Use QThreadPool for torrent creation

The change is in preparation for adding the possibility to create
torrent files via the API.

Rework TorrentCreatorThread to be a more lightweight QRunnable class.
The parameters are now defined on construction time and are fixed
throughout the lifecycle of the TorrentCreator. The lifecycle of the
object is not bound to the one of QDialog anymore; it is now handled
by the QThreadPool. This will enable easier queueing of multiple torrent
creation jobs without risk of spawning many threads.

PR #19500.

src/base/CMakeLists.txt

@@ -35,7 +35,7 @@ add_library(qbt_base STATIC
     bittorrent/torrent.h
     bittorrent/torrentcontenthandler.h
     bittorrent/torrentcontentlayout.h
-    bittorrent/torrentcreatorthread.h
+    bittorrent/torrentcreator.h
     bittorrent/torrentdescriptor.h
     bittorrent/torrentimpl.h
     bittorrent/torrentinfo.h
@@ -132,7 +132,7 @@ add_library(qbt_base STATIC
     bittorrent/speedmonitor.cpp
     bittorrent/torrent.cpp
     bittorrent/torrentcontenthandler.cpp
-    bittorrent/torrentcreatorthread.cpp
+    bittorrent/torrentcreator.cpp
     bittorrent/torrentdescriptor.cpp
     bittorrent/torrentimpl.cpp
     bittorrent/torrentinfo.cpp

src/base/bittorrent/torrentcreator.cpp

@@ -26,7 +26,7 @@
  * exception statement from your version.
  */
 
-#include "torrentcreatorthread.h"
+#include "torrentcreator.h"
 
 #include <fstream>
 
@@ -74,35 +74,34 @@ namespace
 
 using namespace BitTorrent;
 
-TorrentCreatorThread::TorrentCreatorThread(QObject *parent)
-    : QThread(parent)
+TorrentCreator::TorrentCreator(const TorrentCreatorParams &params, QObject *parent)
+    : QObject(parent)
+    , m_params {params}
 {
 }
 
-TorrentCreatorThread::~TorrentCreatorThread()
-{
-    requestInterruption();
-    wait();
-}
-
-void TorrentCreatorThread::create(const TorrentCreatorParams &params)
-{
-    m_params = params;
-    start();
-}
-
-void TorrentCreatorThread::sendProgressSignal(int currentPieceIdx, int totalPieces)
+void TorrentCreator::sendProgressSignal(int currentPieceIdx, int totalPieces)
 {
     emit updateProgress(static_cast<int>((currentPieceIdx * 100.) / totalPieces));
 }
 
-void TorrentCreatorThread::checkInterruptionRequested() const
+void TorrentCreator::checkInterruptionRequested() const
 {
     if (isInterruptionRequested())
         throw RuntimeError(tr("Operation aborted"));
 }
 
-void TorrentCreatorThread::run()
+void TorrentCreator::requestInterruption()
+{
+    m_interruptionRequested.storeRelaxed(1);
+}
+
+bool TorrentCreator::isInterruptionRequested() const
+{
+    return m_interruptionRequested.loadRelaxed() != 0;
+}
+
+void TorrentCreator::run()
 {
     emit updateProgress(0);
 
@@ -225,9 +224,9 @@ void TorrentCreatorThread::run()
 }
 
 #ifdef QBT_USES_LIBTORRENT2
-int TorrentCreatorThread::calculateTotalPieces(const Path &inputPath, const int pieceSize, const TorrentFormat torrentFormat)
+int TorrentCreator::calculateTotalPieces(const Path &inputPath, const int pieceSize, const TorrentFormat torrentFormat)
 #else
-int TorrentCreatorThread::calculateTotalPieces(const Path &inputPath, const int pieceSize, const bool isAlignmentOptimized, const int paddedFileSizeLimit)
+int TorrentCreator::calculateTotalPieces(const Path &inputPath, const int pieceSize, const bool isAlignmentOptimized, const int paddedFileSizeLimit)
 #endif
 {
     if (inputPath.isEmpty())

src/base/bittorrent/torrentcreator.h

@@ -28,8 +28,10 @@
 
 #pragma once
 
+#include <QAtomicInt>
+#include <QObject>
+#include <QRunnable>
 #include <QStringList>
-#include <QThread>
 
 #include "base/path.h"
 
@@ -62,16 +64,20 @@ namespace BitTorrent
         QStringList urlSeeds;
     };
 
-    class TorrentCreatorThread final : public QThread
+    class TorrentCreator final : public QObject, public QRunnable
     {
         Q_OBJECT
-        Q_DISABLE_COPY_MOVE(TorrentCreatorThread)
+        Q_DISABLE_COPY_MOVE(TorrentCreator)
 
     public:
-        explicit TorrentCreatorThread(QObject *parent = nullptr);
-        ~TorrentCreatorThread() override;
+        explicit TorrentCreator(const TorrentCreatorParams &params, QObject *parent = nullptr);
 
-        void create(const TorrentCreatorParams &params);
+        void run() override;
+
+        bool isInterruptionRequested() const;
+
+    public slots:
+        void requestInterruption();
 
 #ifdef QBT_USES_LIBTORRENT2
         static int calculateTotalPieces(const Path &inputPath, int pieceSize, TorrentFormat torrentFormat);
@@ -86,10 +92,10 @@ namespace BitTorrent
         void updateProgress(int progress);
 
     private:
-        void run() override;
         void sendProgressSignal(int currentPieceIdx, int totalPieces);
         void checkInterruptionRequested() const;
 
         TorrentCreatorParams m_params;
+        QAtomicInt m_interruptionRequested;
     };
 }