[Advance][Circular dependency][fix] resolve circular use second third cache

Author: m1a2st

src/main/java/org/m1a2st/aop/autoproxy/DefaultAdvisorAutoProxyCreator.java

@@ -13,6 +13,8 @@
 import org.m1a2st.beans.factory.support.DefaultListableBeanFactory;
 
 import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
 
 /**
  * @Author m1a2st
@@ -23,6 +25,8 @@ public class DefaultAdvisorAutoProxyCreator implements InstantiationAwareBeanPos
 
     private DefaultListableBeanFactory beanFactory;
 
+    private final Set<Object> earlyProxyReferences = new HashSet<>();
+
     @Override
     public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
         this.beanFactory = (DefaultListableBeanFactory) beanFactory;
@@ -38,8 +42,21 @@ public boolean postProcessAfterInstantiation(Object bean, String beanName) throw
         return true;
     }
 
+    @Override
+    public Object getEarlyBeanReference(Object bean, String beanName) throws BeansException {
+        earlyProxyReferences.add(beanName);
+        return wrapIfNecessary(bean, beanName);
+    }
+
     @Override
     public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
+        if (!earlyProxyReferences.contains(beanName)) {
+            return wrapIfNecessary(bean, beanName);
+        }
+        return bean;
+    }
+
+    protected Object wrapIfNecessary(Object bean, String beanName) {
         // 避免死循環
         if (isInfrastructureClass(bean.getClass())) {
             return null;

src/main/java/org/m1a2st/beans/factory/ObjectFactory.java

@@ -0,0 +1,13 @@
+package org.m1a2st.beans.factory;
+
+import org.m1a2st.beans.BeansException;
+
+/**
+ * @Author m1a2st
+ * @Date 2023/7/26
+ * @Version v1.0
+ */
+public interface ObjectFactory<T> {
+
+    T getObject() throws BeansException;
+}

src/main/java/org/m1a2st/beans/factory/config/InstantiationAwareBeanPostProcessor.java

@@ -40,4 +40,16 @@ public interface InstantiationAwareBeanPostProcessor extends BeanPostProcessor {
      * @throws BeansException bean處理異常
      */
     PropertyValues postProcessPropertyValues(PropertyValues pvs, Object bean, String beanName) throws BeansException;
+
+    /**
+     * 提前曝露 bean
+     *
+     * @param bean     bean實例
+     * @param beanName bean的名稱
+     * @return bean實例
+     * @throws BeansException bean處理異常
+     */
+    default Object getEarlyBeanReference(Object bean, String beanName) throws BeansException {
+        return bean;
+    }
 }

src/main/java/org/m1a2st/beans/factory/support/AbstractAutowireCapableBeanFactory.java

@@ -75,7 +75,10 @@ protected Object doCreateBean(String beanName, BeanDefinition beanDefinition) th
             // 創造Bean 實體
             bean = createBeanInstance(beanDefinition);
             // 為解決循環依賴，將實例化的Bean放入緩存提前暴露
-            earlySingletonObjects.put(beanName, bean);
+            if (beanDefinition.isSingleton()) {
+                Object finalBean = bean;
+                addSingletonFactory(beanName, () -> getEarlyBeanReference(beanName, beanDefinition, finalBean));
+            }
             // bean 實例化後進行
             if (!applyBeanPostProcessorsAfterInstantiation(beanName, bean)) {
                 return bean;
@@ -91,10 +94,27 @@ protected Object doCreateBean(String beanName, BeanDefinition beanDefinition) th
         }
         // 註冊有銷毀方法的Bean
         registerDisposableBeanIfNecessary(beanName, bean, beanDefinition);
+
+        Object exposeObject = bean;
         if (beanDefinition.isSingleton()) {
-            addSingleton(beanName, bean);
+            // 如果有代理對象，此處獲取代理對象
+            exposeObject = getSingleton(beanName);
+            addSingleton(beanName, exposeObject);
         }
-        return bean;
+        return exposeObject;
+    }
+
+    protected Object getEarlyBeanReference(String beanName, BeanDefinition beanDefinition, Object bean) {
+        Object exposedObject = bean;
+        for (BeanPostProcessor bp : getBeanPostProcessors()) {
+            if (bp instanceof InstantiationAwareBeanPostProcessor) {
+                exposedObject = ((InstantiationAwareBeanPostProcessor) bp).getEarlyBeanReference(exposedObject, beanName);
+                if (exposedObject == null) {
+                    return null;
+                }
+            }
+        }
+        return exposedObject;
     }
 
     /**

src/main/java/org/m1a2st/beans/factory/support/DefaultSingletonBeanRegistry.java

@@ -2,6 +2,7 @@
 
 import org.m1a2st.beans.BeansException;
 import org.m1a2st.beans.factory.DisposableBean;
+import org.m1a2st.beans.factory.ObjectFactory;
 import org.m1a2st.beans.factory.config.SingletonBeanRegistry;
 
 import java.util.ArrayList;
@@ -20,22 +21,44 @@
  */
 public class DefaultSingletonBeanRegistry implements SingletonBeanRegistry {
 
+    // 二級緩存
+    protected final Map<String, Object> earlySingletonObjects = new ConcurrentHashMap<>();
+    // 一級緩存
     private final Map<String, Object> singletonObjects = new ConcurrentHashMap<>();
+    // 三級緩存
+    private final Map<String, ObjectFactory<?>> singletonFactories = new ConcurrentHashMap<>();
+
     private final Map<String, DisposableBean> disposableBeans = new ConcurrentHashMap<>();
-    protected final Map<String, Object> earlySingletonObjects = new ConcurrentHashMap<>();
 
     @Override
     public Object getSingleton(String beanName) {
-        Object bean = singletonObjects.get(beanName);
-        if (bean == null) {
-            bean = earlySingletonObjects.get(beanName);
+        Object singletonObject = singletonObjects.get(beanName);
+        if (singletonObject == null) {
+            singletonObject = earlySingletonObjects.get(beanName);
+            if (singletonObject == null) {
+                ObjectFactory<?> singletonFactory = singletonFactories.get(beanName);
+                if (singletonFactory != null) {
+                    // 這裡的singletonObject是一個ObjectFactory，而不是bean實例
+                    singletonObject = singletonFactory.getObject();
+                    // 從三級緩存放進二級緩存
+                    earlySingletonObjects.put(beanName, singletonObject);
+                    // 從三級緩存移除
+                    singletonFactories.remove(beanName);
+                }
+            }
         }
-        return bean;
+        return singletonObject;
+    }
+
+    protected void addSingletonFactory(String beanName, ObjectFactory<?> singletonFactory) {
+        singletonFactories.put(beanName, singletonFactory);
     }
 
     @Override
     public void addSingleton(String beanName, Object singletonObject) {
         singletonObjects.put(beanName, singletonObject);
+        earlySingletonObjects.remove(beanName);
+        singletonFactories.remove(beanName);
     }
 
     public void registerDisposableBean(String beanName, DisposableBean bean) {