Improve headless Ardour somewhat

* Allow to exit cleanly (using access-action)
* Terminate when the backend is halted
* Handle various commandline arguments as advertised
  - print version
  - disable hardware optimization
  - set client-name
  - prevent port-connections
* Use JACK -- previously hardour only worked if
  Ardour was compiled with JACK as *only* backend.
  Other backends are listed before JACK, set_default_backend()
  never picks JACK unless it's the only one.
  Other backends need configuration, or EngineState from config.
  This is currently handled in the GUI's engine-dialog..

headless/load_session.cc

@@ -2,14 +2,20 @@
 #include <cstdlib>
 #include <getopt.h>
 
+#include <glibmm.h>
+
+#include "pbd/convert.h"
 #include "pbd/failed_constructor.h"
 #include "pbd/error.h"
 #include "pbd/debug.h"
 
 #include "ardour/ardour.h"
 #include "ardour/audioengine.h"
+#include "ardour/revision.h"
 #include "ardour/session.h"
 
+#include "control_protocol/control_protocol.h"
+
 #include "misc.h"
 
 using namespace std;
@@ -23,12 +29,16 @@ using namespace PBD;
 
 static const char* localedir = LOCALEDIR;
 
+static string backend_client_name;
+static string backend_name = "JACK";
+static volatile bool run_headless = true;
+
 TestReceiver test_receiver;
 
 /** @param dir Session directory.
  *  @param state Session state file, without .ardour suffix.
  */
-Session *
+static Session *
 load_session (string dir, string state)
 {
 	SessionEvent::create_per_thread_pool ("test", 512);
@@ -40,8 +50,8 @@ load_session (string dir, string state)
 
 	AudioEngine* engine = AudioEngine::create ();
 
-	if (!engine->set_default_backend ()) {
-		std::cerr << "Cannot create Audio/MIDI engine\n";
+	if (!engine->set_backend (backend_name, backend_client_name, "")) {
+		std::cerr << "Cannot set Audio/MIDI engine backend\n";
 		::exit (1);
 	}
 
@@ -55,15 +65,43 @@ load_session (string dir, string state)
 	return session;
 }
 
-string session_name = "";
-string backend_client_name = "ardour";
-string backend_session_uuid;
-bool just_version = false;
-bool use_vst = true;
-bool try_hw_optimization = true;
-bool no_connect_ports = false;
+static void
+access_action (const std::string& action_group, const std::string& action_item)
+{
+	if (action_group == "Common" && action_item == "Quit") {
+		run_headless = false;
+	}
+}
 
-void
+static void
+engine_halted (const char* reason)
+{
+	cerr << "The audio backend has either been shutdown";
+	if (reason && strlen (reason) > 0) {
+		cerr << ": " << reason;
+	} else {
+		cerr << ".";
+	}
+	cerr << endl;
+	run_headless = false;
+}
+
+static void
+print_version ()
+{
+	cout
+		<< PROGRAM_NAME
+		<< VERSIONSTRING
+		<< " (built using "
+		<< ARDOUR::revision
+#ifdef __GNUC__
+		<< " and GCC version " << __VERSION__
+#endif
+		<< ')'
+		<< endl;
+}
+
+static void
 print_help ()
 {
 	cout << "Usage: hardour [OPTIONS]... DIR SNAPSHOT_NAME\n\n"
@@ -103,6 +141,11 @@ int main (int argc, char* argv[])
 	int option_index = 0;
 	int c = 0;
 
+	bool use_vst = true;
+	bool try_hw_optimization = true;
+
+	backend_client_name = PBD::downcase (std::string(PROGRAM_NAME));
+
 	while (1) {
 		c = getopt_long (argc, argv, optstring, longopts, &option_index);
 
@@ -115,7 +158,8 @@ int main (int argc, char* argv[])
 			break;
 
 		case 'v':
-			just_version = true;
+			print_version ();
+			::exit (0);
 			break;
 
 		case 'h':
@@ -146,7 +190,7 @@ int main (int argc, char* argv[])
 			break;
 
 		case 'P':
-			no_connect_ports = true;
+			ARDOUR::Port::set_connecting_blocked (true);
 			break;
 
 		case 'V':
@@ -155,10 +199,6 @@ int main (int argc, char* argv[])
 #endif /* WINDOWS_VST_SUPPORT */
 			break;
 
-		case 'U':
-			backend_session_uuid = optarg;
-                        break;
-
 		default:
 			print_help ();
 			::exit (1);
@@ -170,7 +210,7 @@ int main (int argc, char* argv[])
 		::exit (1);
 	}
 
-	if (!ARDOUR::init (false, true, localedir)) {
+	if (!ARDOUR::init (use_vst, try_hw_optimization, localedir)) {
 		cerr << "Ardour failed to initialize\n" << endl;
 		::exit (1);
 	}
@@ -193,9 +233,15 @@ int main (int argc, char* argv[])
 		exit (EXIT_FAILURE);
 	}
 
+	PBD::ScopedConnectionList con;
+	BasicUI::AccessAction.connect_same_thread (con, boost::bind (&access_action, _1, _2));
+	AudioEngine::instance()->Halted.connect_same_thread (con, boost::bind (&engine_halted, _1));
+
 	s->request_transport_speed (1.0);
 
-	sleep (-1);
+	while (run_headless) {
+		Glib::usleep (500000);
+	}
 
 	AudioEngine::instance()->remove_session ();
 	delete s;