Begin refactoring feed updating routines for speed

Make sure that property change signals are only emitted when something
has really changed.  So far part "feed" has been done.  Entries,
enclosures and entry authors still need to be done.

src/datamanager.cpp

@@ -30,7 +30,7 @@ DataManager::DataManager()
             feed->setDescription(description);
             feed->setLastUpdated(lastUpdated);
             //qDebug() << "Retrieving authors";
-            feed->retrieveAuthors();
+            feed->updateAuthors();
             // TODO: signal feedmodel: Q_EMIT dataChanged(createIndex(i, 0), createIndex(i, 0));
         }
     });

src/feed.cpp

@@ -40,7 +40,7 @@ Feed::Feed(QString const feedurl)
     m_errorId = 0;
     m_errorString = QLatin1String("");
 
-    retrieveAuthors();
+    updateAuthors();
 
     connect(&Fetcher::instance(), &Fetcher::startedFetchingFeed, this, [this](const QString &url) {
         if (url == m_url) {
@@ -78,21 +78,50 @@ Feed::~Feed()
 {
 }
 
-void Feed::retrieveAuthors()
+void Feed::updateAuthors()
 {
-    //qDebug() << "Start retrieving authors for" << m_name;
-    for (int i=0; i < m_authors.count(); i++) {
-        delete m_authors[i];
-    }
-    m_authors.clear();
+    QVector<Author *> newAuthors;
+    bool haveAuthorsChanged = false;
+
     QSqlQuery authorQuery;
     authorQuery.prepare(QStringLiteral("SELECT * FROM Authors WHERE id='' AND feed=:feed"));
     authorQuery.bindValue(QStringLiteral(":feed"), m_url);
     Database::instance().execute(authorQuery);
     while (authorQuery.next()) {
-        m_authors += new Author(authorQuery.value(QStringLiteral("name")).toString(), authorQuery.value(QStringLiteral("email")).toString(), authorQuery.value(QStringLiteral("uri")).toString(), nullptr);
+        // check if author already exists, if so, then reuse
+        bool existingAuthor = false;
+        QString name = authorQuery.value(QStringLiteral("name")).toString();
+        QString email = authorQuery.value(QStringLiteral("email")).toString();
+        QString url = authorQuery.value(QStringLiteral("uri")).toString();
+        //qDebug() << name << email << url;
+        for (int i=0; i < m_authors.count(); i++) {
+            //qDebug() << "old authors" << m_authors[i]->name() << m_authors[i]->email() << m_authors[i]->url();
+            if (m_authors[i] && m_authors[i]->name() == name
+                && m_authors[i]->email() == email
+                && m_authors[i]->url() == url) {
+                existingAuthor = true;
+                newAuthors += m_authors[i];
+            }
+        }
+        if (!existingAuthor) {
+            newAuthors += new Author(name, email, url, nullptr);
+            haveAuthorsChanged = true;
+        }
     }
-    Q_EMIT authorsChanged(m_authors);
+
+    // Finally check whether m_authors and newAuthors are identical
+    // if not, then delete the authors that were removed
+    for (int i=0; i < m_authors.count(); i++) {
+        if (!newAuthors.contains(m_authors[i])) {
+            delete m_authors[i];
+            haveAuthorsChanged = true;
+        }
+    }
+
+    m_authors = newAuthors;
+
+    if (haveAuthorsChanged) Q_EMIT authorsChanged(m_authors);
+    //qDebug() << "feed" << m_name << "authors have changed?" << haveAuthorsChanged;
 }
 
 QString Feed::url() const
@@ -182,26 +211,34 @@ QString Feed::errorString() const
 
 void Feed::setName(const QString &name)
 {
-    m_name = name;
-    Q_EMIT nameChanged(m_name);
+    if (name != m_name) {
+        m_name = name;
+        Q_EMIT nameChanged(m_name);
+    }
 }
 
 void Feed::setImage(const QString &image)
 {
-    m_image = image;
-    Q_EMIT imageChanged(m_image);
+    if (image != m_image) {
+        m_image = image;
+        Q_EMIT imageChanged(m_image);
+    }
 }
 
 void Feed::setLink(const QString &link)
 {
-    m_link = link;
-    Q_EMIT linkChanged(m_link);
+    if (link != m_link) {
+        m_link = link;
+        Q_EMIT linkChanged(m_link);
+    }
 }
 
 void Feed::setDescription(const QString &description)
 {
-    m_description = description;
-    Q_EMIT descriptionChanged(m_description);
+    if (description != m_description) {
+        m_description = description;
+        Q_EMIT descriptionChanged(m_description);
+    }
 }
 
 void Feed::setAuthors(const QVector<Author *> &authors)
@@ -228,32 +265,42 @@ void Feed::setDeleteAfterType(int type)
 
 void Feed::setLastUpdated(const QDateTime &lastUpdated)
 {
-    m_lastUpdated = lastUpdated;
-    Q_EMIT lastUpdatedChanged(m_lastUpdated);
+    if (lastUpdated != m_lastUpdated) {
+        m_lastUpdated = lastUpdated;
+        Q_EMIT lastUpdatedChanged(m_lastUpdated);
+    }
 }
 
 void Feed::setNotify(bool notify)
 {
-    m_notify = notify;
-    Q_EMIT notifyChanged(m_notify);
+    if (notify != m_notify) {
+        m_notify = notify;
+        Q_EMIT notifyChanged(m_notify);
+    }
 }
 
 void Feed::setRefreshing(bool refreshing)
 {
-    m_refreshing = refreshing;
-    Q_EMIT refreshingChanged(m_refreshing);
+    if (refreshing != m_refreshing) {
+        m_refreshing = refreshing;
+        Q_EMIT refreshingChanged(m_refreshing);
+    }
 }
 
 void Feed::setErrorId(int errorId)
 {
-    m_errorId = errorId;
-    Q_EMIT errorIdChanged(m_errorId);
+    if (errorId != m_errorId) {
+        m_errorId = errorId;
+        Q_EMIT errorIdChanged(m_errorId);
+    }
 }
 
 void Feed::setErrorString(const QString &errorString)
 {
-    m_errorString = errorString;
-    Q_EMIT errorStringChanged(m_errorString);
+    if (errorString != m_errorString) {
+        m_errorString = errorString;
+        Q_EMIT errorStringChanged(m_errorString);
+    }
 }
 
 void Feed::refresh()

src/feed.h

@@ -43,7 +43,7 @@ public:
 
     ~Feed();
 
-    void retrieveAuthors();
+    void updateAuthors();
 
     QString url() const;
     QString name() const;

src/fetcher.cpp

@@ -76,9 +76,13 @@ void Fetcher::processFeed(Syndication::FeedPtr feed, const QString &url)
     query.prepare(QStringLiteral("SELECT new FROM Feeds WHERE url=:url;"));
     query.bindValue(QStringLiteral(":url"), url);
     Database::instance().execute(query);
-    if (query.next())
+    if (query.next()) {
         isNewFeed = query.value(QStringLiteral("new")).toBool();
-    qDebug() << "New feed" << feed->title() << ":" << isNewFeed;
+    } else {
+        qDebug() << "Feed not found in database" << url;
+        return;
+    }
+    if (isNewFeed) qDebug() << "New feed" << feed->title() << ":" << isNewFeed;
 
     // Retrieve "other" fields; this will include the "itunes" tags
     QMultiMap<QString, QDomElement> otherItems = feed->additionalProperties();