Threading Framework & Threaded Collisions (scp-fs2open#6814)

* Dispatch ship weapon collisions and defer handling

* multithread ship weapon collision

* properly spin

* proper memory order

* externalize generic threadpool settings

* Wait for threads to shut down

* Add result pipelining

* cleanup

* incorrect nullopt type

* randomrange todo

* parallelize ship ship collisions

* bogus debug return

* remove warnings

* clang tidy

Author: BMagnu

code/cmdline/cmdline.cpp

@@ -534,6 +534,7 @@ cmdline_parm luadev_arg("-luadev", "Make lua errors non-fatal", AT_NONE);	// Cmd
 cmdline_parm override_arg("-override_data", "Enable override directory", AT_NONE);	// Cmdline_override_data
 cmdline_parm imgui_debug_arg("-imgui_debug", nullptr, AT_NONE);
 cmdline_parm vulkan("-vulkan", nullptr, AT_NONE);
+cmdline_parm multithreading("-threads", nullptr, AT_INT);
 
 char *Cmdline_start_mission = NULL;
 int Cmdline_dis_collisions = 0;
@@ -572,6 +573,7 @@ bool Cmdline_lua_devmode = false;
 bool Cmdline_override_data = false;
 bool Cmdline_show_imgui_debug = false;
 bool Cmdline_vulkan = false;
+int Cmdline_multithreading = 1;
 
 // Other
 cmdline_parm get_flags_arg(GET_FLAGS_STRING, "Output the launcher flags file", AT_STRING);
@@ -2407,6 +2409,14 @@ bool SetCmdlineParams()
 		}
 	}
 
+	if (multithreading.found()) {
+		Cmdline_multithreading = abs(multithreading.get_int());
+		if (Cmdline_multithreading < 1) {
+			Cmdline_multithreading = 1;
+			Warning(LOCATION,"-threads must be an integer greater or equal to 1. Invalid thread count will be disregarded.");
+		}
+	}
+
 	return true; 
 }
 

code/cmdline/cmdline.h

@@ -159,6 +159,7 @@ extern bool Cmdline_lua_devmode;
 extern bool Cmdline_override_data;
 extern bool Cmdline_show_imgui_debug;
 extern bool Cmdline_vulkan;
+extern int Cmdline_multithreading;
 
 enum class WeaponSpewType { NONE = 0, STANDARD, ALL };
 extern WeaponSpewType Cmdline_spew_weapon_stats;

code/model/modelcollide.cpp

@@ -30,25 +30,24 @@
 // checking a collision rather than passing a bunch of parameters around. These are
 // not persistant between calls to model_collide
 
-static mc_info		*Mc;				// The mc_info passed into model_collide
-	
-static polymodel	*Mc_pm;			// The polygon model we're checking
-static int			Mc_submodel;	// The current submodel we're checking
+thread_local static mc_info		*Mc;				// The mc_info passed into model_collide
+
+thread_local static polymodel	*Mc_pm;			// The polygon model we're checking
+thread_local static int			Mc_submodel;	// The current submodel we're checking
 
-static polymodel_instance *Mc_pmi;
+thread_local static polymodel_instance *Mc_pmi;
 
-static matrix		Mc_orient;		// A matrix to rotate a world point into the current
+thread_local static matrix		Mc_orient;		// A matrix to rotate a world point into the current
 											// submodel's frame of reference.
-static vec3d		Mc_base;			// A point used along with Mc_orient.
+thread_local static vec3d		Mc_base;			// A point used along with Mc_orient.
 
-static vec3d		Mc_p0;			// The ray origin rotated into the current submodel's frame of reference
-static vec3d		Mc_p1;			// The ray end rotated into the current submodel's frame of reference
-static float		Mc_mag;			// The length of the ray
-static vec3d		Mc_direction;	// A vector from the ray's origin to its end, in the current submodel's frame of reference
+thread_local static vec3d		Mc_p0;			// The ray origin rotated into the current submodel's frame of reference
+thread_local static vec3d		Mc_p1;			// The ray end rotated into the current submodel's frame of reference
+thread_local static float		Mc_mag;			// The length of the ray
+thread_local static vec3d		Mc_direction;	// A vector from the ray's origin to its end, in the current submodel's frame of reference
 
-static vec3d 		**Mc_point_list = NULL;		// A pointer to the current submodel's vertex list
+thread_local static vec3d 		**Mc_point_list = nullptr;		// A pointer to the current submodel's vertex list
 
-static float		Mc_edge_time;
 
 
 void model_collide_free_point_list()
@@ -1135,7 +1134,6 @@ int model_collide(mc_info *mc_info_obj)
 	Mc_orient = *Mc->orient;
 	Mc_base = *Mc->pos;
 	Mc_mag = vm_vec_dist( Mc->p0, Mc->p1 );
-	Mc_edge_time = FLT_MAX;
 
 	if ( Mc->model_instance_num >= 0 ) {
 		Mc_pmi = model_get_instance(Mc->model_instance_num);