Support for incremental init of subsystems.

Allow subsystem init to be incremental, i.e requiring repeated init calls until a 'done' code is returned. Use this to support incremental init in groups and the manager. (It would also be possible to support it in an individual subsystem).

Note that if you use the existing init() calls, behaviour is unchanged.

simgear/structure/subsystem_mgr.cxx

@@ -56,6 +56,13 @@ SGSubsystem::init ()
 {
 }
 
+SGSubsystem::InitStatus
+SGSubsystem::incrementalInit ()
+{
+  init();
+  return INIT_DONE;
+}
+
 void
 SGSubsystem::postinit ()
 {
@@ -135,13 +142,15 @@ public:
     double elapsed_sec;
     bool collectTimeStats;
     int exceptionCount;
+    int initTime;
 };
 
 
 
 SGSubsystemGroup::SGSubsystemGroup () :
   _fixedUpdateTime(-1.0),
-  _updateTimeRemainder(0.0)
+  _updateTimeRemainder(0.0),
+  _initPosition(-1)
 {
 }
 
@@ -161,6 +170,26 @@ SGSubsystemGroup::init ()
         _members[i]->subsystem->init();
 }
 
+SGSubsystem::InitStatus
+SGSubsystemGroup::incrementalInit()
+{
+  if (_initPosition < 0)
+    _initPosition = 0;
+  
+  if (_initPosition >= _members.size())
+    return INIT_DONE;
+  
+  SGTimeStamp st;
+  st.stamp();
+  InitStatus memberStatus = _members[_initPosition]->subsystem->incrementalInit();
+  _members[_initPosition]->initTime += st.elapsedMSec();
+  
+  if (memberStatus == INIT_DONE)
+    ++_initPosition;
+  
+  return INIT_CONTINUE;
+}
+
 void
 SGSubsystemGroup::postinit ()
 {
@@ -181,6 +210,7 @@ SGSubsystemGroup::shutdown ()
     // reverse order to prevent order dependency problems
     for (unsigned int i = _members.size(); i > 0; i--)
         _members[i-1]->subsystem->shutdown();
+  _initPosition = -1;
 }
 
 void
@@ -333,7 +363,8 @@ SGSubsystemGroup::Member::Member ()
       subsystem(0),
       min_step_sec(0),
       elapsed_sec(0),
-      exceptionCount(0)
+      exceptionCount(0),
+      initTime(0)
 {
 }
 
@@ -380,7 +411,8 @@ SGSubsystemGroup::Member::update (double delta_time_sec)
 ////////////////////////////////////////////////////////////////////////
 
 
-SGSubsystemMgr::SGSubsystemMgr ()
+SGSubsystemMgr::SGSubsystemMgr () :
+  _initPosition(-1)
 {
   for (int i = 0; i < MAX_GROUPS; i++) {
     _groups[i] = new SGSubsystemGroup;
@@ -405,6 +437,22 @@ SGSubsystemMgr::init ()
             _groups[i]->init();
 }
 
+SGSubsystem::InitStatus
+SGSubsystemMgr::incrementalInit()
+{
+  if (_initPosition < 0)
+    _initPosition = 0;
+  
+  if (_initPosition >= MAX_GROUPS)
+    return INIT_DONE;
+  
+  InitStatus memberStatus = _groups[_initPosition]->incrementalInit();  
+  if (memberStatus == INIT_DONE)
+    ++_initPosition;
+  
+  return INIT_CONTINUE;
+}
+
 void
 SGSubsystemMgr::postinit ()
 {
@@ -425,6 +473,8 @@ SGSubsystemMgr::shutdown ()
     // reverse order to prevent order dependency problems
     for (int i = MAX_GROUPS-1; i >= 0; i--)
         _groups[i]->shutdown();
+  
+    _initPosition = -1;
 }
 
 

simgear/structure/subsystem_mgr.hxx

@@ -150,6 +150,13 @@ public:
    */
   virtual void init ();
 
+  typedef enum
+  {
+    INIT_DONE,      ///< subsystem is fully initialised
+    INIT_CONTINUE   ///< init should be called again
+  } InitStatus;
+  
+  virtual InitStatus incrementalInit ();
 
   /**
    * Initialize parts that depend on other subsystems having been initialized.
@@ -289,7 +296,8 @@ public:
     SGSubsystemGroup ();
     virtual ~SGSubsystemGroup ();
 
-    virtual void init ();
+    virtual void init();
+    virtual InitStatus incrementalInit ();
     virtual void postinit ();
     virtual void reinit ();
     virtual void shutdown ();
@@ -322,6 +330,9 @@ private:
     
     double _fixedUpdateTime;
     double _updateTimeRemainder;
+    
+  /// index of the member we are currently init-ing
+    int _initPosition;
 };
 
 
@@ -364,6 +375,7 @@ public:
     virtual ~SGSubsystemMgr ();
 
     virtual void init ();
+    virtual InitStatus incrementalInit ();
     virtual void postinit ();
     virtual void reinit ();
     virtual void shutdown ();
@@ -394,7 +406,8 @@ public:
 
 private:
     SGSubsystemGroup* _groups[MAX_GROUPS];
-
+    int _initPosition;
+  
     typedef std::map<std::string, SGSubsystem*> SubsystemDict;
     SubsystemDict _subsystem_map;
 };