gui: ipc: Support cancellation of preview generation

gui/ipcpreviewworker.cpp

@@ -3,29 +3,24 @@
 #include "previewgeneratormapfunctor.h"
 IPCPreviewWorker::IPCPreviewWorker()
 {
+	this->connect(&previewWorkerWatcher, &QFutureWatcher<QByteArray>::resultReadyAt, this,
+				  [this](int index) { emit previewGenerated(previewWorkerWatcher.resultAt(index)); });
+	connect(&previewWorkerWatcher, &QFutureWatcher<QByteArray>::finished, this, [this] { emit finished(); });
 }
 
 void IPCPreviewWorker::start(RenderConfig config, const QVector<RenderTarget> &targets, QLocalSocket *peer)
 {
-	connect(&previewWorkerWatcher, &QFutureWatcher<QByteArray>::resultReadyAt, this,
-			[peer, this](int index)
-			{
-				QDataStream stream{peer};
-				stream << previewWorkerWatcher.resultAt(index);
-				peer->flush();
-			});
-	connect(&previewWorkerWatcher, &QFutureWatcher<QByteArray>::finished, this,
-			[peer]
-			{
-				/* TODO /
-
-				/*peer->waitForBytesWritten();
-				peer->disconnectFromServer();
-				peer->deleteLater();*/
-			});
 
+	stop();
+	/* TODO: memleak */
 	auto mapFunctor = new PreviewGeneratorMapFunctor();
 	mapFunctor->setRenderConfig(config);
 
 	previewWorkerWatcher.setFuture(QtConcurrent::mapped(targets, *mapFunctor));
 }
+
+void IPCPreviewWorker::stop()
+{
+	previewWorkerWatcher.cancel();
+	previewWorkerWatcher.waitForFinished();
+}

gui/ipcpreviewworker.h

@@ -15,6 +15,10 @@ class IPCPreviewWorker : public QObject
   public:
 	IPCPreviewWorker();
 	void start(RenderConfig config, const QVector<RenderTarget> &targets, QLocalSocket *peer);
+	void stop();
+  signals:
+	void previewGenerated(QByteArray);
+	void finished();
 };
 
 #endif // IPCPREVIEWWORKER_H

gui/ipcserver.cpp

@@ -15,7 +15,11 @@
 
 IpcServer::IpcServer()
 {
+	/* Only 1, we are doing work for the GUI, not a service for general availability */
+	this->spawningServer.setMaxPendingConnections(1);
 	connect(&this->spawningServer, &QLocalServer::newConnection, this, &IpcServer::spawnerNewConnection);
+	connect(&this->previewWorker, &IPCPreviewWorker::previewGenerated, this, &IpcServer::handlePreviewGenerated);
+	connect(&this->previewWorker, &IPCPreviewWorker::finished, this, [this] { this->currentSocket->flush(); });
 }
 
 bool IpcServer::startSpawner(QString socketPath)
@@ -28,6 +32,7 @@ void IpcServer::spawnerNewConnection()
 {
 	QLocalSocket *socket = this->spawningServer.nextPendingConnection();
 	connect(socket, &QLocalSocket::disconnected, socket, &QLocalSocket::deleteLater);
+	this->currentSocket = socket;
 	if(socket != nullptr)
 	{
 		if(!socket->waitForReadyRead())
@@ -39,10 +44,8 @@ void IpcServer::spawnerNewConnection()
 		stream >> command;
 		if(command == GeneratePreviews)
 		{
-			IPCPreviewWorker *worker = new IPCPreviewWorker();
 			RenderConfig renderConfig;
 			QVector<RenderTarget> targets;
-
 			do
 			{
 				/* TODO: this is not entirely robust */
@@ -53,7 +56,18 @@ void IpcServer::spawnerNewConnection()
 
 			stream << targets.count();
 			socket->flush();
-			worker->start(renderConfig, targets, socket);
+			previewWorker.start(renderConfig, targets, socket);
+		}
+		if(command == StopGeneratePreviews)
+		{
+			previewWorker.stop();
 		}
 	}
 }
+
+void IpcServer::handlePreviewGenerated(QByteArray ba)
+{
+	QDataStream stream{this->currentSocket};
+	stream << ba;
+	this->currentSocket->flush();
+}

gui/ipcserver.h

@@ -4,14 +4,19 @@
 #include <QLocalServer>
 #include "ipc.h"
 #include "filesaver.h"
+#include "ipcpreviewworker.h"
+
 class IpcServer : public QObject
 {
 	Q_OBJECT
   private:
+	IPCPreviewWorker previewWorker;
 	QLocalServer spawningServer;
+	QLocalSocket *currentSocket = nullptr;
 	SaveFileResult addFile(QString file);
   private slots:
 	void spawnerNewConnection();
+	void handlePreviewGenerated(QByteArray ba);
 
   public:
 	IpcServer();