gui: PreviewGeneratorPdf: Guard cache lookup with mutex

No guarantes the read-only lookup is thread-safe so better
just lock there too

gui/mainwindow.h

@@ -23,16 +23,6 @@ class MainWindow : public QMainWindow
 {
 	Q_OBJECT
 
-  public:
-	explicit MainWindow(QWidget *parent, QString socketPath);
-	~MainWindow();
-  signals:
-	void beginSearch(const QString &query);
-	void startPdfPreviewGeneration(QVector<SearchResult> paths, double scalefactor);
-
-  protected:
-	void closeEvent(QCloseEvent *event) override;
-
   private:
 	DatabaseFactory *dbFactory;
 	SqliteDbService *dbService;
@@ -40,40 +30,39 @@ class MainWindow : public QMainWindow
 	IPCPreviewClient ipcPreviewClient;
 	QThread ipcClientThread;
 	QThread syncerThread;
+	Indexer *indexer;
 	IndexSyncer *indexSyncer;
 	QProgressDialog progressDialog;
-
-	Indexer *indexer;
 	QFileIconProvider iconProvider;
-	bool previewDirty;
 	QSqlDatabase db;
 	QFutureWatcher<QVector<SearchResult>> searchWatcher;
-	void add(QString path, unsigned int page);
 	QVector<SearchResult> previewableSearchResults;
-	void connectSignals();
-	void makePreviews(int page);
-	bool previewTabActive();
-	bool indexerTabActive();
-	void keyPressEvent(QKeyEvent *event) override;
-	unsigned int processedPdfPreviews;
-	void handleSearchResults(const QVector<SearchResult> &results);
-	void handleSearchError(QString error);
 	LooqsQuery contentSearchQuery;
-	int previewsPerPage;
-	void createSearchResutlMenu(QMenu &menu, const QFileInfo &fileInfo);
-	void openDocument(QString path, int num);
-	void openFile(QString path);
-	unsigned int currentPreviewGeneration = 1;
-	void initSettingsTabs();
-	int currentSelectedScale();
-	void processShortcut(int key);
-	bool eventFilter(QObject *object, QEvent *event);
 	QVector<QString> searchHistory;
 	int currentSearchHistoryIndex = 0;
 	QString currentSavedSearchText;
 	QHash<QString, int> previewOrder; /* Quick lookup for the order a preview should have */
 	QMap<int, QWidget *>
 		previewWidgetOrderCache /* Saves those that arrived out of order to be inserted later at the correct pos */;
+	bool previewDirty;
+	int previewsPerPage;
+	unsigned int processedPdfPreviews;
+	unsigned int currentPreviewGeneration = 1;
+
+	void connectSignals();
+	void makePreviews(int page);
+	bool previewTabActive();
+	bool indexerTabActive();
+	void keyPressEvent(QKeyEvent *event) override;
+	void handleSearchResults(const QVector<SearchResult> &results);
+	void handleSearchError(QString error);
+	void createSearchResutlMenu(QMenu &menu, const QFileInfo &fileInfo);
+	void openDocument(QString path, int num);
+	void openFile(QString path);
+	void initSettingsTabs();
+	int currentSelectedScale();
+	void processShortcut(int key);
+	bool eventFilter(QObject *object, QEvent *event);
 
   private slots:
 	void lineEditReturnPressed();
@@ -94,6 +83,16 @@ class MainWindow : public QMainWindow
 	void startIpcPreviews(RenderConfig config, const QVector<RenderTarget> &targets);
 	void stopIpcPreviews();
 	void beginIndexSync();
+
+  public:
+	explicit MainWindow(QWidget *parent, QString socketPath);
+	~MainWindow();
+  signals:
+	void beginSearch(const QString &query);
+	void startPdfPreviewGeneration(QVector<SearchResult> paths, double scalefactor);
+
+  protected:
+	void closeEvent(QCloseEvent *event) override;
 };
 
 #endif // MAINWINDOW_H

gui/previewgenerator.cpp

@@ -1,20 +1,24 @@
 #include "../shared/common.h"
 #include "previewgenerator.h"
+#include <QMutexLocker>
 #include "previewgeneratorpdf.h"
 #include "previewgeneratorplaintext.h"
 #include "previewgeneratorodt.h"
 
 static PreviewGenerator *plainTextGenerator = new PreviewGeneratorPlainText();
 
-static QMap<QString, PreviewGenerator *> generators{
+static QHash<QString, PreviewGenerator *> generators{
 	{"pdf", new PreviewGeneratorPdf()}, {"txt", plainTextGenerator},  {"md", plainTextGenerator},
 	{"py", plainTextGenerator},			{"java", plainTextGenerator}, {"js", plainTextGenerator},
 	{"cpp", plainTextGenerator},		{"c", plainTextGenerator},	  {"sql", plainTextGenerator},
 	{"odt", new PreviewGeneratorOdt()}};
 
+static QMutex generatorsMutex;
 PreviewGenerator *PreviewGenerator::get(QFileInfo &info)
 {
+	QMutexLocker locker(&generatorsMutex);
 	PreviewGenerator *result = generators.value(info.suffix(), nullptr);
+	locker.unlock();
 	if(result == nullptr)
 	{
 		if(Common::isTextFile(info))

gui/previewgeneratorpdf.cpp

@@ -7,10 +7,12 @@ static QMutex cacheMutex;
 
 Poppler::Document *PreviewGeneratorPdf::document(QString path)
 {
+	QMutexLocker locker(&cacheMutex);
 	if(documentcache.contains(path))
 	{
 		return documentcache.value(path);
 	}
+	locker.unlock();
 	Poppler::Document *result = Poppler::Document::load(path);
 	if(result == nullptr)
 	{
@@ -19,7 +21,7 @@ Poppler::Document *PreviewGeneratorPdf::document(QString path)
 	}
 	result->setRenderHint(Poppler::Document::TextAntialiasing);
 
-	QMutexLocker locker(&cacheMutex);
+	locker.relock();
 	documentcache.insert(path, result);
 	locker.unlock();
 	return result;