feat: add shared application context for plugin (#2174)

* feat: add shared application context for plugin

* chore: remove todo notes

* fix: router function composite

src/main/java/run/halo/app/plugin/PluginApplicationContext.java

@@ -1,17 +1,6 @@
 package run.halo.app.plugin;
 
-import java.lang.reflect.Field;
-import java.util.Set;
-import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
-import org.springframework.context.ApplicationEvent;
-import org.springframework.context.PayloadApplicationEvent;
-import org.springframework.context.event.ApplicationEventMulticaster;
-import org.springframework.context.support.AbstractApplicationContext;
 import org.springframework.context.support.GenericApplicationContext;
-import org.springframework.core.ResolvableType;
-import org.springframework.lang.NonNull;
-import org.springframework.lang.Nullable;
-import org.springframework.util.Assert;
 
 /**
  * The generic IOC container for plugins.
@@ -25,56 +14,6 @@ public class PluginApplicationContext extends GenericApplicationContext {
 
     private String pluginId;
 
-    /**
-     * <p>覆盖父类方法中判断context parent不为空时使用parent context广播事件的逻辑。
-     * 如果主应用桥接事件到插件中且设置了parent会导致发布事件时死循环.</p>
-     *
-     * @param event the event to publish (may be an {@link ApplicationEvent} or a payload object
-     * to be turned into a {@link PayloadApplicationEvent})
-     * @param eventType the resolved event type, if known
-     */
-    @Override
-    protected void publishEvent(@NonNull Object event, @Nullable ResolvableType eventType) {
-        Assert.notNull(event, "Event must not be null");
-
-        // Decorate event as an ApplicationEvent if necessary
-        ApplicationEvent applicationEvent;
-        if (event instanceof ApplicationEvent) {
-            applicationEvent = (ApplicationEvent) event;
-        } else {
-            applicationEvent = new PayloadApplicationEvent<>(this, event);
-            if (eventType == null) {
-                eventType = ((PayloadApplicationEvent<?>) applicationEvent).getResolvableType();
-            }
-        }
-
-        // Multicast right now if possible - or lazily once the multicaster is initialized
-        Set<ApplicationEvent> earlyApplicationEvents = getEarlyApplicationEvents();
-        if (earlyApplicationEvents != null) {
-            earlyApplicationEvents.add(applicationEvent);
-        } else {
-            getApplicationEventMulticaster().multicastEvent(applicationEvent, eventType);
-        }
-    }
-
-    private ApplicationEventMulticaster getApplicationEventMulticaster() {
-        ConfigurableListableBeanFactory beanFactory = getBeanFactory();
-        return beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME,
-            ApplicationEventMulticaster.class);
-    }
-
-    @SuppressWarnings("unchecked")
-    protected Set<ApplicationEvent> getEarlyApplicationEvents() {
-        try {
-            Field earlyApplicationEventsField =
-                AbstractApplicationContext.class.getDeclaredField("earlyApplicationEvents");
-            return (Set<ApplicationEvent>) earlyApplicationEventsField.get(this);
-        } catch (NoSuchFieldException | IllegalAccessException e) {
-            // ignore this exception
-            return null;
-        }
-    }
-
     public String getPluginId() {
         return pluginId;
     }

src/main/java/run/halo/app/plugin/PluginApplicationInitializer.java

@@ -24,9 +24,12 @@ public class PluginApplicationInitializer {
     protected final HaloPluginManager haloPluginManager;
 
     private final ExtensionContextRegistry contextRegistry = ExtensionContextRegistry.getInstance();
+    private final SharedApplicationContextHolder sharedApplicationContextHolder;
 
     public PluginApplicationInitializer(HaloPluginManager springPluginManager) {
         this.haloPluginManager = springPluginManager;
+        sharedApplicationContextHolder = springPluginManager.getRootApplicationContext()
+            .getBean(SharedApplicationContextHolder.class);
     }
 
     public ApplicationContext getRootApplicationContext() {
@@ -40,7 +43,11 @@ public class PluginApplicationInitializer {
         StopWatch stopWatch = new StopWatch("initialize-plugin-context");
         stopWatch.start("Create PluginApplicationContext");
         PluginApplicationContext pluginApplicationContext = new PluginApplicationContext();
-        pluginApplicationContext.setParent(getRootApplicationContext());
+
+        if (sharedApplicationContextHolder != null) {
+            pluginApplicationContext.setParent(sharedApplicationContextHolder.getInstance());
+        }
+
         pluginApplicationContext.setClassLoader(pluginClassLoader);
         // populate plugin to plugin application context
         pluginApplicationContext.setPluginId(pluginId);

src/main/java/run/halo/app/plugin/PluginCompositeRouterFunction.java

@@ -1,5 +1,6 @@
 package run.halo.app.plugin;
 
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
@@ -75,17 +76,19 @@ public class PluginCompositeRouterFunction implements RouterFunction<ServerRespo
         RouterFunction<ServerResponse> reverseProxyRouterFunction =
             reverseProxyRouterFunctionFactory.create(pluginApplicationContext);
 
-        routerFunctions(pluginApplicationContext)
+        List<RouterFunction<ServerResponse>> routerFunctions =
-            .stream()
+            routerFunctions(pluginApplicationContext);
-            .reduce(RouterFunction::and)
+
-            .map(compositeRouterFunction -> {
+        List<RouterFunction<ServerResponse>> combinedRouterFunctions =
+            new ArrayList<>(routerFunctions);
         if (reverseProxyRouterFunction != null) {
-                    compositeRouterFunction.andOther(reverseProxyRouterFunction);
+            combinedRouterFunctions.add(reverseProxyRouterFunction);
         }
-                return compositeRouterFunction;
+
-            })
+        combinedRouterFunctions.stream()
-            .ifPresent(routerFunction -> {
+            .reduce(RouterFunction::and)
-                routerFunctionRegistry.put(plugin.getPluginId(), routerFunction);
+            .ifPresent(compositeRouterFunction -> {
+                routerFunctionRegistry.put(plugin.getPluginId(), compositeRouterFunction);
             });
     }
 
@@ -98,9 +101,6 @@ public class PluginCompositeRouterFunction implements RouterFunction<ServerRespo
     @SuppressWarnings("unchecked")
     private List<RouterFunction<ServerResponse>> routerFunctions(
         PluginApplicationContext applicationContext) {
-        // TODO: Since the parent of the ApplicationContext of the plugin is RootApplicationContext
-        //  obtaining the RouterFunction here will obtain the existing in the parent
-        //  resulting in a loop when there is no matching route
         List<RouterFunction<ServerResponse>> functions =
             applicationContext.getBeanProvider(RouterFunction.class)
                 .orderedStream()

src/main/java/run/halo/app/plugin/SharedApplicationContext.java

@@ -0,0 +1,15 @@
+package run.halo.app.plugin;
+
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.support.GenericApplicationContext;
+
+/**
+ * <p>An {@link ApplicationContext} implementation shared by plugins.</p>
+ * <p>Beans in the Core that need to be shared with plugins will be injected into this
+ * {@link SharedApplicationContext}.</p>
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+public class SharedApplicationContext extends GenericApplicationContext {
+}

src/main/java/run/halo/app/plugin/SharedApplicationContextHolder.java

@@ -0,0 +1,64 @@
+package run.halo.app.plugin;
+
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
+import org.springframework.context.ApplicationContext;
+import org.springframework.stereotype.Component;
+import run.halo.app.extension.DefaultSchemeManager;
+import run.halo.app.extension.ExtensionClient;
+
+/**
+ * <p>This {@link SharedApplicationContextHolder} class is used to hold a singleton instance of
+ * {@link SharedApplicationContext}.</p>
+ * <p>If sharedApplicationContext cache is null when calling the {@link #getInstance()} method,
+ * then it will call {@link #createSharedApplicationContext()} to create and cache it. Otherwise,
+ * it will be obtained directly.</p>
+ * <p>It is thread safe.</p>
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Component
+public class SharedApplicationContextHolder {
+
+    private final ApplicationContext rootApplicationContext;
+    private volatile SharedApplicationContext sharedApplicationContext;
+
+    public SharedApplicationContextHolder(ApplicationContext applicationContext) {
+        this.rootApplicationContext = applicationContext;
+    }
+
+    /**
+     * Get singleton instance of {@link SharedApplicationContext}.
+     *
+     * @return a singleton instance of {@link SharedApplicationContext}.
+     */
+    public SharedApplicationContext getInstance() {
+        if (this.sharedApplicationContext == null) {
+            synchronized (SharedApplicationContextHolder.class) {
+                if (this.sharedApplicationContext == null) {
+                    this.sharedApplicationContext = createSharedApplicationContext();
+                }
+            }
+        }
+        return this.sharedApplicationContext;
+    }
+
+    SharedApplicationContext createSharedApplicationContext() {
+        // TODO Optimize creation timing
+        SharedApplicationContext sharedApplicationContext = new SharedApplicationContext();
+        sharedApplicationContext.refresh();
+
+        DefaultListableBeanFactory beanFactory =
+            (DefaultListableBeanFactory) sharedApplicationContext.getBeanFactory();
+
+        // register shared object here
+        ExtensionClient extensionClient = rootApplicationContext.getBean(ExtensionClient.class);
+        beanFactory.registerSingleton("extensionClient", extensionClient);
+        DefaultSchemeManager defaultSchemeManager =
+            rootApplicationContext.getBean(DefaultSchemeManager.class);
+        beanFactory.registerSingleton("schemeManager", defaultSchemeManager);
+        // TODO add more shared instance here
+
+        return sharedApplicationContext;
+    }
+}

src/test/java/run/halo/app/plugin/SharedApplicationContextHolderTest.java

@@ -0,0 +1,37 @@
+package run.halo.app.plugin;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureTestDatabase;
+import org.springframework.boot.test.context.SpringBootTest;
+
+/**
+ * Tests for {@link SharedApplicationContextHolder}.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@SpringBootTest
+@AutoConfigureTestDatabase
+class SharedApplicationContextHolderTest {
+
+    @Autowired
+    SharedApplicationContextHolder sharedApplicationContextHolder;
+
+    @Test
+    void getInstance() {
+        SharedApplicationContext instance1 = sharedApplicationContextHolder.getInstance();
+        SharedApplicationContext instance2 = sharedApplicationContextHolder.getInstance();
+        assertThat(instance1).isNotNull();
+        assertThat(instance1).isEqualTo(instance2);
+    }
+
+    @Test
+    void createSharedApplicationContext() {
+        SharedApplicationContext sharedApplicationContext =
+            sharedApplicationContextHolder.createSharedApplicationContext();
+        assertThat(sharedApplicationContext).isNotNull();
+    }
+}