Plasmashell freezes when trying to get free space info from mounted remote filesystem after losing connection to it

Summary:
BUG: 397537

Earlier plasmashell assumed that you'll get free space info immediately (which is not true in case of losing connection to server containing a mounted filesystem - statfs will wait for response forever and freeze everything since it's happening in main thread)

I moved obtaining that info into different thread so that case won't freeze anything anymore.
It creates exactly one thread per one path. If a path is already being processed, new thread won't be created.
Also I implemented a timer used to notify about broken connection after 15 seconds.

Reviewers: broulik, ngraham, davidedmundson

Reviewed By: broulik

Subscribers: ngraham, anthonyfieroni, davidedmundson, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D14895

dataengines/soliddevice/CMakeLists.txt

@@ -18,6 +18,7 @@ target_link_libraries(plasma_engine_soliddevice
   KF5::Plasma
   KF5::Solid
   KF5::CoreAddons
+  KF5::Notifications
 )
 
 kcoreaddons_desktop_to_json(plasma_engine_soliddevice plasma-dataengine-soliddevice.desktop)

dataengines/soliddevice/soliddeviceengine.cpp

@@ -24,9 +24,11 @@
 #include <Solid/GenericInterface>
 #include <klocalizedstring.h>
 
+#include <QApplication>
 #include <QDebug>
-#include <KDiskFreeSpaceInfo>
 #include <KFormat>
+#include <KIO/FileSystemFreeSpaceJob>
+#include <KNotification>
 
 #include <Plasma/DataContainer>
 
@@ -547,12 +549,39 @@ bool SolidDeviceEngine::updateStorageSpace(const QString &udi)
         return false;
     }
 
-    KDiskFreeSpaceInfo info = KDiskFreeSpaceInfo::freeSpaceInfo(storageaccess->filePath());
-    if (info.isValid()) {
-        setData(udi, I18N_NOOP("Free Space"), QVariant(info.available()));
-        setData(udi, I18N_NOOP("Free Space Text"), KFormat().formatByteSize(info.available()));
-        setData(udi, I18N_NOOP("Size"), QVariant(info.size()));
-        return true;
+    QString path = storageaccess->filePath();
+    if (!m_paths.contains(path)) {
+        QTimer *timer = new QTimer(this);
+        timer->setSingleShot(true);
+        connect(timer, &QTimer::timeout, [path]() {
+            KNotification::event(KNotification::Error, i18n("Filesystem is not responding", path),
+                                 i18n("Filesystem mounted at '%1' is not responding", path));
+        });
+
+        m_paths.insert(path);
+
+        // create job
+        KIO::FileSystemFreeSpaceJob *job = KIO::fileSystemFreeSpace(QUrl::fromLocalFile(path));
+
+        // delete later timer
+        connect(job, &KIO::FileSystemFreeSpaceJob::result, timer, &QTimer::deleteLater);
+
+        // collect and process info
+        connect(job, &KIO::FileSystemFreeSpaceJob::result, this,
+                [this, timer, path, udi](KIO::Job *job, KIO::filesize_t size, KIO::filesize_t available) {
+            timer->stop();
+
+            if (!job->error()) {
+                setData(udi, I18N_NOOP("Free Space"), QVariant(available));
+                setData(udi, I18N_NOOP("Free Space Text"), KFormat().formatByteSize(available));
+                setData(udi, I18N_NOOP("Size"), QVariant(size));
+            }
+
+            m_paths.remove(path);
+        });
+
+        // start timer: after 15 seconds we will get an error
+        timer->start(15000);
     }
 
     return false;

dataengines/soliddevice/soliddeviceengine.h

@@ -35,6 +35,7 @@
 #include "devicesignalmapmanager.h"
 #include "devicesignalmapper.h"
 #include "hddtemp.h"
+#include <KIO/FileSystemFreeSpaceJob>
 
 enum State {
     Idle = 0,
@@ -80,6 +81,8 @@ private:
     QMap<QString, Solid::Device> m_devicemap;
     //udi, corresponding encrypted container udi;
     QMap<QString, QString> m_encryptedContainerMap;
+    //path, corresponding timer
+    QSet<QString> m_paths;
     DeviceSignalMapManager *m_signalmanager;
 
     HddTemp *m_temperature;