Update recent projects asynchronously

Avoid blocking Qt Creator whenever it gets active or projects change, if
some kind of network mapped path is in the list of recent projects. We
check for existence of recent projects, and that can take a long time in
that case, especially if the target is not connected. We already avoid
checking on explicit IDevices, but that doesn't help for other kinds of
mounted directories.

Maintain an "exists" state for each item and update that
asynchronously, informing all interested parties of changes with the
recentProjectsChanged signal. The state is saved in the settings,
meaning that projects that were not found previously start out hidden,
under the assumption that the existence check is fast for them if they
become available again.

Fixes: QTCREATORBUG-30681
Change-Id: Ic39a88b6b5128c3ae4582a6c66fc16be4b297e56
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/libs/utils/algorithm.h

@@ -987,6 +987,14 @@ C filtered(const C &container, R (S::*predicate)() const)
     return out;
 }
 
+template<typename C, typename R, typename S>
+Q_REQUIRED_RESULT C filtered(const C &container, R S::*predicate)
+{
+    C out;
+    std::copy_if(std::begin(container), std::end(container), inserter(out), std::mem_fn(predicate));
+    return out;
+}
+
 //////////////////
 // filteredCast
 /////////////////

src/plugins/projectexplorer/projectexplorer.cpp

@@ -128,6 +128,7 @@
 
 #include <utils/action.h>
 #include <utils/algorithm.h>
+#include <utils/async.h>
 #include <utils/fileutils.h>
 #include <utils/macroexpander.h>
 #include <utils/mimeutils.h>
@@ -262,6 +263,7 @@ const char PROJECT_OPEN_LOCATIONS_CONTEXT_MENU[]  = "Project.P.OpenLocation.CtxM
 
 const char RECENTPROJECTS_FILE_NAMES_KEY[] = "ProjectExplorer/RecentProjects/FileNames";
 const char RECENTPROJECTS_DISPLAY_NAMES_KEY[] = "ProjectExplorer/RecentProjects/DisplayNames";
+const char RECENTPROJECTS_EXISTENCE_KEY[] = "ProjectExplorer/RecentProjects/Existence";
 
 const char CUSTOM_PARSER_COUNT_KEY[] = "ProjectExplorer/Settings/CustomParserCount";
 const char CUSTOM_PARSER_PREFIX_KEY[] = "ProjectExplorer/Settings/CustomParser";
@@ -503,6 +505,7 @@ public:
     void setStartupProject(Project *project);
     bool closeAllFilesInProject(const Project *project);
 
+    void checkRecentProjectsAsync();
     void updateRecentProjectMenu();
     void clearRecentProjects();
     void openRecentProject(const FilePath &filePath);
@@ -613,6 +616,8 @@ public:
 
     QHash<QString, std::function<Project *(const FilePath &)>> m_projectCreators;
     RecentProjectsEntries m_recentProjects; // pair of filename, displayname
+    QFuture<RecentProjectsEntry> m_recentProjectsFuture;
+    QThreadPool m_recentProjectsPool;
     static const int m_maxRecentProjects = 25;
 
     FilePath m_lastOpenDirectory;
@@ -772,6 +777,24 @@ ProjectExplorerPlugin *ProjectExplorerPlugin::instance()
     return m_instance;
 }
 
+static void restoreRecentProjects(QtcSettings *s)
+{
+    const QStringList filePaths = s->value(Constants::RECENTPROJECTS_FILE_NAMES_KEY).toStringList();
+    const QStringList displayNames
+        = s->value(Constants::RECENTPROJECTS_DISPLAY_NAMES_KEY).toStringList();
+    // filename -> bool:
+    const QHash<QString, QVariant> existence
+        = s->value(Constants::RECENTPROJECTS_EXISTENCE_KEY).toHash();
+    if (QTC_GUARD(filePaths.size() == displayNames.size())) {
+        for (int i = 0; i < filePaths.size(); ++i) {
+            const bool exists = existence.value(filePaths.at(i), true).toBool();
+            dd->m_recentProjects.append(
+                {FilePath::fromUserInput(filePaths.at(i)), displayNames.at(i), exists});
+        }
+    }
+    dd->checkRecentProjectsAsync();
+}
+
 bool ProjectExplorerPlugin::initialize(const QStringList &arguments, QString *error)
 {
     Q_UNUSED(error)
@@ -1139,8 +1162,11 @@ bool ProjectExplorerPlugin::initialize(const QStringList &arguments, QString *er
     mrecent->menu()->setTitle(Tr::tr("Recent P&rojects"));
     mrecent->setOnAllDisabledBehavior(ActionContainer::Show);
     mfile->addMenu(mrecent, Core::Constants::G_FILE_OPEN);
-    connect(mfile->menu(), &QMenu::aboutToShow,
-            dd, &ProjectExplorerPluginPrivate::updateRecentProjectMenu);
+    connect(
+        m_instance,
+        &ProjectExplorerPlugin::recentProjectsChanged,
+        dd,
+        &ProjectExplorerPluginPrivate::updateRecentProjectMenu);
 
     // unload action
     dd->m_unloadAction = new Action(Tr::tr("Close Project"), Tr::tr("Close Pro&ject \"%1\""),
@@ -1603,18 +1629,12 @@ bool ProjectExplorerPlugin::initialize(const QStringList &arguments, QString *er
             dd, &ProjectExplorerPluginPrivate::savePersistentSettings);
     connect(qApp, &QApplication::applicationStateChanged, this, [](Qt::ApplicationState state) {
         if (!PluginManager::isShuttingDown() && state == Qt::ApplicationActive)
-            dd->updateWelcomePage();
+            dd->checkRecentProjectsAsync();
     });
 
     QtcSettings *s = ICore::settings();
-    const QStringList fileNames = s->value(Constants::RECENTPROJECTS_FILE_NAMES_KEY).toStringList();
-    const QStringList displayNames = s->value(Constants::RECENTPROJECTS_DISPLAY_NAMES_KEY)
-                                         .toStringList();
-    if (fileNames.size() == displayNames.size()) {
-        for (int i = 0; i < fileNames.size(); ++i) {
-            dd->m_recentProjects.append({FilePath::fromUserInput(fileNames.at(i)), displayNames.at(i)});
-        }
-    }
+
+    restoreRecentProjects(s);
 
     const int customParserCount = s->value(Constants::CUSTOM_PARSER_COUNT_KEY).toInt();
     for (int i = 0; i < customParserCount; ++i) {
@@ -2115,6 +2135,35 @@ bool ProjectExplorerPluginPrivate::closeAllFilesInProject(const Project *project
     return EditorManager::closeDocuments(openFiles);
 }
 
+void ProjectExplorerPluginPrivate::checkRecentProjectsAsync()
+{
+    m_recentProjectsFuture.cancel();
+
+    m_recentProjectsFuture
+        = QtConcurrent::mapped(&m_recentProjectsPool, m_recentProjects, [](RecentProjectsEntry p) {
+              // check if project is available, but avoid querying devices
+              p.exists = p.filePath.needsDevice() || p.filePath.isFile();
+              return p;
+          });
+    PluginManager::futureSynchronizer()->addFuture(m_recentProjectsFuture);
+
+    onResultReady(m_recentProjectsFuture, this, [this](const RecentProjectsEntry &p) {
+        auto it = std::find_if(
+            m_recentProjects.begin(), m_recentProjects.end(), [&p](const RecentProjectsEntry &e) {
+                return p.filePath == e.filePath;
+            });
+        // nothing to do if it no longer is in the recent projects, or if the state already was
+        // correct
+        if (it == m_recentProjects.end())
+            return;
+        if (it->exists == p.exists)
+            return;
+
+        *it = p;
+        emit m_instance->recentProjectsChanged();
+    });
+}
+
 void ProjectExplorerPluginPrivate::savePersistentSettings()
 {
     if (PluginManager::isShuttingDown())
@@ -2128,17 +2177,21 @@ void ProjectExplorerPluginPrivate::savePersistentSettings()
     QtcSettings *s = ICore::settings();
     s->remove("ProjectExplorer/RecentProjects/Files");
 
-    QStringList fileNames;
+    QStringList filePaths;
     QStringList displayNames;
+    QHash<QString, QVariant> existence;
     RecentProjectsEntries::const_iterator it, end;
     end = dd->m_recentProjects.constEnd();
     for (it = dd->m_recentProjects.constBegin(); it != end; ++it) {
-        fileNames << (*it).first.toUserOutput();
-        displayNames << (*it).second;
+        const QString filePath = it->filePath.toUserOutput();
+        filePaths << filePath;
+        displayNames << it->displayName;
+        existence.insert(filePath, it->exists);
     }
 
-    s->setValueWithDefault(Constants::RECENTPROJECTS_FILE_NAMES_KEY, fileNames);
+    s->setValueWithDefault(Constants::RECENTPROJECTS_FILE_NAMES_KEY, filePaths);
     s->setValueWithDefault(Constants::RECENTPROJECTS_DISPLAY_NAMES_KEY, displayNames);
+    s->setValueWithDefault(Constants::RECENTPROJECTS_EXISTENCE_KEY, existence);
 
     buildPropertiesSettings().writeSettings(); // FIXME: Should not be needed.
 
@@ -2451,10 +2504,7 @@ void ProjectExplorerPluginPrivate::buildQueueFinished(bool success)
 
 RecentProjectsEntries ProjectExplorerPluginPrivate::recentProjects() const
 {
-    return Utils::filtered(dd->m_recentProjects, [](const RecentProjectsEntry &p) {
-        // check if project is available, but avoid querying devices
-        return p.first.needsDevice() || p.first.isFile();
-    });
+    return filtered(m_recentProjects, &RecentProjectsEntry::exists);
 }
 
 void ProjectExplorerPluginPrivate::updateActions()
@@ -3018,16 +3068,13 @@ void ProjectExplorerPluginPrivate::addToRecentProjects(const FilePath &filePath,
     if (filePath.isEmpty())
         return;
 
-    RecentProjectsEntries::iterator it;
-    for (it = m_recentProjects.begin(); it != m_recentProjects.end();)
-        if ((*it).first == filePath)
-            it = m_recentProjects.erase(it);
-        else
-            ++it;
-
-    if (m_recentProjects.count() > m_maxRecentProjects)
+    Utils::erase(m_recentProjects, [filePath](const RecentProjectsEntry &e) {
+        return e.filePath == filePath;
+    });
+    if (m_recentProjects.size() >= m_maxRecentProjects)
         m_recentProjects.removeLast();
-    m_recentProjects.push_front({filePath, displayName});
+    m_recentProjects.push_front({filePath, displayName, true});
+    checkRecentProjectsAsync();
     m_lastOpenDirectory = filePath.absolutePath();
     emit m_instance->recentProjectsChanged();
 }
@@ -3054,7 +3101,7 @@ void ProjectExplorerPluginPrivate::updateRecentProjectMenu()
     const RecentProjectsEntries projects = recentProjects();
     //projects (ignore sessions, they used to be in this list)
     for (const RecentProjectsEntry &item : projects) {
-        const FilePath &filePath = item.first;
+        const FilePath &filePath = item.filePath;
         if (filePath.endsWith(QLatin1String(".qws")))
             continue;
 
@@ -3079,13 +3126,12 @@ void ProjectExplorerPluginPrivate::updateRecentProjectMenu()
         connect(action, &QAction::triggered,
                 this, &ProjectExplorerPluginPrivate::clearRecentProjects);
     }
-    emit m_instance->recentProjectsChanged();
 }
 
 void ProjectExplorerPluginPrivate::clearRecentProjects()
 {
     m_recentProjects.clear();
-    updateWelcomePage();
+    emit m_instance->recentProjectsChanged();
 }
 
 void ProjectExplorerPluginPrivate::openRecentProject(const FilePath &filePath)
@@ -3101,8 +3147,10 @@ void ProjectExplorerPluginPrivate::removeFromRecentProjects(const FilePath &file
 {
     QTC_ASSERT(!filePath.isEmpty(), return);
     QTC_CHECK(Utils::eraseOne(m_recentProjects, [filePath](const RecentProjectsEntry &entry) {
-        return entry.first == filePath;
+        return entry.filePath == filePath;
     }));
+    checkRecentProjectsAsync();
+    emit m_instance->recentProjectsChanged();
 }
 
 void ProjectExplorerPluginPrivate::invalidateProject(Project *project)

src/plugins/projectexplorer/projectexplorer.h

@@ -37,7 +37,14 @@ class AppOutputSettings;
 class MiniProjectTargetSelector;
 }
 
-using RecentProjectsEntry = QPair<Utils::FilePath, QString>;
+class RecentProjectsEntry
+{
+public:
+    Utils::FilePath filePath;
+    QString displayName;
+    bool exists = true;
+};
+
 using RecentProjectsEntries = QList<RecentProjectsEntry>;
 
 class PROJECTEXPLORER_EXPORT OpenProjectResult

src/plugins/projectexplorer/projectwelcomepage.cpp

@@ -106,12 +106,12 @@ QVariant ProjectModel::data(const QModelIndex &index, int role) const
     RecentProjectsEntry data = m_projects.at(index.row());
     switch (role) {
     case Qt::DisplayRole:
-        return data.second;
+        return data.displayName;
     case Qt::ToolTipRole:
     case FilePathRole:
-        return data.first.toVariant();
+        return data.filePath.toVariant();
     case PrettyFilePathRole:
-        return data.first.withTildeHomePath(); // FIXME: FilePath::displayName() ?
+        return data.filePath.withTildeHomePath(); // FIXME: FilePath::displayName() ?
     case ShortcutRole: {
         const Id projectBase = PROJECT_BASE_ID;
         if (Command *cmd = ActionManager::command(projectBase.withSuffix(index.row() + 1)))

src/plugins/studiowelcome/studiowelcomeplugin.cpp

@@ -455,20 +455,20 @@ QVariant ProjectModel::data(const QModelIndex &index, int role) const
             ProjectExplorer::ProjectExplorerPlugin::recentProjects().at(index.row());
     switch (role) {
     case Qt::DisplayRole:
-        return data.second;
+        return data.displayName;
         break;
     case FilePathRole:
-        return data.first.toVariant();
+        return data.filePath.toVariant();
     case PrettyFilePathRole:
-        return data.first.absolutePath().withTildeHomePath();
+        return data.filePath.absolutePath().withTildeHomePath();
     case PreviewUrl:
-        return QVariant(QStringLiteral("image://project_preview/") +
-                        QmlProjectManager::ProjectFileContentTools::appQmlFile(
-                            data.first));
+        return QVariant(
+            QStringLiteral("image://project_preview/")
+            + QmlProjectManager::ProjectFileContentTools::appQmlFile(data.filePath));
     case TagData:
-        return tags(data.first);
+        return tags(data.filePath);
     case Description:
-        return description(data.first);
+        return description(data.filePath);
     default:
         return QVariant();
     }