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Override ApplicationContext prepareRefresh() and onRefresh() methods.

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Add option to copy configuration from the pre-refresh BeanFactory to the post-refresh BeanFactory instance.

Apply appropriate Spring @NonNull and @Nullable annotations.

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This commit is contained in:
John Blum
2020-04-24 15:55:36 -07:00
parent 2deb202c21
commit b1e9a30e10
1 changed files with 94 additions and 25 deletions
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119
spring-geode/src/main/java/org/springframework/geode/context/annotation/RefreshableAnnotationConfigApplicationContext.java
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@@ -24,6 +24,8 @@ import java.util.Set;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanNameGenerator;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
@@ -34,7 +36,10 @@ import org.springframework.context.annotation.AnnotationConfigUtils;
import org.springframework.context.annotation.ClassPathBeanDefinitionScanner;
import org.springframework.context.annotation.ScopeMetadataResolver;
import org.springframework.context.support.AbstractRefreshableConfigApplicationContext;
import org.springframework.data.gemfire.config.annotation.PeerCacheApplication;
import org.springframework.data.gemfire.util.ArrayUtils;
import org.springframework.data.gemfire.util.SpringUtils;
import org.springframework.lang.NonNull;
import org.springframework.lang.Nullable;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;
@@ -43,8 +48,17 @@ import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A {@literal refreshable} {@link ApplicationContext} capable of loading {@link Class component classes} common
* in {@link Annotation} based configuration as well as scanning {@link String configuration locations}.
* A {@literal refreshable} {@link ApplicationContext} capable of loading {@link Class component classes} used for
* {@link Annotation} based configuration in addition to scanning {@link String configuration locations}, and then
* providing the ability to reload/refresh the context at some point later during runtime.
*
* DISCLAIMER: Currently, this {@link ApplicationContext} implementation (and extension) is being used exclusively for
* testing and experimental (R&D) purposes. It was designed around Apache Geode & Pivotal GemFire's forced-disconnect
* / auto-reconnect functionality, providing support for this behavior inside a Spring context. Specifically, this
* concern is only applicable when using Spring Boot to configure and bootstrap Apache Geode or Pivotal GemFire peer
* member {@link org.apache.geode.cache.Cache} applications, such as when annotating your Spring Boot application with
* SDG's {@link PeerCacheApplication} annotation. This {@link ApplicationContext} implementation is not recommended for
* use in Production Systems/Applications (yet).
*
* @author John Blum
* @see org.springframework.beans.factory.config.BeanDefinition
@@ -63,11 +77,13 @@ import org.slf4j.LoggerFactory;
public class RefreshableAnnotationConfigApplicationContext extends AbstractRefreshableConfigApplicationContext
implements AnnotationConfigRegistry {
protected static final boolean DEFAULT_COPY_CONFIGURATION = false;
protected static final boolean USE_DEFAULT_FILTERS = true;
@Nullable
private BeanNameGenerator beanNameGenerator;
@Nullable
private volatile DefaultListableBeanFactory beanFactory;
private final Logger logger = LoggerFactory.getLogger(getClass());
@@ -78,27 +94,39 @@ public class RefreshableAnnotationConfigApplicationContext extends AbstractRefre
@Nullable
private ScopeMetadataResolver scopeMetadataResolver;
// TODO: WARNING - Calling refreshBeanFactory() in the constructor to eagerly create a BeanFactory is problematic.
// However, it does follow the BeanFactory creation pattern used by the GenericApplicationContext (and extensions
// like AnnotationConfigApplicationContext) that this RefreshableAnnotationConfigApplicationContext implementation
// is trying to preserve. Although, the AnnotationConfigApplicationContext implementation is NOT refreshable either,
// yet the AnnotationConfigWebApplicationContext is but doesn't eagerly create a BeanFactory during construction,
// so... The main problem with eagerly creating the BeanFactory in the constructor is the BeanFactory will be
// closed and reconstructed on refresh, as well as on each refresh thereafter.
/**
* Constructs an new instance of the {@link RefreshableAnnotationConfigApplicationContext}
* with default container state an no {@literal parent} {@link ApplicationContext}.
* with default container state and no {@literal parent} {@link ApplicationContext}.
*
* @see #refreshBeanFactory()
* @see #RefreshableAnnotationConfigApplicationContext(ApplicationContext)
*/
public RefreshableAnnotationConfigApplicationContext() {
refreshBeanFactory(); // TODO: Not certain this is a good idea; see comment below on createBeanFactory() method!
this(null);
}
/**
* Constructs a new instance of the {@link RefreshableAnnotationConfigApplicationContext} initialized with
* the {@literal parent} {@link ApplicationContext}.
*
* @param parent parent {@link ApplicationContext} to this context.
* Additionally, this constructor eagerly initializes a {@link ConfigurableListableBeanFactory},
* unlike {@link org.springframework.context.support.AbstractRefreshableApplicationContext} implementations,
* but exactly like {@link org.springframework.context.support.GenericApplicationContext} implementations.
*
* @param parent parent {@link ApplicationContext} to this child context.
* @see org.springframework.context.ApplicationContext
* @see #refreshBeanFactory()
*/
public RefreshableAnnotationConfigApplicationContext(@Nullable ApplicationContext parent) {
super(parent);
refreshBeanFactory(); // TODO: Not certain this is a good idea; see comment below on createBeanFactory() method!
refreshBeanFactory();
}
/**
@@ -127,12 +155,12 @@ public class RefreshableAnnotationConfigApplicationContext extends AbstractRefre
}
/**
* Returns the configured {@link Logger} used to log framework {@link String messages} to the application log.
* Returns the configured {@link Logger} used to log framework messages to the application log.
*
* @return the configured {@link Logger}.
* @see org.slf4j.Logger
*/
protected Logger getLogger() {
protected @NonNull Logger getLogger() {
return this.logger;
}
@@ -161,10 +189,26 @@ public class RefreshableAnnotationConfigApplicationContext extends AbstractRefre
return Optional.ofNullable(this.scopeMetadataResolver);
}
protected boolean isCopyConfigurationEnabled() {
return DEFAULT_COPY_CONFIGURATION;
}
protected boolean isUsingDefaultFilters() {
return USE_DEFAULT_FILTERS;
}
/**
* Loads {@link BeanDefinition BeanDefinitions} from Annotation configuration (component) classes
* as well as from other resource locations (e.g. XML).
*
* @param beanFactory {@link DefaultListableBeanFactory} to configure.
* @throws BeansException if loading and configuring the {@link BeanDefinition BeanDefintions} for the target
* {@link DefaultListableBeanFactory} fails.
* @see org.springframework.beans.factory.support.DefaultListableBeanFactory
* @see #newAnnotatedBeanDefinitionReader(BeanDefinitionRegistry)
* @see #newClassBeanDefinitionScanner(BeanDefinitionRegistry)
* @see #getConfigLocations()
*/
@Override
protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException {
@@ -225,22 +269,6 @@ public class RefreshableAnnotationConfigApplicationContext extends AbstractRefre
return scanner;
}
// TODO: Not entirely certain this is a good idea (yet); However, it does follow the BeanFactory creation pattern
// used by // the GenericApplicationContext (& extensions, e.g. AnnotationConfigApplicationContext) that I am
// trying to // preserve in this RefreshableAnnotationConfigApplicationContext implementation. However, the
// AnnotationConfigApplicationContext implementation is NOT refreshable either, although
// AnnotationConfigWebApplicationContext is, so... hmm!
// This overridden createBeanFactory() method effectively maintains the BeanFactory as a Singleton!
@Override
protected synchronized DefaultListableBeanFactory createBeanFactory() {
if (this.beanFactory == null) {
this.beanFactory = super.createBeanFactory();
}
return this.beanFactory;
}
protected AnnotatedBeanDefinitionReader newAnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry) {
return new AnnotatedBeanDefinitionReader(registry, getEnvironment());
}
@@ -249,6 +277,47 @@ public class RefreshableAnnotationConfigApplicationContext extends AbstractRefre
return new ClassPathBeanDefinitionScanner(registry, isUsingDefaultFilters(), getEnvironment());
}
/**
* Re-registers Singleton beans registered with the previous {@link ConfigurableListableBeanFactory BeanFactory}
* (prior to refresh) with this {@link ApplicationContext}, iff this context was previously active
* and subsequently refreshed.
*
* @see org.springframework.beans.factory.config.ConfigurableListableBeanFactory#copyConfigurationFrom(ConfigurableBeanFactory)
* @see org.springframework.beans.factory.config.ConfigurableListableBeanFactory#registerSingleton(String, Object)
* @see #getBeanFactory()
*/
@Override
protected void onRefresh() {
super.onRefresh();
ConfigurableListableBeanFactory currentBeanFactory = getBeanFactory();
if (this.beanFactory != null) {
Arrays.stream(ArrayUtils.nullSafeArray(this.beanFactory.getSingletonNames(), String.class))
.filter(singletonBeanName -> !currentBeanFactory.containsSingleton(singletonBeanName))
.forEach(singletonBeanName -> currentBeanFactory
.registerSingleton(singletonBeanName, this.beanFactory.getSingleton(singletonBeanName)));
if (isCopyConfigurationEnabled()) {
currentBeanFactory.copyConfigurationFrom(this.beanFactory);
}
}
}
/**
* Stores a reference to the previous {@link ConfigurableListableBeanFactory} in order to copy its configuration
* and state on {@link ApplicationContext} refresh invocations.
*
* @see #getBeanFactory()
*/
@Override
protected void prepareRefresh() {
this.beanFactory = (DefaultListableBeanFactory) SpringUtils.safeGetValue(this::getBeanFactory);
super.prepareRefresh();
}
/**
* @inheritDoc
*/