ProjectExplorer: Use LRU for sorting sessions in menu

Right now, upon start-up of Qt Creator, entries in the Sessions menu are
sorted in reverse order of the time the corresponding files were last
modified on disk, which often (but not always) corresponds to a "least
recently used" order. This order is unchanged during the lifetime of the
current instance of Qt Creator, and potentially changes again after the
next start.
As this can be confusing to users, we now ensure LRU sorting at all
times.

Task-number: QTCREATORBUG-28202
Change-Id: I758371ac1cb968dd3f2e4278fc5066d1e74397c6
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/projectexplorer/projectexplorer.cpp

@@ -145,7 +145,9 @@
 #include <QTimer>
 #include <QVBoxLayout>
 
+#include <algorithm>
 #include <functional>
+#include <iterator>
 #include <memory>
 #include <vector>
 
@@ -4174,7 +4176,10 @@ void ProjectExplorerPluginPrivate::updateSessionMenu()
     connect(ag, &QActionGroup::triggered, this, &ProjectExplorerPluginPrivate::setSession);
     const QString activeSession = SessionManager::activeSession();
 
-    const QStringList sessions = SessionManager::sessions();
+    QStringList sessions = SessionManager::sessions();
+    std::sort(std::next(sessions.begin()), sessions.end(), [](const QString &s1, const QString &s2) {
+        return SessionManager::lastActiveTime(s1) > SessionManager::lastActiveTime(s2);
+    });
     for (int i = 0; i < sessions.size(); ++i) {
         const QString &session = sessions[i];
 

src/plugins/projectexplorer/session.cpp

@@ -48,6 +48,7 @@ using namespace ProjectExplorer::Internal;
 namespace ProjectExplorer {
 
 const char DEFAULT_SESSION[] = "default";
+const char LAST_ACTIVE_TIMES_KEY[] = "LastActiveTimes";
 
 /*!
      \class ProjectExplorer::SessionManager
@@ -88,6 +89,7 @@ public:
 
     mutable QStringList m_sessions;
     mutable QHash<QString, QDateTime> m_sessionDateTimes;
+    QHash<QString, QDateTime> m_lastActiveTimes;
 
     Project *m_startupProject = nullptr;
     QList<Project *> m_projects;
@@ -119,6 +121,13 @@ SessionManager::SessionManager(QObject *parent) : QObject(parent)
     connect(ModeManager::instance(), &ModeManager::currentModeChanged,
             this, &SessionManager::saveActiveMode);
 
+    connect(ICore::instance(), &ICore::saveSettingsRequested, this, [] {
+        QVariantMap times;
+        for (auto it = d->m_lastActiveTimes.cbegin(); it != d->m_lastActiveTimes.cend(); ++it)
+            times.insert(it.key(), it.value());
+        ICore::settings()->setValue(LAST_ACTIVE_TIMES_KEY, times);
+    });
+
     connect(EditorManager::instance(), &EditorManager::editorCreated,
             this, &SessionManager::configureEditor);
     connect(this, &SessionManager::projectAdded,
@@ -776,9 +785,14 @@ QStringList SessionManager::sessions()
         // We are not initialized yet, so do that now
         const FilePaths sessionFiles =
                 ICore::userResourcePath().dirEntries({{"*qws"}}, QDir::Time | QDir::Reversed);
+        const QVariantMap lastActiveTimes = ICore::settings()->value(LAST_ACTIVE_TIMES_KEY).toMap();
         for (const FilePath &file : sessionFiles) {
             const QString &name = file.completeBaseName();
             d->m_sessionDateTimes.insert(name, file.lastModified());
+            const auto lastActiveTime = lastActiveTimes.find(name);
+            d->m_lastActiveTimes.insert(name, lastActiveTime != lastActiveTimes.end()
+                    ? lastActiveTime->toDateTime()
+                    : file.lastModified());
             if (name != QLatin1String(DEFAULT_SESSION))
                 d->m_sessions << name;
         }
@@ -792,6 +806,11 @@ QDateTime SessionManager::sessionDateTime(const QString &session)
     return d->m_sessionDateTimes.value(session);
 }
 
+QDateTime SessionManager::lastActiveTime(const QString &session)
+{
+    return d->m_lastActiveTimes.value(session);
+}
+
 FilePath SessionManager::sessionNameToFileName(const QString &session)
 {
     return ICore::userResourcePath(session + ".qws");
@@ -807,6 +826,7 @@ bool SessionManager::createSession(const QString &session)
         return false;
     Q_ASSERT(d->m_sessions.size() > 0);
     d->m_sessions.insert(1, session);
+    d->m_lastActiveTimes.insert(session, QDateTime::currentDateTime());
     return true;
 }
 
@@ -844,6 +864,7 @@ bool SessionManager::deleteSession(const QString &session)
     if (!d->m_sessions.contains(session))
         return false;
     d->m_sessions.removeOne(session);
+    d->m_lastActiveTimes.remove(session);
     emit instance()->sessionRemoved(session);
     QFile fi(sessionNameToFileName(session).toString());
     if (fi.exists())
@@ -1115,6 +1136,7 @@ bool SessionManager::loadSession(const QString &session, bool initial)
     }
 
     d->m_casadeSetActive = reader.restoreValue(QLatin1String("CascadeSetActive"), false).toBool();
+    d->m_lastActiveTimes.insert(session, QDateTime::currentDateTime());
 
     emit m_instance->sessionLoaded(session);
 

src/plugins/projectexplorer/session.h

@@ -41,6 +41,7 @@ public:
     static QString startupSession();
     static QStringList sessions();
     static QDateTime sessionDateTime(const QString &session);
+    static QDateTime lastActiveTime(const QString &session);
 
     static bool createSession(const QString &session);