check if the feed has changed by using publishDate of the feed or the first entry

src/main/java/com/commafeed/backend/dao/GenericDAO.java

@@ -1,6 +1,7 @@
 package com.commafeed.backend.dao;
 
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.List;
 
 import javax.annotation.PostConstruct;
@@ -38,13 +39,13 @@ public abstract class GenericDAO<T extends AbstractModel> {
 		em.persist(object);
 	}
 
-	public void save(List<T> objects) {
+	public void save(Collection<T> objects) {
 		for (Object object : objects) {
 			em.persist(object);
 		}
 	}
 
-	public void update(List<T> objects) {
+	public void update(Collection<T> objects) {
 		for (Object object : objects) {
 			em.merge(object);
 		}

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

@@ -36,16 +36,18 @@ public class FeedFetcher {
 
 		HttpResult result = getter.getBinary(feedUrl, lastModified, eTag);
 		if (extractFeedUrlFromHtml) {
-			String extractedUrl = extractFeedUrl(StringUtils
-					.newStringUtf8(result.getContent()), feedUrl);
+			String extractedUrl = extractFeedUrl(
+					StringUtils.newStringUtf8(result.getContent()), feedUrl);
 			if (org.apache.commons.lang.StringUtils.isNotBlank(extractedUrl)) {
 				result = getter.getBinary(extractedUrl, lastModified, eTag);
 				feedUrl = extractedUrl;
 			}
 		}
 		feed = parser.parse(feedUrl, result.getContent());
+
 		feed.setLastModifiedHeader(result.getLastModifiedSince());
 		feed.setEtagHeader(result.geteTag());
+		feed.setFetchDuration(result.getDuration());
 		return feed;
 	}
 

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

@@ -39,8 +39,9 @@ public class FeedParser {
 
 		try {
 			InputSource source = new InputSource(new ByteArrayInputStream(xml));
-			if (new String(ArrayUtils.subarray(xml, 0, 100)).split(SystemUtils.LINE_SEPARATOR)[0]
-					.toUpperCase().contains("ISO-8859-1")) {
+			if (new String(ArrayUtils.subarray(xml, 0, 100))
+					.split(SystemUtils.LINE_SEPARATOR)[0].toUpperCase()
+					.contains("ISO-8859-1")) {
 				// they probably use word, we need to handle curly quotes and
 				// other word special characters
 				source.setEncoding("windows-1252");
@@ -70,6 +71,13 @@ public class FeedParser {
 
 				feed.getEntries().add(entry);
 			}
+			Date publishedDate = rss.getPublishedDate();
+			if (publishedDate == null && !feed.getEntries().isEmpty()) {
+				FeedEntry first = feed.getEntries().iterator().next();
+				publishedDate = first.getUpdated();
+			}
+			feed.setPublishedDate(publishedDate);
+
 		} catch (Exception e) {
 			throw new FeedException(String.format(
 					"Could not parse feed from %s : %s", feedUrl,

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

@@ -86,6 +86,13 @@ public class FeedRefreshWorker {
 		try {
 			fetchedFeed = fetcher.fetch(feed.getUrl(), false,
 					feed.getLastModifiedHeader(), feed.getEtagHeader());
+			if (fetchedFeed.getPublishedDate() != null
+					&& feed.getLastUpdateSuccess() != null
+					&& fetchedFeed.getPublishedDate().before(
+							feed.getLastUpdateSuccess())) {
+				throw new NotModifiedException();
+			}
+			feed.setLastUpdateSuccess(Calendar.getInstance().getTime());
 		} catch (NotModifiedException e) {
 			modified = false;
 			log.debug("Feed not modified (304) : " + feed.getUrl());

src/main/java/com/commafeed/backend/model/Feed.java

@@ -31,19 +31,44 @@ public class Feed extends AbstractModel {
 	@Index(name = "urlHash_index")
 	private String urlHash;
 
+	/**
+	 * title of the feed, used only when fetching, not stored
+	 */
 	@Transient
 	private String title;
 
+	/**
+	 * time it took to fetch the feed, used only when fetching, not stored
+	 */
+	@Transient
+	private long fetchDuration;
+
+	/**
+	 * extracted published date from the feed, used only when fetching, not
+	 * stored
+	 */
+	@Transient
+	private Date publishedDate;
+
 	/**
 	 * The url of the website, extracted from the feed
 	 */
 	@Column(length = 2048)
 	private String link;
 
+	/**
+	 * Last time we tried to fetch the feed
+	 */
 	@Temporal(TemporalType.TIMESTAMP)
 	@Index(name = "lastupdated_index")
 	private Date lastUpdated;
 
+	/**
+	 * Last time we successfully refreshed the feed
+	 */
+	@Temporal(TemporalType.TIMESTAMP)
+	private Date lastUpdateSuccess;
+
 	@Column(length = 1024)
 	private String message;
 
@@ -169,4 +194,28 @@ public class Feed extends AbstractModel {
 		this.etagHeader = etagHeader;
 	}
 
+	public long getFetchDuration() {
+		return fetchDuration;
+	}
+
+	public void setFetchDuration(long fetchDuration) {
+		this.fetchDuration = fetchDuration;
+	}
+
+	public Date getPublishedDate() {
+		return publishedDate;
+	}
+
+	public void setPublishedDate(Date publishedDate) {
+		this.publishedDate = publishedDate;
+	}
+
+	public Date getLastUpdateSuccess() {
+		return lastUpdateSuccess;
+	}
+
+	public void setLastUpdateSuccess(Date lastUpdateSuccess) {
+		this.lastUpdateSuccess = lastUpdateSuccess;
+	}
+
 }