Use a better data structure to track uniques songs when removing duplicate.

src/core/song.cpp

@@ -1114,12 +1114,6 @@ bool Song::IsMetadataEqual(const Song& other) const {
          d->cue_path_ == other.d->cue_path_;
 }
 
-bool Song::IsDuplicate(const Song& other) const {
-  return url() == other.url() ||
-    (title().toLower() == other.title().toLower() &&
-     artist().toLower() == other.artist().toLower());
-}
-
 bool Song::IsEditable() const {
   return d->valid_ && !d->url_.isEmpty() && !is_stream() &&
          d->filetype_ != Type_Unknown && !has_cue();
@@ -1136,6 +1130,16 @@ uint qHash(const Song& song) {
   return qHash(song.url().toString()) ^ qHash(song.beginning_nanosec());
 }
 
+bool Song::IsSimilar(const Song& other) const {
+  return title().compare(other.title(), Qt::CaseInsensitive) == 0 &&
+         artist().compare(other.artist(), Qt::CaseInsensitive) == 0;
+}
+
+uint HashSimilar(const Song& song) {
+  // Should compare the same fields as function IsSimilar
+  return qHash(song.title().toLower()) ^ qHash(song.artist().toLower());
+}
+
 bool Song::IsOnSameAlbum(const Song& other) const {
   if (is_compilation() != other.is_compilation())
     return false;

src/core/song.h

@@ -262,7 +262,7 @@ class Song {
   // Comparison functions
   bool IsMetadataEqual(const Song& other) const;
   bool IsOnSameAlbum(const Song& other) const;
-  bool IsDuplicate(const Song& other) const;
+  bool IsSimilar(const Song& other) const;
 
   bool operator==(const Song& other) const;
 
@@ -283,5 +283,7 @@ typedef QList<Song> SongList;
 Q_DECLARE_METATYPE(QList<Song>);
 
 uint qHash(const Song& song);
+// Hash function using field checked in IsSimilar function
+uint HashSimilar(const Song& song);
 
 #endif // SONG_H

src/playlist/playlist.cpp

@@ -62,6 +62,7 @@
 #include <QtDebug>
 
 #include <algorithm>
+#include <unordered_map>
 #include <boost/bind.hpp>
 
 using smart_playlists::Generator;
@@ -1919,36 +1920,45 @@ void Playlist::RemoveDeletedSongs() {
   removeRows(rows_to_remove);
 }
 
+struct SongSimilarHash {
+  long operator() (const Song& song) const {
+    return HashSimilar(song);
+  }
+};
+
+struct SongSimilarEqual {
+  long operator() (const Song& song1, const Song& song2) const {
+    return song1.IsSimilar(song2);
+  }
+};
+
 void Playlist::RemoveDuplicateSongs() {
   QList<int> rows_to_remove;
-  QHash<Song, int> unique_songs;
+  std::unordered_map<Song, int, SongSimilarHash, SongSimilarEqual> unique_songs;
 
   for (int row = 0; row < items_.count(); ++row) {
     PlaylistItemPtr item = items_[row];
-    Song song = item->Metadata();
+    const Song& song = item->Metadata();
 
     bool found_duplicate = false;
-    QHashIterator<Song, int> iterator(unique_songs);
 
-    while (iterator.hasNext() && !found_duplicate) {
-      iterator.next();
-      Song uniq_song = iterator.key();
+    auto uniq_song_it = unique_songs.find(song);
+    if (uniq_song_it != unique_songs.end()) {
+      const Song& uniq_song = uniq_song_it->first;
 
-      if (song.IsDuplicate(uniq_song)) {
-        if (song.bitrate() > uniq_song.bitrate()) {
-          rows_to_remove.append(unique_songs[uniq_song]);
-          unique_songs.remove(uniq_song);
-          unique_songs.insert(song, row);
-        }
-        else {
-          rows_to_remove.append(row);
-        }
-        found_duplicate = true;
+      if (song.bitrate() > uniq_song.bitrate()) {
+        rows_to_remove.append(unique_songs[uniq_song]);
+        unique_songs.erase(uniq_song);
+        unique_songs.insert(std::make_pair(song, row));
+      } else {
+        rows_to_remove.append(row);
       }
+      found_duplicate = true;
     }
 
-    if (!found_duplicate)
-      unique_songs.insert(song, row);
+    if (!found_duplicate) {
+      unique_songs.insert(std::make_pair(song, row));
+    }
   }
 
   removeRows(rows_to_remove);