only allow one thread to update entries for a feed, avoids duplicates if two feeds containing the same entry are updating at the same time

src/main/java/com/commafeed/backend/feeds/FeedRefreshUpdater.java

@@ -0,0 +1,33 @@
+package com.commafeed.backend.feeds;
+
+import java.util.Collection;
+
+import javax.ejb.Asynchronous;
+import javax.ejb.Stateless;
+import javax.inject.Inject;
+
+import org.apache.commons.collections.CollectionUtils;
+
+import com.commafeed.backend.dao.FeedDAO;
+import com.commafeed.backend.model.Feed;
+import com.commafeed.backend.model.FeedEntry;
+import com.commafeed.backend.services.FeedUpdateService;
+
+@Stateless
+public class FeedRefreshUpdater {
+
+	@Inject
+	FeedUpdateService feedUpdateService;
+
+	@Inject
+	FeedDAO feedDAO;
+
+	@Asynchronous
+	public void updateEntries(Feed feed, Collection<FeedEntry> entries) {
+		if (CollectionUtils.isNotEmpty(entries)) {
+			feedUpdateService.updateEntries(feed, entries);
+		}
+		feedDAO.update(feed);
+	}
+
+}

src/main/java/com/commafeed/backend/feeds/FeedRefreshWorker.java

@@ -20,7 +20,6 @@ import org.slf4j.LoggerFactory;
 import com.commafeed.backend.HttpGetter.NotModifiedException;
 import com.commafeed.backend.model.Feed;
 import com.commafeed.backend.model.FeedEntry;
-import com.commafeed.backend.services.FeedUpdateService;
 import com.sun.syndication.io.FeedException;
 
 public class FeedRefreshWorker {
@@ -29,7 +28,7 @@ public class FeedRefreshWorker {
 			.getLogger(FeedRefreshWorker.class);
 
 	@Inject
-	FeedUpdateService feedUpdateService;
+	FeedRefreshUpdater feedRefreshUpdater;
 
 	@Inject
 	FeedFetcher fetcher;
@@ -127,7 +126,7 @@ public class FeedRefreshWorker {
 			feed.setEtagHeader(fetchedFeed.getFeed().getEtagHeader());
 			entries = fetchedFeed.getEntries();
 		}
-		feedUpdateService.updateEntries(feed, entries);
+		feedRefreshUpdater.updateEntries(feed, entries);
 
 	}
 

src/main/java/com/commafeed/backend/services/FeedUpdateService.java

@@ -5,15 +5,14 @@ import java.util.Calendar;
 import java.util.Collection;
 import java.util.List;
 
-import javax.ejb.Asynchronous;
+import javax.ejb.Lock;
-import javax.ejb.Stateless;
+import javax.ejb.LockType;
+import javax.ejb.Singleton;
 import javax.inject.Inject;
 
-import org.apache.commons.collections.CollectionUtils;
 import org.apache.commons.lang.ObjectUtils;
 import org.apache.commons.lang.StringUtils;
 
-import com.commafeed.backend.dao.FeedDAO;
 import com.commafeed.backend.dao.FeedEntryDAO;
 import com.commafeed.backend.dao.FeedEntryStatusDAO;
 import com.commafeed.backend.dao.FeedSubscriptionDAO;
@@ -25,12 +24,9 @@ import com.commafeed.backend.model.FeedEntryStatus;
 import com.commafeed.backend.model.FeedSubscription;
 import com.google.common.collect.Lists;
 
-@Stateless
+@Singleton
 public class FeedUpdateService {
 
-	@Inject
-	FeedDAO feedDAO;
-
 	@Inject
 	FeedSubscriptionDAO feedSubscriptionDAO;
 
@@ -40,10 +36,9 @@ public class FeedUpdateService {
 	@Inject
 	FeedEntryStatusDAO feedEntryStatusDAO;
 
-	@Asynchronous
+	@Lock(LockType.WRITE)
 	public void updateEntries(Feed feed, Collection<FeedEntry> entries) {
 
-		if (CollectionUtils.isNotEmpty(entries)) {
 		List<FeedEntry> existingEntries = getExistingEntries(entries);
 		List<FeedSubscription> subscriptions = feedSubscriptionDAO
 				.findByFeed(feed);
@@ -57,8 +52,7 @@ public class FeedUpdateService {
 			if (foundEntry == null) {
 				FeedEntryContent content = entry.getContent();
 
-					content.setContent(FeedUtils.handleContent(content
+				content.setContent(FeedUtils.handleContent(content.getContent()));
-							.getContent()));
 				String title = FeedUtils.handleContent(content.getTitle());
 				if (title != null) {
 					content.setTitle(title.substring(0,
@@ -71,8 +65,7 @@ public class FeedUpdateService {
 			} else {
 				boolean foundFeed = false;
 				for (Feed existingFeed : foundEntry.getFeeds()) {
-						if (ObjectUtils.equals(existingFeed.getId(),
+					if (ObjectUtils.equals(existingFeed.getId(), feed.getId())) {
-								feed.getId())) {
 						foundFeed = true;
 						break;
 					}
@@ -96,8 +89,6 @@ public class FeedUpdateService {
 		feedEntryDAO.saveOrUpdate(entryUpdateList);
 		feedEntryStatusDAO.saveOrUpdate(statusUpdateList);
 	}
-		feedDAO.update(feed);
-	}
 
 	private FeedEntry findEntry(List<FeedEntry> existingEntries, FeedEntry entry) {
 		FeedEntry foundEntry = null;