Avoid heavy weight function object

Also, by switching to template we can avoid the cost of converting to some specific type and
perfectly forward the parameter to the final function.

PR #21572.

src/base/bittorrent/resumedatastorage.cpp

@@ -35,8 +35,6 @@
 #include <QMutexLocker>
 #include <QThread>
 
-#include "base/global.h"
-
 const int TORRENTIDLIST_TYPEID = qRegisterMetaType<QList<BitTorrent::TorrentID>>();
 
 BitTorrent::ResumeDataStorage::ResumeDataStorage(const Path &path, QObject *parent)

src/base/bittorrent/sessionimpl.cpp

@@ -71,7 +71,6 @@
 #include <QRegularExpression>
 #include <QString>
 #include <QThread>
-#include <QThreadPool>
 #include <QTimer>
 #include <QUuid>
 
@@ -3013,11 +3012,6 @@ void SessionImpl::removeMappedPorts(const QSet<quint16> &ports)
     });
 }
 
-void SessionImpl::invokeAsync(std::function<void ()> func)
-{
-    m_asyncWorker->start(std::move(func));
-}
-
 // Add a torrent to libtorrent session in hidden mode
 // and force it to download its metadata
 bool SessionImpl::downloadMetadata(const TorrentDescriptor &torrentDescr)

src/base/bittorrent/sessionimpl.h

@@ -44,6 +44,7 @@
 #include <QMap>
 #include <QPointer>
 #include <QSet>
+#include <QThreadPool>
 
 #include "base/path.h"
 #include "base/settingvalue.h"
@@ -57,7 +58,6 @@
 #include "trackerentrystatus.h"
 
 class QString;
-class QThreadPool;
 class QTimer;
 class QUrl;
 
@@ -482,7 +482,11 @@ namespace BitTorrent
             QMetaObject::invokeMethod(this, std::forward<Func>(func), Qt::QueuedConnection);
         }
 
-        void invokeAsync(std::function<void ()> func);
+        template <typename Func>
+        void invokeAsync(Func &&func)
+        {
+            m_asyncWorker->start(std::forward<Func>(func));
+        }
 
     signals:
         void addTorrentAlertsReceived(qsizetype count);

src/webui/api/torrentscontroller.cpp

@@ -28,6 +28,7 @@
 
 #include "torrentscontroller.h"
 
+#include <concepts>
 #include <functional>
 
 #include <QBitArray>
@@ -135,7 +136,9 @@ namespace
 
     const QSet<QString> SUPPORTED_WEB_SEED_SCHEMES {u"http"_s, u"https"_s, u"ftp"_s};
 
-    void applyToTorrents(const QStringList &idList, const std::function<void (BitTorrent::Torrent *torrent)> &func)
+    template <typename Func>
+    void applyToTorrents(const QStringList &idList, Func func)
+        requires std::invocable<Func, BitTorrent::Torrent *>
     {
         if ((idList.size() == 1) && (idList[0] == u"all"))
         {