From 0dec0e37886ce35edd500767f454d321059605ce Mon Sep 17 00:00:00 2001
From: Athou <jeremiepanzer@gmail.com>
Date: Wed, 3 Jul 2024 14:16:09 +0200
Subject: [PATCH] fix a race condition where a feed could be refreshed before
 it was created

---
 .../backend/dao/FeedSubscriptionDAO.java      | 30 +++++++++++++++++++
 .../service/FeedSubscriptionService.java      | 19 ++++++++++--
 2 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/commafeed-server/src/main/java/com/commafeed/backend/dao/FeedSubscriptionDAO.java b/commafeed-server/src/main/java/com/commafeed/backend/dao/FeedSubscriptionDAO.java
index 32122507..26ea8cd0 100644
--- a/commafeed-server/src/main/java/com/commafeed/backend/dao/FeedSubscriptionDAO.java
+++ b/commafeed-server/src/main/java/com/commafeed/backend/dao/FeedSubscriptionDAO.java
@@ -2,9 +2,16 @@ package com.commafeed.backend.dao;
 
 import java.util.List;
 import java.util.Set;
+import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
 import org.hibernate.SessionFactory;
+import org.hibernate.engine.spi.SessionFactoryImplementor;
+import org.hibernate.event.service.spi.EventListenerRegistry;
+import org.hibernate.event.spi.EventType;
+import org.hibernate.event.spi.PostInsertEvent;
+import org.hibernate.event.spi.PostInsertEventListener;
+import org.hibernate.persister.entity.EntityPersister;
 
 import com.commafeed.backend.model.AbstractModel;
 import com.commafeed.backend.model.Feed;
@@ -24,9 +31,32 @@ public class FeedSubscriptionDAO extends GenericDAO<FeedSubscription> {
 
 	private final QFeedSubscription sub = QFeedSubscription.feedSubscription;
 
+	private final SessionFactory sessionFactory;
+
 	@Inject
 	public FeedSubscriptionDAO(SessionFactory sessionFactory) {
 		super(sessionFactory);
+		this.sessionFactory = sessionFactory;
+	}
+
+	public void onPostCommitInsert(Consumer<FeedSubscription> consumer) {
+		sessionFactory.unwrap(SessionFactoryImplementor.class)
+				.getServiceRegistry()
+				.getService(EventListenerRegistry.class)
+				.getEventListenerGroup(EventType.POST_COMMIT_INSERT)
+				.appendListener(new PostInsertEventListener() {
+					@Override
+					public void onPostInsert(PostInsertEvent event) {
+						if (event.getEntity() instanceof FeedSubscription s) {
+							consumer.accept(s);
+						}
+					}
+
+					@Override
+					public boolean requiresPostCommitHandling(EntityPersister persister) {
+						return true;
+					}
+				});
 	}
 
 	public FeedSubscription findById(User user, Long id) {
diff --git a/commafeed-server/src/main/java/com/commafeed/backend/service/FeedSubscriptionService.java b/commafeed-server/src/main/java/com/commafeed/backend/service/FeedSubscriptionService.java
index 2bd11e56..444b9f34 100644
--- a/commafeed-server/src/main/java/com/commafeed/backend/service/FeedSubscriptionService.java
+++ b/commafeed-server/src/main/java/com/commafeed/backend/service/FeedSubscriptionService.java
@@ -23,11 +23,9 @@ import com.commafeed.frontend.model.UnreadCount;
 
 import jakarta.inject.Inject;
 import jakarta.inject.Singleton;
-import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
 @Slf4j
-@RequiredArgsConstructor(onConstructor = @__({ @Inject }))
 @Singleton
 public class FeedSubscriptionService {
 
@@ -39,6 +37,22 @@ public class FeedSubscriptionService {
 	private final CacheService cache;
 	private final CommaFeedConfiguration config;
 
+	@Inject
+	public FeedSubscriptionService(FeedDAO feedDAO, FeedEntryStatusDAO feedEntryStatusDAO, FeedSubscriptionDAO feedSubscriptionDAO,
+			FeedService feedService, FeedRefreshEngine feedRefreshEngine, CacheService cache, CommaFeedConfiguration config) {
+		this.feedDAO = feedDAO;
+		this.feedEntryStatusDAO = feedEntryStatusDAO;
+		this.feedSubscriptionDAO = feedSubscriptionDAO;
+		this.feedService = feedService;
+		this.feedRefreshEngine = feedRefreshEngine;
+		this.cache = cache;
+		this.config = config;
+
+		// automatically refresh feeds after they are subscribed to
+		// we need to use this hook because the feed needs to have been persisted because the queue processing is asynchronous
+		feedSubscriptionDAO.onPostCommitInsert(sub -> feedRefreshEngine.refreshImmediately(sub.getFeed()));
+	}
+
 	public long subscribe(User user, String url, String title) {
 		return subscribe(user, url, title, null, 0);
 	}
@@ -83,7 +97,6 @@ public class FeedSubscriptionService {
 		sub.setTitle(FeedUtils.truncate(title, 128));
 		feedSubscriptionDAO.saveOrUpdate(sub);
 
-		feedRefreshEngine.refreshImmediately(feed);
 		cache.invalidateUserRootCategory(user);
 		return sub.getId();
 	}