Keep RSS articles sorted by date in memory do avoid sorting them all the time

Optimization to address issue #34.

src/rss/rss_imp.cpp

@@ -490,11 +490,9 @@ void RSSImp::refreshArticleList(QTreeWidgetItem* item) {
   qDebug("Getting the list of news");
   RssArticleList news;
   if (rss_item == m_rssManager)
-    news = rss_item->unreadArticleList();
+    news = rss_item->unreadArticleListByDateDesc();
   else if (rss_item)
-    news = rss_item->articleList();
-  // Sort
-  RssManager::sortArticleListByDateDesc(news);
+    news = rss_item->articleListByDateDesc();
   // Clear the list first
   textBrowser->clear();
   m_currentArticle = 0;

src/rss/rssfeed.cpp

@@ -41,6 +41,11 @@
 #include "downloadthread.h"
 #include "fs_utils.h"
 
+bool rssArticleDateRecentThan(const RssArticlePtr& left, const RssArticlePtr& right)
+{
+  return left->date() > right->date();
+}
+
 RssFeed::RssFeed(RssManager* manager, RssFolder* parent, const QString &url):
   m_manager(manager), m_parent(parent), m_icon(":/Icons/oxygen/application-rss+xml.png"),
   m_unreadCount(0), m_dirty(false), m_inErrorState(false), m_loading(false) {
@@ -95,11 +100,30 @@ void RssFeed::loadItemsFromDisk() {
   foreach (const QVariant &var_it, old_items) {
     QHash<QString, QVariant> item = var_it.toHash();
     RssArticlePtr rss_item = hashToRssArticle(this, item);
-    if (rss_item) {
-      m_articles.insert(rss_item->guid(), rss_item);
-      if (!rss_item->isRead())
-        ++m_unreadCount;
+    if (rss_item)
+      addArticle(rss_item);
   }
+}
+
+void RssFeed::addArticle(const RssArticlePtr& article)
+{
+  Q_ASSERT(!m_articles.contains(article->guid()));
+  // Update unreadCount
+  if (!article->isRead())
+    ++m_unreadCount;
+  // Insert in hash table
+  m_articles[article->guid()] = article;
+  // Insertion sort
+  RssArticleList::Iterator lowerBound = qLowerBound(m_articlesByDate.begin(), m_articlesByDate.end(), article, rssArticleDateRecentThan);
+  m_articlesByDate.insert(lowerBound, article);
+  // Restrict size
+  const int max_articles = RssSettings().getRSSMaxArticlesPerFeed();
+  if (m_articlesByDate.size() > max_articles) {
+    RssArticlePtr oldestArticle = m_articlesByDate.takeLast();
+    m_articles.remove(oldestArticle->guid());
+    // Update unreadCount
+    if (!oldestArticle->isRead())
+      --m_unreadCount;
   }
 }
 
@@ -201,18 +225,18 @@ uint RssFeed::unreadCount() const
   return m_unreadCount;
 }
 
-RssArticleList RssFeed::articleList() const {
-  return m_articles.values();
+RssArticleList RssFeed::articleListByDateDesc() const {
+  return m_articlesByDate;
 }
 
-RssArticleList RssFeed::unreadArticleList() const {
+RssArticleList RssFeed::unreadArticleListByDateDesc() const {
   RssArticleList unread_news;
 
-  RssArticleHash::ConstIterator it = m_articles.begin();
-  RssArticleHash::ConstIterator itend = m_articles.end();
+  RssArticleList::ConstIterator it = m_articlesByDate.begin();
+  RssArticleList::ConstIterator itend = m_articlesByDate.end();
   for ( ; it != itend; ++it) {
-    if (!it.value()->isRead())
-      unread_news << it.value();
+    if (!(*it)->isRead())
+      unread_news << *it;
   }
   return unread_news;
 }
@@ -223,22 +247,6 @@ QString RssFeed::iconUrl() const {
   return QString("http://")+QUrl(m_url).host()+QString("/favicon.ico");
 }
 
-void RssFeed::removeOldArticles() {
-  const uint max_articles = RssSettings().getRSSMaxArticlesPerFeed();
-  const uint nb_articles = m_articles.size();
-  if (nb_articles > max_articles) {
-    RssArticleList listItems = m_articles.values();
-    RssManager::sortArticleListByDateDesc(listItems);
-    const int excess = nb_articles - max_articles;
-    for (uint i=nb_articles-excess; i<nb_articles; ++i) {
-      RssArticlePtr article = m_articles.take(listItems.at(i)->guid());
-      // Update unreadCount
-      if (!article->isRead())
-        --m_unreadCount;
-    }
-  }
-}
-
 // read and store the downloaded rss' informations
 void RssFeed::handleFinishedDownload(const QString& url, const QString &file_path) {
   if (url == m_url) {
@@ -290,7 +298,7 @@ void RssFeed::handleNewArticle(const QString& feedUrl, const QVariantHash& artic
 
   RssArticlePtr article = hashToRssArticle(this, articleData);
   Q_ASSERT(article);
-  m_articles[guid] = article;
+  addArticle(article);
 
   // Download torrent if necessary.
   if (RssSettings().isRssDownloadingEnabled()) {
@@ -307,9 +315,6 @@ void RssFeed::handleNewArticle(const QString& feedUrl, const QVariantHash& artic
         QBtSession::instance()->downloadUrlAndSkipDialog(torrent_url, matching_rule->savePath(), matching_rule->label());
     }
   }
-  // Update unreadCount if necessary
-  if (!article->isRead())
-    ++m_unreadCount;
 
   m_manager->forwardFeedInfosChanged(m_url, displayName(), m_unreadCount);
   // FIXME: We should forward the information here but this would seriously decrease
@@ -327,9 +332,6 @@ void RssFeed::handleFeedParsingFinished(const QString& feedUrl, const QString& e
     qWarning() << "Reason:" << error;
   }
 
-  // Make sure we limit the number of articles
-  removeOldArticles();
-
   m_loading = false;
   m_inErrorState = !error.isEmpty();
 

src/rss/rssfeed.h

@@ -45,6 +45,8 @@ typedef QHash<QString, RssArticlePtr> RssArticleHash;
 typedef QSharedPointer<RssFeed> RssFeedPtr;
 typedef QList<RssFeedPtr> RssFeedList;
 
+bool rssArticleDateRecentThan(const RssArticlePtr& left, const RssArticlePtr& right);
+
 class RssFeed: public QObject, public RssFile {
   Q_OBJECT
 
@@ -70,9 +72,9 @@ public:
   uint count() const;
   virtual void markAsRead();
   virtual uint unreadCount() const;
-  virtual RssArticleList articleList() const;
+  virtual RssArticleList articleListByDateDesc() const;
   const RssArticleHash& articleHash() const { return m_articles; }
-  virtual RssArticleList unreadArticleList() const;
+  virtual RssArticleList unreadArticleListByDateDesc() const;
   void decrementUnreadCount();
 
 private slots:
@@ -83,14 +85,15 @@ private slots:
   void handleFeedParsingFinished(const QString& feedUrl, const QString& error);
 
 private:
-  void removeOldArticles();
   QString iconUrl() const;
   void loadItemsFromDisk();
+  void addArticle(const RssArticlePtr& article);
 
 private:
   RssManager* m_manager;
   RssArticleHash m_articles;
-  RssFolder *m_parent;
+  RssArticleList m_articlesByDate; // Articles sorted by date (more recent first)
+  RssFolder* m_parent;
   QString m_title;
   QString m_url;
   QString m_alias;

src/rss/rssfile.h

@@ -59,8 +59,8 @@ public:
   virtual RssFolder* parent() const = 0;
   virtual void setParent(RssFolder* parent) = 0;
   virtual void refresh() = 0;
-  virtual RssArticleList articleList() const = 0;
-  virtual RssArticleList unreadArticleList() const = 0;
+  virtual RssArticleList articleListByDateDesc() const = 0;
+  virtual RssArticleList unreadArticleListByDateDesc() const = 0;
   virtual void removeAllSettings() = 0;
   virtual void saveItemsToDisk() = 0;
   QStringList pathHierarchy() const;

src/rss/rssfolder.cpp

@@ -91,24 +91,28 @@ void RssFolder::refresh() {
   }
 }
 
-RssArticleList RssFolder::articleList() const {
+RssArticleList RssFolder::articleListByDateDesc() const {
   RssArticleList news;
 
   RssFileHash::ConstIterator it = m_children.begin();
   RssFileHash::ConstIterator itend = m_children.end();
   for ( ; it != itend; ++it) {
-    news << it.value()->articleList();
+    int n = news.size();
+    news << it.value()->articleListByDateDesc();
+    std::inplace_merge(news.begin(), news.begin() + n, news.end(), rssArticleDateRecentThan);
   }
   return news;
 }
 
-RssArticleList RssFolder::unreadArticleList() const {
+RssArticleList RssFolder::unreadArticleListByDateDesc() const {
   RssArticleList unread_news;
 
   RssFileHash::ConstIterator it = m_children.begin();
   RssFileHash::ConstIterator itend = m_children.end();
   for ( ; it != itend; ++it) {
-    unread_news << it.value()->unreadArticleList();
+    int n = unread_news.size();
+    unread_news << it.value()->unreadArticleListByDateDesc();
+    std::inplace_merge(unread_news.begin(), unread_news.begin() + n, unread_news.end(), rssArticleDateRecentThan);
   }
   return unread_news;
 }

src/rss/rssfolder.h

@@ -62,8 +62,8 @@ public:
   virtual QString displayName() const;
   virtual QString id() const;
   bool hasChild(const QString &childId);
-  virtual RssArticleList articleList() const;
-  virtual RssArticleList unreadArticleList() const;
+  virtual RssArticleList articleListByDateDesc() const;
+  virtual RssArticleList unreadArticleListByDateDesc() const;
   virtual void removeAllSettings();
   virtual void saveItemsToDisk();
   void removeAllItems();

src/rss/rssmanager.cpp

@@ -151,15 +151,6 @@ void RssManager::saveStreamList() const {
   settings.setRssFeedsAliases(aliases);
 }
 
-static bool laterItemDate(const RssArticlePtr& a, const RssArticlePtr& b)
-{
-  return (a->date() > b->date());
-}
-
-void RssManager::sortArticleListByDateDesc(RssArticleList& news_list) {
-  qSort(news_list.begin(), news_list.end(), laterItemDate);
-}
-
 RssDownloadRuleList *RssManager::downloadRules() const
 {
   Q_ASSERT(m_downloadRules);

src/rss/rssmanager.h

@@ -52,7 +52,6 @@ public:
 
   DownloadThread* rssDownloader() const;
   RssParser* rssParser() const;
-  static void sortArticleListByDateDesc(RssArticleList& news_list);
 
   RssDownloadRuleList* downloadRules() const;