Clover coverage report - Code Coverage for hivemind release 1.1-alpha-2
Coverage timestamp: Wed Feb 23 2005 09:59:04 EST
file stats: LOC: 271   Methods: 7
NCLOC: 137   Classes: 1
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 Source file Conditionals Statements Methods TOTAL
SingletonServiceModel.java 87.5% 98.7% 100% 97.9%
coverage coverage
 1   
 // Copyright 2004, 2005 The Apache Software Foundation
 2   
 //
 3   
 // Licensed under the Apache License, Version 2.0 (the "License");
 4   
 // you may not use this file except in compliance with the License.
 5   
 // You may obtain a copy of the License at
 6   
 //
 7   
 //     http://www.apache.org/licenses/LICENSE-2.0
 8   
 //
 9   
 // Unless required by applicable law or agreed to in writing, software
 10   
 // distributed under the License is distributed on an "AS IS" BASIS,
 11   
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 12   
 // See the License for the specific language governing permissions and
 13   
 // limitations under the License.
 14   
 
 15   
 package org.apache.hivemind.impl.servicemodel;
 16   
 
 17   
 import java.lang.reflect.Constructor;
 18   
 import java.lang.reflect.Modifier;
 19   
 
 20   
 import org.apache.hivemind.ApplicationRuntimeException;
 21   
 import org.apache.hivemind.events.RegistryShutdownListener;
 22   
 import org.apache.hivemind.impl.ConstructableServicePoint;
 23   
 import org.apache.hivemind.impl.ProxyBuilder;
 24   
 import org.apache.hivemind.internal.ServicePoint;
 25   
 import org.apache.hivemind.service.BodyBuilder;
 26   
 import org.apache.hivemind.service.ClassFab;
 27   
 import org.apache.hivemind.service.MethodSignature;
 28   
 
 29   
 /**
 30   
  * Subclass of {@link org.apache.hivemind.impl.servicemodel.AbstractServiceModelImpl} which
 31   
  * supports creation of a singleton service proxy (deferring the actual construction of the service
 32   
  * until absolutely necessary). This is used with the singleton service type, which is the default.
 33   
  * 
 34   
  * @author Howard Lewis Ship
 35   
  */
 36   
 public final class SingletonServiceModel extends AbstractServiceModelImpl
 37   
 {
 38   
     /**
 39   
      * Name of a method in the deferred proxy that is used to obtain the constructed service.
 40   
      */
 41   
     protected static final String SERVICE_ACCESSOR_METHOD_NAME = "_service";
 42   
 
 43   
     private Object _serviceProxy;
 44   
 
 45   
     private SingletonInnerProxy _innerProxy;
 46   
 
 47   
     private Object _constructedService;
 48   
 
 49  874
     public SingletonServiceModel(ConstructableServicePoint servicePoint)
 50   
     {
 51  874
         super(servicePoint);
 52   
     }
 53   
 
 54  875
     public synchronized Object getService()
 55   
     {
 56  875
         if (_serviceProxy == null)
 57  874
             _serviceProxy = createSingletonProxy();
 58   
 
 59  875
         return _serviceProxy;
 60   
     }
 61   
 
 62   
     /**
 63   
      * This is invoked by the proxy to create the actual implementation.
 64   
      */
 65  430
     public synchronized Object getActualServiceImplementation()
 66   
     {
 67  430
         if (_constructedService == null)
 68  430
             _constructedService = constructServiceImplementation();
 69   
 
 70   
         // The inner proxy needs the service to implement the service interface.
 71   
         // For bean services (not interface services) with no interceptors,
 72   
         // the implementation may be the bean provided by the factory ... which
 73   
         // does not implement the service interface (which was created at runtime).
 74   
         // So we introduce a "bridge" between the two.
 75   
 
 76  430
         Class serviceInterface = getServicePoint().getServiceInterface();
 77   
 
 78  430
         if (!serviceInterface.isInstance(_constructedService))
 79  2
             _constructedService = constructBridgeProxy(_constructedService);
 80   
 
 81  430
         return _constructedService;
 82   
     }
 83   
 
 84   
     /**
 85   
      * Creates a proxy class for the service and then construct the class itself.
 86   
      */
 87  874
     private Object createSingletonProxy()
 88   
     {
 89  874
         if (_log.isDebugEnabled())
 90  4
             _log.debug("Creating SingletonProxy for service "
 91   
                     + getServicePoint().getExtensionPointId());
 92   
 
 93  874
         try
 94   
         {
 95   
 
 96   
             // Create the outer proxy, the one visible to client code (including
 97   
             // other services). It is dependent on an inner proxy.
 98   
 
 99  874
             Class proxyClass = createSingletonProxyClass();
 100   
 
 101   
             // Create the inner proxy, whose job is to replace itself
 102   
             // when the first service method is invoked.
 103   
 
 104  874
             Class innerProxyClass = createInnerProxyClass(proxyClass);
 105   
 
 106   
             // Create the outer proxy.
 107   
 
 108  874
             Object result = proxyClass.newInstance();
 109   
 
 110   
             // The inner proxy's construct invokes a method on the
 111   
             // outer proxy to connect the two.
 112   
 
 113  874
             Constructor c = innerProxyClass.getConstructor(new Class[]
 114   
             { proxyClass, getClass() });
 115   
 
 116  874
             _innerProxy = (SingletonInnerProxy) c.newInstance(new Object[]
 117   
             { result, this });
 118   
 
 119  874
             getServicePoint().getShutdownCoordinator().addRegistryShutdownListener(
 120   
                     (RegistryShutdownListener) result);
 121   
 
 122  874
             return result;
 123   
         }
 124   
         catch (Exception ex)
 125   
         {
 126  0
             throw new ApplicationRuntimeException(ex);
 127   
         }
 128   
 
 129   
     }
 130   
 
 131   
     /**
 132   
      * Creates a class that implements the service interface. Implements a private synchronized
 133   
      * method, _service(), that constructs the service as needed, and has each service interface
 134   
      * method re-invoke on _service(). Adds a toString() method if the service interface does not
 135   
      * define toString().
 136   
      */
 137  874
     private Class createSingletonProxyClass()
 138   
     {
 139  874
         ConstructableServicePoint servicePoint = getServicePoint();
 140   
 
 141  874
         ProxyBuilder proxyBuilder = new ProxyBuilder("SingletonProxy", servicePoint, true);
 142   
 
 143  874
         ClassFab classFab = proxyBuilder.getClassFab();
 144   
 
 145  874
         Class serviceInterface = servicePoint.getServiceInterface();
 146   
 
 147   
         // This will initally be the inner proxy, then switch over to the
 148   
         // service implementation.
 149   
 
 150  874
         classFab.addField("_inner", serviceInterface);
 151  874
         classFab.addField("_shutdown", boolean.class);
 152   
 
 153  874
         classFab.addInterface(RegistryShutdownListener.class);
 154   
 
 155  874
         classFab.addMethod(Modifier.PUBLIC | Modifier.FINAL, new MethodSignature(void.class,
 156   
                 "registryDidShutdown", null, null), "{ _shutdown = true; }");
 157   
 
 158  874
         classFab.addMethod(
 159   
                 Modifier.PUBLIC | Modifier.SYNCHRONIZED | Modifier.FINAL,
 160   
                 new MethodSignature(void.class, "_setInner", new Class[]
 161   
                 { serviceInterface }, null),
 162   
                 "{ _inner = $1; }");
 163   
 
 164  874
         BodyBuilder builder = new BodyBuilder();
 165  874
         builder.begin();
 166  874
         builder.addln("if (_shutdown)");
 167  874
         builder.begin();
 168  874
         builder.addln("_inner = null;");
 169  874
         builder.addln("throw org.apache.hivemind.HiveMind#createRegistryShutdownException();");
 170  874
         builder.end();
 171   
 
 172  874
         builder.addln("return _inner;");
 173  874
         builder.end();
 174   
 
 175  874
         classFab.addMethod(Modifier.PRIVATE, new MethodSignature(serviceInterface, "_getInner",
 176   
                 null, null), builder.toString());
 177   
 
 178  874
         proxyBuilder.addServiceMethods("_getInner()");
 179   
 
 180  874
         return classFab.createClass();
 181   
     }
 182   
 
 183  874
     private Class createInnerProxyClass(Class deferredProxyClass)
 184   
     {
 185  874
         ServicePoint servicePoint = getServicePoint();
 186   
 
 187  874
         Class serviceInterface = servicePoint.getServiceInterface();
 188  874
         ProxyBuilder builder = new ProxyBuilder("InnerProxy", servicePoint);
 189   
 
 190  874
         ClassFab classFab = builder.getClassFab();
 191   
 
 192  874
         classFab.addField("_deferredProxy", deferredProxyClass);
 193  874
         classFab.addField("_service", serviceInterface);
 194  874
         classFab.addField("_serviceModel", getClass());
 195   
 
 196  874
         BodyBuilder body = new BodyBuilder();
 197   
 
 198   
         // The constructor remembers the outer proxy and registers itself
 199   
         // with the outer proxy.
 200   
 
 201  874
         body.begin();
 202   
 
 203  874
         body.addln("super();");
 204  874
         body.addln("_deferredProxy = $1;");
 205  874
         body.addln("_serviceModel = $2;");
 206  874
         body.addln("_deferredProxy._setInner(this);");
 207   
 
 208  874
         body.end();
 209   
 
 210  874
         classFab.addConstructor(new Class[]
 211   
         { deferredProxyClass, getClass() }, null, body.toString());
 212   
 
 213   
         // Method _service() will look up the service implementation,
 214   
         // then update the deferred proxy to go directly to the
 215   
         // service implementation, bypassing itself!
 216   
 
 217  874
         body.clear();
 218  874
         body.begin();
 219   
 
 220  874
         body.add("if (_service == null)");
 221  874
         body.begin();
 222   
 
 223  874
         body.add("_service = (");
 224  874
         body.add(serviceInterface.getName());
 225  874
         body.addln(") _serviceModel.getActualServiceImplementation();");
 226   
 
 227  874
         body.add("_deferredProxy._setInner(_service);");
 228   
 
 229  874
         body.end();
 230   
 
 231  874
         body.add("return _service;");
 232   
 
 233  874
         body.end();
 234   
 
 235  874
         classFab.addMethod(
 236   
                 Modifier.PRIVATE | Modifier.FINAL | Modifier.SYNCHRONIZED,
 237   
                 new MethodSignature(serviceInterface, "_service", null, null),
 238   
                 body.toString());
 239   
 
 240  874
         builder.addServiceMethods("_service()");
 241   
 
 242   
         // Build the implementation of interface SingletonInnerProxy
 243   
 
 244  874
         body.clear();
 245  874
         body.begin();
 246   
 
 247  874
         body.add("_service();");
 248   
 
 249  874
         body.end();
 250   
 
 251  874
         classFab.addMethod(Modifier.PUBLIC | Modifier.FINAL, new MethodSignature(void.class,
 252   
                 "_instantiateServiceImplementation", null, null), body.toString());
 253   
 
 254  874
         classFab.addInterface(SingletonInnerProxy.class);
 255   
 
 256  874
         return classFab.createClass();
 257   
     }
 258   
 
 259  1
     public void instantiateService()
 260   
     {
 261   
         // Ensure that the outer and inner proxies have been created
 262   
 
 263  1
         getService();
 264   
 
 265   
         // Force the inner proxy to resolve the service and install the result into
 266   
         // the outer proxy.
 267   
 
 268  1
         _innerProxy._instantiateServiceImplementation();
 269   
     }
 270   
 
 271   
 }