/*
* Copyright 2010-2013 the original author or authors.
*
* 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.springframework.data.gemfire;
import java.util.Properties;
import java.util.concurrent.atomic.AtomicReference;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.wiring.BeanConfigurerSupport;
import org.springframework.beans.factory.wiring.BeanWiringInfo;
import org.springframework.beans.factory.wiring.BeanWiringInfoResolver;
import org.springframework.context.ApplicationListener;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.data.gemfire.support.SpringContextBootstrappingInitializer;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
import com.gemstone.gemfire.cache.Declarable;
/**
* The LazyWiringDeclarableSupport class is an implementation of the GemFire Declarable interface that enables support
* for wiring GemFire components with Spring bean dependencies defined in the Spring context.
*
* @author John Blum
* @see java.util.Properties
* @see org.springframework.beans.factory.DisposableBean
* @see org.springframework.context.ApplicationListener
* @see org.springframework.context.event.ContextRefreshedEvent
* @see org.springframework.data.gemfire.DeclarableSupport
* @see org.springframework.data.gemfire.WiringDeclarableSupport
* @see com.gemstone.gemfire.cache.Declarable
* @since 1.3.4
*/
@SuppressWarnings("unused")
public abstract class LazyWiringDeclarableSupport implements ApplicationListener<ContextRefreshedEvent>,
Declarable, DisposableBean {
// The name of the template bean defined in the Spring context for wiring this Declarable instance.
protected static final String BEAN_NAME_PARAMETER = "bean-name";
// atomic reference to the parameter passed by GemFire when this Declared was constructed
// and the init method was called.
private final AtomicReference<Properties> parametersReference = new AtomicReference<Properties>();
volatile boolean initialized = false;
/**
* Constructs an instance of the LazyWiringDeclarableSupport class registered with the
* SpringContextBootstrappingInitializer. This Declarable will receive notifications from the
* SpringContextBootstrappingInitializer when the Spring context is created and initialized (refreshed).
* The notification is necessary in order for this Declarable component to be configured and properly initialized
* with any required Spring bean dependencies.
*
* @see org.springframework.data.gemfire.support.SpringContextBootstrappingInitializer
* #register(org.springframework.context.ApplicationListener)
*/
public LazyWiringDeclarableSupport() {
SpringContextBootstrappingInitializer.register(this);
}
/**
* Asserts that this Declarable object has been properly configured and initialized by the Spring container
* after GemFire has constructed this Declarable object during startup. It is recommended to call this method
* in any GemFire CacheCallback/Declarable object operational method (e.g. CacheLoader.load(..)) before use
* in order to ensure that this Declarable was properly constructed, configured and initialized.
*
* @throws IllegalStateException if the Declarable object has not been properly configured or initialized
* by the Spring container.
* @see #init(java.util.Properties)
* @see #isInitialized()
*/
protected void assertInitialized() {
Assert.state(isInitialized(), String.format(
"This Declarable object (%1$s) has not been properly configured and initialized!",
getClass().getName()));
}
/**
* Asserts that this Declarable object has not yet been used, or activated prior to being fully configured
* and initialized. It is possible, though rare, that the init(:Properties) might be called multiple times
* by GemFire before the Spring container configure, initializes and puts this component to use.
*
* @throws java.lang.IllegalStateException if the Declarable object has already been configured and initialized
* by the Spring container.
* @see #init(java.util.Properties)
* @see #isInitialized()
*/
protected void assertUninitialized() {
Assert.state(!isInitialized(), String.format(
"This Declarable object (%1$s) has already been configured and initialized, and is currently active!",
getClass().getName()));
}
/**
* Performs the actual configuration and initialization of this Declarable object before use. This method
* is triggered by an ApplicationEvent (specifically, the ContextRefreshedEvent) indicating that the Spring context
* has been created and refreshed.
*
* @param beanFactory the ConfigurableListableBeanFactory used to configure and initialize this Declarable GemFire
* component.
* @param parameters Properties instance containing the parameters from GemFire's configuration file
* (e.g. cache.xml) to configure and initialize this Declarable object.
* @throws IllegalArgumentException if the bean-name parameter was specified in GemFire configuration meta-data
* but no bean with the specified name could be found in the Spring context.
* @see #init(java.util.Properties)
* @see #doPostInit(java.util.Properties)
* @see org.springframework.beans.factory.wiring.BeanConfigurerSupport
* @see org.springframework.beans.factory.wiring.BeanWiringInfo
* @see org.springframework.beans.factory.wiring.BeanWiringInfoResolver
*/
/* package-private */ void doInit(final ConfigurableListableBeanFactory beanFactory, final Properties parameters) {
BeanConfigurerSupport beanConfigurer = new BeanConfigurerSupport();
beanConfigurer.setBeanFactory(beanFactory);
final String templateBeanName = parameters.getProperty(BEAN_NAME_PARAMETER);
if (StringUtils.hasText(templateBeanName)) {
if (beanFactory.containsBean(templateBeanName)) {
beanConfigurer.setBeanWiringInfoResolver(new BeanWiringInfoResolver() {
@Override public BeanWiringInfo resolveWiringInfo(final Object beanInstance) {
return new BeanWiringInfo(templateBeanName);
}
});
}
else {
throw new IllegalArgumentException(String.format(
"No bean with name '%1$s' was found in the Spring context '%2$s'.", templateBeanName, beanFactory));
}
}
beanConfigurer.afterPropertiesSet();
beanConfigurer.configureBean(this);
beanConfigurer.destroy();
initialized = true;
doPostInit(parameters);
}
/**
* Default no operation method performed post initialization of this Declarable GemFire component to be overridden
* by subclasses for application specific extension and behavior.
*
* @param parameters Properties instance containing the parameters from GemFire's configuration file
* (e.g. cache.xml) to configure and initialize this Declarable object.
* @see #doInit(org.springframework.beans.factory.config.ConfigurableListableBeanFactory, java.util.Properties)
*/
protected void doPostInit(final Properties parameters) {
}
/**
* Initialization method called by GemFire with configured parameters once this Declarable object has been
* constructed during GemFire startup using an <initalizer> element in GemFire's configuration meta-data.
*
* @param parameters the configured parameters passed from the GemFire configuration (e.g. cache.xml) to this
* Declarable as a Properties instance.
* @throws IllegalStateException if this Declarable object has already been configured/initialized
* by the Spring container and is currently active.
* @see #doInit(org.springframework.beans.factory.config.ConfigurableListableBeanFactory, java.util.Properties)
* @see java.util.Properties
*/
@Override
public final void init(final Properties parameters) {
assertUninitialized();
parametersReference.set(parameters);
}
/**
* Determines whether this Declarable object has been configured and initialized (i.e. the doInit method
* has been called) by the Spring container.
*
* @return a boolean value indicating whether this Declarable object has been configured and initialized by
* the Spring container.
* @see #assertInitialized()
* @see #doInit(org.springframework.beans.factory.config.ConfigurableListableBeanFactory, java.util.Properties)
*/
protected boolean isInitialized() {
return initialized;
}
/**
* Null-safe operation to return the parameters passed to this Declarable object when created by GemFire from it's
* configuration meta-data.
*
* @return a Properties object containing the a parameters specified for this Declarable, or an
* empty Properties object if no parameters were supplied.
* @see java.util.Properties
*/
protected Properties nullSafeGetParameters() {
Properties parameters = parametersReference.get();
return (parameters != null ? parameters : new Properties());
}
/**
* Event handler method called when GemFire has created and initialized (refreshed) the Spring ApplicationContext
* using the SpringContextBootstrappingInitializer Declarable class.
*
* @param event the ContextRefreshedEvent published by the Spring ApplicationContext after it is successfully
* created and initialized by GemFire.
* @throws IllegalArgumentException if the ApplicationContext is not an instance of ConfigurableApplicationContext.
* @see #doInit(org.springframework.beans.factory.config.ConfigurableListableBeanFactory, java.util.Properties)
* @see #nullSafeGetParameters()
* @see org.springframework.context.ApplicationListener#onApplicationEvent(org.springframework.context.ApplicationEvent)
* @see org.springframework.context.event.ContextRefreshedEvent
*/
@Override
public final void onApplicationEvent(final ContextRefreshedEvent event) {
Assert.isTrue(event.getApplicationContext() instanceof ConfigurableApplicationContext,
String.format("The Spring ApplicationContext (%1$s) must be an instance of ConfigurableApplicationContext.",
ObjectUtils.nullSafeClassName(event.getApplicationContext())));
doInit(((ConfigurableApplicationContext) event.getApplicationContext()).getBeanFactory(),
nullSafeGetParameters());
}
/**
* When this bean gets destroyed by the Spring container, make sure this component gets unregistered from the
* SpringContextBootstrappingInitializer.
*
* @throws Exception if bean destruction is unsuccessful.
* @see org.springframework.data.gemfire.support.SpringContextBootstrappingInitializer
* #unregister(org.springframework.context.ApplicationListener)
*/
@Override
public void destroy() throws Exception {
SpringContextBootstrappingInitializer.unregister(this);
parametersReference.set(null);
initialized = false;
}
}