db/DatabasePlaylist: pass Database reference around

Reduce global variable usage, move to frontend code.

src/SongLoader.cxx

@@ -92,11 +92,12 @@ SongLoader::LoadSong(const char *uri_utf8, Error &error) const
 		/* URI relative to the music directory */
 
 #ifdef ENABLE_DATABASE
-		return DatabaseDetachSong(uri_utf8, error);
+		if (db != nullptr)
-#else
+			return DatabaseDetachSong(*db, uri_utf8, error);
+#endif
+
 		error.Set(playlist_domain, int(PlaylistResult::NO_SUCH_SONG),
 			  "No database");
 		return nullptr;
-#endif
 	}
 }

src/SongLoader.hxx

@@ -20,9 +20,13 @@
 #ifndef MPD_SONG_LOADER_HXX
 #define MPD_SONG_LOADER_HXX
 
+#include "check.h"
 #include "Compiler.h"
 
+#include <cstddef>
+
 class Client;
+class Database;
 class DetachedSong;
 class Error;
 
@@ -35,11 +39,26 @@ class Error;
 class SongLoader {
 	const Client *const client;
 
+#ifdef ENABLE_DATABASE
+	const Database *const db;
+#endif
+
 public:
+#ifdef ENABLE_DATABASE
+	SongLoader(const Client *_client, const Database *_db=nullptr)
+		:client(_client), db(_db) {}
+	explicit SongLoader(const Client &_client)
+		:client(&_client), db(nullptr) {}
+	explicit SongLoader(const Database *_db)
+		:client(nullptr), db(_db) {}
+	explicit SongLoader(std::nullptr_t)
+		:client(nullptr), db(nullptr) {}
+#else
 	explicit SongLoader(const Client &_client)
 		:client(&_client) {}
 	explicit SongLoader(const Client *_client)
 		:client(_client) {}
+#endif
 
 	gcc_nonnull_all
 	DetachedSong *LoadSong(const char *uri_utf8, Error &error) const;

src/command/DatabaseCommands.cxx

@@ -19,6 +19,7 @@
 
 #include "config.h"
 #include "DatabaseCommands.hxx"
+#include "db/DatabaseGlue.hxx"
 #include "db/DatabaseQueue.hxx"
 #include "db/DatabasePlaylist.hxx"
 #include "db/DatabasePrint.hxx"
@@ -119,7 +120,11 @@ handle_searchaddpl(Client &client, int argc, char *argv[])
 	}
 
 	Error error;
-	return search_add_to_playlist("", playlist, &filter, error)
+	const Database *db = GetDatabase(error);
+	if (db == nullptr)
+		return print_error(client, error);
+
+	return search_add_to_playlist(*db, "", playlist, &filter, error)
 		? CommandResult::OK
 		: print_error(client, error);
 }

src/command/PlaylistCommands.cxx

@@ -19,6 +19,7 @@
 
 #include "config.h"
 #include "PlaylistCommands.hxx"
+#include "db/DatabaseGlue.hxx"
 #include "db/DatabasePlaylist.hxx"
 #include "CommandError.hxx"
 #include "PlaylistPrint.hxx"
@@ -192,7 +193,11 @@ handle_playlistadd(Client &client, gcc_unused int argc, char *argv[])
 		success = spl_append_uri(playlist, loader, uri, error);
 	} else {
 #ifdef ENABLE_DATABASE
-		success = search_add_to_playlist(uri, playlist, nullptr,
+		const Database *db = GetDatabase(error);
+		if (db == nullptr)
+			return print_error(client, error);
+
+		success = search_add_to_playlist(*db, uri, playlist, nullptr,
 						 error);
 #else
 		success = false;

src/db/DatabasePlaylist.cxx

@@ -21,7 +21,6 @@
 #include "DatabasePlaylist.hxx"
 #include "Selection.hxx"
 #include "PlaylistFile.hxx"
-#include "DatabaseGlue.hxx"
 #include "DatabasePlugin.hxx"
 #include "DetachedSong.hxx"
 #include "Mapper.hxx"
@@ -37,17 +36,14 @@ AddSong(const char *playlist_path_utf8,
 }
 
 bool
-search_add_to_playlist(const char *uri, const char *playlist_path_utf8,
+search_add_to_playlist(const Database &db,
+		       const char *uri, const char *playlist_path_utf8,
 		       const SongFilter *filter,
 		       Error &error)
 {
-	const Database *db = GetDatabase(error);
-	if (db == nullptr)
-		return false;
-
 	const DatabaseSelection selection(uri, true, filter);
 
 	using namespace std::placeholders;
 	const auto f = std::bind(AddSong, playlist_path_utf8, _1, _2);
-	return db->Visit(selection, f, error);
+	return db.Visit(selection, f, error);
 }

src/db/DatabasePlaylist.hxx

@@ -22,12 +22,14 @@
 
 #include "Compiler.h"
 
+class Database;
 class SongFilter;
 class Error;
 
-gcc_nonnull(1,2)
+gcc_nonnull(2,3)
 bool
-search_add_to_playlist(const char *uri, const char *path_utf8,
+search_add_to_playlist(const Database &db,
+		       const char *uri, const char *path_utf8,
 		       const SongFilter *filter,
 		       Error &error);
 

src/db/DatabaseSong.cxx

@@ -19,23 +19,18 @@
 
 #include "config.h"
 #include "DatabaseSong.hxx"
-#include "DatabaseGlue.hxx"
 #include "DatabasePlugin.hxx"
 #include "DetachedSong.hxx"
 #include "Mapper.hxx"
 
 DetachedSong *
-DatabaseDetachSong(const char *uri, Error &error)
+DatabaseDetachSong(const Database &db, const char *uri, Error &error)
 {
-	const Database *db = GetDatabase(error);
+	const LightSong *tmp = db.GetSong(uri, error);
-	if (db == nullptr)
-		return nullptr;
-
-	const LightSong *tmp = db->GetSong(uri, error);
 	if (tmp == nullptr)
 		return nullptr;
 
 	DetachedSong *song = new DetachedSong(map_song_detach(*tmp));
-	db->ReturnSong(tmp);
+	db.ReturnSong(tmp);
 	return song;
 }

src/db/DatabaseSong.hxx

@@ -22,6 +22,7 @@
 
 #include "Compiler.h"
 
+class Database;
 class DetachedSong;
 class Error;
 
@@ -33,6 +34,6 @@ class Error;
  */
 gcc_malloc gcc_nonnull_all
 DetachedSong *
-DatabaseDetachSong(const char *uri, Error &error);
+DatabaseDetachSong(const Database &db, const char *uri, Error &error);
 
 #endif

test/test_translate_song.cxx

@@ -117,7 +117,8 @@ static const char *uri1 = "/foo/bar.ogg";
 static const char *uri2 = "foo/bar.ogg";
 
 DetachedSong *
-DatabaseDetachSong(const char *uri, gcc_unused Error &error)
+DatabaseDetachSong(gcc_unused const Database &db, const char *uri,
+		   gcc_unused Error &error)
 {
 	if (strcmp(uri, uri2) == 0)
 		return new DetachedSong(uri, MakeTag2a());
@@ -236,7 +237,7 @@ class TranslateSongTest : public CppUnit::TestFixture {
 	}
 
 	void TestInDatabase() {
-		const SongLoader loader(nullptr);
+		const SongLoader loader(reinterpret_cast<const Database *>(1));
 
 		DetachedSong song1("doesntexist");
 		CPPUNIT_ASSERT(!playlist_check_translate_song(song1, nullptr,
@@ -258,8 +259,9 @@ class TranslateSongTest : public CppUnit::TestFixture {
 	}
 
 	void TestRelative() {
-		const SongLoader secure_loader(nullptr);
+		const Database &db = *reinterpret_cast<const Database *>(1);
-		const SongLoader insecure_loader(reinterpret_cast<const Client *>(1));
+		const SongLoader secure_loader(&db);
+		const SongLoader insecure_loader(reinterpret_cast<const Client *>(1), &db);
 
 		/* map to music_directory */
 		DetachedSong song1("bar.ogg", MakeTag2b());