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 *  This code is distributed in the hope that it will be useful, but WITHOUT
 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 *  accompanied this code).
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 *  You should have received a copy of the GNU General Public License version
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package org.graalvm.visualvm.modules.tracer;

import org.graalvm.visualvm.core.datasource.DataSource;

/**
 * ProbeStateHandler interface allows an implementing TracerProbe to be
 * notified about Tracer session state. See TracerProbe.getStateHandler().
 *
 * @author Jiri Sedlacek
 * @param <X> any DataSource type
 */
public interface ProbeStateHandler<X extends DataSource> {

    /**
     * Invoked when the is added into the Timeline view.
     *
     * @param dataSource monitored DataSource
     */
    public void probeAdded(X dataSource);

    /**
     * Invoked when the probe is removed from the Timeline view.
     *
     * @param dataSource monitored DataSource
     */
    public void probeRemoved(X dataSource);


    /**
     * Invoked when setting up a new Tracer session. This method allows a
     * Probe to notify the user about initialization progress. The actual
     * initialization (and updating the TracerProgressObject) should be
     * performed in the sessionStarting() method. Useful for example for
     * messaging a delay during instrumention of classes in target application.
     *
     * @param dataSource monitored DataSource
     * @param refresh session refresh rate in miliseconds
     * @return TracerProgressObject to track initialization progress
     */
    public TracerProgressObject sessionInitializing(X dataSource, int refresh);

    /**
     * Invoked when starting a new Tracer session. Any probe initialization
     * should be performed in this method. If provided by the
     * sessionInitializing method, a TracerProgressObject should be updated to
     * reflect the initialization progress. This method may throw a
     * SessionInitializationException in case of initialization failure. Any
     * packages/probes initialized so far will be correctly finished, however the
     * probe throwing the SessionInitializationException is responsible for
     * cleaning up any used resources and restoring its state without any
     * following events.
     *
     * @param dataSource monitored DataSource
     * @throws SessionInitializationException in case of initialization failure
     */
    public void sessionStarting(X dataSource)
            throws SessionInitializationException;

    /**
     * Invoked when all packages/probes have been started and the Tracer session
     * is running and collecting data.
     *
     * @param dataSource monitored DataSource
     */
    public void sessionRunning(X dataSource);

    /**
     * Invoked when stopping the Tracer session. Any probe cleanup should be
     * performed in this method. Any long-running cleanup code should preferably
     * be invoked in a separate worker thread to allow the Tracer session to
     * finish as fast as possible. Be sure to check/wait for the cleanup thread
     * when starting a new Tracer session in sessionStarting().
     *
     * @param dataSource monitored DataSource
     */
    public void sessionStopping(X dataSource);

    /**
     * Invoked when the Tracer session has finished.
     *
     * @param dataSource monitored DataSource
     */
    public void sessionFinished(X dataSource);

    /**
     * Invoked when refresh rate of the Tracer session has been changed.
     *
     * @param dataSource monitored DataSource
     * @param refresh session refresh rate in miliseconds
     */
    public void refreshRateChanged(X dataSource, int refresh);


    /**
     * An abstract adapter class for receiving Tracer session state notifications.
     *
     * @param <X> any DataSource type
     */
    public abstract class Adapter<X extends DataSource> implements ProbeStateHandler<X> {

        public void probeAdded(X dataSource) {}

        public void probeRemoved(X dataSource) {}

        /**
         * Invoked when setting up a new Tracer session. This method allows a
         * Probe to notify the user about initialization progress. The actual
         * initialization (and updating the TracerProgressObject) should be
         * performed in the sessionStarting() method. Useful for example for
         * messaging a delay during instrumention of classes in target application.
         *
         * @param dataSource monitored DataSource
         * @param refresh session refresh rate in miliseconds
         * @return TracerProgressObject null in default implementation
         */
        public TracerProgressObject sessionInitializing(X dataSource, int refresh) {
            return null;
        }

        public void sessionStarting(X dataSource)
                throws SessionInitializationException {}

        public void sessionRunning(X dataSource) {}

        public void sessionStopping(X dataSource) {}

        public void sessionFinished(X dataSource) {}

        public void refreshRateChanged(X dataSource, int refresh) {}

    }

}
