[netinstall] Improve loader queue API a bit

- use load() to start loading
- the FetchNextUnless class is useful in more spots in
  the loading process
- set status explicitly on success (otherwise, a failure in a
  previous URL would leave a failure message lying around even
  when the module shows something useful)

src/modules/netinstall/Config.cpp

@@ -54,9 +54,11 @@ Config::status() const
     case Status::FailedBadData:
         return tr( "Network Installation. (Disabled: Received invalid groups data)" );
     case Status::FailedInternalError:
-        return tr( "Network Installation. (Disabled: internal error)" );
+        return tr( "Network Installation. (Disabled: Internal error)" );
     case Status::FailedNetworkError:
         return tr( "Network Installation. (Disabled: Unable to fetch package lists, check your network connection)" );
+    case Status::FailedNoData:
+        return tr( "Network Installation. (Disabled: No package list)" );
     }
     __builtin_unreachable();
 }
@@ -89,6 +91,11 @@ Config::loadGroupList( const QVariantList& groupData )
     if ( m_model->rowCount() < 1 )
     {
         cWarning() << "NetInstall groups data was empty.";
+        setStatus( Status::FailedNoData );
+    }
+    else
+    {
+        setStatus( Status::Ok );
     }
     emit statusReady();
 }
@@ -134,7 +141,7 @@ Config::setConfigurationMap( const QVariantMap& configurationMap )
         m_queue = new LoaderQueue( this );
         m_queue->append( SourceItem::makeSourceItem( groupsUrlVariant.toString(), configurationMap ) );
     }
-    else if ( groupsUrlVariant.type() == QVariant::StringList )
+    else if ( groupsUrlVariant.type() == QVariant::List )
     {
         m_queue = new LoaderQueue( this );
         for ( const auto& s : groupsUrlVariant.toStringList() )
@@ -142,10 +149,11 @@ Config::setConfigurationMap( const QVariantMap& configurationMap )
             m_queue->append( SourceItem::makeSourceItem( s, configurationMap ) );
         }
     }
-    if ( m_queue )
+    if ( m_queue && m_queue->count() > 0 )
     {
+        cDebug() << "Loading netinstall from" << m_queue->count() << "alternate sources.";
         connect( m_queue, &LoaderQueue::done, this, &Config::loadingDone );
-        QMetaObject::invokeMethod( m_queue, "fetchNext", Qt::QueuedConnection );
+        m_queue->load();
     }
 }
 

src/modules/netinstall/Config.h

@@ -47,7 +47,9 @@ public:
         FailedBadConfiguration,
         FailedInternalError,
         FailedNetworkError,
-        FailedBadData
+        FailedBadData,
+        FailedNoData
+
     };
 
     QString status() const;

src/modules/netinstall/LoaderQueue.cpp

@@ -20,6 +20,32 @@
 #include <QNetworkReply>
 #include <QTimer>
 
+/** @brief Call fetchNext() on the queue if it can
+ *
+ * On destruction, a new call to fetchNext() is queued, so that
+ * the queue continues loading. Calling release() before the
+ * destructor skips the fetchNext(), ending the queue-loading.
+ */
+class FetchNextUnless
+{
+public:
+    FetchNextUnless( LoaderQueue* q )
+        : m_q( q )
+    {
+    }
+    ~FetchNextUnless()
+    {
+        if ( m_q )
+        {
+            QMetaObject::invokeMethod( m_q, "fetchNext", Qt::QueuedConnection );
+        }
+    }
+    void release() { m_q = nullptr; }
+
+private:
+    LoaderQueue* m_q = nullptr;
+};
+
 SourceItem
 SourceItem::makeSourceItem( const QString& groupsUrl, const QVariantMap& configurationMap )
 {
@@ -45,6 +71,13 @@ LoaderQueue::append( SourceItem&& i )
     m_queue.append( std::move( i ) );
 }
 
+void
+LoaderQueue::load()
+{
+    QMetaObject::invokeMethod( this, "fetchNext", Qt::QueuedConnection );
+}
+
+
 void
 LoaderQueue::fetchNext()
 {
@@ -67,13 +100,16 @@ LoaderQueue::fetchNext()
     }
 }
 
-
 void
 LoaderQueue::fetch( const QUrl& url )
 {
+    FetchNextUnless next( this );
+
     if ( !url.isValid() )
     {
         m_config->setStatus( Config::Status::FailedBadConfiguration );
+        cDebug() << "Invalid URL" << url;
+        return;
     }
 
     using namespace CalamaresUtils::Network;
@@ -85,42 +121,20 @@ LoaderQueue::fetch( const QUrl& url )
 
     if ( !reply )
     {
-        cDebug() << Logger::Continuation << "request failed immediately.";
+        cDebug() << Logger::SubEntry << "Request failed immediately.";
+        // If nobody sets a different status, this will remain
         m_config->setStatus( Config::Status::FailedBadConfiguration );
     }
     else
     {
+        // When the network request is done, **then** we might
+        // do the next item from the queue, so don't call fetchNext() now.
+        next.release();
         m_reply = reply;
         connect( reply, &QNetworkReply::finished, this, &LoaderQueue::dataArrived );
     }
 }
 
-/** @brief Call fetchNext() on the queue if it can
- *
- * On destruction, a new call to fetchNext() is queued, so that
- * the queue continues loading. Calling release() before the
- * destructor skips the fetchNext(), ending the queue-loading.
- */
-class FetchNextUnless
-{
-public:
-    FetchNextUnless( LoaderQueue* q )
-        : m_q( q )
-    {
-    }
-    ~FetchNextUnless()
-    {
-        if ( m_q )
-        {
-            QMetaObject::invokeMethod( m_q, "fetchNext", Qt::QueuedConnection );
-        }
-    }
-    void release() { m_q = nullptr; }
-
-private:
-    LoaderQueue* m_q = nullptr;
-};
-
 void
 LoaderQueue::dataArrived()
 {

src/modules/netinstall/LoaderQueue.h

@@ -41,7 +41,14 @@ struct SourceItem
     static SourceItem makeSourceItem( const QString& groupsUrl, const QVariantMap& configurationMap );
 };
 
-
+/** @brief Queue of source items to load
+ *
+ * Queue things up by calling append() and then kick things off
+ * by calling load(). This will try to load the items, in order;
+ * the first one that succeeds will end the loading process.
+ *
+ * Signal done() is emitted when done (also when all of the items fail).
+ */
 class LoaderQueue : public QObject
 {
     Q_OBJECT
@@ -49,9 +56,12 @@ public:
     LoaderQueue( Config* parent );
 
     void append( SourceItem&& i );
-    void fetchNext();
+    int count() const { return m_queue.count(); }
 
 public Q_SLOTS:
+    void load();
+
+    void fetchNext();
     void fetch( const QUrl& url );
     void dataArrived();