introduce a render engine configuration facade

src/backend/engine/engine-config.cpp

@@ -0,0 +1,94 @@
+/*
+  EngineConfig  -  access point to any kind of engine configuration parameters
+
+  Copyright (C)         Lumiera.org
+    2013,               Hermann Vosseler <Ichthyostega@web.de>
+
+  This program is free software; you can redistribute it and/or
+  modify it under the terms of the GNU General Public License as
+  published by the Free Software Foundation; either version 2 of
+  the License, or (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+* *****************************************************/
+
+
+#include "backend/engine/engine-config.h"
+#include "lib/time/timevalue.hpp"
+
+#include <boost/rational.hpp>
+
+
+using boost::rational;
+using lib::time::FrameRate;
+
+
+namespace backend{
+namespace engine {
+  
+  namespace { // Hard wired placeholder settings...
+    
+    const rational<uint> ONE_THIRD(1,3);
+    const rational<uint> EIGHTY_PERCENT(8,10);
+    
+    const Duration DEFAULT_ENGINE_LATENCY = EIGHTY_PERCENT * Duration(1, FrameRate::PAL);
+    
+    
+  }//(End)hard wired settings
+  
+  
+  EngineConfig::~EngineConfig() { }
+  
+  
+  /** storage for the Singleton accessor */
+  lib::Singleton<EngineConfig> EngineConfig::get;
+  
+  
+  /** build up a new engine configuration set,
+   *  based on reasonable default values
+   *  
+   * @warning using hard wired values as of 1/2013
+   */
+  EngineConfig::EngineConfig()
+    { }
+  
+  
+  
+  
+  Duration
+  EngineConfig::currentEngineLatency()  const
+  {
+    return DEFAULT_ENGINE_LATENCY;
+  }
+  
+  
+  
+}} // namespace backend::engine
+
+namespace {
+  using backend::engine::EngineConfig;
+  
+  // any C adapter functions go here...
+  
+}
+
+
+
+
+extern "C" { /* ==== implementation C interface for engine configuration ======= */
+  
+gavl_time_t
+lumiera_engine_get_latency  ()
+{
+  return _raw (EngineConfig::get().currentEngineLatency());
+}
+
+}//extern "C"

src/backend/engine/engine-config.h

@@ -0,0 +1,108 @@
+/*
+  ENGINE-CONFIG.h  -  access point to any kind of engine configuration parameters
+
+  Copyright (C)         Lumiera.org
+    2013,               Hermann Vosseler <Ichthyostega@web.de>
+
+  This program is free software; you can redistribute it and/or
+  modify it under the terms of the GNU General Public License as
+  published by the Free Software Foundation; either version 2 of
+  the License, or (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+
+#ifndef BACKEND_ENGINE_ENGINE_CONFIG_H
+#define BACKEND_ENGINE_ENGINE_CONFIG_H
+
+
+
+#include "lib/time.h"
+
+
+#ifdef __cplusplus  /* ============== C++ Interface ================= */
+
+#include "lib/time/timevalue.hpp"
+#include "lib/singleton.hpp"
+
+
+namespace backend{
+namespace engine {
+  
+  using lib::time::Duration;
+  
+  
+  /**
+   * Point of access for any kind of engine configuration, setup and performance tweaks.
+   * Most of these parameters are derived from static system configuration or more focused
+   * configuration settings within the session, but some values will be updated \em live
+   * as a result of engine self monitoring. The user of this interface remains unaware
+   * of this distinction. There is a sub interface (TODO planned 1/2013) for publishing
+   * statistics changes and monitoring information.
+   * 
+   * @note while this interface \em exposes configuration, it is decoupled from
+   *       any concerns regarding session and configuration representation.
+   * 
+   * @todo WIP-WIP as of 1/2013
+   * @todo anything regarding configuration and session storage
+   * @todo find out about the degree of locking required. Right now (1/13), there
+   *       is no locking and all values are hard coded. It is conceivable to implement
+   *       the \em access in a lock-free manner (by loosening any guarantee regarding
+   *       the actual time point when a changed setting becomes visible)
+   */
+  class EngineConfig
+    {
+      EngineConfig();
+     ~EngineConfig();
+      
+      friend class lib::singleton::StaticCreate<EngineConfig>;
+      
+    public:
+      /** access point to the Engine Interface.
+       * @internal this is an facade interface for internal use
+       *           by the player. Client code should use the Player.
+       */
+      static lib::Singleton<EngineConfig> get;
+
+      
+      //////////////////////////////////////////////////////////////////// TODO: find out about required configuration and tweaking values
+      
+      
+      /** reasonable guess of the current engine working delay.
+       *  This is the latency to expect when requesting the calculation
+       *  of a typical and average data frame, based on self observation
+       *  in the recent past
+       * @todo hard wired value as of 1/2013
+       */
+      Duration currentEngineLatency()  const;
+      
+    };
+
+}} // namespace backend::engine
+
+
+
+
+
+extern "C" {
+#endif /* =========================== CL Interface ===================== */
+
+
+/** guess of the current effective engine calculation delay */
+gavl_time_t lumiera_engine_get_latency  ();
+
+
+
+#ifdef __cplusplus
+}
+#endif
+#endif/*BACKEND_ENGINE_ENGINE_CONFIG_H*/

src/backend/engine/scheduler-frontend.hpp

@@ -45,7 +45,7 @@ namespace engine {
     public:
        ///// TODO: find out about the public operations
        // note: the play controller lives in the proc-layer,
-       //       but is a subsystem separate of the sesison.
+       //       but is a subsystem separate of the session.
       
     private:
       

src/proc/engine/engine-service.hpp

@@ -41,6 +41,8 @@
  ** @see EngineInterface_test
  ** @see CalcStream_test
  ** @see proc::play::PlayerService
+ ** @see backend::engine::EngineConfig
+ ** 
  */