[LAD] [Jackit-devel] Abstraction for JACK control API

[Stéphane Letz]

Le 25 janv. 08 à 23:05, Nedko Arnaudov a écrit :

> After some discussion on IRC with Stéphane Letz, I created abstract
> description of the API that is needed to implement current jackdbus
> functionality (i.e. without the coming patchbay and transport control
> interfaces). I've decided to describe it in C++ just because it will  
> be
> more clear to general public than plain C OO abstraction, or UML
> diagram. jackdbus code itself is in plain C. Hope is that such
> abstraction will help to have same D-Bus interface implemented (and  
> much
> of related code - shared) for both jackd and jackdmp.
>
> // -*- Mode: C++ ; c-basic-offset: 2 -*-
> ///////////////////////////////////////////////////////////////////////////////
> //
> // DESCRIPTION:
> //  Abstraction of the API needed to implement jackdbus
> //
> ///////////////////////////////////////////////////////////////////////////////
>
> #ifndef JACKSERVER_H__775F79BA_DDE0_4FEA_AC4B_7BE05638499C__INCLUDED
> #define JACKSERVER_H__775F79BA_DDE0_4FEA_AC4B_7BE05638499C__INCLUDED
>
> /** Parameter types, intentionally similar to  
> jack_driver_param_type_t */
> typedef enum
> {
>  JackParamInt = 1,
>  JackParamUInt,
>  JackParamChar,
>  JackParamString,
>  JackParamBool,
> } jack_param_type_t;
>
> class ImmutableString;
> class ImmutableVariant;
> template<class T> class ImmutableSet;
>
> class JackConfigurationParameter
> {
> public:
>  ImmutableString& GetName() const;
>  ImmutableString& GetShortDescription() const;
>  ImmutableString& GetLongDescription() const;
>  jack_param_type_t GetType() const;
>  ImmutableVariant& GetValue() const;
>  void SetValue(ImmutableVariant& value);
> };
>
> class JackConfigurationDriverParameter: public  
> JackConfigurationParameter
> {
> public:
>  bool IsSet() const;
>  ImmutableVariant GetDefault() const;
> };
>
> class JackConfigurableObject
> {
> public:
>  virtual ImmutableSet<JackConfigurationParameter>& GetParameters()  
> const = 0;
>
>  // helpers
>  JackConfigurationParameter& FindParameter(ImmutableString&  
> parameter_name);
> };
>
> class JackDriver: public JackConfigurableObject
> {
> };
>
> class JackEngine: public JackConfigurableObject
> {
> };
>
> class JackServerInterface: public JackEngine
> {
> public:
>  ImmutableSet<JackDriver> GetAvailableDrivers();
>
>  void StartServer(JackDriver& driver);
>  // next ones are called only on started server
>  void StopServer();
>  double GetLoad() const;       // In percent
>  unsigned int GetSampleRate() const; // in Hz
>  double GetLatency() const;    // in milliseconds
>  bool IsRealtime() const;      // whether engine is running
>  unsigned int GetXruns() const;
>  void ResetXruns();            // reset value being returned by  
> GetXruns() to 0
> };
>
> #endif // #ifndef  
> JACKSERVER_H__775F79BA_DDE0_4FEA_AC4B_7BE05638499C__INCLUDED
>

Could JackEngine here be renamed "JackServer"? I think It would  
correspond more to what "engine" and "server" are internally. Then why  
not translate that in a pure C API, something like:

typedef void* jack_server;
typedef void* jack_driver;

int jack_start_server(jack_server* server);
int jack_stop_server(jack_server* server);

double  jack_get_load(jack_server* server);
unsigned int  jack_get_sample_rate(jack_server* server);
double  jack_get_latency(jack_server* server);
int jack_is_realtime(jack_server* server);
int jack_get_xruns(jack_server* server);
void  jack_reset_xruns(jack_server* server);

int jack_get_drivers_num(jack_server* server);
jack_driver* jack_get_driver(jack_server* server, int driver_index);

.... and so on....

Stephane