Reduce the number of torrent_handle::torrent_file() calls in QTorrentHandle::prioritize_files(). Closes #2161.

It was reported (#2161) that enabling/disabling a downloading of a file
is considerably slow on libtorrent 1.0.3, but not on 0.16.x. The problem
is that a function torrent_file() in libttorrent 1.0.3 does a deep copy
of torrent_info, while get_torrent_info() in libtorrent 0.16.x only
returns a reference.

src/qtlibtorrent/qtorrenthandle.cpp

@@ -245,9 +245,9 @@ size_type QTorrentHandle::filesize_at(unsigned int index) const {
 
 QString QTorrentHandle::filepath_at(unsigned int index) const {
 #if LIBTORRENT_VERSION_NUM < 10000
-  return fsutils::fromNativePath(misc::toQStringU(torrent_handle::get_torrent_info().files().file_path(index)));
+  return filepath_at(torrent_handle::get_torrent_info(), index);
 #else
-  return fsutils::fromNativePath(misc::toQStringU(torrent_handle::torrent_file()->files().file_path(index)));
+  return filepath_at(*torrent_handle::torrent_file(), index);
 #endif
 }
 
@@ -508,10 +508,12 @@ void QTorrentHandle::file_priority(int index, int priority) const {
 
 void QTorrentHandle::prioritize_files(const vector<int> &files) const {
 #if LIBTORRENT_VERSION_NUM < 10000
-  if ((int)files.size() != torrent_handle::get_torrent_info().num_files()) return;
+  torrent_info const& info = torrent_handle::get_torrent_info();
 #else
-  if ((int)files.size() != torrent_handle::torrent_file()->num_files()) return;
+  boost::intrusive_ptr<torrent_info const> info_ptr = torrent_handle::torrent_file();
+  torrent_info const& info = *info_ptr;
 #endif
+  if ((int)files.size() != info.num_files()) return;
   qDebug() << Q_FUNC_INFO;
   bool was_seed = is_seed();
   qDebug() << Q_FUNC_INFO << "Changing files priorities...";
@@ -521,14 +523,15 @@ void QTorrentHandle::prioritize_files(const vector<int> &files) const {
   QString spath = save_path();
 
   for (uint i = 0; i < files.size(); ++i) {
+    QString filepath = filepath_at(info, i);
     // Move unwanted files to a .unwanted subfolder
     if (files[i] == 0) {
-      QString old_abspath = QDir(spath).absoluteFilePath(filepath_at(i));
+      QString old_abspath = QDir(spath).absoluteFilePath(filepath);
       QString parent_abspath = fsutils::branchPath(old_abspath);
       // Make sure the file does not already exists
       if (QDir(parent_abspath).dirName() != ".unwanted") {
         QString unwanted_abspath = parent_abspath+"/.unwanted";
-        QString new_abspath = unwanted_abspath+"/"+filename_at(i);
+        QString new_abspath = unwanted_abspath+"/"+fsutils::fileName(filepath);
         qDebug() << "Unwanted path is" << unwanted_abspath;
         if (QFile::exists(new_abspath)) {
           qWarning() << "File" << new_abspath << "already exists at destination.";
@@ -548,17 +551,17 @@ void QTorrentHandle::prioritize_files(const vector<int> &files) const {
 #else
         Q_UNUSED(created);
 #endif
-        QString parent_path = fsutils::branchPath(filepath_at(i));
+        QString parent_path = fsutils::branchPath(filepath);
         if (!parent_path.isEmpty() && !parent_path.endsWith("/"))
           parent_path += "/";
-        rename_file(i, parent_path+".unwanted/"+filename_at(i));
+        rename_file(i, parent_path+".unwanted/"+fsutils::fileName(filepath));
       }
     }
     // Move wanted files back to their original folder
     if (files[i] > 0) {
-      QString parent_relpath = fsutils::branchPath(filepath_at(i));
+      QString parent_relpath = fsutils::branchPath(filepath);
       if (QDir(parent_relpath).dirName() == ".unwanted") {
-        QString old_name = filename_at(i);
+        QString old_name = fsutils::fileName(filepath);
         QString new_relpath = fsutils::branchPath(parent_relpath);
         if (new_relpath.isEmpty())
             rename_file(i, old_name);
@@ -664,3 +667,8 @@ float QTorrentHandle::progress(const libtorrent::torrent_status &status) {
   Q_ASSERT(progress >= 0.f && progress <= 1.f);
   return progress;
 }
+
+QString QTorrentHandle::filepath_at(const libtorrent::torrent_info &info, unsigned int index) {
+  return fsutils::fromNativePath(misc::toQStringU(info.files().file_path(index)));
+
+}

src/qtlibtorrent/qtorrenthandle.h

@@ -121,6 +121,7 @@ public:
   static bool is_checking(const libtorrent::torrent_status &status);
   static bool has_error(const libtorrent::torrent_status &status);
   static float progress(const libtorrent::torrent_status &status);
+  static QString filepath_at(const libtorrent::torrent_info &info, unsigned int index);
 
 private:
   void prioritize_first_last_piece(int file_index, bool b) const;