AbstractEventBroker.java

/*
 * JBoss, Home of Professional Open Source.
 *
 * See the LEGAL.txt file distributed with this work for information regarding copyright ownership and licensing.
 *
 * See the AUTHORS.txt file distributed with this work for a full listing of individual contributors.
 */

package org.teiid.core.designer.event;

import java.util.EventObject;
import java.util.Iterator;
import java.util.List;
import org.eclipse.core.runtime.IStatus;
import org.teiid.core.designer.CoreModelerPlugin;
import org.teiid.core.designer.CoreModelerPlugin;
import org.teiid.core.designer.util.CoreArgCheck;


/**
 * @since 8.0
 */
abstract public class AbstractEventBroker extends AbstractEventSource implements EventBroker {
    private static final String CANNOT_ADD_SELF_AS_LISTENER_MESSAGE = CoreModelerPlugin.Util.getString("AbstractEventBroker.CannotAddSelfAsListener"); //$NON-NLS-1$
    private boolean shutdownRequested = false;
    private boolean shutdownComplete = false;
    private String name = ""; //$NON-NLS-1$

    // variables used when event performance monitoring
    private static final boolean EVENT_PERF;
    private static final double EVENT_FLOOR;
    private StringBuffer eventPerfMsg = new StringBuffer();

    static {
        EVENT_PERF = (System.getProperty("eventPerf") != null); //$NON-NLS-1$

        if (EVENT_PERF) {
            final double DEFAULT = 10D;
            double temp = DEFAULT;
            String txt = System.getProperty("eventFloor"); //$NON-NLS-1$

            if (txt != null) {
                try {
                    temp = Double.parseDouble(txt);
                    temp = (temp < 0) ? 0 : temp;
                } catch (NumberFormatException theException) {
                    temp = DEFAULT;
                }
            }
            EVENT_FLOOR = temp;
        } else {
            EVENT_FLOOR = 0;
        }
    }

    protected AbstractEventBroker() {
    }

    protected void setName( String name ) {
        if (name == null) {
            CoreArgCheck.isNotNull(name,
                                   CoreModelerPlugin.Util.getString("AbstractEventBroker.The_name_of_the_event_broker_may_not_be_null")); //$NON-NLS-1$
        }
        if (name.length() == 0) {
            CoreArgCheck.isNotZeroLength(name,
                                         CoreModelerPlugin.Util.getString("AbstractEventBroker.The_name_of_the_event_broker_may_not_be_zero-length")); //$NON-NLS-1$
        }
        this.name = name;
    }

    public String getName() {
        return this.name;
    }

    @Override
    public String toString() {
        return this.name;
    }

    @Override
    public void addListener( Class eventClass,
                             EventObjectListener listener ) {

        // Do not allow add EventBroker to add itself to the list of listeners
        CoreArgCheck.isNotNull(listener, CANNOT_ADD_SELF_AS_LISTENER_MESSAGE);

        // Do not allow a listener to be added if the event broker is shutdown
        assertReady();
        super.addListener(eventClass, listener);
    }

    @Override
    public void addListener( EventObjectListener listener ) {

        // Do not allow add EventBroker to add itself to the list of listeners
        CoreArgCheck.isNotNull(listener, CANNOT_ADD_SELF_AS_LISTENER_MESSAGE);

        // Do not allow a listener to be added if the event broker is shutdown
        assertReady();
        super.addListener(listener);
    }

    @Override
	public void processEvent( EventObject obj ) {
        // Do not allow an event to be processed if the event broker is shutdown
        assertReady();
        if (obj != null) {
            this.process(obj);
        }
    }

    public boolean isShutdown() {
        return isShutdownComplete();
    }

    protected void notifyListeners( EventObject obj ) {
        if (obj != null) {

            if (EVENT_PERF && (eventPerfMsg.length() == 0)) {
                eventPerfMsg.append('\n');
            }

            // variables used for event performance monitoring
            double eventTime = 0;
            int count = 0;

            // System.out.println("\nProcessing event event ... \n" +
            // "   Event type : " + obj.getClass().getName() + "\n" +
            // "   Source     : " + obj.getSource().getClass().getName());

            List listeners = super.getListeners(obj.getClass());
            // System.out.println("#listeners = " + listeners.size() );
            Iterator itr = listeners.iterator();
            while (itr.hasNext()) {
                EventObjectListener listener = (EventObjectListener)itr.next();
                // RMH: Don't want to check this, 'cause most of the time the source & the listener are NOT the same object
                // RMH: if (listener != obj.getSource()) {
                if (listener != null) {
                    try {
                        if (EVENT_PERF) {
                            double start = System.currentTimeMillis();
                            listener.processEvent(obj);
                            double totalTime = System.currentTimeMillis() - start;
                            eventTime += totalTime;
                            count++;

                            if (totalTime >= EVENT_FLOOR) {
                                final Object[] params = new Object[] {new Double(totalTime), getShortClassName(listener)};
                                eventPerfMsg.append(CoreModelerPlugin.Util.getString("AbstractEventBroker.eventFloorExceeded", params)); //$NON-NLS-1$
                            }
                        } else {
                            listener.processEvent(obj);
                        }
                    } catch (Throwable t) {
                        CoreModelerPlugin.Util.log(IStatus.ERROR,
                                                   t,
                                                   CoreModelerPlugin.Util.getString("AbstractEventBroker.Error_during_event_processing", this.getName())); //$NON-NLS-1$
                    }
                }
                // RMH: }
            }

            if (EVENT_PERF && (eventTime >= EVENT_FLOOR)) {
                final Object[] params = new Object[] {new Double(eventTime), new Integer(count), getShortClassName(obj),
                    getShortClassName(obj.getSource())};
                eventPerfMsg.append(CoreModelerPlugin.Util.getString("AbstractEventBroker.basePerformanceMessage", params)); //$NON-NLS-1$

                eventPerfMsg.append('\n');

                CoreModelerPlugin.Util.log(IStatus.ERROR, eventPerfMsg.toString());
                eventPerfMsg.setLength(0);
            }
        }
    }

    protected void assertReady() {
        if (this.shutdownRequested || this.shutdownComplete) {
            throw new IllegalStateException(
                                            CoreModelerPlugin.Util.getString("AbstractEventBroker.No_events_can_be_processed_EventBroker_is_shutdown", this.getName())); //$NON-NLS-1$
        }
    }

    private static String getShortClassName( Object theObject ) {
        String className = theObject.getClass().getName();
        int index = className.lastIndexOf('.');
        return (index == -1) ? className : className.substring(index + 1);
    }

    protected abstract void process( EventObject obj );

    protected abstract void waitToCompleteShutdown();

    protected boolean isShutdownRequested() {
        return this.shutdownRequested;
    }

    protected boolean isShutdownComplete() {
        return this.shutdownComplete;
    }

    protected void setShutdownComplete( boolean shutdownComplete ) {
        this.shutdownComplete = shutdownComplete;
    }
}