change inheritance so that an AudioBackend IS-A PortEngine

This allows a derived (concrete) implementation to share information (e.g. sample rate, buffer size)
between the audio backend side of things and the port management side of things.

libs/ardour/ardour/audio_backend.h

@@ -29,17 +29,15 @@
 #include <boost/function.hpp>
 
 #include "ardour/types.h"
+#include "ardour/audioengine.h"
+#include "ardour/port_engine.h"
 
 namespace ARDOUR {
 
-class AudioEngine;
+class AudioBackend : public PortEngine {
-class PortEngine;
-class PortManager;
-
-class AudioBackend {
   public:
 
-    AudioBackend (AudioEngine& e) : engine (e){}
+    AudioBackend (AudioEngine& e) : PortEngine (e), engine (e) {}
     virtual ~AudioBackend () {}
 
     /** Return the name of this backend.
@@ -49,17 +47,6 @@ class AudioBackend {
      */
     virtual std::string name() const = 0;
 
-    /** Return a private, type-free pointer to any data
-     * that might be useful to a concrete implementation
-     */
-    virtual void* private_handle() const = 0;
-
-    /** Return true if the underlying mechanism/API is still available
-     * for us to utilize. return false if some or all of the AudioBackend
-     * API can no longer be effectively used.
-     */
-    virtual bool connected() const = 0;
-
     /** Return true if the callback from the underlying mechanism/API
      * (CoreAudio, JACK, ASIO etc.) occurs in a thread subject to realtime
      * constraints. Return false otherwise.
@@ -416,11 +403,22 @@ class AudioBackend {
 struct AudioBackendInfo {
     const char* name;
 
+    /** Using arg1 and arg2, initialize this audiobackend.
+     * 
+     * Returns zero on success, non-zero otherwise.
+     */
     int (*instantiate) (const std::string& arg1, const std::string& arg2);
+
+    /** Release all resources associated with this audiobackend
+     */
     int (*deinstantiate) (void);
 
-    boost::shared_ptr<AudioBackend> (*backend_factory) (AudioEngine&);
+    /** Factory method to create an AudioBackend-derived class.
-    boost::shared_ptr<PortEngine> (*portengine_factory) (PortManager&);
+     * 
+     * Returns a valid shared_ptr to the object if successfull,
+     * or a "null" shared_ptr otherwise.
+     */
+    boost::shared_ptr<AudioBackend> (*factory) (AudioEngine&);
 
     /** Return true if the underlying mechanism/API has been
      * configured and does not need (re)configuration in order

libs/ardour/ardour/audioengine.h

@@ -200,8 +200,6 @@ public:
 
     static AudioEngine*       _instance;
 
-    boost::shared_ptr<AudioBackend> _backend;
-
     Glib::Threads::Mutex      _process_lock;
     Glib::Threads::Cond        session_removed;
     bool                       session_remove_pending;

libs/ardour/ardour/port_engine.h

@@ -79,6 +79,11 @@ class PortEngine {
     PortEngine (PortManager& pm) : manager (pm) {}
     virtual ~PortEngine() {}
     
+    /** Return a private, type-free pointer to any data
+     * that might be useful to a concrete implementation
+     */
+    virtual void* private_handle() const = 0;
+
     /* We use void* here so that the API can be defined for any implementation.
      * 
      * We could theoretically use a template (PortEngine<T>) and define
@@ -89,21 +94,16 @@ class PortEngine {
        
     typedef void* PortHandle;
 
-    /** Return a typeless pointer to an object that may be of interest
-     * that understands the internals of a particular PortEngine
-     * implementation.
-     *
-     * XXX the existence of this method is a band-aid over some design
-     * issues and will it will be removed in the future
-     */
-    virtual void* private_handle() const = 0;
-
-    virtual bool connected() const = 0;
-
     /** Return the name of this process as used by the port manager
      * when naming ports.
      */
     virtual const std::string& my_name() const = 0;
+ 
+    /** Return true if the underlying mechanism/API is still available
+     * for us to utilize. return false if some or all of the AudioBackend
+     * API can no longer be effectively used.
+     */
+    virtual bool available() const = 0;
 
     /** Return the maximum size of a port name 
      */

libs/ardour/ardour/port_manager.h

@@ -34,10 +34,12 @@
 #include "ardour/chan_count.h"
 #include "ardour/midiport_manager.h"
 #include "ardour/port.h"
-#include "ardour/port_engine.h"
 
 namespace ARDOUR {
 
+class PortEngine;
+class AudioBackend;
+
 class PortManager 
 {
   public:
@@ -47,8 +49,7 @@ class PortManager
     PortManager ();
     virtual ~PortManager() {}
 
-    void set_port_engine (PortEngine& pe);
+    PortEngine& port_engine();
-    PortEngine& port_engine() { return *_impl; }
 
     uint32_t port_name_size() const;
     std::string my_name() const;
@@ -134,7 +135,7 @@ class PortManager
     PBD::Signal5<void, boost::weak_ptr<Port>, std::string, boost::weak_ptr<Port>, std::string, bool> PortConnectedOrDisconnected;
 
   protected:
-    boost::shared_ptr<PortEngine> _impl;
+    boost::shared_ptr<AudioBackend> _backend;
     SerializedRCUManager<Ports> ports;
     bool _port_remove_in_progress;
 

libs/ardour/audioengine.cc

@@ -572,8 +572,7 @@ AudioEngine::set_backend (const std::string& name, const std::string& arg1, cons
 			throw failed_constructor ();
 		}
 
-		_backend = b->second->backend_factory (*this);
+		_backend = b->second->factory (*this);
-		_impl = b->second->portengine_factory (*this);
 
 	} catch (exception& e) {
 		error << string_compose (_("Could not create backend for %1: %2"), name, e.what()) << endmsg;
@@ -704,7 +703,7 @@ AudioEngine::connected() const
 		return false;
 	}
 
-	return _backend->connected();
+	return _backend->available();
 }
 
 void

libs/ardour/port.cc

@@ -122,7 +122,7 @@ Port::disconnect_all ()
 bool
 Port::connected_to (std::string const & o) const
 {
-	if (!port_engine.connected()) {
+	if (!port_engine.available()) {
 		return false;
 	}
 
@@ -132,7 +132,7 @@ Port::connected_to (std::string const & o) const
 int
 Port::get_connections (std::vector<std::string> & c) const
 {
-	if (!port_engine.connected()) {
+	if (!port_engine.available()) {
 		c.insert (c.end(), _connections.begin(), _connections.end());
 		return c.size();
 	}

libs/ardour/port_manager.cc

@@ -20,11 +20,12 @@
 #include "pbd/error.h"
 
 #include "ardour/async_midi_port.h"
-#include "ardour/debug.h"
+#include "ardour/audio_backend.h"
-#include "ardour/port_manager.h"
 #include "ardour/audio_port.h"
+#include "ardour/debug.h"
 #include "ardour/midi_port.h"
 #include "ardour/midiport_manager.h"
+#include "ardour/port_manager.h"
 
 #include "i18n.h"
 
@@ -68,13 +69,13 @@ PortManager::remove_all_ports ()
 string
 PortManager::make_port_name_relative (const string& portname) const
 {
-	if (!_impl) {
+	if (!_backend) {
 		return portname;
 	}
 
 	string::size_type len;
 	string::size_type n;
-	string self = _impl->my_name();
+	string self = _backend->my_name();
 
 	len = portname.length();
 
@@ -100,7 +101,7 @@ PortManager::make_port_name_non_relative (const string& portname) const
 		return portname;
 	}
 
-	str  = _impl->my_name();
+	str  = _backend->my_name();
 	str += ':';
 	str += portname;
 
@@ -110,11 +111,11 @@ PortManager::make_port_name_non_relative (const string& portname) const
 bool
 PortManager::port_is_mine (const string& portname) const
 {
-	if (!_impl) {
+	if (!_backend) {
 		return true;
 	}
 
-	string self = _impl->my_name();
+	string self = _backend->my_name();
 
 	if (portname.find_first_of (':') != string::npos) {
 		if (portname.substr (0, self.length ()) != self) {
@@ -128,54 +129,54 @@ PortManager::port_is_mine (const string& portname) const
 bool
 PortManager::port_is_physical (const std::string& portname) const
 {
-	if (!_impl) {
+	if (!_backend) {
 		return false;
 	}
 
-	PortEngine::PortHandle ph = _impl->get_port_by_name (portname);
+	PortEngine::PortHandle ph = _backend->get_port_by_name (portname);
 	if (!ph) {
 		return false;
 	}
 
-	return _impl->port_is_physical (ph);
+	return _backend->port_is_physical (ph);
 }
 
 void
 PortManager::get_physical_outputs (DataType type, std::vector<std::string>& s)
 {
-	if (!_impl) {
+	if (!_backend) {
 		return;
 	}
-	_impl->get_physical_outputs (type, s);
+	_backend->get_physical_outputs (type, s);
 }
  
 void
 PortManager::get_physical_inputs (DataType type, std::vector<std::string>& s)
 {
-	if (!_impl) {
+	if (!_backend) {
 		return;
 	}
 
-	_impl->get_physical_inputs (type, s);
+	_backend->get_physical_inputs (type, s);
 }
  
 ChanCount
 PortManager::n_physical_outputs () const
 {
-	if (!_impl) {
+	if (!_backend) {
 		return ChanCount::ZERO;
 	}
 
-	return _impl->n_physical_outputs ();
+	return _backend->n_physical_outputs ();
 }
  
 ChanCount
 PortManager::n_physical_inputs () const
 {
-	if (!_impl) {
+	if (!_backend) {
 		return ChanCount::ZERO;
 	}
-	return _impl->n_physical_inputs ();
+	return _backend->n_physical_inputs ();
 }
 
 /** @param name Full or short name of port
@@ -185,7 +186,7 @@ PortManager::n_physical_inputs () const
 boost::shared_ptr<Port>
 PortManager::get_port_by_name (const string& portname)
 {
-	if (!_impl) {
+	if (!_backend) {
 		return boost::shared_ptr<Port>();
 	}
 
@@ -204,7 +205,7 @@ PortManager::get_port_by_name (const string& portname)
 		   and cheap), and if so, rename the port (which will alter
 		   the port map as a side effect).
 		*/
-		const std::string check = make_port_name_relative (_impl->get_port_name (x->second->port_handle()));
+		const std::string check = make_port_name_relative (_backend->get_port_name (x->second->port_handle()));
 		if (check != rel) {
 			x->second->set_name (check);
 		}
@@ -243,26 +244,26 @@ PortManager::get_ports (DataType type, PortList& pl)
 int
 PortManager::get_ports (const string& port_name_pattern, DataType type, PortFlags flags, vector<string>& s)
 {
-	if (!_impl) {
+	if (!_backend) {
 		return 0;
 	}
 
-	return _impl->get_ports (port_name_pattern, type, flags, s);
+	return _backend->get_ports (port_name_pattern, type, flags, s);
 }
 
 void
 PortManager::port_registration_failure (const std::string& portname)
 {
-	if (!_impl) {
+	if (!_backend) {
 		return;
 	}
 
-	string full_portname = _impl->my_name();
+	string full_portname = _backend->my_name();
 	full_portname += ':';
 	full_portname += portname;
 
 
-	PortEngine::PortHandle p = _impl->get_port_by_name (full_portname);
+	PortEngine::PortHandle p = _backend->get_port_by_name (full_portname);
 	string reason;
 
 	if (p) {
@@ -356,17 +357,17 @@ PortManager::unregister_port (boost::shared_ptr<Port> port)
 bool
 PortManager::connected (const string& port_name)
 {
-	if (!_impl) {
+	if (!_backend) {
 		return false;
 	}
 
-	PortEngine::PortHandle handle = _impl->get_port_by_name (port_name);
+	PortEngine::PortHandle handle = _backend->get_port_by_name (port_name);
 
 	if (!handle) {
 		return false;
 	}
 
-	return _impl->connected (handle);
+	return _backend->connected (handle);
 }
 
 int
@@ -387,8 +388,8 @@ PortManager::connect (const string& source, const string& destination)
 	} else {
 		/* neither port is known to us ...hand-off to the PortEngine
 		 */
-		if (_impl) {
+		if (_backend) {
-			ret = _impl->connect (s, d);
+			ret = _backend->connect (s, d);
 		} else {
 			ret = -1;
 		}
@@ -423,8 +424,8 @@ PortManager::disconnect (const string& source, const string& destination)
 	} else {
 		/* neither port is known to us ...hand-off to the PortEngine
 		 */
-		if (_impl) {
+		if (_backend) {
-			ret = _impl->disconnect (s, d);
+			ret = _backend->disconnect (s, d);
 		} else {
 			ret = -1;
 		}
@@ -516,59 +517,59 @@ PortManager::registration_callback ()
 bool
 PortManager::can_request_input_monitoring () const
 {
-	if (!_impl) {
+	if (!_backend) {
 		return false;
 	}
 
-	return _impl->can_monitor_input ();
+	return _backend->can_monitor_input ();
 }
  
 void
 PortManager::request_input_monitoring (const string& name, bool yn) const
 {
-	if (!_impl) {
+	if (!_backend) {
 		return;
 	}
 
-	PortEngine::PortHandle ph = _impl->get_port_by_name (name);
+	PortEngine::PortHandle ph = _backend->get_port_by_name (name);
 
 	if (ph) {
-		_impl->request_input_monitoring (ph, yn);
+		_backend->request_input_monitoring (ph, yn);
 	}
 }
  
 void
 PortManager::ensure_input_monitoring (const string& name, bool yn) const
 {
-	if (!_impl) {
+	if (!_backend) {
 		return;
 	}
 
-	PortEngine::PortHandle ph = _impl->get_port_by_name (name);
+	PortEngine::PortHandle ph = _backend->get_port_by_name (name);
 
 	if (ph) {
-		_impl->ensure_input_monitoring (ph, yn);
+		_backend->ensure_input_monitoring (ph, yn);
 	}
 }
 
 uint32_t
 PortManager::port_name_size() const
 {
-	if (!_impl) {
+	if (!_backend) {
 		return 0;
 	}
 	
-	return _impl->port_name_size ();
+	return _backend->port_name_size ();
 }
 
 string
 PortManager::my_name() const
 {
-	if (!_impl) {
+	if (!_backend) {
 		return string();
 	}
 	
-	return _impl->my_name();
+	return _backend->my_name();
 }
 
 int
@@ -657,3 +658,10 @@ PortManager::fade_out (gain_t base_gain, gain_t gain_step, pframes_t nframes)
 		}
 	}
 }
+
+PortEngine&
+PortManager::port_engine()
+{
+	assert (_backend);
+	return *_backend;
+}