Avoid KJob::exec() in DolphinView

This commit replaces an error-prone usage of KIO::StatJob::exec() in
DolphinView with the recommended KIO::StatJob::start().

The containing method DolphinView::statusBarText() is changed to be a
method without return value: requestStatusBarText()
The new status bar text is instead returned through a new
setStatusBarText() signal that will be emitted asynchronously if
necessary.

The calling code that deals with status bar text is refactored to
correctly work despite the new asynchronicity. The helper method
calculateItemCount() is moved into requestStatusBarText() and some
other code from requestStatusBarText() is moved into a new helper
method emitStatusBarText().

The documentation of KIO::KJob::exec() explains why it should be
avoided. A reproducible crash is the reason for this commit.

1 files changed, 67 insertions, 48 deletions

diff --git a/src/views/dolphinview.cpp b/src/views/dolphinview.cpp
index d03b75ddd..3fa8b800a 100644
--- a/src/views/dolphinview.cpp
+++ b/src/views/dolphinview.cpp
@@ -528,17 +528,18 @@ QStringList DolphinView::mimeTypeFilters() const
     return m_model->mimeTypeFilters();
 }
 
-QString DolphinView::statusBarText() const
+void DolphinView::requestStatusBarText()
 {
-    QString summary;
-    QString foldersText;
-    QString filesText;
-
-    int folderCount = 0;
-    int fileCount = 0;
-    KIO::filesize_t totalFileSize = 0;
+    if (m_statJobForStatusBarText) {
+        // Kill the pending request.
+        m_statJobForStatusBarText->kill();
+    }
 
     if (m_container->controller()->selectionManager()->hasSelection()) {
+        int folderCount = 0;
+        int fileCount = 0;
+        KIO::filesize_t totalFileSize = 0;
+
         // Give a summary of the status of the selected files
         const KFileItemList list = selectedItems();
         for (const KFileItem& item : list) {
@@ -552,14 +553,37 @@ QString DolphinView::statusBarText() const
 
         if (folderCount + fileCount == 1) {
             // If only one item is selected, show info about it
-            return list.first().getStatusBarInfo();
+            Q_EMIT statusBarTextChanged(list.first().getStatusBarInfo());
         } else {
             // At least 2 items are selected
-            foldersText = i18ncp("@info:status", "1 Folder selected", "%1 Folders selected", folderCount);
-            filesText = i18ncp("@info:status", "1 File selected", "%1 Files selected", fileCount);
+            emitStatusBarText(folderCount, fileCount, totalFileSize, HasSelection);
         }
+    } else { // has no selection
+        if (!m_model->rootItem().url().isValid()) {
+            return;
+        }
+
+        m_statJobForStatusBarText = KIO::statDetails(m_model->rootItem().url(),
+                        KIO::StatJob::SourceSide, KIO::StatRecursiveSize, KIO::HideProgressInfo);
+        connect(m_statJobForStatusBarText, &KJob::result,
+                this, &DolphinView::slotStatJobResult);
+        m_statJobForStatusBarText->start();
+    }
+}
+
+void DolphinView::emitStatusBarText(const int folderCount, const int fileCount,
+                                    KIO::filesize_t totalFileSize, const Selection selection)
+{
+    QString foldersText;
+    QString filesText;
+    QString summary;
+
+    if (selection == HasSelection) {
+        // At least 2 items are selected because the case of 1 selected item is handled in
+        // DolphinView::requestStatusBarText().
+        foldersText = i18ncp("@info:status", "1 Folder selected", "%1 Folders selected", folderCount);
+        filesText = i18ncp("@info:status", "1 File selected", "%1 Files selected", fileCount);
     } else {
-        calculateItemCount(fileCount, folderCount, totalFileSize);
         foldersText = i18ncp("@info:status", "1 Folder", "%1 Folders", folderCount);
         filesText = i18ncp("@info:status", "1 File", "%1 Files", fileCount);
     }
@@ -577,8 +601,7 @@ QString DolphinView::statusBarText() const
     } else {
         summary = i18nc("@info:status", "0 Folders, 0 Files");
     }
-
-    return summary;
+    Q_EMIT statusBarTextChanged(summary);
 }
 
 QList<QAction*> DolphinView::versionControlActions(const KFileItemList& items) const
@@ -1271,6 +1294,36 @@ void DolphinView::emitSelectionChangedSignal()
     Q_EMIT selectionChanged(selectedItems());
 }
 
+void DolphinView::slotStatJobResult(KJob *job)
+{
+    int folderCount = 0;
+    int fileCount = 0;
+    KIO::filesize_t totalFileSize = 0;
+    bool countFileSize = true;
+
+    const auto entry =  static_cast<KIO::StatJob *>(job)->statResult();
+    if (entry.contains(KIO::UDSEntry::UDS_RECURSIVE_SIZE)) {
+        // We have a precomputed value.
+        totalFileSize = static_cast<KIO::filesize_t>(
+                                entry.numberValue(KIO::UDSEntry::UDS_RECURSIVE_SIZE));
+        countFileSize = false;
+    }
+
+    const int itemCount = m_model->count();
+    for (int i = 0; i < itemCount; ++i) {
+        const KFileItem item = m_model->fileItem(i);
+        if (item.isDir()) {
+            ++folderCount;
+        } else {
+            ++fileCount;
+            if (countFileSize) {
+                totalFileSize += item.size();
+            }
+        }
+    }
+    emitStatusBarText(folderCount, fileCount, totalFileSize, NoSelection);
+}
+
 void DolphinView::updateSortRole(const QByteArray& role)
 {
     ViewProperties props(viewPropertiesUrl());
@@ -1537,40 +1590,6 @@ void DolphinView::hideToolTip(const ToolTipManager::HideBehavior behavior)
 #endif
 }
 
-void DolphinView::calculateItemCount(int& fileCount,
-                                     int& folderCount,
-                                     KIO::filesize_t& totalFileSize) const
-{
-    const int itemCount = m_model->count();
-
-    bool countFileSize = true;
-
-    if (!m_model->rootItem().url().isValid()) {
-        return;
-    }
-
-    // In case we have a precomputed value
-    const auto job = KIO::statDetails(m_model->rootItem().url(), KIO::StatJob::SourceSide, KIO::StatRecursiveSize, KIO::HideProgressInfo);
-    job->exec();
-    const auto entry =  job->statResult();
-    if (entry.contains(KIO::UDSEntry::UDS_RECURSIVE_SIZE)) {
-        totalFileSize = static_cast<KIO::filesize_t>(entry.numberValue(KIO::UDSEntry::UDS_RECURSIVE_SIZE));
-        countFileSize = false;
-    }
-
-    for (int i = 0; i < itemCount; ++i) {
-        const KFileItem item = m_model->fileItem(i);
-        if (item.isDir()) {
-            ++folderCount;
-        } else {
-            ++fileCount;
-            if (countFileSize) {
-                totalFileSize += item.size();
-            }
-        }
-    }
-}
-
 void DolphinView::slotTwoClicksRenamingTimerTimeout()
 {
     const KItemListSelectionManager* selectionManager = m_container->controller()->selectionManager();