Lazy bean behaviour

[alesj]

I'm doing (apart from AS5_PS ... no worries ;-)) some GUI example console for MC and was missing the following feature - lazy 'instantiation/install' of the bean.

e.g. I have some service that has many dependencies - many injected beans. One of them is rarely used and/or is fully installed in some later-on deployment unit. But I would still like to have that first service up and running.

So, I hacked a lazy notion to our beans - lazy proxies.

What you can do now is the following XML

 <bean name="bean" class="org.jboss.test.kernel.lazy.support.RareBean"/>

 <lazy name="proxy" bean="bean" exposeClass="true">
 <interface>org.jboss.test.kernel.lazy.support.IRare</interface>
 </lazy>

or the straight API

 AbstractLazyMetaData lazy = new AbstractLazyMetaData("bean");
 lazy.setInterfaces(Collections.singleton(IRare.class.getName()));

And the test to show that lazyness :-)

 AbstractBeanMetaData bean = new AbstractBeanMetaData("bean", RareBean.class.getName());
 bean.setMode(ControllerMode.MANUAL);

 KernelControllerContext beanContext = controller.install(bean);
 controller.change(beanContext, ControllerState.NOT_INSTALLED);

 ModifiedLazyMetaData lazy = new ModifiedLazyMetaData("bean", getFactoryClassName());
 lazy.setInterfaces(Collections.singleton(IRare.class.getName()));
 KernelControllerContext lazyContext = controller.install(lazy);

 assertNotNull(lazyContext);
 assertEquals(ControllerState.DESCRIBED, lazyContext.getState());

 controller.change(beanContext, ControllerState.DESCRIBED);
 controller.change(lazyContext, ControllerState.INSTALLED);

 IRare lazyRare = (IRare)lazyContext.getTarget();
 assertNotNull(lazyRare);

 try
 {
 lazyRare.getHits();
 throw new RuntimeException("Should not be here.");
 }
 catch(Throwable t)
 {
 assertInstanceOf(t, IllegalArgumentException.class);
 }

 controller.change(beanContext, ControllerState.INSTALLED);

 assertEquals(0, lazyRare.getHits());
 lazyRare.setHits(10);
 assertEquals(5, lazyRare.checkHits(15));

The code checks for the first available proxy generator - Javassist, JBossAOP (wip), JDK, ... (possible additions CGLIB, ASM, ...)

 static
 {
 initializerMap = new LinkedHashMap<String, String>();
 // test class name, actual LazyInitializer implementation
 initializerMap.put("javassist.util.proxy.ProxyObject", "org.jboss.kernel.plugins.lazy.JavassistLazyInitializer");
 initializerMap.put("org.jboss.aop.proxy.container.AOPProxyFactoryParameters", "org.jboss.aop.microcontainer.lazy.JBossAOPLazyInitializer");
 initializerMap.put("java.lang.reflect.Proxy", "org.jboss.kernel.plugins.lazy.JDKLazyInitializer");
 }

 /**
 * Get the LazyInitializater instance.
 *
 * @param configurator the configurator
 * @return initializer instance
 */
 protected static LazyInitializer getInitializer(KernelConfigurator configurator)
 {
 if (initializer == null)
 {
 for(Map.Entry<String, String> entry : initializerMap.entrySet())
 {
 if (testLibExists(entry.getKey()))
 {
 initializer = createInitializer(configurator, entry.getValue());
 if (initializer != null)
 break;
 }
 }
 }
 if (initializer == null)
 throw new IllegalArgumentException("Cannot initialize LazyInitializater, check classpath for missing classes.");
 return initializer;
 }

The proxies use KernelBus to do the invocation.

Currently you need to specify which interfaces are exposed.
Perhaps this can be done automa(g|t)ically?

[alesj]

Hmmm ... just thinking that this is almost the same as @Install on the setter - a callback injection.

Perhaps only useful if the proxy is passed around as a ref.