Add support for saving songs in a separate thread.

Updates issue #542

src/CMakeLists.txt

@@ -521,6 +521,7 @@ endif(APPLE)
 list(APPEND OTHER_SOURCES
   core/macglobalshortcutbackend.h
   core/macglobalshortcutbackend.mm
+  core/modelfuturewatcher.h
   devices/afcdevice.cpp
   devices/afcdevice.h
   devices/afcfile.cpp

src/core/modelfuturewatcher.h

@@ -0,0 +1,25 @@
+#ifndef MODELFUTUREWATCHER_H
+#define MODELFUTUREWATCHER_H
+
+#include <QFutureWatcher>
+#include <QModelIndex>
+
+template <typename T>
+class ModelFutureWatcher : public QFutureWatcher<T> {
+ public:
+  ModelFutureWatcher(const QModelIndex& index, QObject* parent = 0)
+      : QFutureWatcher<T>(parent),
+        index_(index) {
+  }
+
+  ~ModelFutureWatcher() {
+  }
+
+  const QModelIndex& index() const { return index_; }
+
+ private:
+  QModelIndex index_;
+
+};
+
+#endif

src/core/song.cpp

@@ -50,6 +50,8 @@
 #include <QTextCodec>
 #include <QVariant>
 
+#include <QtConcurrentRun>
+
 #include <boost/scoped_ptr.hpp>
 using boost::scoped_ptr;
 
@@ -829,3 +831,12 @@ bool Song::Save() const {
 
   return ret;
 }
+
+bool Song::Save(const Song& song) {
+  return song.Save();
+}
+
+QFuture<bool> Song::BackgroundSave() const {
+  QFuture<bool> future = QtConcurrent::run(&Song::Save, Song(*this));
+  return future;
+}

src/core/song.h

@@ -17,6 +17,7 @@
 #ifndef SONG_H
 #define SONG_H
 
+#include <QFuture>
 #include <QHash>
 #include <QImage>
 #include <QList>
@@ -185,6 +186,7 @@ class Song {
   // Setters
   bool IsEditable() const;
   bool Save() const;
+  QFuture<bool> BackgroundSave() const;
 
   void set_id(int id) { d->id_ = id; }
   void set_valid(bool v) { d->valid_ = v; }
@@ -225,6 +227,7 @@ class Song {
 
  private:
   void GuessFileType(TagLib::FileRef* fileref);
+  static bool Save(const Song& song);
 
   // Helper methods for taglib
   static void SetTextFrame(const QString& id, const QString& value,

src/playlist/playlist.cpp

@@ -22,6 +22,7 @@
 #include "songloaderinserter.h"
 #include "songmimedata.h"
 #include "songplaylistitem.h"
+#include "core/modelfuturewatcher.h"
 #include "library/library.h"
 #include "library/librarybackend.h"
 #include "library/libraryplaylistitem.h"
@@ -240,11 +241,20 @@ bool Playlist::setData(const QModelIndex &index, const QVariant &value, int) {
   if(!set_column_value(song, (Column)index.column(), value))
     return false;
 
-  song.Save();
-  item_at(row)->Reload();
+  QFuture<bool> future = song.BackgroundSave();
+  ModelFutureWatcher<bool>* watcher = new ModelFutureWatcher<bool>(index, this);
+  watcher->setFuture(future);
+  connect(watcher, SIGNAL(finished()), SLOT(SongSaveComplete()));
+  return true;
+}
+
+void Playlist::SongSaveComplete() {
+  ModelFutureWatcher<bool>* watcher = static_cast<ModelFutureWatcher<bool>*>(sender());
+  watcher->deleteLater();
+  const QModelIndex& index = watcher->index();
+  item_at(index.row())->Reload();
   emit dataChanged(index, index);
   emit EditingFinished(index);
-  return true;
 }
 
 int Playlist::current_index() const {

src/playlist/playlist.h

@@ -202,6 +202,7 @@ class Playlist : public QAbstractListModel {
   void TracksDequeued();
   void TracksEnqueued(const QModelIndex&, int begin, int end);
   void QueueLayoutChanged();
+  void SongSaveComplete();
 
  private:
   PlaylistFilter* proxy_;