Playlist: pass Database to DatabaseModified()

Don't use global variable.

src/Instance.cxx

@@ -22,6 +22,7 @@
 #include "Partition.hxx"
 #include "Idle.hxx"
 #include "Stats.hxx"
+#include "db/DatabaseGlue.hxx"
 
 #ifdef ENABLE_DATABASE
 
@@ -35,7 +36,7 @@ void
 Instance::DatabaseModified()
 {
 	stats_invalidate();
-	partition->DatabaseModified();
+	partition->DatabaseModified(*GetDatabase());
 	idle_add(IDLE_DATABASE);
 }
 

src/Partition.cxx

@@ -25,9 +25,9 @@
 #ifdef ENABLE_DATABASE
 
 void
-Partition::DatabaseModified()
+Partition::DatabaseModified(const Database &db)
 {
-	playlist.DatabaseModified();
+	playlist.DatabaseModified(db);
 }
 
 #endif

src/Partition.hxx

@@ -178,7 +178,7 @@ struct Partition {
 	 * The database has been modified.  Propagate the change to
 	 * all subsystems.
 	 */
-	void DatabaseModified();
+	void DatabaseModified(const Database &db);
 #endif
 
 	/**

src/Playlist.hxx

@@ -26,6 +26,7 @@
 enum TagType : uint8_t;
 struct PlayerControl;
 class DetachedSong;
+class Database;
 class Error;
 
 struct playlist {
@@ -141,7 +142,7 @@ public:
 	/**
 	 * The database has been modified.  Pull all updates.
 	 */
-	void DatabaseModified();
+	void DatabaseModified(const Database &db);
 #endif
 
 	PlaylistResult AppendSong(PlayerControl &pc,

src/PlaylistUpdate.cxx

@@ -19,7 +19,6 @@
 
 #include "config.h"
 #include "Playlist.hxx"
-#include "db/DatabaseGlue.hxx"
 #include "db/DatabasePlugin.hxx"
 #include "db/LightSong.hxx"
 #include "DetachedSong.hxx"
@@ -56,17 +55,12 @@ UpdatePlaylistSong(const Database &db, DetachedSong &song)
 }
 
 void
-playlist::DatabaseModified()
+playlist::DatabaseModified(const Database &db)
 {
-	const Database *db = GetDatabase();
-	if (db == nullptr)
-		/* how can this ever happen? */
-		return;
-
 	bool modified = false;
 
 	for (unsigned i = 0, n = queue.GetLength(); i != n; ++i) {
-		if (UpdatePlaylistSong(*db, queue.Get(i))) {
+		if (UpdatePlaylistSong(db, queue.Get(i))) {
 			queue.ModifyAtPosition(i);
 			modified = true;
 		}