Fix the problem that lucene crashes when searching for posts (#2791)

#### What type of PR is this?

/kind bug
/area core
/milestone 2.0.0-rc.2

#### What this PR does / why we need it:

This PR mainly refactor PostEventListener into PostEventReconciler to reconcile post events synchronously. After that, the concurrent issue will be gone.

#### Which issue(s) this PR fixes:

Fixes https://github.com/halo-dev/halo/issues/2756
Fixes https://github.com/halo-dev/halo/issues/2757

#### Does this PR introduce a user-facing change?

```release-note
None
```

src/main/java/run/halo/app/event/post/PostDeletedEvent.java

@@ -1,17 +0,0 @@
-package run.halo.app.event.post;
-
-import org.springframework.context.ApplicationEvent;
-
-public class PostDeletedEvent extends ApplicationEvent {
-
-    private final String postName;
-
-    public PostDeletedEvent(Object source, String postName) {
-        super(source);
-        this.postName = postName;
-    }
-
-    public String getPostName() {
-        return postName;
-    }
-}

src/main/java/run/halo/app/event/post/PostEvent.java

@@ -0,0 +1,7 @@
+package run.halo.app.event.post;
+
+public interface PostEvent {
+
+    String getName();
+
+}

src/main/java/run/halo/app/event/post/PostPublishedEvent.java

@@ -2,7 +2,7 @@ package run.halo.app.event.post;
 
 import org.springframework.context.ApplicationEvent;
 
-public class PostPublishedEvent extends ApplicationEvent {
+public class PostPublishedEvent extends ApplicationEvent implements PostEvent {
 
     private final String postName;
 
@@ -11,7 +11,8 @@ public class PostPublishedEvent extends ApplicationEvent {
         this.postName = postName;
     }
 
-    public String getPostName() {
+    @Override
+    public String getName() {
         return postName;
     }
 

src/main/java/run/halo/app/event/post/PostRecycledEvent.java

@@ -2,7 +2,7 @@ package run.halo.app.event.post;
 
 import org.springframework.context.ApplicationEvent;
 
-public class PostRecycledEvent extends ApplicationEvent {
+public class PostRecycledEvent extends ApplicationEvent implements PostEvent {
 
     private final String postName;
 
@@ -11,7 +11,7 @@ public class PostRecycledEvent extends ApplicationEvent {
         this.postName = postName;
     }
 
-    public String getPostName() {
+    public String getName() {
         return postName;
     }
 }

src/main/java/run/halo/app/event/post/PostUnpublishedEvent.java

@@ -2,7 +2,7 @@ package run.halo.app.event.post;
 
 import org.springframework.context.ApplicationEvent;
 
-public class PostUnpublishedEvent extends ApplicationEvent {
+public class PostUnpublishedEvent extends ApplicationEvent implements PostEvent {
 
     private final String postName;
 
@@ -11,7 +11,8 @@ public class PostUnpublishedEvent extends ApplicationEvent {
         this.postName = postName;
     }
 
-    public String getPostName() {
+    @Override
+    public String getName() {
         return postName;
     }
 

src/main/java/run/halo/app/extension/controller/DefaultController.java

@@ -11,6 +11,7 @@ import java.util.function.Supplier;
 import java.util.stream.IntStream;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.commons.lang3.concurrent.BasicThreadFactory;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StopWatch;
 import run.halo.app.extension.controller.RequestQueue.DelayedEntry;
@@ -32,6 +33,7 @@ public class DefaultController<R> implements Controller {
 
     private final ExecutorService executor;
 
+    @Nullable
     private final Synchronizer<R> synchronizer;
 
     private final Duration minDelay;
@@ -144,7 +146,9 @@ public class DefaultController<R> implements Controller {
         @Override
         public void run() {
             log.info("Controller worker {} started", this.name);
-            synchronizer.start();
+            if (synchronizer != null) {
+                synchronizer.start();
+            }
             while (!isDisposed() && !Thread.currentThread().isInterrupted()) {
                 try {
                     var entry = queue.take();
@@ -213,7 +217,9 @@ public class DefaultController<R> implements Controller {
         disposed = true;
         log.info("Disposing controller {}", name);
 
-        synchronizer.dispose();
+        if (synchronizer != null) {
+            synchronizer.dispose();
+        }
 
         executor.shutdownNow();
         try {

src/main/java/run/halo/app/search/post/LucenePostSearchService.java

@@ -100,10 +100,10 @@ public class LucenePostSearchService implements PostSearchService, DisposableBea
                 var doc = this.convert(post);
                 try {
                     var seqNum =
-                        writer.updateDocument(new Term(PostDoc.ID_FIELD, post.getName()), doc);
+                        writer.updateDocument(new Term(PostDoc.ID_FIELD, post.name()), doc);
                     if (log.isDebugEnabled()) {
                         log.debug("Updated document({}) with sequence number {} returned",
-                            post.getName(), seqNum);
+                            post.name(), seqNum);
                     }
                 } catch (IOException e) {
                     throw Exceptions.propagate(e);
@@ -142,19 +142,19 @@ public class LucenePostSearchService implements PostSearchService, DisposableBea
 
     private Document convert(PostDoc post) {
         var doc = new Document();
-        doc.add(new StringField("name", post.getName(), YES));
+        doc.add(new StringField("name", post.name(), YES));
-        doc.add(new StoredField("title", post.getTitle()));
+        doc.add(new StoredField("title", post.title()));
 
-        var content = Jsoup.clean(stripToEmpty(post.getExcerpt()) + stripToEmpty(post.getContent()),
+        var content = Jsoup.clean(stripToEmpty(post.excerpt()) + stripToEmpty(post.content()),
             Safelist.none());
 
         doc.add(new StoredField("content", content));
-        doc.add(new TextField("searchable", post.getTitle() + content, NO));
+        doc.add(new TextField("searchable", post.title() + content, NO));
 
-        long publishTimestamp = post.getPublishTimestamp().toEpochMilli();
+        long publishTimestamp = post.publishTimestamp().toEpochMilli();
         doc.add(new LongPoint("publishTimestamp", publishTimestamp));
         doc.add(new StoredField("publishTimestamp", publishTimestamp));
-        doc.add(new StoredField("permalink", post.getPermalink()));
+        doc.add(new StoredField("permalink", post.permalink()));
         return doc;
     }
 

src/main/java/run/halo/app/search/post/PostDoc.java

@@ -1,36 +1,34 @@
 package run.halo.app.search.post;
 
 import java.time.Instant;
-import lombok.Data;
+import org.springframework.util.Assert;
 import run.halo.app.theme.finders.vo.PostVo;
 
-@Data
+public record PostDoc(String name,
-public class PostDoc {
+                      String title,
+                      String excerpt,
+                      String content,
+                      Instant publishTimestamp,
+                      String permalink) {
 
     public static final String ID_FIELD = "name";
 
-    private String name;
+    public PostDoc {
-
+        Assert.hasText(name, "Name must not be blank");
-    private String title;
+        Assert.hasText(title, "Title must not be blank");
-
+        Assert.hasText(permalink, "Permalink must not be blank");
-    private String excerpt;
+        Assert.notNull(publishTimestamp, "PublishTimestamp must not be null");
-
+    }
-    private String content;
-
-    private Instant publishTimestamp;
-
-    private String permalink;
 
     // TODO Move this static method to other place.
     public static PostDoc from(PostVo postVo) {
-        var post = new PostDoc();
+        return new PostDoc(
-        post.setName(postVo.getMetadata().getName());
+            postVo.getMetadata().getName(),
-        post.setTitle(postVo.getSpec().getTitle());
+            postVo.getSpec().getTitle(),
-        post.setExcerpt(postVo.getStatus().getExcerpt());
+            postVo.getStatus().getExcerpt(),
-        post.setPublishTimestamp(postVo.getSpec().getPublishTime());
+            postVo.getContent().getContent(),
-        post.setContent(postVo.getContent().getContent());
+            postVo.getSpec().getPublishTime(),
-        post.setPermalink(postVo.getStatus().getPermalink());
+            postVo.getStatus().getPermalink()
-        return post;
+        );
     }
-
 }

src/main/java/run/halo/app/search/post/PostEventListener.java

@@ -1,76 +0,0 @@
-package run.halo.app.search.post;
-
-import java.util.List;
-import java.util.Set;
-import java.util.concurrent.CountDownLatch;
-import org.springframework.context.event.EventListener;
-import org.springframework.scheduling.annotation.Async;
-import org.springframework.stereotype.Component;
-import reactor.core.Exceptions;
-import run.halo.app.event.post.PostPublishedEvent;
-import run.halo.app.event.post.PostRecycledEvent;
-import run.halo.app.event.post.PostUnpublishedEvent;
-import run.halo.app.plugin.extensionpoint.ExtensionGetter;
-import run.halo.app.theme.finders.PostFinder;
-
-@Component
-public class PostEventListener {
-
-    private final ExtensionGetter extensionGetter;
-
-    private final PostFinder postFinder;
-
-    public PostEventListener(ExtensionGetter extensionGetter,
-        PostFinder postFinder) {
-        this.extensionGetter = extensionGetter;
-        this.postFinder = postFinder;
-    }
-
-    @Async
-    @EventListener(PostPublishedEvent.class)
-    public void handlePostPublished(PostPublishedEvent publishedEvent) throws InterruptedException {
-        var latch = new CountDownLatch(1);
-        postFinder.getByName(publishedEvent.getPostName())
-            .map(PostDoc::from)
-            .flatMap(postDoc -> extensionGetter.getEnabledExtension(PostSearchService.class)
-                .doOnNext(searchService -> {
-                    try {
-                        searchService.addDocuments(List.of(postDoc));
-                    } catch (Exception e) {
-                        throw Exceptions.propagate(e);
-                    }
-                })
-            )
-            .doFinally(signalType -> latch.countDown())
-            .subscribe();
-        latch.await();
-    }
-
-    @Async
-    @EventListener(PostUnpublishedEvent.class)
-    public void handlePostUnpublished(PostUnpublishedEvent unpublishedEvent)
-        throws InterruptedException {
-        deletePostDoc(unpublishedEvent.getPostName());
-    }
-
-    @Async
-    @EventListener(PostRecycledEvent.class)
-    public void handlePostRecycled(PostRecycledEvent recycledEvent) throws InterruptedException {
-        deletePostDoc(recycledEvent.getPostName());
-    }
-
-    void deletePostDoc(String postName) throws InterruptedException {
-        var latch = new CountDownLatch(1);
-        extensionGetter.getEnabledExtension(PostSearchService.class)
-            .doOnNext(searchService -> {
-                try {
-                    searchService.removeDocuments(Set.of(postName));
-                } catch (Exception e) {
-                    throw Exceptions.propagate(e);
-                }
-            })
-            .doFinally(signalType -> latch.countDown())
-            .subscribe();
-        latch.await();
-    }
-}

src/main/java/run/halo/app/search/post/PostEventReconciler.java

@@ -0,0 +1,160 @@
+package run.halo.app.search.post;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.CountDownLatch;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.context.SmartLifecycle;
+import org.springframework.context.event.EventListener;
+import org.springframework.stereotype.Component;
+import reactor.core.Exceptions;
+import run.halo.app.event.post.PostEvent;
+import run.halo.app.event.post.PostPublishedEvent;
+import run.halo.app.event.post.PostRecycledEvent;
+import run.halo.app.event.post.PostUnpublishedEvent;
+import run.halo.app.extension.controller.Controller;
+import run.halo.app.extension.controller.ControllerBuilder;
+import run.halo.app.extension.controller.DefaultController;
+import run.halo.app.extension.controller.DefaultDelayQueue;
+import run.halo.app.extension.controller.Reconciler;
+import run.halo.app.extension.controller.RequestQueue;
+import run.halo.app.plugin.extensionpoint.ExtensionGetter;
+import run.halo.app.theme.finders.PostFinder;
+
+@Slf4j
+@Component
+public class PostEventReconciler implements Reconciler<PostEvent>, SmartLifecycle {
+
+    private final ExtensionGetter extensionGetter;
+
+    private final PostFinder postFinder;
+
+    private final RequestQueue<PostEvent> postEventQueue;
+
+
+    private final Controller postEventController;
+
+    private boolean running = false;
+
+    public PostEventReconciler(ExtensionGetter extensionGetter,
+        PostFinder postFinder) {
+        this.extensionGetter = extensionGetter;
+        this.postFinder = postFinder;
+
+        postEventQueue = new DefaultDelayQueue<>(Instant::now);
+        postEventController = this.setupWith(null);
+    }
+
+    @Override
+    public Result reconcile(PostEvent postEvent) {
+        if (postEvent instanceof PostPublishedEvent) {
+            try {
+                addPostDoc(postEvent.getName());
+            } catch (InterruptedException e) {
+                throw Exceptions.propagate(e);
+            }
+        }
+        if (postEvent instanceof PostUnpublishedEvent
+            || postEvent instanceof PostRecycledEvent) {
+            try {
+                deletePostDoc(postEvent.getName());
+            } catch (InterruptedException e) {
+                throw Exceptions.propagate(e);
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Controller setupWith(ControllerBuilder builder) {
+        return new DefaultController<>(
+            this.getClass().getName(),
+            this,
+            postEventQueue,
+            null,
+            Duration.ofMillis(100),
+            Duration.ofSeconds(1000)
+        );
+    }
+
+    @EventListener(PostPublishedEvent.class)
+    public void handlePostPublished(PostPublishedEvent publishedEvent) {
+        postEventQueue.addImmediately(publishedEvent);
+    }
+
+    @EventListener(PostUnpublishedEvent.class)
+    public void handlePostUnpublished(PostUnpublishedEvent unpublishedEvent) {
+        postEventQueue.addImmediately(unpublishedEvent);
+    }
+
+    @EventListener(PostRecycledEvent.class)
+    public void handlePostRecycled(PostRecycledEvent recycledEvent) {
+        postEventQueue.addImmediately(recycledEvent);
+    }
+
+    void addPostDoc(String postName) throws InterruptedException {
+        var latch = new CountDownLatch(1);
+        var disposable = postFinder.getByName(postName)
+            .map(PostDoc::from)
+            .flatMap(postDoc -> extensionGetter.getEnabledExtension(PostSearchService.class)
+                .doOnNext(searchService -> {
+                    try {
+                        searchService.addDocuments(List.of(postDoc));
+                    } catch (Exception e) {
+                        throw Exceptions.propagate(e);
+                    }
+                })
+            )
+            .doFinally(signalType -> latch.countDown())
+            .subscribe(service -> {
+            }, throwable -> {
+                throw Exceptions.propagate(throwable);
+            });
+        try {
+            latch.await();
+        } finally {
+            disposable.dispose();
+        }
+    }
+
+    void deletePostDoc(String postName) throws InterruptedException {
+        var latch = new CountDownLatch(1);
+        var disposable = extensionGetter.getEnabledExtension(PostSearchService.class)
+            .doOnNext(searchService -> {
+                try {
+                    searchService.removeDocuments(Set.of(postName));
+                } catch (Exception e) {
+                    throw Exceptions.propagate(e);
+                }
+            })
+            .doFinally(signalType -> latch.countDown())
+            .subscribe(service -> {
+            }, throwable -> {
+                throw Exceptions.propagate(throwable);
+            });
+        try {
+            latch.await();
+        } finally {
+            disposable.dispose();
+        }
+    }
+
+    @Override
+    public void start() {
+        postEventController.start();
+        running = true;
+    }
+
+    @Override
+    public void stop() {
+        running = false;
+        postEventController.dispose();
+    }
+
+    @Override
+    public boolean isRunning() {
+        return running;
+    }
+}