bundles/org.eclipse.osgi/core/framework/org/eclipse/osgi/framework/internal/core/ServiceUse.java - equinox/rt.equinox.framework - Git at Google

 /*******************************************************************************
  * Copyright (c) 2003, 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.osgi.framework.internal.core;

 import java.security.AccessController;
 import java.security.PrivilegedAction;
 import org.eclipse.osgi.framework.debug.Debug;
 import org.eclipse.osgi.util.NLS;
 import org.osgi.framework.*;

 /**
  * This class represents the use of a service by a bundle. One is created for each
  * service acquired by a bundle. This class manages the calls to ServiceFactory
  * and the bundle's use count.
  */

 public class ServiceUse {
 	/** ServiceFactory object if the service instance represents a factory,
 	 null otherwise */
 	protected ServiceFactory factory;
 	/** Service object either registered or that returned by
 	 ServiceFactory.getService() */
 	protected Object service;
 	/** BundleContext associated with this service use */
 	protected BundleContextImpl context;
 	/** ServiceDescription of the registered service */
 	protected ServiceRegistrationImpl registration;
 	/** bundle's use count for this service */
 	protected int useCount;

 	/** Internal framework object. */

 	/**
 	 * Constructs a service use encapsulating the service object.
 	 * Objects of this class should be constrcuted while holding the
 	 * registrations lock.
 	 *
 	 * @param   context bundle getting the service
 	 * @param   registration ServiceRegistration of the service
 	 */
 	protected ServiceUse(BundleContextImpl context, ServiceRegistrationImpl registration) {
 		this.context = context;
 		this.registration = registration;
 		this.useCount = 0;

 		Object service = registration.service;
 		if (service instanceof ServiceFactory) {
 			factory = (ServiceFactory) service;
 			this.service = null;
 		} else {
 			this.factory = null;
 			this.service = service;
 		}
 	}

 	/**
 	 * Get a service's service object.
 	 * Retrieves the service object for a service.
 	 * A bundle's use of a service is tracked by a
 	 * use count. Each time a service's service object is returned by
 	 * {@link #getService}, the context bundle's use count for the service
 	 * is incremented by one. Each time the service is release by
 	 * {@link #ungetService}, the context bundle's use count
 	 * for the service is decremented by one.
 	 * When a bundle's use count for a service
 	 * drops to zero, the bundle should no longer use the service.
 	 *
 	 * <p>The following steps are followed to get the service object:
 	 * <ol>
 	 * <li>The context bundle's use count for this service is incremented by one.
 	 * <li>If the context bundle's use count for the service is now one and
 	 * the service was registered with a {@link ServiceFactory},
 	 * the {@link ServiceFactory#getService ServiceFactory.getService} method
 	 * is called to create a service object for the context bundle.
 	 * This service object is cached by the framework.
 	 * While the context bundle's use count for the service is greater than zero,
 	 * subsequent calls to get the services's service object for the context bundle
 	 * will return the cached service object.
 	 * <br>If the service object returned by the {@link ServiceFactory}
 	 * is not an <code>instanceof</code>
 	 * all the classes named when the service was registered or
 	 * the {@link ServiceFactory} throws an exception,
 	 * <code>null</code> is returned and a
 	 * {@link FrameworkEvent} of type {@link FrameworkEvent#ERROR} is broadcast.
 	 * <li>The service object for the service is returned.
 	 * </ol>
 	 *
 	 * @return A service object for the service associated with this
 	 * reference.
 	 */
 	protected Object getService() {
 		if ((useCount == 0) && (factory != null)) {
 			AbstractBundle factorybundle = registration.context.bundle;
 			Object service;

 			try {
 				service = AccessController.doPrivileged(new PrivilegedAction() {
 					public Object run() {
 						return factory.getService(context.bundle, registration);
 					}
 				});
 			} catch (Throwable t) {
 				if (Debug.DEBUG && Debug.DEBUG_SERVICES) {
 					Debug.println(factory + ".getService() exception: " + t.getMessage()); //$NON-NLS-1$
 					Debug.printStackTrace(t);
 				}
 				// allow the adaptor to handle this unexpected error
 				context.framework.adaptor.handleRuntimeError(t);
 				BundleException be = new BundleException(NLS.bind(Msg.SERVICE_FACTORY_EXCEPTION, factory.getClass().getName(), "getService"), t); //$NON-NLS-1$
 				context.framework.publishFrameworkEvent(FrameworkEvent.ERROR, factorybundle, be);
 				return (null);
 			}

 			if (service == null) {
 				if (Debug.DEBUG && Debug.DEBUG_SERVICES) {
 					Debug.println(factory + ".getService() returned null."); //$NON-NLS-1$
 				}

 				BundleException be = new BundleException(NLS.bind(Msg.SERVICE_OBJECT_NULL_EXCEPTION, factory.getClass().getName()));
 				context.framework.publishFrameworkEvent(FrameworkEvent.ERROR, factorybundle, be);

 				return (null);
 			}

 			String[] clazzes = registration.clazzes;
 			String invalidService = BundleContextImpl.checkServiceClass(clazzes, service);
 			if (invalidService != null) {
 				if (Debug.DEBUG && Debug.DEBUG_SERVICES) {
 					Debug.println("Service object is not an instanceof " + invalidService); //$NON-NLS-1$
 				}
 				throw new IllegalArgumentException(NLS.bind(Msg.SERVICE_NOT_INSTANCEOF_CLASS_EXCEPTION, invalidService));
 			}
 			this.service = service;
 		}

 		useCount++;

 		return (this.service);
 	}

 	/**
 	 * Unget a service's service object.
 	 * Releases the service object for a service.
 	 * If the context bundle's use count for the service is zero, this method
 	 * returns <code>false</code>. Otherwise, the context bundle's use count for the
 	 * service is decremented by one.
 	 *
 	 * <p>The service's service object
 	 * should no longer be used and all references to it should be destroyed
 	 * when a bundle's use count for the service
 	 * drops to zero.
 	 *
 	 * <p>The following steps are followed to unget the service object:
 	 * <ol>
 	 * <li>If the context bundle's use count for the service is zero or
 	 * the service has been unregistered,
 	 * <code>false</code> is returned.
 	 * <li>The context bundle's use count for this service is decremented by one.
 	 * <li>If the context bundle's use count for the service is now zero and
 	 * the service was registered with a {@link ServiceFactory},
 	 * the {@link ServiceFactory#ungetService ServiceFactory.ungetService} method
 	 * is called to release the service object for the context bundle.
 	 * <li><code>true</code> is returned.
 	 * </ol>
 	 *
 	 * @return <code>true</code> if the context bundle's use count for the service
 	 *         is zero otherwise <code>false</code>.
 	 */
 	protected boolean ungetService() {
 		if (useCount == 0) {
 			return (true);
 		}

 		useCount--;

 		if (useCount == 0) {
 			if (factory != null) {
 				try {
 					AccessController.doPrivileged(new PrivilegedAction() {
 						public Object run() {
 							factory.ungetService(context.bundle, registration, service);

 							return null;
 						}
 					});
 				} catch (Throwable t) {
 					if (Debug.DEBUG && Debug.DEBUG_GENERAL) {
 						Debug.println(factory + ".ungetService() exception"); //$NON-NLS-1$
 						Debug.printStackTrace(t);
 					}

 					AbstractBundle factorybundle = registration.context.bundle;
 					BundleException be = new BundleException(NLS.bind(Msg.SERVICE_FACTORY_EXCEPTION, factory.getClass().getName(), "ungetService"), t); //$NON-NLS-1$
 					context.framework.publishFrameworkEvent(FrameworkEvent.ERROR, factorybundle, be);
 				}

 				service = null;
 			}

 			return (true);
 		}

 		return (false);
 	}

 	/**
 	 * Release a service's service object.
 	 * <ol>
 	 * <li>The bundle's use count for this service is set to zero.
 	 * <li>If the service was registered with a {@link ServiceFactory},
 	 * the {@link ServiceFactory#ungetService ServiceFactory.ungetService} method
 	 * is called to release the service object for the bundle.
 	 * </ol>
 	 */
 	protected void releaseService() {
 		if ((useCount > 0) && (factory != null)) {
 			try {
 				AccessController.doPrivileged(new PrivilegedAction() {
 					public Object run() {
 						factory.ungetService(context.bundle, registration, service);

 						return null;
 					}
 				});
 			} catch (Throwable t) {
 				if (Debug.DEBUG && Debug.DEBUG_SERVICES) {
 					Debug.println(factory + ".ungetService() exception"); //$NON-NLS-1$
 					Debug.printStackTrace(t);
 				}

 				AbstractBundle factorybundle = registration.context.bundle;
 				BundleException be = new BundleException(NLS.bind(Msg.SERVICE_FACTORY_EXCEPTION, factory.getClass().getName(), "ungetService"), t); //$NON-NLS-1$
 				context.framework.publishFrameworkEvent(FrameworkEvent.ERROR, factorybundle, be);
 			}

 			service = null;
 		}

 		useCount = 0;
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2003, 2005 IBM Corporation and others.
	* All rights reserved. This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License v1.0
	* which accompanies this distribution, and is available at
	* http://www.eclipse.org/legal/epl-v10.html
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/

	package org.eclipse.osgi.framework.internal.core;

	import java.security.AccessController;
	import java.security.PrivilegedAction;
	import org.eclipse.osgi.framework.debug.Debug;
	import org.eclipse.osgi.util.NLS;
	import org.osgi.framework.*;

	/**
	* This class represents the use of a service by a bundle. One is created for each
	* service acquired by a bundle. This class manages the calls to ServiceFactory
	* and the bundle's use count.
	*/

	public class ServiceUse {
	/** ServiceFactory object if the service instance represents a factory,
	null otherwise */
	protected ServiceFactory factory;
	/** Service object either registered or that returned by
	ServiceFactory.getService() */
	protected Object service;
	/** BundleContext associated with this service use */
	protected BundleContextImpl context;
	/** ServiceDescription of the registered service */
	protected ServiceRegistrationImpl registration;
	/** bundle's use count for this service */
	protected int useCount;

	/** Internal framework object. */

	/**
	* Constructs a service use encapsulating the service object.
	* Objects of this class should be constrcuted while holding the
	* registrations lock.
	*
	* @param context bundle getting the service
	* @param registration ServiceRegistration of the service
	*/
	protected ServiceUse(BundleContextImpl context, ServiceRegistrationImpl registration) {
	this.context = context;
	this.registration = registration;
	this.useCount = 0;

	Object service = registration.service;
	if (service instanceof ServiceFactory) {
	factory = (ServiceFactory) service;
	this.service = null;
	} else {
	this.factory = null;
	this.service = service;
	}
	}

	/**
	* Get a service's service object.
	* Retrieves the service object for a service.
	* A bundle's use of a service is tracked by a
	* use count. Each time a service's service object is returned by
	* {@link #getService}, the context bundle's use count for the service
	* is incremented by one. Each time the service is release by
	* {@link #ungetService}, the context bundle's use count
	* for the service is decremented by one.
	* When a bundle's use count for a service
	* drops to zero, the bundle should no longer use the service.
	*
	* <p>The following steps are followed to get the service object:
	* <ol>
	* <li>The context bundle's use count for this service is incremented by one.
	* <li>If the context bundle's use count for the service is now one and
	* the service was registered with a {@link ServiceFactory},
	* the {@link ServiceFactory#getService ServiceFactory.getService} method
	* is called to create a service object for the context bundle.
	* This service object is cached by the framework.
	* While the context bundle's use count for the service is greater than zero,
	* subsequent calls to get the services's service object for the context bundle
	* will return the cached service object.
	* <br>If the service object returned by the {@link ServiceFactory}
	* is not an <code>instanceof</code>
	* all the classes named when the service was registered or
	* the {@link ServiceFactory} throws an exception,
	* <code>null</code> is returned and a
	* {@link FrameworkEvent} of type {@link FrameworkEvent#ERROR} is broadcast.
	* <li>The service object for the service is returned.
	* </ol>
	*
	* @return A service object for the service associated with this
	* reference.
	*/
	protected Object getService() {
	if ((useCount == 0) && (factory != null)) {
	AbstractBundle factorybundle = registration.context.bundle;
	Object service;

	try {
	service = AccessController.doPrivileged(new PrivilegedAction() {
	public Object run() {
	return factory.getService(context.bundle, registration);
	}
	});
	} catch (Throwable t) {
	if (Debug.DEBUG && Debug.DEBUG_SERVICES) {
	Debug.println(factory + ".getService() exception: " + t.getMessage()); //$NON-NLS-1$
	Debug.printStackTrace(t);
	}
	// allow the adaptor to handle this unexpected error
	context.framework.adaptor.handleRuntimeError(t);
	BundleException be = new BundleException(NLS.bind(Msg.SERVICE_FACTORY_EXCEPTION, factory.getClass().getName(), "getService"), t); //$NON-NLS-1$
	context.framework.publishFrameworkEvent(FrameworkEvent.ERROR, factorybundle, be);
	return (null);
	}

	if (service == null) {
	if (Debug.DEBUG && Debug.DEBUG_SERVICES) {
	Debug.println(factory + ".getService() returned null."); //$NON-NLS-1$
	}

	BundleException be = new BundleException(NLS.bind(Msg.SERVICE_OBJECT_NULL_EXCEPTION, factory.getClass().getName()));
	context.framework.publishFrameworkEvent(FrameworkEvent.ERROR, factorybundle, be);

	return (null);
	}

	String[] clazzes = registration.clazzes;
	String invalidService = BundleContextImpl.checkServiceClass(clazzes, service);
	if (invalidService != null) {
	if (Debug.DEBUG && Debug.DEBUG_SERVICES) {
	Debug.println("Service object is not an instanceof " + invalidService); //$NON-NLS-1$
	}
	throw new IllegalArgumentException(NLS.bind(Msg.SERVICE_NOT_INSTANCEOF_CLASS_EXCEPTION, invalidService));
	}
	this.service = service;
	}

	useCount++;

	return (this.service);
	}

	/**
	* Unget a service's service object.
	* Releases the service object for a service.
	* If the context bundle's use count for the service is zero, this method
	* returns <code>false</code>. Otherwise, the context bundle's use count for the
	* service is decremented by one.
	*
	* <p>The service's service object
	* should no longer be used and all references to it should be destroyed
	* when a bundle's use count for the service
	* drops to zero.
	*
	* <p>The following steps are followed to unget the service object:
	* <ol>
	* <li>If the context bundle's use count for the service is zero or
	* the service has been unregistered,
	* <code>false</code> is returned.
	* <li>The context bundle's use count for this service is decremented by one.
	* <li>If the context bundle's use count for the service is now zero and
	* the service was registered with a {@link ServiceFactory},
	* the {@link ServiceFactory#ungetService ServiceFactory.ungetService} method
	* is called to release the service object for the context bundle.
	* <li><code>true</code> is returned.
	* </ol>
	*
	* @return <code>true</code> if the context bundle's use count for the service
	* is zero otherwise <code>false</code>.
	*/
	protected boolean ungetService() {
	if (useCount == 0) {
	return (true);
	}

	useCount--;

	if (useCount == 0) {
	if (factory != null) {
	try {
	AccessController.doPrivileged(new PrivilegedAction() {
	public Object run() {
	factory.ungetService(context.bundle, registration, service);

	return null;
	}
	});
	} catch (Throwable t) {
	if (Debug.DEBUG && Debug.DEBUG_GENERAL) {
	Debug.println(factory + ".ungetService() exception"); //$NON-NLS-1$
	Debug.printStackTrace(t);
	}

	AbstractBundle factorybundle = registration.context.bundle;
	BundleException be = new BundleException(NLS.bind(Msg.SERVICE_FACTORY_EXCEPTION, factory.getClass().getName(), "ungetService"), t); //$NON-NLS-1$
	context.framework.publishFrameworkEvent(FrameworkEvent.ERROR, factorybundle, be);
	}

	service = null;
	}

	return (true);
	}

	return (false);
	}

	/**
	* Release a service's service object.
	* <ol>
	* <li>The bundle's use count for this service is set to zero.
	* <li>If the service was registered with a {@link ServiceFactory},
	* the {@link ServiceFactory#ungetService ServiceFactory.ungetService} method
	* is called to release the service object for the bundle.
	* </ol>
	*/
	protected void releaseService() {
	if ((useCount > 0) && (factory != null)) {
	try {
	AccessController.doPrivileged(new PrivilegedAction() {
	public Object run() {
	factory.ungetService(context.bundle, registration, service);

	return null;
	}
	});
	} catch (Throwable t) {
	if (Debug.DEBUG && Debug.DEBUG_SERVICES) {
	Debug.println(factory + ".ungetService() exception"); //$NON-NLS-1$
	Debug.printStackTrace(t);
	}

	AbstractBundle factorybundle = registration.context.bundle;
	BundleException be = new BundleException(NLS.bind(Msg.SERVICE_FACTORY_EXCEPTION, factory.getClass().getName(), "ungetService"), t); //$NON-NLS-1$
	context.framework.publishFrameworkEvent(FrameworkEvent.ERROR, factorybundle, be);
	}

	service = null;
	}

	useCount = 0;
	}
	}