Merge pull request #2669 from jroweboy/async_file_watcher

Frontend: Prevent FileSystemWatcher from blocking UI thread
This commit is contained in:
Yuri Kunde Schlesner 2017-05-10 18:44:06 -07:00 committed by GitHub
commit db22b88fea
3 changed files with 35 additions and 46 deletions

View File

@ -2,6 +2,7 @@
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <QApplication>
#include <QFileInfo>
#include <QHeaderView>
#include <QKeyEvent>
@ -194,6 +195,9 @@ void GameList::onFilterCloseClicked() {
}
GameList::GameList(GMainWindow* parent) : QWidget{parent} {
watcher = new QFileSystemWatcher(this);
connect(watcher, &QFileSystemWatcher::directoryChanged, this, &GameList::RefreshGameDirectory);
this->main_window = parent;
layout = new QVBoxLayout;
tree_view = new QTreeView;
@ -218,7 +222,6 @@ GameList::GameList(GMainWindow* parent) : QWidget{parent} {
connect(tree_view, &QTreeView::activated, this, &GameList::ValidateEntry);
connect(tree_view, &QTreeView::customContextMenuRequested, this, &GameList::PopupContextMenu);
connect(&watcher, &QFileSystemWatcher::directoryChanged, this, &GameList::RefreshGameDirectory);
// We must register all custom types with the Qt Automoc system so that we are able to use it
// with signals/slots. In this case, QList falls under the umbrells of custom types.
@ -269,7 +272,22 @@ void GameList::ValidateEntry(const QModelIndex& item) {
emit GameChosen(file_path);
}
void GameList::DonePopulating() {
void GameList::DonePopulating(QStringList watch_list) {
// Clear out the old directories to watch for changes and add the new ones
auto watch_dirs = watcher->directories();
if (!watch_dirs.isEmpty()) {
watcher->removePaths(watch_dirs);
}
// Workaround: Add the watch paths in chunks to allow the gui to refresh
// This prevents the UI from stalling when a large number of watch paths are added
// Also artificially caps the watcher to a certain number of directories
constexpr int LIMIT_WATCH_DIRECTORIES = 5000;
constexpr int SLICE_SIZE = 25;
int len = std::min(watch_list.length(), LIMIT_WATCH_DIRECTORIES);
for (int i = 0; i < len; i += SLICE_SIZE) {
watcher->addPaths(watch_list.mid(i, i + SLICE_SIZE));
QCoreApplication::processEvents();
}
tree_view->setEnabled(true);
int rowCount = tree_view->model()->rowCount();
search_field->setFilterResult(rowCount, rowCount);
@ -309,11 +327,6 @@ void GameList::PopulateAsync(const QString& dir_path, bool deep_scan) {
emit ShouldCancelWorker();
auto watch_dirs = watcher.directories();
if (!watch_dirs.isEmpty()) {
watcher.removePaths(watch_dirs);
}
UpdateWatcherList(dir_path.toStdString(), deep_scan ? 256 : 0);
GameListWorker* worker = new GameListWorker(dir_path, deep_scan);
connect(worker, &GameListWorker::EntryReady, this, &GameList::AddEntry, Qt::QueuedConnection);
@ -359,38 +372,6 @@ void GameList::RefreshGameDirectory() {
}
}
/**
* Adds the game list folder to the QFileSystemWatcher to check for updates.
*
* The file watcher will fire off an update to the game list when a change is detected in the game
* list folder.
*
* Notice: This method is run on the UI thread because QFileSystemWatcher is not thread safe and
* this function is fast enough to not stall the UI thread. If performance is an issue, it should
* be moved to another thread and properly locked to prevent concurrency issues.
*
* @param dir folder to check for changes in
* @param recursion 0 if recursion is disabled. Any positive number passed to this will add each
* directory recursively to the watcher and will update the file list if any of the folders
* change. The number determines how deep the recursion should traverse.
*/
void GameList::UpdateWatcherList(const std::string& dir, unsigned int recursion) {
const auto callback = [this, recursion](unsigned* num_entries_out, const std::string& directory,
const std::string& virtual_name) -> bool {
std::string physical_name = directory + DIR_SEP + virtual_name;
if (FileUtil::IsDirectory(physical_name)) {
UpdateWatcherList(physical_name, recursion - 1);
}
return true;
};
watcher.addPath(QString::fromStdString(dir));
if (recursion > 0) {
FileUtil::ForeachDirectoryEntry(nullptr, dir, callback);
}
}
void GameListWorker::AddFstEntriesToGameList(const std::string& dir_path, unsigned int recursion) {
const auto callback = [this, recursion](unsigned* num_entries_out, const std::string& directory,
const std::string& virtual_name) -> bool {
@ -399,7 +380,8 @@ void GameListWorker::AddFstEntriesToGameList(const std::string& dir_path, unsign
if (stop_processing)
return false; // Breaks the callback loop.
if (!FileUtil::IsDirectory(physical_name) && HasSupportedFileExtension(physical_name)) {
bool is_dir = FileUtil::IsDirectory(physical_name);
if (!is_dir && HasSupportedFileExtension(physical_name)) {
std::unique_ptr<Loader::AppLoader> loader = Loader::GetLoader(physical_name);
if (!loader)
return true;
@ -416,7 +398,8 @@ void GameListWorker::AddFstEntriesToGameList(const std::string& dir_path, unsign
QString::fromStdString(Loader::GetFileTypeString(loader->GetFileType()))),
new GameListItemSize(FileUtil::GetSize(physical_name)),
});
} else if (recursion > 0) {
} else if (is_dir && recursion > 0) {
watch_list.append(QString::fromStdString(physical_name));
AddFstEntriesToGameList(physical_name, recursion - 1);
}
@ -428,8 +411,9 @@ void GameListWorker::AddFstEntriesToGameList(const std::string& dir_path, unsign
void GameListWorker::run() {
stop_processing = false;
watch_list.append(dir_path);
AddFstEntriesToGameList(dir_path.toStdString(), deep_scan ? 256 : 0);
emit Finished();
emit Finished(watch_list);
}
void GameListWorker::Cancel() {

View File

@ -85,10 +85,9 @@ private slots:
private:
void AddEntry(const QList<QStandardItem*>& entry_items);
void ValidateEntry(const QModelIndex& item);
void DonePopulating();
void DonePopulating(QStringList watch_list);
void PopupContextMenu(const QPoint& menu_location);
void UpdateWatcherList(const std::string& path, unsigned int recursion);
void RefreshGameDirectory();
bool containsAllWords(QString haystack, QString userinput);
@ -98,5 +97,5 @@ private:
QTreeView* tree_view = nullptr;
QStandardItemModel* item_model = nullptr;
GameListWorker* current_worker = nullptr;
QFileSystemWatcher watcher;
QFileSystemWatcher* watcher = nullptr;
};

View File

@ -170,9 +170,15 @@ signals:
* @param entry_items a list with `QStandardItem`s that make up the columns of the new entry.
*/
void EntryReady(QList<QStandardItem*> entry_items);
void Finished();
/**
* After the worker has traversed the game directory looking for entries, this signal is emmited
* with a list of folders that should be watched for changes as well.
*/
void Finished(QStringList watch_list);
private:
QStringList watch_list;
QString dir_path;
bool deep_scan;
std::atomic_bool stop_processing;