db/Plugin: migrate from class Error to C++ exceptions

src/db/DatabaseGlue.cxx

@@ -39,5 +39,5 @@ DatabaseGlobalInit(EventLoop &loop, DatabaseListener &listener,
 		return nullptr;
 	}
 
-	return plugin->create(loop, listener, block, error);
+	return plugin->create(loop, listener, block);
 }

src/db/DatabasePlugin.hxx

@@ -27,7 +27,6 @@
 #define MPD_DATABASE_PLUGIN_HXX
 
 struct ConfigBlock;
-class Error;
 class EventLoop;
 class DatabaseListener;
 class Database;
@@ -45,10 +44,11 @@ struct DatabasePlugin {
 
 	/**
 	 * Allocates and configures a database.
+	 *
+	 * Throws #std::runtime_error on error.
 	 */
 	Database *(*create)(EventLoop &loop, DatabaseListener &listener,
-			    const ConfigBlock &block,
-			    Error &error);
+			    const ConfigBlock &block);
 
 	constexpr bool RequireStorage() const {
 		return flags & FLAG_REQUIRE_STORAGE;

src/db/plugins/ProxyDatabasePlugin.cxx

@@ -82,9 +82,9 @@ public:
 class ProxyDatabase final : public Database, SocketMonitor, IdleMonitor {
 	DatabaseListener &listener;
 
-	std::string host;
-	unsigned port;
-	bool keepalive;
+	const std::string host;
+	const unsigned port;
+	const bool keepalive;
 
 	struct mpd_connection *connection;
 
@@ -104,14 +104,11 @@ class ProxyDatabase final : public Database, SocketMonitor, IdleMonitor {
 	bool is_idle;
 
 public:
-	ProxyDatabase(EventLoop &_loop, DatabaseListener &_listener)
-		:Database(proxy_db_plugin),
-		 SocketMonitor(_loop), IdleMonitor(_loop),
-		 listener(_listener) {}
+	ProxyDatabase(EventLoop &_loop, DatabaseListener &_listener,
+		      const ConfigBlock &block);
 
 	static Database *Create(EventLoop &loop, DatabaseListener &listener,
-				const ConfigBlock &block,
-				Error &error);
+				const ConfigBlock &block);
 
 	virtual void Open() override;
 	virtual void Close() override;
@@ -141,8 +138,6 @@ public:
 	}
 
 private:
-	bool Configure(const ConfigBlock &block, Error &error);
-
 	void Connect();
 	void CheckConnection();
 	void EnsureConnected();
@@ -338,27 +333,22 @@ SendConstraints(mpd_connection *connection, const DatabaseSelection &selection)
 	return true;
 }
 
-Database *
-ProxyDatabase::Create(EventLoop &loop, DatabaseListener &listener,
-		      const ConfigBlock &block, Error &error)
+ProxyDatabase::ProxyDatabase(EventLoop &_loop, DatabaseListener &_listener,
+			     const ConfigBlock &block)
+	:Database(proxy_db_plugin),
+	 SocketMonitor(_loop), IdleMonitor(_loop),
+	 listener(_listener),
+	 host(block.GetBlockValue("host", "")),
+	 port(block.GetBlockValue("port", 0u)),
+	 keepalive(block.GetBlockValue("keepalive", false))
 {
-	ProxyDatabase *db = new ProxyDatabase(loop, listener);
-	if (!db->Configure(block, error)) {
-		delete db;
-		db = nullptr;
-	}
-
-	return db;
 }
 
-bool
-ProxyDatabase::Configure(const ConfigBlock &block, gcc_unused Error &error)
+Database *
+ProxyDatabase::Create(EventLoop &loop, DatabaseListener &listener,
+		      const ConfigBlock &block)
 {
-	host = block.GetBlockValue("host", "");
-	port = block.GetBlockValue("port", 0u);
-	keepalive = block.GetBlockValue("keepalive", false);
-
-	return true;
+	return new ProxyDatabase(loop, listener, block);
 }
 
 void
@@ -395,6 +385,9 @@ ProxyDatabase::Connect()
 
 #if LIBMPDCLIENT_CHECK_VERSION(2, 10, 0)
 	mpd_connection_set_keepalive(connection, keepalive);
+#else
+	// suppress -Wunused-private-field
+	(void)keepalive;
 #endif
 
 	idle_received = unsigned(-1);

src/db/plugins/simple/SimpleDatabasePlugin.cxx

@@ -84,7 +84,7 @@ inline SimpleDatabase::SimpleDatabase(AllocatedPath &&_path,
 Database *
 SimpleDatabase::Create(gcc_unused EventLoop &loop,
 		       gcc_unused DatabaseListener &listener,
-		       const ConfigBlock &block, Error &)
+		       const ConfigBlock &block)
 {
 	return new SimpleDatabase(block);
 }

src/db/plugins/simple/SimpleDatabasePlugin.hxx

@@ -73,8 +73,7 @@ class SimpleDatabase : public Database {
 
 public:
 	static Database *Create(EventLoop &loop, DatabaseListener &listener,
-				const ConfigBlock &block,
-				Error &error);
+				const ConfigBlock &block);
 
 	gcc_pure
 	Directory &GetRoot() {

src/db/plugins/upnp/UpnpDatabasePlugin.cxx

@@ -77,8 +77,7 @@ public:
 	UpnpDatabase():Database(upnp_db_plugin) {}
 
 	static Database *Create(EventLoop &loop, DatabaseListener &listener,
-				const ConfigBlock &block,
-				Error &error);
+				const ConfigBlock &block);
 
 	virtual void Open() override;
 	virtual void Close() override;
@@ -103,9 +102,6 @@ public:
 		return 0;
 	}
 
-protected:
-	bool Configure(const ConfigBlock &block, Error &error);
-
 private:
 	bool VisitServer(const ContentDirectoryService &server,
 			 const std::list<std::string> &vpath,
@@ -150,21 +146,9 @@ private:
 Database *
 UpnpDatabase::Create(gcc_unused EventLoop &loop,
 		     gcc_unused DatabaseListener &listener,
-		     const ConfigBlock &block, Error &error)
+		     const ConfigBlock &)
 {
-	UpnpDatabase *db = new UpnpDatabase();
-	if (!db->Configure(block, error)) {
-		delete db;
-		return nullptr;
-	}
-
-	return db;
-}
-
-inline bool
-UpnpDatabase::Configure(const ConfigBlock &, Error &)
-{
-	return true;
+	return new UpnpDatabase();
 }
 
 void

test/DumpDatabase.cxx

@@ -127,13 +127,7 @@ try {
 	if (path != nullptr)
 		block.AddBlockParam("path", path->value.c_str(), path->line);
 
-	Database *db = plugin->create(event_loop, database_listener,
-				      block, error);
-
-	if (db == nullptr) {
-		cerr << error.GetMessage() << endl;
-		return EXIT_FAILURE;
-	}
+	Database *db = plugin->create(event_loop, database_listener, block);
 
 	AtScopeExit(db) { delete db; };