {
                return handleResult(invocationResult);
            }
            return null;
        } catch (InvocationTargetException ex) {
            throw new EPException("Method '" + method.getName() + "' of class '"
                    + method.getJavaMethod().getDeclaringClass().getName() + "' reported an exception: "
                    + ex.getTargetException(), ex.getTargetException());
        }
    }

}