Playlist: copy stream tags from the PlayerThread

src/Instance.hxx

@@ -40,8 +40,8 @@ struct Instance {
 	void DatabaseModified();
 
 	/**
-	 * A tag in the play queue has been modified.  Propagate the
-	 * change to all subsystems.
+	 * A tag in the play queue has been modified by the player
+	 * thread.  Propagate the change to all subsystems.
 	 */
 	void TagModified();
 

src/Partition.cxx

@@ -19,11 +19,16 @@
 
 #include "config.h"
 #include "Partition.hxx"
+#include "Song.hxx"
 
 void
 Partition::TagModified()
 {
-	playlist.TagChanged();
+	Song *song = pc.LockReadTaggedSong();
+	if (song != nullptr) {
+		playlist.TagModified(std::move(*song));
+		song->Free();
+	}
 }
 
 void

src/Partition.hxx

@@ -167,8 +167,8 @@ struct Partition {
 	}
 
 	/**
-	 * A tag in the play queue has been modified.  Propagate the
-	 * change to all subsystems.
+	 * A tag in the play queue has been modified by the player
+	 * thread.  Propagate the change to all subsystems.
 	 */
 	void TagModified();
 

src/PlayerControl.cxx

@@ -53,6 +53,9 @@ player_control::~player_control()
 {
 	if (next_song != nullptr)
 		next_song->Free();
+
+	if (tagged_song != nullptr)
+		tagged_song->Free();
 }
 
 void
@@ -201,6 +204,25 @@ player_control::ClearError()
 }
 
 void
+player_control::LockSetTaggedSong(const Song &song)
+{
+	Lock();
+	if (tagged_song != nullptr)
+		tagged_song->Free();
+	tagged_song = song.DupDetached();
+	Unlock();
+}
+
+void
+player_control::ClearTaggedSong()
+{
+	if (tagged_song != nullptr) {
+		tagged_song->Free();
+		tagged_song = nullptr;
+	}
+}
+
+void
 player_control::EnqueueSong(Song *song)
 {
 	assert(song != nullptr);

src/PlayerControl.hxx

@@ -100,7 +100,7 @@ struct player_control {
 	Thread thread;
 
 	/**
-	 * This lock protects #command, #state, #error.
+	 * This lock protects #command, #state, #error, #tagged_song.
 	 */
 	mutable Mutex mutex;
 
@@ -129,6 +129,18 @@ struct player_control {
 	 */
 	Error error;
 
+	/**
+	 * A copy of the current #Song after its tags have been
+	 * updated by the decoder (for example, a radio stream that
+	 * has sent a new tag after switching to the next song).  This
+	 * shall be used by the GlobalEvents::TAG handler to update
+	 * the current #Song in the queue.
+	 *
+	 * Protected by #mutex.  Set by the PlayerThread and consumed
+	 * by the main thread.
+	 */
+	Song *tagged_song;
+
 	uint16_t bit_rate;
 	AudioFormat audio_format;
 	float total_time;
@@ -356,6 +368,35 @@ public:
 		return error_type;
 	}
 
+	/**
+	 * Set the #tagged_song attribute to a newly allocated copy of
+	 * the given #Song.  Locks and unlocks the object.
+	 */
+	void LockSetTaggedSong(const Song &song);
+
+	void ClearTaggedSong();
+
+	/**
+	 * Read and clear the #tagged_song attribute.
+	 *
+	 * Caller must lock the object.
+	 */
+	Song *ReadTaggedSong() {
+		Song *result = tagged_song;
+		tagged_song = nullptr;
+		return result;
+	}
+
+	/**
+	 * Like ReadTaggedSong(), but locks and unlocks the object.
+	 */
+	Song *LockReadTaggedSong() {
+		Lock();
+		Song *result = ReadTaggedSong();
+		Unlock();
+		return result;
+	}
+
 	void Stop();
 
 	void UpdateAudio();

src/PlayerThread.cxx

@@ -335,6 +335,8 @@ Player::WaitForDecoder()
 		return false;
 	}
 
+	pc.ClearTaggedSong();
+
 	if (song != nullptr)
 		song->Free();
 
@@ -684,7 +686,7 @@ Player::ProcessCommand()
 }
 
 static void
-update_song_tag(Song *song, const Tag &new_tag)
+update_song_tag(player_control &pc, Song *song, const Tag &new_tag)
 {
 	if (song->IsFile())
 		/* don't update tags of local files, only remote
@@ -696,6 +698,8 @@ update_song_tag(Song *song, const Tag &new_tag)
 
 	delete old_tag;
 
+	pc.LockSetTaggedSong(*song);
+
 	/* the main thread will update the playlist version when he
 	   receives this event */
 	GlobalEvents::Emit(GlobalEvents::TAG);
@@ -722,7 +726,7 @@ play_chunk(player_control &pc,
 	assert(chunk->CheckFormat(format));
 
 	if (chunk->tag != nullptr)
-		update_song_tag(song, *chunk->tag);
+		update_song_tag(pc, song, *chunk->tag);
 
 	if (chunk->IsEmpty()) {
 		buffer.Return(chunk);
@@ -1077,6 +1081,8 @@ Player::Run()
 
 	pc.Lock();
 
+	pc.ClearTaggedSong();
+
 	if (queued) {
 		assert(pc.next_song != nullptr);
 		pc.next_song->Free();

src/Playlist.cxx

@@ -22,6 +22,7 @@
 #include "PlaylistError.hxx"
 #include "PlayerControl.hxx"
 #include "Song.hxx"
+#include "tag/Tag.hxx"
 #include "Idle.hxx"
 #include "Log.hxx"
 
@@ -35,13 +36,17 @@ playlist::FullIncrementVersions()
 }
 
 void
-playlist::TagChanged()
+playlist::TagModified(Song &&song)
 {
-	if (!playing)
+	if (!playing || song.tag == nullptr)
 		return;
 
 	assert(current >= 0);
 
+	Song &current_song = queue.GetOrder(current);
+	if (SongEquals(song, current_song))
+		current_song.ReplaceTag(std::move(*song.tag));
+
 	queue.ModifyAtOrder(current);
 	idle_add(IDLE_PLAYLIST);
 }

src/Playlist.hxx

@@ -128,7 +128,12 @@ protected:
 public:
 	void Clear(player_control &pc);
 
-	void TagChanged();
+	/**
+	 * A tag in the play queue has been modified by the player
+	 * thread.  Apply the given song's tag to the current song if
+	 * the song matches.
+	 */
+	void TagModified(Song &&song);
 
 	void FullIncrementVersions();