org.refcodes.component.impls.ConfigurableLifeCycleAutomatonImpl Maven / Gradle / Ivy

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// /////////////////////////////////////////////////////////////////////////////
// REFCODES.ORG
// =============================================================================
// This code is copyright (c) by Siegfried Steiner, Munich, Germany and licensed
// under the following (see "http://en.wikipedia.org/wiki/Multi-licensing")
// licenses:
// =============================================================================
// GNU General Public License, v3.0 ("http://www.gnu.org/licenses/gpl-3.0.html")
// together with the GPL linking exception applied; as being applied by the GNU
// Classpath ("http://www.gnu.org/software/classpath/license.html")
// =============================================================================
// Apache License, v2.0 ("http://www.apache.org/licenses/LICENSE-2.0")
// =============================================================================
// Please contact the copyright holding author(s) of the software artifacts in
// question for licensing issues not being covered by the above listed licenses,
// also regarding commercial licensing models or regarding the compatibility
// with other open source licenses.
// /////////////////////////////////////////////////////////////////////////////

package org.refcodes.component.impls;

import org.refcodes.component.ConfigurableLifeCycleComponent;
import org.refcodes.component.ConfigurableLifeCycleComponent.ConfigurableLifeCycleAutomaton;
import org.refcodes.component.ConfigureException;
import org.refcodes.component.LifeCycleComponent;
import org.refcodes.component.LifeCycleComponent.LifeCycleAutomaton;
import org.refcodes.component.LifeCycleStatus;
import org.refcodes.component.PauseException;
import org.refcodes.component.ResumeException;
import org.refcodes.component.StartException;
import org.refcodes.component.StopException;

/**
 * This class implements a {@link ConfigurableLifeCycleAutomaton}.
 *
 * @param  the context used to initialize the implementing instance.
 */
public class ConfigurableLifeCycleAutomatonImpl implements ConfigurableLifeCycleAutomaton {

	// /////////////////////////////////////////////////////////////////////////
	// VARIABLES:
	// /////////////////////////////////////////////////////////////////////////

	private LifeCycleStatus _lifeCycleStatus = LifeCycleStatus.NONE;
	private ConfigurableLifeCycleComponent _configurableLifeCycleComponent = null;

	// /////////////////////////////////////////////////////////////////////////
	// CONSTRUCTORS:
	// /////////////////////////////////////////////////////////////////////////

	/**
	 * Empty constructor, such {@link LifeCycleAutomaton} cannot do much more
	 * than decline the various {@link LifeCycleStatus} states for you.
	 */
	public ConfigurableLifeCycleAutomatonImpl() {}

	/**
	 * This constructor uses a {@link LifeCycleStatus} for wrapping it inside
	 * the {@link ConfigurableLifeCycleAutomatonImpl}, making sure of obeying
	 * and guarding the correct {@link LifeCycleStatus}'s order of
	 * {@link LifeCycleStatus} states for you.
	 * 
	 * @param aLifeConfigurableCycleComponent The component to be guarded
	 *        regarding the correct declination of the {@link LifeCycleStatus}
	 *        states.
	 */
	public ConfigurableLifeCycleAutomatonImpl( ConfigurableLifeCycleComponent aLifeConfigurableCycleComponent ) {
		_configurableLifeCycleComponent = aLifeConfigurableCycleComponent;
	}

	// /////////////////////////////////////////////////////////////////////////
	// METHODS:
	// /////////////////////////////////////////////////////////////////////////

	@Override
	public synchronized LifeCycleStatus getLifeCycleStatus() {
		return _lifeCycleStatus;
	}

	// /////////////////////////////////////////////////////////////////////////
	// CONVENIANCE METHODS:
	// /////////////////////////////////////////////////////////////////////////

	@Override
	public synchronized void initialize( CTX aContext ) throws ConfigureException {
		if ( !isInitalizable( aContext ) ) {
			throw new ConfigureException( aContext, "Cannot initialize (configure) as the component is in status <" + _lifeCycleStatus + "> which is not the appropriate status for initializing (configuring)." );
		}
		if ( _configurableLifeCycleComponent != null ) {
			_configurableLifeCycleComponent.initialize( aContext );
		}
		_lifeCycleStatus = LifeCycleStatus.INITIALIZED;
	}

	@SuppressWarnings("unchecked")
	@Override
	public synchronized boolean isInitalizable( CTX aContext ) {
		boolean isConfigurable = (_lifeCycleStatus == LifeCycleStatus.NONE) || (isDestroyed());
		if ( isConfigurable && _configurableLifeCycleComponent != null && _configurableLifeCycleComponent instanceof ConfigureAutomaton ) {
			ConfigureAutomaton theConfigureAutomaton = (ConfigureAutomaton) _configurableLifeCycleComponent;
			return theConfigureAutomaton.isInitalizable( aContext );
		}
		return isConfigurable;
	}

	@Override
	public synchronized boolean isInitialized() {
		return (_lifeCycleStatus == LifeCycleStatus.INITIALIZED);
	}

	@Override
	public synchronized boolean isStartable() {
		return (isInitialized() || isStopped());
	}

	@Override
	public synchronized void start() throws StartException {
		if ( !isStartable() ) {
			throw new StartException( "Cannot start as the component is in status <" + _lifeCycleStatus + "> which is not the appropriate status for starting." );
		}
		if ( _configurableLifeCycleComponent != null ) {
			_configurableLifeCycleComponent.start();
		}
		_lifeCycleStatus = LifeCycleStatus.STARTED;
	}

	@Override
	public synchronized boolean isRunning() {
		return (_lifeCycleStatus == LifeCycleStatus.STARTED);
	}

	@Override
	public synchronized boolean isPausable() {
		return isRunning();
	}

	@Override
	public synchronized void pause() throws PauseException {
		if ( !isPausable() ) {
			throw new PauseException( "Cannot pause as the component is in status <" + _lifeCycleStatus + "> which is not the appropriate status for pausing." );
		}
		if ( _configurableLifeCycleComponent != null ) {
			_configurableLifeCycleComponent.pause();
		}
		_lifeCycleStatus = LifeCycleStatus.PAUSED;
	}

	@Override
	public synchronized boolean isPaused() {
		return (_lifeCycleStatus == LifeCycleStatus.PAUSED);
	}

	@Override
	public synchronized boolean isResumable() {
		return isPaused();
	}

	@Override
	public synchronized void resume() throws ResumeException {
		if ( !isResumable() ) {
			throw new ResumeException( "Cannot resume as the component is in status <" + _lifeCycleStatus + "> which is not the appropriate status for resuming." );
		}
		if ( _configurableLifeCycleComponent != null ) {
			_configurableLifeCycleComponent.resume();
		}
		_lifeCycleStatus = LifeCycleStatus.STARTED;
	}

	@Override
	public synchronized boolean isStoppable() {
		return isRunning() || isPaused();
	}

	@Override
	public synchronized void stop() throws StopException {
		if ( !isStoppable() ) {
			throw new StopException( "Cannot stop as the component is in status <" + _lifeCycleStatus + "> which is not the appropriate status for stopping." );
		}
		if ( _configurableLifeCycleComponent != null ) {
			_configurableLifeCycleComponent.stop();
		}
		_lifeCycleStatus = LifeCycleStatus.STOPPED;
	}

	@Override
	public synchronized boolean isStopped() {
		return (_lifeCycleStatus == LifeCycleStatus.STOPPED);
	}

	@Override
	public synchronized boolean isDestroyable() {
		return isStopped();
	}

	@Override
	public synchronized void destroy() {
		if ( !isDestroyable() ) {
			return;
		}
		if ( _configurableLifeCycleComponent != null ) {
			_configurableLifeCycleComponent.destroy();
		}
		_lifeCycleStatus = LifeCycleStatus.DESTROYED;
	}

	@Override
	public synchronized boolean isDestroyed() {
		return (_lifeCycleStatus == LifeCycleStatus.DESTROYED);
	}

	// /////////////////////////////////////////////////////////////////////////
	// HOOKS:
	// /////////////////////////////////////////////////////////////////////////

	/**
	 * Provides access to the {@link LifeCycleComponent} instance.
	 * 
	 * @return The {@link LifeCycleComponent} instance being set.
	 */
	protected ConfigurableLifeCycleComponent getLifeCycleComponent() {
		return _configurableLifeCycleComponent;
	}
}