db/update: convert to OO API

Move global variables into the new classes.  That may allow multiple
update threads for multiple databases one day.

29 files changed, 514 insertions, 520 deletions

diff --git a/Makefile.am b/Makefile.am
index c51a12e6b..a8850ce29 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -124,15 +124,15 @@ src_mpd_SOURCES = \
 	src/filter/FilterInternal.hxx \
 	src/filter/FilterRegistry.cxx src/filter/FilterRegistry.hxx \
 	src/db/update/UpdateDomain.cxx src/db/update/UpdateDomain.hxx \
-	src/db/update/UpdateGlue.cxx src/db/update/UpdateGlue.hxx \
-	src/db/update/UpdateQueue.cxx src/db/update/UpdateQueue.hxx \
+	src/db/update/Service.cxx src/db/update/Service.hxx \
+	src/db/update/UpdateGlue.cxx \
+	src/db/update/Queue.cxx src/db/update/Queue.hxx \
 	src/db/update/UpdateIO.cxx src/db/update/UpdateIO.hxx \
-	src/db/update/UpdateDatabase.cxx src/db/update/UpdateDatabase.hxx \
-	src/db/update/UpdateWalk.cxx src/db/update/UpdateWalk.hxx \
-	src/db/update/UpdateSong.cxx src/db/update/UpdateSong.hxx \
-	src/db/update/UpdateContainer.cxx src/db/update/UpdateContainer.hxx \
-	src/db/update/UpdateInternal.hxx \
-	src/db/update/UpdateRemove.cxx src/db/update/UpdateRemove.hxx \
+	src/db/update/Editor.cxx src/db/update/Editor.hxx \
+	src/db/update/Walk.cxx src/db/update/Walk.hxx \
+	src/db/update/UpdateSong.cxx \
+	src/db/update/Container.cxx \
+	src/db/update/Remove.cxx src/db/update/Remove.hxx \
 	src/db/update/ExcludeList.cxx src/db/update/ExcludeList.hxx \
 	src/client/Client.cxx src/client/Client.hxx \
 	src/client/ClientInternal.hxx \
@@ -486,7 +486,7 @@ if ENABLE_ARCHIVE
 noinst_LIBRARIES += libarchive.a
 
 src_mpd_SOURCES +=  \
-	src/db/update/UpdateArchive.cxx src/db/update/UpdateArchive.hxx
+	src/db/update/Archive.cxx
 
 libarchive_a_SOURCES = \
 	src/archive/ArchiveDomain.cxx src/archive/ArchiveDomain.hxx \
diff --git a/src/GlobalEvents.hxx b/src/GlobalEvents.hxx
index 106eeb8f8..98aa4850f 100644
--- a/src/GlobalEvents.hxx
+++ b/src/GlobalEvents.hxx
@@ -33,9 +33,6 @@ class EventLoop;
 
 namespace GlobalEvents {
 	enum Event {
-		/** database update was finished */
-		UPDATE,
-
 		/** during database update, a song was deleted */
 		DELETE,
 
diff --git a/src/Instance.hxx b/src/Instance.hxx
index a14719839..d67ff9a51 100644
--- a/src/Instance.hxx
+++ b/src/Instance.hxx
@@ -29,6 +29,7 @@
 class NeighborGlue;
 #endif
 
+class UpdateService;
 class ClientList;
 struct Partition;
 
@@ -42,6 +43,8 @@ struct Instance final
 	NeighborGlue *neighbors;
 #endif
 
+	UpdateService *update;
+
 	ClientList *client_list;
 
 	Partition *partition;
diff --git a/src/Main.cxx b/src/Main.cxx
index ab70c875c..2c5d183ea 100644
--- a/src/Main.cxx
+++ b/src/Main.cxx
@@ -23,7 +23,7 @@
 #include "CommandLine.hxx"
 #include "PlaylistFile.hxx"
 #include "PlaylistGlobal.hxx"
-#include "db/update/UpdateGlue.hxx"
+#include "db/update/Service.hxx"
 #include "MusicChunk.hxx"
 #include "StateFile.hxx"
 #include "PlayerThread.hxx"
@@ -448,10 +448,13 @@ int mpd_main(int argc, char *argv[])
 	}
 
 	decoder_plugin_init_all();
-	update_global_init();
 
 	const bool create_db = !glue_db_init_and_load();
 
+	instance->update = db_is_simple()
+		? new UpdateService(*main_loop)
+		: nullptr;
+
 	glue_sticker_init();
 
 	command_init();
@@ -490,7 +493,7 @@ int mpd_main(int argc, char *argv[])
 	if (create_db) {
 		/* the database failed to load: recreate the
 		   database */
-		unsigned job = update_enqueue("", true);
+		unsigned job = instance->update->Enqueue("", true);
 		if (job == 0)
 			FatalError("directory update failed");
 	}
@@ -504,8 +507,9 @@ int mpd_main(int argc, char *argv[])
 
 	if (config_get_bool(CONF_AUTO_UPDATE, false)) {
 #ifdef ENABLE_INOTIFY
-		if (mapper_has_music_directory())
-			mpd_inotify_init(*main_loop,
+		if (mapper_has_music_directory() &&
+		    instance->update != nullptr)
+			mpd_inotify_init(*main_loop, *instance->update,
 					 config_get_unsigned(CONF_AUTO_UPDATE_DEPTH,
 							     G_MAXUINT));
 #else
@@ -558,6 +562,8 @@ int mpd_main(int argc, char *argv[])
 	}
 #endif
 
+	delete instance->update;
+
 	const clock_t start = clock();
 	DatabaseGlobalDeinit();
 	FormatDebug(main_domain,
@@ -575,7 +581,6 @@ int mpd_main(int argc, char *argv[])
 	mapper_finish();
 	delete instance->partition;
 	command_finish();
-	update_global_finish();
 	decoder_plugin_deinit_all();
 #ifdef ENABLE_ARCHIVE
 	archive_plugin_deinit_all();
diff --git a/src/command/OtherCommands.cxx b/src/command/OtherCommands.cxx
index f8976e561..2aa67f22c 100644
--- a/src/command/OtherCommands.cxx
+++ b/src/command/OtherCommands.cxx
@@ -20,7 +20,7 @@
 #include "config.h"
 #include "OtherCommands.hxx"
 #include "DatabaseCommands.hxx"
-#include "db/update/UpdateGlue.hxx"
+#include "db/update/Service.hxx"
 #include "CommandError.hxx"
 #include "db/Uri.hxx"
 #include "DetachedSong.hxx"
@@ -46,6 +46,7 @@
 #include "client/ClientFile.hxx"
 #include "client/Client.hxx"
 #include "Partition.hxx"
+#include "Instance.hxx"
 #include "Idle.hxx"
 
 #include <assert.h>
@@ -186,7 +187,6 @@ CommandResult
 handle_update(Client &client, gcc_unused int argc, char *argv[])
 {
 	const char *path = "";
-	unsigned ret;
 
 	assert(argc <= 2);
 	if (argc == 2) {
@@ -202,7 +202,13 @@ handle_update(Client &client, gcc_unused int argc, char *argv[])
 		}
 	}
 
-	ret = update_enqueue(path, false);
+	UpdateService *update = client.partition.instance.update;
+	if (update == nullptr) {
+		command_error(client, ACK_ERROR_NO_EXIST, "No database");
+		return CommandResult::ERROR;
+	}
+
+	unsigned ret = update->Enqueue(path, false);
 	if (ret > 0) {
 		client_printf(client, "updating_db: %i\n", ret);
 		return CommandResult::OK;
@@ -217,7 +223,6 @@ CommandResult
 handle_rescan(Client &client, gcc_unused int argc, char *argv[])
 {
 	const char *path = "";
-	unsigned ret;
 
 	assert(argc <= 2);
 	if (argc == 2) {
@@ -230,7 +235,13 @@ handle_rescan(Client &client, gcc_unused int argc, char *argv[])
 		}
 	}
 
-	ret = update_enqueue(path, true);
+	UpdateService *update = client.partition.instance.update;
+	if (update == nullptr) {
+		command_error(client, ACK_ERROR_NO_EXIST, "No database");
+		return CommandResult::ERROR;
+	}
+
+	unsigned ret = update->Enqueue(path, true);
 	if (ret > 0) {
 		client_printf(client, "updating_db: %i\n", ret);
 		return CommandResult::OK;
diff --git a/src/command/PlayerCommands.cxx b/src/command/PlayerCommands.cxx
index 5dc55b485..d51dbdc3d 100644
--- a/src/command/PlayerCommands.cxx
+++ b/src/command/PlayerCommands.cxx
@@ -22,10 +22,11 @@
 #include "CommandError.hxx"
 #include "Playlist.hxx"
 #include "PlaylistPrint.hxx"
-#include "db/update/UpdateGlue.hxx"
+#include "db/update/Service.hxx"
 #include "client/Client.hxx"
 #include "mixer/Volume.hxx"
 #include "Partition.hxx"
+#include "Instance.hxx"
 #include "protocol/Result.hxx"
 #include "protocol/ArgParser.hxx"
 #include "AudioFormat.hxx"
@@ -111,7 +112,6 @@ handle_status(Client &client,
 	      gcc_unused int argc, gcc_unused char *argv[])
 {
 	const char *state = nullptr;
-	int updateJobId;
 	int song;
 
 	const auto player_status = client.player_control.GetStatus();
@@ -187,7 +187,11 @@ handle_status(Client &client,
 		}
 	}
 
-	if ((updateJobId = isUpdatingDB())) {
+	const UpdateService *update_service = client.partition.instance.update;
+	unsigned updateJobId = update_service != nullptr
+		? update_service->GetId()
+		: 0;
+	if (updateJobId != 0) {
 		client_printf(client,
 			      COMMAND_STATUS_UPDATING_DB ": %i\n",
 			      updateJobId);
diff --git a/src/db/update/UpdateArchive.cxx b/src/db/update/Archive.cxx
index 5e733202d..6d47ae0d1 100644
--- a/src/db/update/UpdateArchive.cxx
+++ b/src/db/update/Archive.cxx
@@ -18,8 +18,7 @@
  */
 
 #include "config.h" /* must be first for large file support */
-#include "UpdateArchive.hxx"
-#include "UpdateInternal.hxx"
+#include "Walk.hxx"
 #include "UpdateDomain.hxx"
 #include "db/DatabaseLock.hxx"
 #include "db/Directory.hxx"
@@ -35,10 +34,11 @@
 
 #include <string>
 
+#include <sys/stat.h>
 #include <string.h>
 
-static void
-update_archive_tree(Directory &directory, const char *name)
+void
+UpdateWalk::UpdateArchiveTree(Directory &directory, const char *name)
 {
 	const char *tmp = strchr(name, '/');
 	if (tmp) {
@@ -51,7 +51,7 @@ update_archive_tree(Directory &directory, const char *name)
 		db_unlock();
 
 		//create directories first
-		update_archive_tree(*subdir, tmp+1);
+		UpdateArchiveTree(*subdir, tmp + 1);
 	} else {
 		if (strlen(name) == 0) {
 			LogWarning(update_domain,
@@ -78,6 +78,21 @@ update_archive_tree(Directory &directory, const char *name)
 	}
 }
 
+class UpdateArchiveVisitor final : public ArchiveVisitor {
+	UpdateWalk &walk;
+	Directory *directory;
+
+ public:
+	UpdateArchiveVisitor(UpdateWalk &_walk, Directory *_directory)
+		:walk(_walk), directory(_directory) {}
+
+	virtual void VisitArchiveEntry(const char *path_utf8) override {
+		FormatDebug(update_domain,
+			    "adding archive file: %s", path_utf8);
+		walk.UpdateArchiveTree(*directory, path_utf8);
+	}
+};
+
 /**
  * Updates the file listing from an archive file.
  *
@@ -86,10 +101,10 @@ update_archive_tree(Directory &directory, const char *name)
  * @param st stat() information on the archive file
  * @param plugin the archive plugin which fits this archive type
  */
-static void
-update_archive_file2(Directory &parent, const char *name,
-		     const struct stat *st,
-		     const struct archive_plugin *plugin)
+void
+UpdateWalk::UpdateArchiveFile(Directory &parent, const char *name,
+			      const struct stat *st,
+			      const archive_plugin &plugin)
 {
 	db_lock();
 	Directory *directory = parent.FindChild(name);
@@ -105,7 +120,7 @@ update_archive_file2(Directory &parent, const char *name,
 
 	/* open archive */
 	Error error;
-	ArchiveFile *file = archive_file_open(plugin, path_fs.c_str(), error);
+	ArchiveFile *file = archive_file_open(&plugin, path_fs.c_str(), error);
 	if (file == nullptr) {
 		LogError(error);
 		return;
@@ -126,44 +141,21 @@ update_archive_file2(Directory &parent, const char *name,
 
 	directory->mtime = st->st_mtime;
 
-	class UpdateArchiveVisitor final : public ArchiveVisitor {
-		Directory *directory;
-
-	public:
-		UpdateArchiveVisitor(Directory *_directory)
-			:directory(_directory) {}
-
-		virtual void VisitArchiveEntry(const char *path_utf8) override {
-			FormatDebug(update_domain,
-				    "adding archive file: %s", path_utf8);
-			update_archive_tree(*directory, path_utf8);
-		}
-	};
-
-	UpdateArchiveVisitor visitor(directory);
+	UpdateArchiveVisitor visitor(*this, directory);
 	file->Visit(visitor);
 	file->Close();
 }
 
 bool
-update_archive_file(Directory &directory,
-		    const char *name, const char *suffix,
-		    const struct stat *st)
+UpdateWalk::UpdateArchiveFile(Directory &directory,
+			      const char *name, const char *suffix,
+			      const struct stat *st)
 {
-#ifdef ENABLE_ARCHIVE
 	const struct archive_plugin *plugin =
 		archive_plugin_from_suffix(suffix);
 	if (plugin == nullptr)
 		return false;
 
-	update_archive_file2(directory, name, st, plugin);
+	UpdateArchiveFile(directory, name, st, *plugin);
 	return true;
-#else
-	(void)directory;
-	(void)name;
-	(void)suffix;
-	(void)st;
-
-	return false;
-#endif
 }
diff --git a/src/db/update/UpdateContainer.cxx b/src/db/update/Container.cxx
index c03d88748..38aacea0a 100644
--- a/src/db/update/UpdateContainer.cxx
+++ b/src/db/update/Container.cxx
@@ -18,9 +18,7 @@
  */
 
 #include "config.h" /* must be first for large file support */
-#include "UpdateContainer.hxx"
-#include "UpdateInternal.hxx"
-#include "UpdateDatabase.hxx"
+#include "Walk.hxx"
 #include "UpdateDomain.hxx"
 #include "db/DatabaseLock.hxx"
 #include "db/Directory.hxx"
@@ -33,19 +31,13 @@
 #include "tag/TagBuilder.hxx"
 #include "Log.hxx"
 
+#include <sys/stat.h>
+
 #include <glib.h>
 
-/**
- * Create the specified directory object if it does not exist already
- * or if the #stat object indicates that it has been modified since
- * the last update.  Returns nullptr when it exists already and is
- * unmodified.
- *
- * The caller must lock the database.
- */
-static Directory *
-make_directory_if_modified(Directory &parent, const char *name,
-			   const struct stat *st)
+Directory *
+UpdateWalk::MakeDirectoryIfModified(Directory &parent, const char *name,
+				    const struct stat *st)
 {
 	Directory *directory = parent.FindChild(name);
 
@@ -56,7 +48,7 @@ make_directory_if_modified(Directory &parent, const char *name,
 			return nullptr;
 		}
 
-		delete_directory(directory);
+		editor.DeleteDirectory(directory);
 		modified = true;
 	}
 
@@ -73,10 +65,9 @@ SupportsContainerSuffix(const DecoderPlugin &plugin, const char *suffix)
 }
 
 bool
-update_container_file(Directory &directory,
-		      const char *name,
-		      const struct stat *st,
-		      const char *suffix)
+UpdateWalk::UpdateContainerFile(Directory &directory,
+				const char *name, const char *suffix,
+				const struct stat *st)
 {
 	const DecoderPlugin *_plugin = decoder_plugins_find([suffix](const DecoderPlugin &plugin){
 			return SupportsContainerSuffix(plugin, suffix);
@@ -86,7 +77,7 @@ update_container_file(Directory &directory,
 	const DecoderPlugin &plugin = *_plugin;
 
 	db_lock();
-	Directory *contdir = make_directory_if_modified(directory, name, st);
+	Directory *contdir = MakeDirectoryIfModified(directory, name, st);
 	if (contdir == nullptr) {
 		/* not modified */
 		db_unlock();
@@ -128,7 +119,7 @@ update_container_file(Directory &directory,
 
 	if (tnum == 1) {
 		db_lock();
-		delete_directory(contdir);
+		editor.DeleteDirectory(contdir);
 		db_unlock();
 		return false;
 	} else
diff --git a/src/db/update/UpdateDatabase.cxx b/src/db/update/Editor.cxx
index 72a68de14..369bad24b 100644
--- a/src/db/update/UpdateDatabase.cxx
+++ b/src/db/update/Editor.cxx
@@ -18,8 +18,8 @@
  */
 
 #include "config.h" /* must be first for large file support */
-#include "UpdateDatabase.hxx"
-#include "UpdateRemove.hxx"
+#include "Editor.hxx"
+#include "Remove.hxx"
 #include "db/PlaylistVector.hxx"
 #include "db/Directory.hxx"
 #include "db/Song.hxx"
@@ -29,7 +29,7 @@
 #include <stddef.h>
 
 void
-delete_song(Directory &dir, Song *del)
+DatabaseEditor::DeleteSong(Directory &dir, Song *del)
 {
 	assert(del->parent == &dir);
 
@@ -39,7 +39,7 @@ delete_song(Directory &dir, Song *del)
 	db_unlock(); /* temporary unlock, because update_remove_song() blocks */
 
 	/* now take it out of the playlist (in the main_task) */
-	update_remove_song(del);
+	remove.Remove(del);
 
 	/* finally, all possible references gone, free it */
 	del->Free();
@@ -53,32 +53,32 @@ delete_song(Directory &dir, Song *del)
  *
  * Caller must lock the #db_mutex.
  */
-static void
-clear_directory(Directory &directory)
+inline void
+DatabaseEditor::ClearDirectory(Directory &directory)
 {
 	Directory *child, *n;
 	directory_for_each_child_safe(child, n, directory)
-		delete_directory(child);
+		DeleteDirectory(child);
 
 	Song *song, *ns;
 	directory_for_each_song_safe(song, ns, directory) {
 		assert(song->parent == &directory);
-		delete_song(directory, song);
+		DeleteSong(directory, song);
 	}
 }
 
 void
-delete_directory(Directory *directory)
+DatabaseEditor::DeleteDirectory(Directory *directory)
 {
 	assert(directory->parent != nullptr);
 
-	clear_directory(*directory);
+	ClearDirectory(*directory);
 
 	directory->Delete();
 }
 
 bool
-delete_name_in(Directory &parent, const char *name)
+DatabaseEditor::DeleteNameIn(Directory &parent, const char *name)
 {
 	bool modified = false;
 
@@ -86,13 +86,13 @@ delete_name_in(Directory &parent, const char *name)
 	Directory *directory = parent.FindChild(name);
 
 	if (directory != nullptr) {
-		delete_directory(directory);
+		DeleteDirectory(directory);
 		modified = true;
 	}
 
 	Song *song = parent.FindSong(name);
 	if (song != nullptr) {
-		delete_song(parent, song);
+		DeleteSong(parent, song);
 		modified = true;
 	}
 
diff --git a/src/db/update/UpdateDatabase.hxx b/src/db/update/Editor.hxx
index bd7c395f2..a9093d662 100644
--- a/src/db/update/UpdateDatabase.hxx
+++ b/src/db/update/Editor.hxx
@@ -21,30 +21,40 @@
 #define MPD_UPDATE_DATABASE_HXX
 
 #include "check.h"
+#include "Remove.hxx"
 
 struct Directory;
 struct Song;
+class UpdateRemoveService;
 
-/**
- * Caller must lock the #db_mutex.
- */
-void
-delete_song(Directory &parent, Song *song);
+class DatabaseEditor final {
+	UpdateRemoveService remove;
 
-/**
- * Recursively free a directory and all its contents.
- *
- * Caller must lock the #db_mutex.
- */
-void
-delete_directory(Directory *directory);
+public:
+	DatabaseEditor(EventLoop &_loop)
+		:remove(_loop) {}
 
-/**
- * Caller must NOT lock the #db_mutex.
- *
- * @return true if the database was modified
- */
-bool
-delete_name_in(Directory &parent, const char *name);
+	/**
+	 * Caller must lock the #db_mutex.
+	 */
+	void DeleteSong(Directory &parent, Song *song);
+
+	/**
+	 * Recursively free a directory and all its contents.
+	 *
+	 * Caller must lock the #db_mutex.
+	 */
+	void DeleteDirectory(Directory *directory);
+
+	/**
+	 * Caller must NOT lock the #db_mutex.
+	 *
+	 * @return true if the database was modified
+	 */
+	bool DeleteNameIn(Directory &parent, const char *name);
+
+private:
+	void ClearDirectory(Directory &directory);
+};
 
 #endif
diff --git a/src/db/update/InotifyQueue.cxx b/src/db/update/InotifyQueue.cxx
index f4bccf7ae..013200f98 100644
--- a/src/db/update/InotifyQueue.cxx
+++ b/src/db/update/InotifyQueue.cxx
@@ -20,7 +20,7 @@
 #include "config.h"
 #include "InotifyQueue.hxx"
 #include "InotifyDomain.hxx"
-#include "UpdateGlue.hxx"
+#include "Service.hxx"
 #include "Log.hxx"
 
 #include <string.h>
@@ -40,7 +40,7 @@ InotifyQueue::OnTimeout()
 	while (!queue.empty()) {
 		const char *uri_utf8 = queue.front().c_str();
 
-		id = update_enqueue(uri_utf8, false);
+		id = update.Enqueue(uri_utf8, false);
 		if (id == 0) {
 			/* retry later */
 			ScheduleSeconds(INOTIFY_UPDATE_DELAY_S);
diff --git a/src/db/update/InotifyQueue.hxx b/src/db/update/InotifyQueue.hxx
index 99e2635b1..a9abc2969 100644
--- a/src/db/update/InotifyQueue.hxx
+++ b/src/db/update/InotifyQueue.hxx
@@ -26,11 +26,16 @@
 #include <list>
 #include <string>
 
+class UpdateService;
+
 class InotifyQueue final : private TimeoutMonitor {
+	UpdateService &update;
+
 	std::list<std::string> queue;
 
 public:
-	InotifyQueue(EventLoop &_loop):TimeoutMonitor(_loop) {}
+	InotifyQueue(EventLoop &_loop, UpdateService &_update)
+		:TimeoutMonitor(_loop), update(_update) {}
 
 	void Enqueue(const char *uri_utf8);
 
diff --git a/src/db/update/InotifyUpdate.cxx b/src/db/update/InotifyUpdate.cxx
index 72f22ceb1..3ba92ebf0 100644
--- a/src/db/update/InotifyUpdate.cxx
+++ b/src/db/update/InotifyUpdate.cxx
@@ -285,7 +285,7 @@ mpd_inotify_callback(int wd, unsigned mask,
 }
 
 void
-mpd_inotify_init(EventLoop &loop, unsigned max_depth)
+mpd_inotify_init(EventLoop &loop, UpdateService &update, unsigned max_depth)
 {
 	LogDebug(inotify_domain, "initializing inotify");
 
@@ -320,7 +320,7 @@ mpd_inotify_init(EventLoop &loop, unsigned max_depth)
 
 	recursive_watch_subdirectories(inotify_root, path, 0);
 
-	inotify_queue = new InotifyQueue(loop);
+	inotify_queue = new InotifyQueue(loop, update);
 
 	LogDebug(inotify_domain, "watching music directory");
 }
diff --git a/src/db/update/InotifyUpdate.hxx b/src/db/update/InotifyUpdate.hxx
index 7cf486e5a..0260a4ff5 100644
--- a/src/db/update/InotifyUpdate.hxx
+++ b/src/db/update/InotifyUpdate.hxx
@@ -24,11 +24,12 @@
 #include "Compiler.h"
 
 class EventLoop;
+class UpdateService;
 
 #ifdef HAVE_INOTIFY_INIT
 
 void
-mpd_inotify_init(EventLoop &loop, unsigned max_depth);
+mpd_inotify_init(EventLoop &loop, UpdateService &update, unsigned max_depth);
 
 void
 mpd_inotify_finish(void);
@@ -36,7 +37,9 @@ mpd_inotify_finish(void);
 #else /* !HAVE_INOTIFY_INIT */
 
 static inline void
-mpd_inotify_init(gcc_unused EventLoop &loop, gcc_unused unsigned max_depth)
+mpd_inotify_init(gcc_unused EventLoop &loop,
+		 gcc_unused UpdateService &update,
+		 gcc_unused unsigned max_depth)
 {
 }
 
diff --git a/src/db/update/UpdateQueue.cxx b/src/db/update/Queue.cxx
index a6002f854..4bb0ae725 100644
--- a/src/db/update/UpdateQueue.cxx
+++ b/src/db/update/Queue.cxx
@@ -18,17 +18,10 @@
  */
 
 #include "config.h"
-#include "UpdateQueue.hxx"
-
-#include <queue>
-#include <list>
-
-static constexpr unsigned MAX_UPDATE_QUEUE_SIZE = 32;
-
-static std::queue<UpdateQueueItem, std::list<UpdateQueueItem>> update_queue;
+#include "Queue.hxx"
 
 bool
-update_queue_push(const char *path, bool discard, unsigned id)
+UpdateQueue::Push(const char *path, bool discard, unsigned id)
 {
 	if (update_queue.size() >= MAX_UPDATE_QUEUE_SIZE)
 		return false;
@@ -38,7 +31,7 @@ update_queue_push(const char *path, bool discard, unsigned id)
 }
 
 UpdateQueueItem
-update_queue_shift()
+UpdateQueue::Pop()
 {
 	if (update_queue.empty())
 		return UpdateQueueItem();
diff --git a/src/db/update/UpdateQueue.hxx b/src/db/update/Queue.hxx
index e4228f5ed..a5b2aa9ac 100644
--- a/src/db/update/UpdateQueue.hxx
+++ b/src/db/update/Queue.hxx
@@ -23,6 +23,8 @@
 #include "check.h"
 
 #include <string>
+#include <queue>
+#include <list>
 
 struct UpdateQueueItem {
 	std::string path_utf8;
@@ -39,10 +41,15 @@ struct UpdateQueueItem {
 	}
 };
 
-bool
-update_queue_push(const char *path, bool discard, unsigned id);
+class UpdateQueue {
+	static constexpr unsigned MAX_UPDATE_QUEUE_SIZE = 32;
 
-UpdateQueueItem
-update_queue_shift();
+	std::queue<UpdateQueueItem, std::list<UpdateQueueItem>> update_queue;
+
+public:
+	bool Push(const char *path, bool discard, unsigned id);
+
+	UpdateQueueItem Pop();
+};
 
 #endif
diff --git a/src/db/update/UpdateRemove.cxx b/src/db/update/Remove.cxx
index c57758aef..e2c172a4b 100644
--- a/src/db/update/UpdateRemove.cxx
+++ b/src/db/update/Remove.cxx
@@ -18,7 +18,7 @@
  */
 
 #include "config.h" /* must be first for large file support */
-#include "UpdateRemove.hxx"
+#include "Remove.hxx"
 #include "UpdateDomain.hxx"
 #include "GlobalEvents.hxx"
 #include "thread/Mutex.hxx"
@@ -36,17 +36,12 @@
 
 #include <assert.h>
 
-static const Song *removed_song;
-
-static Mutex remove_mutex;
-static Cond remove_cond;
-
 /**
  * Safely remove a song from the database.  This must be done in the
  * main task, to be sure that there is no pointer left to it.
  */
-static void
-song_remove_event(void)
+void
+UpdateRemoveService::RunDeferred()
 {
 	assert(removed_song != nullptr);
 
@@ -74,19 +69,13 @@ song_remove_event(void)
 }
 
 void
-update_remove_global_init(void)
-{
-	GlobalEvents::Register(GlobalEvents::DELETE, song_remove_event);
-}
-
-void
-update_remove_song(const Song *song)
+UpdateRemoveService::Remove(const Song *song)
 {
 	assert(removed_song == nullptr);
 
 	removed_song = song;
 
-	GlobalEvents::Emit(GlobalEvents::DELETE);
+	DeferredMonitor::Schedule();
 
 	remove_mutex.lock();
 
diff --git a/src/db/update/UpdateRemove.hxx b/src/db/update/Remove.hxx
index d54e3aa80..1970c0a07 100644
--- a/src/db/update/UpdateRemove.hxx
+++ b/src/db/update/Remove.hxx
@@ -21,18 +21,37 @@
 #define MPD_UPDATE_REMOVE_HXX
 
 #include "check.h"
+#include "event/DeferredMonitor.hxx"
+#include "thread/Mutex.hxx"
+#include "thread/Cond.hxx"
 
 struct Song;
 
-void
-update_remove_global_init(void);
-
 /**
- * Sends a signal to the main thread which will in turn remove the
- * song: from the sticker database and from the playlist.  This
- * serialized access is implemented to avoid excessive locking.
+ * This class handles #Song removal.  It defers the action to the main
+ * thread to ensure that all references to the #Song are gone.
  */
-void
-update_remove_song(const Song *song);
+class UpdateRemoveService final : DeferredMonitor {
+	Mutex remove_mutex;
+	Cond remove_cond;
+
+	const Song *removed_song;
+
+public:
+	UpdateRemoveService(EventLoop &_loop)
+		:DeferredMonitor(_loop) {}
+
+	/**
+	 * Sends a signal to the main thread which will in turn remove
+	 * the song: from the sticker database and from the playlist.
+	 * This serialized access is implemented to avoid excessive
+	 * locking.
+	 */
+	void Remove(const Song *song);
+
+private:
+	/* virtual methods from class DeferredMonitor */
+	virtual void RunDeferred() override;
+};
 
 #endif
diff --git a/src/db/update/UpdateInternal.hxx b/src/db/update/Service.cxx
index 2e373bd06..cc2a86968 100644
--- a/src/db/update/UpdateInternal.hxx
+++ b/src/db/update/Service.cxx
@@ -17,12 +17,5 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#ifndef MPD_UPDATE_INTERNAL_H
-#define MPD_UPDATE_INTERNAL_H
-
-#include "check.h"
-
-extern bool walk_discard;
-extern bool modified;
-
-#endif
+#include "config.h"
+#include "Service.hxx"
diff --git a/src/db/update/Service.hxx b/src/db/update/Service.hxx
new file mode 100644
index 000000000..3ea4baea1
--- /dev/null
+++ b/src/db/update/Service.hxx
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_UPDATE_SERVICE_HXX
+#define MPD_UPDATE_SERVICE_HXX
+
+#include "check.h"
+#include "Queue.hxx"
+#include "Walk.hxx"
+#include "event/DeferredMonitor.hxx"
+#include "thread/Thread.hxx"
+
+/**
+ * This class manages the update queue and runs the update thread.
+ */
+class UpdateService final : DeferredMonitor {
+	enum Progress {
+		UPDATE_PROGRESS_IDLE = 0,
+		UPDATE_PROGRESS_RUNNING = 1,
+		UPDATE_PROGRESS_DONE = 2
+	};
+
+	Progress progress;
+
+	bool modified;
+
+	Thread update_thread;
+
+	static const unsigned update_task_id_max = 1 << 15;
+
+	unsigned update_task_id;
+
+	UpdateQueue queue;
+
+	UpdateQueueItem next;
+
+	UpdateWalk walk;
+
+public:
+	UpdateService(EventLoop &_loop);
+
+	/**
+	 * Returns a non-zero job id when we are currently updating
+	 * the database.
+	 */
+	unsigned GetId() const {
+		return next.id;
+	}
+
+	/**
+	 * Add this path to the database update queue.
+	 *
+	 * @param path a path to update; if an empty string,
+	 * the whole music directory is updated
+	 * @return the job id, or 0 on error
+	 */
+	gcc_nonnull_all
+	unsigned Enqueue(const char *path, bool discard);
+
+private:
+	/* virtual methods from class DeferredMonitor */
+	virtual void RunDeferred() override;
+
+	/* the update thread */
+	void Task();
+	static void Task(void *ctx);
+
+	void StartThread(UpdateQueueItem &&i);
+
+	unsigned GenerateId();
+};
+
+#endif
diff --git a/src/db/update/UpdateArchive.hxx b/src/db/update/UpdateArchive.hxx
deleted file mode 100644
index 1fc9af349..000000000
--- a/src/db/update/UpdateArchive.hxx
+++ /dev/null
@@ -1,50 +0,0 @@
-/*
- * Copyright (C) 2003-2014 The Music Player Daemon Project
- * http://www.musicpd.org
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
-
-#ifndef MPD_UPDATE_ARCHIVE_HXX
-#define MPD_UPDATE_ARCHIVE_HXX
-
-#include "check.h"
-#include "Compiler.h"
-
-#include <sys/stat.h>
-
-struct Directory;
-
-#ifdef ENABLE_ARCHIVE
-
-bool
-update_archive_file(Directory &directory,
-		    const char *name, const char *suffix,
-		    const struct stat *st);
-
-#else
-
-static inline bool
-update_archive_file(gcc_unused Directory &directory,
-		    gcc_unused const char *name,
-		    gcc_unused const char *suffix,
-		    gcc_unused const struct stat *st)
-{
-	return false;
-}
-
-#endif
-
-#endif
diff --git a/src/db/update/UpdateContainer.hxx b/src/db/update/UpdateContainer.hxx
deleted file mode 100644
index 8125f71ee..000000000
--- a/src/db/update/UpdateContainer.hxx
+++ /dev/null
@@ -1,36 +0,0 @@
-/*
- * Copyright (C) 2003-2014 The Music Player Daemon Project
- * http://www.musicpd.org
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
-
-#ifndef MPD_UPDATE_CONTAINER_HXX
-#define MPD_UPDATE_CONTAINER_HXX
-
-#include "check.h"
-
-#include <sys/stat.h>
-
-struct Directory;
-struct DecoderPlugin;
-
-bool
-update_container_file(Directory &directory,
-		      const char *name,
-		      const struct stat *st,
-		      const char *suffix);
-
-#endif
diff --git a/src/db/update/UpdateGlue.cxx b/src/db/update/UpdateGlue.cxx
index d18747ba1..2214bb2f7 100644
--- a/src/db/update/UpdateGlue.cxx
+++ b/src/db/update/UpdateGlue.cxx
@@ -18,15 +18,11 @@
  */
 
 #include "config.h"
-#include "UpdateGlue.hxx"
-#include "UpdateQueue.hxx"
-#include "UpdateWalk.hxx"
-#include "UpdateRemove.hxx"
+#include "Service.hxx"
 #include "UpdateDomain.hxx"
 #include "Mapper.hxx"
 #include "db/DatabaseSimple.hxx"
 #include "Idle.hxx"
-#include "GlobalEvents.hxx"
 #include "util/Error.hxx"
 #include "Log.hxx"
 #include "Main.hxx"
@@ -38,30 +34,8 @@
 
 #include <assert.h>
 
-static enum update_progress {
-	UPDATE_PROGRESS_IDLE = 0,
-	UPDATE_PROGRESS_RUNNING = 1,
-	UPDATE_PROGRESS_DONE = 2
-} progress;
-
-static bool modified;
-
-static Thread update_thread;
-
-static const unsigned update_task_id_max = 1 << 15;
-
-static unsigned update_task_id;
-
-static UpdateQueueItem next;
-
-unsigned
-isUpdatingDB(void)
-{
-	return next.id;
-}
-
-static void
-update_task(gcc_unused void *ctx)
+inline void
+UpdateService::Task()
 {
 	if (!next.path_utf8.empty())
 		FormatDebug(update_domain, "starting: %s",
@@ -71,7 +45,7 @@ update_task(gcc_unused void *ctx)
 
 	SetThreadIdlePriority();
 
-	modified = update_walk(next.path_utf8.c_str(), next.discard);
+	modified = walk.Walk(next.path_utf8.c_str(), next.discard);
 
 	if (modified || !db_exists()) {
 		Error error;
@@ -86,11 +60,18 @@ update_task(gcc_unused void *ctx)
 		LogDebug(update_domain, "finished");
 
 	progress = UPDATE_PROGRESS_DONE;
-	GlobalEvents::Emit(GlobalEvents::UPDATE);
+	DeferredMonitor::Schedule();
 }
 
-static void
-spawn_update_task(UpdateQueueItem &&i)
+void
+UpdateService::Task(void *ctx)
+{
+	UpdateService &service = *(UpdateService *)ctx;
+	return service.Task();
+}
+
+void
+UpdateService::StartThread(UpdateQueueItem &&i)
 {
 	assert(main_thread.IsInside());
 
@@ -100,15 +81,15 @@ spawn_update_task(UpdateQueueItem &&i)
 	next = std::move(i);
 
 	Error error;
-	if (!update_thread.Start(update_task, nullptr, error))
+	if (!update_thread.Start(Task, this, error))
 		FatalError(error);
 
 	FormatDebug(update_domain,
 		    "spawned thread for update job id %i", next.id);
 }
 
-static unsigned
-generate_update_id()
+unsigned
+UpdateService::GenerateId()
 {
 	unsigned id = update_task_id + 1;
 	if (id > update_task_id_max)
@@ -117,7 +98,7 @@ generate_update_id()
 }
 
 unsigned
-update_enqueue(const char *path, bool discard)
+UpdateService::Enqueue(const char *path, bool discard)
 {
 	assert(main_thread.IsInside());
 
@@ -125,16 +106,16 @@ update_enqueue(const char *path, bool discard)
 		return 0;
 
 	if (progress != UPDATE_PROGRESS_IDLE) {
-		const unsigned id = generate_update_id();
-		if (!update_queue_push(path, discard, id))
+		const unsigned id = GenerateId();
+		if (!queue.Push(path, discard, id))
 			return 0;
 
 		update_task_id = id;
 		return id;
 	}
 
-	const unsigned id = update_task_id = generate_update_id();
-	spawn_update_task(UpdateQueueItem(path, discard, id));
+	const unsigned id = update_task_id = GenerateId();
+	StartThread(UpdateQueueItem(path, discard, id));
 
 	idle_add(IDLE_UPDATE);
 
@@ -144,7 +125,8 @@ update_enqueue(const char *path, bool discard)
 /**
  * Called in the main thread after the database update is finished.
  */
-static void update_finished_event(void)
+void
+UpdateService::RunDeferred()
 {
 	assert(progress == UPDATE_PROGRESS_DONE);
 	assert(next.IsDefined());
@@ -158,24 +140,16 @@ static void update_finished_event(void)
 		/* send "idle" events */
 		instance->DatabaseModified();
 
-	auto i = update_queue_shift();
+	auto i = queue.Pop();
 	if (i.IsDefined()) {
 		/* schedule the next path */
-		spawn_update_task(std::move(i));
+		StartThread(std::move(i));
 	} else {
 		progress = UPDATE_PROGRESS_IDLE;
 	}
 }
 
-void update_global_init(void)
-{
-	GlobalEvents::Register(GlobalEvents::UPDATE, update_finished_event);
-
-	update_remove_global_init();
-	update_walk_global_init();
-}
-
-void update_global_finish(void)
+UpdateService::UpdateService(EventLoop &_loop)
+	:DeferredMonitor(_loop), walk(_loop)
 {
-	update_walk_global_finish();
 }
diff --git a/src/db/update/UpdateGlue.hxx b/src/db/update/UpdateGlue.hxx
deleted file mode 100644
index 6e247414e..000000000
--- a/src/db/update/UpdateGlue.hxx
+++ /dev/null
@@ -1,43 +0,0 @@
-/*
- * Copyright (C) 2003-2014 The Music Player Daemon Project
- * http://www.musicpd.org
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
-
-#ifndef MPD_UPDATE_GLUE_HXX
-#define MPD_UPDATE_GLUE_HXX
-
-#include "Compiler.h"
-
-void update_global_init(void);
-
-void update_global_finish(void);
-
-unsigned
-isUpdatingDB(void);
-
-/**
- * Add this path to the database update queue.
- *
- * @param path a path to update; if an empty string,
- * the whole music directory is updated
- * @return the job id, or 0 on error
- */
-gcc_nonnull_all
-unsigned
-update_enqueue(const char *path, bool discard);
-
-#endif
diff --git a/src/db/update/UpdateSong.cxx b/src/db/update/UpdateSong.cxx
index ac2d01cd2..afd609f9a 100644
--- a/src/db/update/UpdateSong.cxx
+++ b/src/db/update/UpdateSong.cxx
@@ -18,11 +18,8 @@
  */
 
 #include "config.h" /* must be first for large file support */
-#include "UpdateSong.hxx"
-#include "UpdateInternal.hxx"
+#include "Service.hxx"
 #include "UpdateIO.hxx"
-#include "UpdateDatabase.hxx"
-#include "UpdateContainer.hxx"
 #include "UpdateDomain.hxx"
 #include "db/DatabaseLock.hxx"
 #include "db/Directory.hxx"
@@ -32,10 +29,10 @@
 
 #include <unistd.h>
 
-static void
-update_song_file2(Directory &directory,
-		  const char *name, const struct stat *st,
-		  const char *suffix)
+inline void
+UpdateWalk::UpdateSongFile2(Directory &directory,
+			    const char *name, const char *suffix,
+			    const struct stat *st)
 {
 	db_lock();
 	Song *song = directory.FindSong(name);
@@ -47,7 +44,7 @@ update_song_file2(Directory &directory,
 			    directory.GetPath(), name);
 		if (song != nullptr) {
 			db_lock();
-			delete_song(directory, song);
+			editor.DeleteSong(directory, song);
 			db_unlock();
 		}
 
@@ -56,10 +53,10 @@ update_song_file2(Directory &directory,
 
 	if (!(song != nullptr && st->st_mtime == song->mtime &&
 	      !walk_discard) &&
-	    update_container_file(directory, name, st, suffix)) {
+	    UpdateContainerFile(directory, name, suffix, st)) {
 		if (song != nullptr) {
 			db_lock();
-			delete_song(directory, song);
+			editor.DeleteSong(directory, song);
 			db_unlock();
 		}
 
@@ -92,7 +89,7 @@ update_song_file2(Directory &directory,
 				    "deleting unrecognized file %s/%s",
 				    directory.GetPath(), name);
 			db_lock();
-			delete_song(directory, song);
+			editor.DeleteSong(directory, song);
 			db_unlock();
 		}
 
@@ -101,13 +98,13 @@ update_song_file2(Directory &directory,
 }
 
 bool
-update_song_file(Directory &directory,
-		 const char *name, const char *suffix,
-		 const struct stat *st)
+UpdateWalk::UpdateSongFile(Directory &directory,
+			   const char *name, const char *suffix,
+			   const struct stat *st)
 {
 	if (!decoder_plugins_supports_suffix(suffix))
 		return false;
 
-	update_song_file2(directory, name, st, suffix);
+	UpdateSongFile2(directory, name, suffix, st);
 	return true;
 }
diff --git a/src/db/update/UpdateSong.hxx b/src/db/update/UpdateSong.hxx
deleted file mode 100644
index 5feb01928..000000000
--- a/src/db/update/UpdateSong.hxx
+++ /dev/null
@@ -1,34 +0,0 @@
-/*
- * Copyright (C) 2003-2014 The Music Player Daemon Project
- * http://www.musicpd.org
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
-
-#ifndef MPD_UPDATE_SONG_HXX
-#define MPD_UPDATE_SONG_HXX
-
-#include "check.h"
-
-#include <sys/stat.h>
-
-struct Directory;
-
-bool
-update_song_file(Directory &directory,
-		 const char *name, const char *suffix,
-		 const struct stat *st);
-
-#endif
diff --git a/src/db/update/UpdateWalk.hxx b/src/db/update/UpdateWalk.hxx
deleted file mode 100644
index e908829e3..000000000
--- a/src/db/update/UpdateWalk.hxx
+++ /dev/null
@@ -1,37 +0,0 @@
-/*
- * Copyright (C) 2003-2014 The Music Player Daemon Project
- * http://www.musicpd.org
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
-
-#ifndef MPD_UPDATE_WALK_HXX
-#define MPD_UPDATE_WALK_HXX
-
-#include "check.h"
-
-void
-update_walk_global_init(void);
-
-void
-update_walk_global_finish(void);
-
-/**
- * Returns true if the database was modified.
- */
-bool
-update_walk(const char *path, bool discard);
-
-#endif
diff --git a/src/db/update/UpdateWalk.cxx b/src/db/update/Walk.cxx
index 95c7e6a81..5a799d8f7 100644
--- a/src/db/update/UpdateWalk.cxx
+++ b/src/db/update/Walk.cxx
@@ -18,11 +18,9 @@
  */
 
 #include "config.h" /* must be first for large file support */
-#include "UpdateWalk.hxx"
+#include "Walk.hxx"
 #include "UpdateIO.hxx"
-#include "UpdateDatabase.hxx"
-#include "UpdateSong.hxx"
-#include "UpdateArchive.hxx"
+#include "Editor.hxx"
 #include "UpdateDomain.hxx"
 #include "db/DatabaseLock.hxx"
 #include "db/DatabaseSimple.hxx"
@@ -49,21 +47,8 @@
 #include <stdlib.h>
 #include <errno.h>
 
-bool walk_discard;
-bool modified;
-
-#ifndef WIN32
-
-static constexpr bool DEFAULT_FOLLOW_INSIDE_SYMLINKS = true;
-static constexpr bool DEFAULT_FOLLOW_OUTSIDE_SYMLINKS = true;
-
-static bool follow_inside_symlinks;
-static bool follow_outside_symlinks;
-
-#endif
-
-void
-update_walk_global_init(void)
+UpdateWalk::UpdateWalk(EventLoop &_loop)
+	:editor(_loop)
 {
 #ifndef WIN32
 	follow_inside_symlinks =
@@ -76,11 +61,6 @@ update_walk_global_init(void)
 #endif
 }
 
-void
-update_walk_global_finish(void)
-{
-}
-
 static void
 directory_set_stat(Directory &dir, const struct stat *st)
 {
@@ -89,9 +69,9 @@ directory_set_stat(Directory &dir, const struct stat *st)
 	dir.have_stat = true;
 }
 
-static void
-remove_excluded_from_directory(Directory &directory,
-			       const ExcludeList &exclude_list)
+inline void
+UpdateWalk::RemoveExcludedFromDirectory(Directory &directory,
+					const ExcludeList &exclude_list)
 {
 	db_lock();
 
@@ -100,7 +80,7 @@ remove_excluded_from_directory(Directory &directory,
 		const auto name_fs = AllocatedPath::FromUTF8(child->GetName());
 
 		if (name_fs.IsNull() || exclude_list.Check(name_fs)) {
-			delete_directory(child);
+			editor.DeleteDirectory(child);
 			modified = true;
 		}
 	}
@@ -111,7 +91,7 @@ remove_excluded_from_directory(Directory &directory,
 
 		const auto name_fs = AllocatedPath::FromUTF8(song->uri);
 		if (name_fs.IsNull() || exclude_list.Check(name_fs)) {
-			delete_song(directory, song);
+			editor.DeleteSong(directory, song);
 			modified = true;
 		}
 	}
@@ -119,8 +99,8 @@ remove_excluded_from_directory(Directory &directory,
 	db_unlock();
 }
 
-static void
-purge_deleted_from_directory(Directory &directory)
+inline void
+UpdateWalk::PurgeDeletedFromDirectory(Directory &directory)
 {
 	Directory *child, *n;
 	directory_for_each_child_safe(child, n, directory) {
@@ -128,7 +108,7 @@ purge_deleted_from_directory(Directory &directory)
 			continue;
 
 		db_lock();
-		delete_directory(child);
+		editor.DeleteDirectory(child);
 		db_unlock();
 
 		modified = true;
@@ -139,7 +119,7 @@ purge_deleted_from_directory(Directory &directory)
 		const auto path = map_song_fs(*song);
 		if (path.IsNull() || !FileExists(path)) {
 			db_lock();
-			delete_song(directory, song);
+			editor.DeleteSong(directory, song);
 			db_unlock();
 
 			modified = true;
@@ -195,10 +175,10 @@ find_inode_ancestor(Directory *parent, ino_t inode, dev_t device)
 	return 0;
 }
 
-static bool
-update_playlist_file2(Directory &directory,
-		      const char *name, const char *suffix,
-		      const struct stat *st)
+inline bool
+UpdateWalk::UpdatePlaylistFile(Directory &directory,
+			       const char *name, const char *suffix,
+			       const struct stat *st)
 {
 	if (!playlist_suffix_supported(suffix))
 		return false;
@@ -212,30 +192,27 @@ update_playlist_file2(Directory &directory,
 	return true;
 }
 
-static bool
-update_regular_file(Directory &directory,
-		    const char *name, const struct stat *st)
+inline bool
+UpdateWalk::UpdateRegularFile(Directory &directory,
+			      const char *name, const struct stat *st)
 {
 	const char *suffix = uri_get_suffix(name);
 	if (suffix == nullptr)
 		return false;
 
-	return update_song_file(directory, name, suffix, st) ||
-		update_archive_file(directory, name, suffix, st) ||
-		update_playlist_file2(directory, name, suffix, st);
+	return UpdateSongFile(directory, name, suffix, st) ||
+		UpdateArchiveFile(directory, name, suffix, st) ||
+		UpdatePlaylistFile(directory, name, suffix, st);
 }
 
-static bool
-update_directory(Directory &directory, const struct stat *st);
-
-static void
-update_directory_child(Directory &directory,
-		       const char *name, const struct stat *st)
+void
+UpdateWalk::UpdateDirectoryChild(Directory &directory,
+				 const char *name, const struct stat *st)
 {
 	assert(strchr(name, '/') == nullptr);
 
 	if (S_ISREG(st->st_mode)) {
-		update_regular_file(directory, name, st);
+		UpdateRegularFile(directory, name, st);
 	} else if (S_ISDIR(st->st_mode)) {
 		if (find_inode_ancestor(&directory, st->st_ino, st->st_dev))
 			return;
@@ -246,9 +223,9 @@ update_directory_child(Directory &directory,
 
 		assert(&directory == subdir->parent);
 
-		if (!update_directory(*subdir, st)) {
+		if (!UpdateDirectory(*subdir, st)) {
 			db_lock();
-			delete_directory(subdir);
+			editor.DeleteDirectory(subdir);
 			db_unlock();
 		}
 	} else {
@@ -268,8 +245,9 @@ static bool skip_path(Path path_fs)
 }
 
 gcc_pure
-static bool
-skip_symlink(const Directory *directory, const char *utf8_name)
+bool
+UpdateWalk::SkipSymlink(const Directory *directory,
+			const char *utf8_name) const
 {
 #ifndef WIN32
 	const auto path_fs = map_directory_child_fs(*directory, utf8_name);
@@ -333,8 +311,8 @@ skip_symlink(const Directory *directory, const char *utf8_name)
 #endif
 }
 
-static bool
-update_directory(Directory &directory, const struct stat *st)
+bool
+UpdateWalk::UpdateDirectory(Directory &directory, const struct stat *st)
 {
 	assert(S_ISDIR(st->st_mode));
 
@@ -358,9 +336,9 @@ update_directory(Directory &directory, const struct stat *st)
 	exclude_list.LoadFile(AllocatedPath::Build(path_fs, ".mpdignore"));
 
 	if (!exclude_list.IsEmpty())
-		remove_excluded_from_directory(directory, exclude_list);
+		RemoveExcludedFromDirectory(directory, exclude_list);
 
-	purge_deleted_from_directory(directory);
+	PurgeDeletedFromDirectory(directory);
 
 	while (reader.ReadEntry()) {
 		std::string utf8;
@@ -375,15 +353,15 @@ update_directory(Directory &directory, const struct stat *st)
 		if (utf8.empty())
 			continue;
 
-		if (skip_symlink(&directory, utf8.c_str())) {
-			modified |= delete_name_in(directory, utf8.c_str());
+		if (SkipSymlink(&directory, utf8.c_str())) {
+			modified |= editor.DeleteNameIn(directory, utf8.c_str());
 			continue;
 		}
 
 		if (stat_directory_child(directory, utf8.c_str(), &st2) == 0)
-			update_directory_child(directory, utf8.c_str(), &st2);
+			UpdateDirectoryChild(directory, utf8.c_str(), &st2);
 		else
-			modified |= delete_name_in(directory, utf8.c_str());
+			modified |= editor.DeleteNameIn(directory, utf8.c_str());
 	}
 
 	directory.mtime = st->st_mtime;
@@ -391,8 +369,8 @@ update_directory(Directory &directory, const struct stat *st)
 	return true;
 }
 
-static Directory *
-directory_make_child_checked(Directory &parent, const char *name_utf8)
+inline Directory *
+UpdateWalk::DirectoryMakeChildChecked(Directory &parent, const char *name_utf8)
 {
 	db_lock();
 	Directory *directory = parent.FindChild(name_utf8);
@@ -406,7 +384,7 @@ directory_make_child_checked(Directory &parent, const char *name_utf8)
 	    find_inode_ancestor(&parent, st.st_ino, st.st_dev))
 		return nullptr;
 
-	if (skip_symlink(&parent, name_utf8))
+	if (SkipSymlink(&parent, name_utf8))
 		return nullptr;
 
 	/* if we're adding directory paths, make sure to delete filenames
@@ -414,7 +392,7 @@ directory_make_child_checked(Directory &parent, const char *name_utf8)
 	db_lock();
 	Song *conflicting = parent.FindSong(name_utf8);
 	if (conflicting)
-		delete_song(parent, conflicting);
+		editor.DeleteSong(parent, conflicting);
 
 	directory = parent.CreateChild(name_utf8);
 	db_unlock();
@@ -423,8 +401,8 @@ directory_make_child_checked(Directory &parent, const char *name_utf8)
 	return directory;
 }
 
-static Directory *
-directory_make_uri_parent_checked(const char *uri)
+inline Directory *
+UpdateWalk::DirectoryMakeUriParentChecked(const char *uri)
 {
 	Directory *directory = db_get_root();
 	char *duplicated = xstrdup(uri);
@@ -436,8 +414,8 @@ directory_make_uri_parent_checked(const char *uri)
 		if (*name_utf8 == 0)
 			continue;
 
-		directory = directory_make_child_checked(*directory,
-							 name_utf8);
+		directory = DirectoryMakeChildChecked(*directory,
+						      name_utf8);
 		if (directory == nullptr)
 			break;
 
@@ -448,37 +426,37 @@ directory_make_uri_parent_checked(const char *uri)
 	return directory;
 }
 
-static void
-update_uri(const char *uri)
+inline void
+UpdateWalk::UpdateUri(const char *uri)
 {
-	Directory *parent = directory_make_uri_parent_checked(uri);
+	Directory *parent = DirectoryMakeUriParentChecked(uri);
 	if (parent == nullptr)
 		return;
 
 	const char *name = PathTraitsUTF8::GetBase(uri);
 
 	struct stat st;
-	if (!skip_symlink(parent, name) &&
+	if (!SkipSymlink(parent, name) &&
 	    stat_directory_child(*parent, name, &st) == 0)
-		update_directory_child(*parent, name, &st);
+		UpdateDirectoryChild(*parent, name, &st);
 	else
-		modified |= delete_name_in(*parent, name);
+		modified |= editor.DeleteNameIn(*parent, name);
 }
 
 bool
-update_walk(const char *path, bool discard)
+UpdateWalk::Walk(const char *path, bool discard)
 {
 	walk_discard = discard;
 	modified = false;
 
 	if (path != nullptr && !isRootDirectory(path)) {
-		update_uri(path);
+		UpdateUri(path);
 	} else {
 		Directory *directory = db_get_root();
 		struct stat st;
 
 		if (stat_directory(*directory, &st) == 0)
-			update_directory(*directory, &st);
+			UpdateDirectory(*directory, &st);
 	}
 
 	return modified;
diff --git a/src/db/update/Walk.hxx b/src/db/update/Walk.hxx
new file mode 100644
index 000000000..12274ccdf
--- /dev/null
+++ b/src/db/update/Walk.hxx
@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_UPDATE_WALK_HXX
+#define MPD_UPDATE_WALK_HXX
+
+#include "check.h"
+#include "Editor.hxx"
+
+#include <sys/stat.h>
+
+struct stat;
+struct Directory;
+struct archive_plugin;
+class ExcludeList;
+
+class UpdateWalk final {
+#ifdef ENABLE_ARCHIVE
+	friend class UpdateArchiveVisitor;
+#endif
+
+#ifndef WIN32
+	static constexpr bool DEFAULT_FOLLOW_INSIDE_SYMLINKS = true;
+	static constexpr bool DEFAULT_FOLLOW_OUTSIDE_SYMLINKS = true;
+
+	bool follow_inside_symlinks;
+	bool follow_outside_symlinks;
+#endif
+
+	bool walk_discard;
+	bool modified;
+
+	DatabaseEditor editor;
+
+public:
+	UpdateWalk(EventLoop &_loop);
+
+	/**
+	 * Returns true if the database was modified.
+	 */
+	bool Walk(const char *path, bool discard);
+
+private:
+	gcc_pure
+	bool SkipSymlink(const Directory *directory,
+			 const char *utf8_name) const;
+
+	void RemoveExcludedFromDirectory(Directory &directory,
+					 const ExcludeList &exclude_list);
+
+	void PurgeDeletedFromDirectory(Directory &directory);
+
+	void UpdateSongFile2(Directory &directory,
+			     const char *name, const char *suffix,
+			     const struct stat *st);
+
+	bool UpdateSongFile(Directory &directory,
+			    const char *name, const char *suffix,
+			    const struct stat *st);
+
+	bool UpdateContainerFile(Directory &directory,
+				 const char *name, const char *suffix,
+				 const struct stat *st);
+
+
+#ifdef ENABLE_ARCHIVE
+	void UpdateArchiveTree(Directory &parent, const char *name);
+
+	bool UpdateArchiveFile(Directory &directory,
+			       const char *name, const char *suffix,
+			       const struct stat *st);
+
+	void UpdateArchiveFile(Directory &directory, const char *name,
+			       const struct stat *st,
+			       const archive_plugin &plugin);
+
+
+#else
+	bool UpdateArchiveFile(gcc_unused Directory &directory,
+			       gcc_unused const char *name,
+			       gcc_unused const char *suffix,
+			       gcc_unused const struct stat *st) {
+		return false;
+	}
+#endif
+
+	bool UpdatePlaylistFile(Directory &directory,
+				const char *name, const char *suffix,
+				const struct stat *st);
+
+	bool UpdateRegularFile(Directory &directory,
+			       const char *name, const struct stat *st);
+
+	void UpdateDirectoryChild(Directory &directory,
+				  const char *name, const struct stat *st);
+
+	bool UpdateDirectory(Directory &directory, const struct stat *st);
+
+	/**
+	 * Create the specified directory object if it does not exist
+	 * already or if the #stat object indicates that it has been
+	 * modified since the last update.  Returns nullptr when it
+	 * exists already and is unmodified.
+	 *
+	 * The caller must lock the database.
+	 */
+	Directory *MakeDirectoryIfModified(Directory &parent, const char *name,
+					   const struct stat *st);
+
+	Directory *DirectoryMakeChildChecked(Directory &parent,
+					     const char *name_utf8);
+
+	Directory *DirectoryMakeUriParentChecked(const char *uri);
+
+	void UpdateUri(const char *uri);
+};
+
+#endif