diff --git a/cockatrice/src/interface/card_picture_loader/card_picture_loader.cpp b/cockatrice/src/interface/card_picture_loader/card_picture_loader.cpp index b8a54761a..8e34942e1 100644 --- a/cockatrice/src/interface/card_picture_loader/card_picture_loader.cpp +++ b/cockatrice/src/interface/card_picture_loader/card_picture_loader.cpp @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -43,6 +44,7 @@ CardPictureLoader::CardPictureLoader() : QObject(nullptr) qRegisterMetaType("ExactCard"); connect(worker, &CardPictureLoaderWorker::imageLoaded, this, &CardPictureLoader::imageLoaded); + connect(worker, &CardPictureLoaderWorker::networkCacheCleared, this, &CardPictureLoader::networkCacheCleared); statusBar = new CardPictureLoaderStatusBar(nullptr); QMainWindow *mainWindow = qobject_cast(QApplication::activeWindow()); @@ -58,7 +60,18 @@ CardPictureLoader::CardPictureLoader() : QObject(nullptr) CardPictureLoader::~CardPictureLoader() { - worker->deleteLater(); + if (worker) { + // Capture the thread first: shutdownThread() blocks until the worker has been freed by the + // finished() -> deleteLater chain, after which the worker pointer must not be dereferenced. + QThread *pictureLoaderThread = worker->workerThread(); + const bool stopped = worker->shutdownThread(); + worker = nullptr; + // Deleting a QThread that is still running is undefined behaviour, so only free it once the + // bounded wait in shutdownThread() confirmed that it stopped. + if (stopped) { + delete pictureLoaderThread; + } + } } void CardPictureLoader::getCardBackPixmap(QPixmap &pixmap, QSize size) @@ -457,7 +470,17 @@ void CardPictureLoader::clearPixmapCache() void CardPictureLoader::clearNetworkCache() { - getInstance().worker->clearNetworkCache(); + // During teardown the worker is released before this singleton, so a queued clear may still + // arrive with no worker left to run it. + CardPictureLoaderWorker *worker = getInstance().worker; + if (!worker) { + return; + } + // The disk cache and redirect cache are owned by the worker thread, so the clear has to run + // there. Invoke it asynchronously to keep the GUI responsive while the worker may be walking + // the user's picture directories or recursively deleting the cache directory; callers that + // need to know when it is done can listen for networkCacheCleared(). + QMetaObject::invokeMethod(worker, &CardPictureLoaderWorker::clearNetworkCache, Qt::QueuedConnection); } void CardPictureLoader::cacheCardPixmaps(const QList &cards) diff --git a/cockatrice/src/interface/card_picture_loader/card_picture_loader.h b/cockatrice/src/interface/card_picture_loader/card_picture_loader.h index 0a4934e6d..6224befbf 100644 --- a/cockatrice/src/interface/card_picture_loader/card_picture_loader.h +++ b/cockatrice/src/interface/card_picture_loader/card_picture_loader.h @@ -117,6 +117,9 @@ public: public slots: /** * @brief Clears the network disk cache of the worker. + * + * The clear runs on the worker thread, so this returns before it has completed; connect to + * networkCacheCleared() to act once it is done. */ static void clearNetworkCache(); @@ -131,6 +134,10 @@ public slots: void installPrintingOverride(const ExactCard &originalCard, const ExactCard &overrideCard); void installPrintingOverrideOnLoad(const ExactCard &originalCard, const ExactCard &overrideCard); +signals: + /** @brief Emitted after the worker has finished clearing the network and redirect caches. */ + void networkCacheCleared(); + private slots: /** * @brief Triggered when the user changes the picture download settings. diff --git a/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker.cpp b/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker.cpp index 5bb513809..eed84f3a6 100644 --- a/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker.cpp +++ b/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker.cpp @@ -21,6 +21,7 @@ static constexpr int MIN_HOST_QUOTA = DownloadSettings::MIN_HOST_REQUEST_LIMIT; static constexpr qint64 QUOTA_RECOVER_MS = 60000; ///< Idle time before a reduced quota starts recovering static constexpr int DISPATCH_INTERVAL_MS = 100; ///< Pacing between individual network requests static constexpr qint64 QUOTA_RESET_INTERVAL_MS = 1000; ///< Interval at which the request quota resets +static constexpr int THREAD_SHUTDOWN_WAIT_MS = 5000; ///< Bounded wait for the worker thread to stop at exit CardPictureLoaderWorker::CardPictureLoaderWorker() : QObject(nullptr), picDownload(SettingsCache::instance().downloads().getPicDownload()), @@ -59,6 +60,9 @@ CardPictureLoaderWorker::CardPictureLoaderWorker() localLoader = new CardPictureLoaderLocal(this); pictureLoaderThread = new QThread; + // The worker object frees itself once its thread finishes, so no event loop is left + // running and the QThread is never destroyed while still executing. + connect(pictureLoaderThread, &QThread::finished, this, &QObject::deleteLater); pictureLoaderThread->start(QThread::LowPriority); moveToThread(pictureLoaderThread); @@ -82,7 +86,33 @@ CardPictureLoaderWorker::CardPictureLoaderWorker() CardPictureLoaderWorker::~CardPictureLoaderWorker() { saveRedirectCache(); - pictureLoaderThread->deleteLater(); +} + +bool CardPictureLoaderWorker::shutdownThread() +{ + // The finished() -> deleteLater chain (wired in the constructor) frees this worker as soon as + // its event loop exits, so nothing - not even a member read - may run once wait() returns. + // QThread::quit() and QThread::wait() are thread-safe and may be called from the owning thread. + QThread *thread = pictureLoaderThread; + if (!thread) { + return true; + } + thread->quit(); + // Only an unbounded wait() would guarantee the thread stops, but this runs from a function-local + // static destructor after main() has returned, with no UI left to interrupt a worker stuck in a + // slow slot or on a stalled filesystem. Bound the wait and leave such a thread to the OS rather + // than hanging the process forever. + if (!thread->wait(THREAD_SHUTDOWN_WAIT_MS)) { + qCWarning(CardPictureLoaderWorkerLog) << "Picture loader worker thread did not stop within" + << THREAD_SHUTDOWN_WAIT_MS << "ms; leaving it to be torn down by the OS"; + return false; + } + return true; +} + +QThread *CardPictureLoaderWorker::workerThread() const +{ + return pictureLoaderThread; } void CardPictureLoaderWorker::queueRequest(const QUrl &url, CardPictureLoaderWorkerWork *worker) @@ -494,4 +524,5 @@ void CardPictureLoaderWorker::clearNetworkCache() { networkManager->cache()->clear(); redirectCache.clear(); + emit networkCacheCleared(); } diff --git a/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker.h b/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker.h index b720247cb..e2829c6ee 100644 --- a/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker.h +++ b/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker.h @@ -74,10 +74,37 @@ public: */ void onHostRateLimited(const QString &host); - /** @brief Clears the network cache and redirect cache. */ - void clearNetworkCache(); + /** + * @brief Stops the worker thread and reports whether it stopped. + * + * Called from the owning thread (CardPictureLoader) on its way out. QThread::quit() posts an + * exit request to the worker's event loop and QThread::wait() blocks (bounded) until the loop + * has returned and the thread finished. Only QThread members are touched here, so this method + * is safe to call from the owning thread. The worker object itself is freed by the finished() + * -> deleteLater chain (see the constructor); the QThread object is deleted afterwards by the + * owner (CardPictureLoader::~CardPictureLoader), not by this method. + * + * @return true if the thread stopped within the timeout, false if it is still running (in + * which case the owner must not delete the QThread). + */ + [[nodiscard]] bool shutdownThread(); + + /** + * @brief Returns the worker's QThread. + * @return The worker thread + * + * Only meaningful while the worker object is alive; capture it before calling shutdownThread(). + */ + QThread *workerThread() const; public slots: + /** + * @brief Clears the network cache and redirect cache. + * + * Runs on the worker thread; invoke it via a queued call when coming from another thread, + * since both caches are owned by the worker thread. + */ + void clearNetworkCache(); /** * @brief Makes a network request for the given URL using the specified worker. * @param url URL to load @@ -198,6 +225,9 @@ signals: /** @brief Emitted when a network request successfully completes. */ void imageRequestSucceeded(const QUrl &url); + + /** @brief Emitted after clearNetworkCache() has finished clearing both caches. */ + void networkCacheCleared(); }; #endif // PICTURE_LOADER_WORKER_H diff --git a/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker_work.cpp b/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker_work.cpp index b70207ff4..19c6be469 100644 --- a/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker_work.cpp +++ b/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker_work.cpp @@ -27,8 +27,8 @@ const ServerRateLimiter &CardPictureLoaderWorkerWork::rateLimiter() return s_rateLimiter; } -CardPictureLoaderWorkerWork::CardPictureLoaderWorkerWork(const CardPictureLoaderWorker *worker, const ExactCard &toLoad) - : QObject(nullptr), cardToDownload(CardPictureToLoad(toLoad)), +CardPictureLoaderWorkerWork::CardPictureLoaderWorkerWork(CardPictureLoaderWorker *worker, const ExactCard &toLoad) + : QObject(worker), cardToDownload(CardPictureToLoad(toLoad)), picDownload(SettingsCache::instance().downloads().getPicDownload()) { // Hook up signals to the orchestrator diff --git a/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker_work.h b/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker_work.h index c5aa07d10..eb8b11a24 100644 --- a/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker_work.h +++ b/cockatrice/src/interface/card_picture_loader/card_picture_loader_worker_work.h @@ -37,10 +37,11 @@ class CardPictureLoaderWorkerWork : public QObject public: /** * @brief Constructs a worker for downloading a specific card image. - * @param worker The orchestrating CardPictureLoaderWorker + * @param worker The orchestrating CardPictureLoaderWorker; the work object becomes its child so + * it is destroyed with the worker even if it never reaches concludeImageLoad(). * @param toLoad The ExactCard to download */ - explicit CardPictureLoaderWorkerWork(const CardPictureLoaderWorker *worker, const ExactCard &toLoad); + explicit CardPictureLoaderWorkerWork(CardPictureLoaderWorker *worker, const ExactCard &toLoad); CardPictureToLoad cardToDownload; ///< The card and associated URLs to try downloading diff --git a/cockatrice/src/interface/widgets/settings_page/storage_settings_page.cpp b/cockatrice/src/interface/widgets/settings_page/storage_settings_page.cpp index 17838e501..4aad91115 100644 --- a/cockatrice/src/interface/widgets/settings_page/storage_settings_page.cpp +++ b/cockatrice/src/interface/widgets/settings_page/storage_settings_page.cpp @@ -181,9 +181,14 @@ StorageSettingsPage::StorageSettingsPage() void StorageSettingsPage::clearDownloadedPicsButtonClicked() { - CardPictureLoader::clearNetworkCache(); + // The network cache is cleared asynchronously on the worker thread, so wait for the completion + // signal before confirming; the in-memory pixmap cache is cleared synchronously right away. + connect( + &CardPictureLoader::getInstance(), &CardPictureLoader::networkCacheCleared, this, + [this] { QMessageBox::information(this, tr("Success"), tr("Cached card pictures have been reset.")); }, + Qt::SingleShotConnection); CardPictureLoader::clearPixmapCache(); - QMessageBox::information(this, tr("Success"), tr("Cached card pictures have been reset.")); + CardPictureLoader::clearNetworkCache(); } void StorageSettingsPage::clearImageBackupsButtonClicked()