| // Copyright 2007 The Apache Software Foundation |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package org.apache.tapestry.ioc.internal.services; |
| |
| import org.apache.tapestry.ioc.ObjectCreator; |
| import org.apache.tapestry.ioc.internal.EagerLoadServiceProxy; |
| import org.apache.tapestry.ioc.internal.ServiceActivityTracker; |
| import org.apache.tapestry.ioc.services.RegistryShutdownListener; |
| import org.apache.tapestry.ioc.services.Status; |
| |
| /** |
| * Invoked from a fabricated service delegate to get or realize (instantiate and configure) the service implementation. |
| * This includes synchronization logic, to prevent multiple threads from attempting to realize the same service at the |
| * same time (a service should be realized only once). The additional interfaces implemented by this class support eager |
| * loading of services (at application startup), and orderly shutdown of proxies. |
| */ |
| public class JustInTimeObjectCreator implements ObjectCreator, EagerLoadServiceProxy, |
| RegistryShutdownListener |
| { |
| private final ServiceActivityTracker tracker; |
| |
| private ObjectCreator creator; |
| |
| private boolean shutdown; |
| |
| private Object object; |
| |
| private final String serviceId; |
| |
| public JustInTimeObjectCreator(ServiceActivityTracker tracker, ObjectCreator creator, |
| String serviceId) |
| { |
| this.tracker = tracker; |
| this.creator = creator; |
| this.serviceId = serviceId; |
| } |
| |
| /** |
| * Checks to see if the proxy has been shutdown, then invokes {@link ObjectCreator#createObject()} if it has not |
| * already done so. |
| * |
| * @throws IllegalStateException if the registry has been shutdown |
| */ |
| public synchronized Object createObject() |
| { |
| if (shutdown) |
| throw new IllegalStateException(ServiceMessages.registryShutdown(serviceId)); |
| |
| if (object == null) |
| { |
| try |
| { |
| object = creator.createObject(); |
| |
| // And if that's successful ... |
| |
| tracker.setStatus(serviceId, Status.REAL); |
| |
| creator = null; |
| } |
| catch (RuntimeException ex) |
| { |
| throw new RuntimeException(ServiceMessages.serviceBuildFailure(serviceId, ex), ex); |
| } |
| } |
| |
| return object; |
| } |
| |
| /** |
| * Invokes {@link #createObject()} to force the creation of the underlying service. |
| */ |
| public void eagerLoadService() |
| { |
| // Force object creation now |
| |
| createObject(); |
| } |
| |
| /** |
| * Sets the shutdown flag and releases the object and the creator. |
| */ |
| public synchronized void registryDidShutdown() |
| { |
| shutdown = true; |
| object = null; |
| creator = null; |
| } |
| |
| } |