new class to isolate UpdateChannel connections

cockatrice/CMakeLists.txt

@@ -110,6 +110,7 @@ set(cockatrice_SOURCES
     src/client/ui/widgets/printing_selector/printing_selector_view_options_widget.cpp
     src/client/ui/widgets/printing_selector/set_name_and_collectors_number_display_widget.cpp
     src/client/network/release_channel.cpp
+    src/client/network/client_update_checker.cpp
     src/server/remote/remote_client.cpp
     src/server/remote/remote_decklist_tree_widget.cpp
     src/server/remote/remote_replay_list_tree_widget.cpp

cockatrice/src/client/network/client_update_checker.cpp

@@ -0,0 +1,35 @@
+#include "client_update_checker.h"
+
+#include "../../settings/cache_settings.h"
+#include "release_channel.h"
+
+ClientUpdateChecker::ClientUpdateChecker(QObject *parent) : QObject(parent)
+{
+}
+
+void ClientUpdateChecker::check()
+{
+    auto releaseChannel = SettingsCache::instance().getUpdateReleaseChannel();
+
+    finishedCheckConnection =
+        connect(releaseChannel, &ReleaseChannel::finishedCheck, this, &ClientUpdateChecker::actFinishedCheck);
+    errorConnection = connect(releaseChannel, &ReleaseChannel::error, this, &ClientUpdateChecker::actError);
+
+    releaseChannel->checkForUpdates();
+}
+
+void ClientUpdateChecker::actFinishedCheck(bool needToUpdate, bool isCompatible, Release *release)
+{
+    disconnect(finishedCheckConnection);
+    disconnect(errorConnection);
+
+    emit finishedCheck(needToUpdate, isCompatible, release);
+}
+
+void ClientUpdateChecker::actError(const QString &errorString)
+{
+    disconnect(finishedCheckConnection);
+    disconnect(errorConnection);
+
+    emit error(errorString);
+}

cockatrice/src/client/network/client_update_checker.h

@@ -0,0 +1,45 @@
+#ifndef CLIENT_UPDATE_CHECKER_H
+#define CLIENT_UPDATE_CHECKER_H
+#include <QObject>
+
+class Release;
+
+/**
+ * We use a singleton instance of UpdateChannel, which can cause interference and feedback loops when multiple objects
+ * connect to it.
+ *
+ * This class encapsulates the usage of that UpdateChannel to ensure that the check only happens once per connection and
+ * the connection is destroyed after it's been used.
+ */
+class ClientUpdateChecker : public QObject
+{
+    Q_OBJECT
+
+    QMetaObject::Connection finishedCheckConnection;
+    QMetaObject::Connection errorConnection;
+
+    void actFinishedCheck(bool needToUpdate, bool isCompatible, Release *release);
+    void actError(const QString &errorString);
+
+public:
+    explicit ClientUpdateChecker(QObject *parent = nullptr);
+    /**
+     * Actually performs the check, using the currently selected update channel in the settings.
+     * Any resulting signals will only be sent once.
+     * This method should only be called ONCE per instance.
+     */
+    void check();
+
+signals:
+    /**
+     * Forwarded from UpdateChannel::finishedCheck
+     */
+    void finishedCheck(bool needToUpdate, bool isCompatible, Release *release);
+
+    /**
+     * Forwarded from UpdateChannel::error
+     */
+    void error(const QString &errorString);
+};
+
+#endif // CLIENT_UPDATE_CHECKER_H

cockatrice/src/dialogs/dlg_update.cpp

@@ -1,5 +1,6 @@
 #include "dlg_update.h"
 
+#include "../client/network/client_update_checker.h"
 #include "../client/network/release_channel.h"
 #include "../client/ui/window_main.h"
 #include "../settings/cache_settings.h"
@@ -71,11 +72,6 @@ DlgUpdate::DlgUpdate(QWidget *parent) : QDialog(parent)
     connect(uDownloader, SIGNAL(progressMade(qint64, qint64)), this, SLOT(downloadProgressMade(qint64, qint64)));
     connect(uDownloader, SIGNAL(error(QString)), this, SLOT(downloadError(QString)));
 
-    ReleaseChannel *channel = SettingsCache::instance().getUpdateReleaseChannel();
-    connect(channel, SIGNAL(finishedCheck(bool, bool, Release *)), this,
-            SLOT(finishedUpdateCheck(bool, bool, Release *)));
-    connect(channel, SIGNAL(error(QString)), this, SLOT(updateCheckError(QString)));
-
     // Check for updates
     beginUpdateCheck();
 }
@@ -110,7 +106,12 @@ void DlgUpdate::beginUpdateCheck()
     progress->setMinimum(0);
     progress->setMaximum(0);
     setLabel(tr("Checking for updates..."));
-    SettingsCache::instance().getUpdateReleaseChannel()->checkForUpdates();
+
+    auto checker = new ClientUpdateChecker(this);
+    connect(checker, SIGNAL(finishedCheck(bool, bool, Release *)), this,
+            SLOT(finishedUpdateCheck(bool, bool, Release *)));
+    connect(checker, SIGNAL(error(QString)), this, SLOT(updateCheckError(QString)));
+    checker->check();
 }
 
 void DlgUpdate::finishedUpdateCheck(bool needToUpdate, bool isCompatible, Release *release)