Fixed objects which store Lua callback functions to avoid attempting to use dead coroutines when deleting the reference to the callback function. Should fix crashes when coroutines are mixed with those objects.

Also improved the performance of World:rayCast and World:queryBoundingBox.

src/modules/love/love.cpp

@@ -238,8 +238,10 @@ static int w_love_isVersionCompatible(lua_State *L)
 	return 1;
 }
 
-int luaopen_love(lua_State * L)
+int luaopen_love(lua_State *L)
 {
+	love::luax_insistpinnedthread(L);
+
 	love::luax_insistglobal(L, "love");
 
 	// Set version information.

src/modules/physics/box2d/Body.cpp

@@ -535,15 +535,7 @@ int Body::setUserData(lua_State *L)
 		body->SetUserData((void *) udata);
 	}
 
-	if (udata->ref != nullptr)
-	{
-		// We set the Reference's lua_State to this one before deleting it, so
-		// it unrefs using the current lua_State's stack. This is necessary
-		// if setUserData is called in a coroutine.
-		udata->ref->setL(L);
-		delete udata->ref;
-	}
-
+	delete udata->ref;
 	udata->ref = new Reference(L);
 
 	return 0;

src/modules/physics/box2d/Body.h

@@ -48,7 +48,7 @@ class Fixture;
 struct bodyudata
 {
 	// Reference to arbitrary data.
-	Reference *ref;
+	Reference *ref = nullptr;
 };
 
 /**

src/modules/physics/box2d/Fixture.cpp

@@ -227,15 +227,7 @@ int Fixture::setUserData(lua_State *L)
 {
 	love::luax_assert_argc(L, 1, 1);
 
-	if (data->ref != nullptr)
-	{
-		// We set the Reference's lua_State to this one before deleting it, so
-		// it unrefs using the current lua_State's stack. This is necessary
-		// if setUserData is called in a coroutine.
-		data->ref->setL(L);
-		delete data->ref;
-	}
-
+	delete data->ref;
 	data->ref = new Reference(L);
 
 	return 0;

src/modules/physics/box2d/Fixture.h

@@ -47,7 +47,7 @@ namespace box2d
 struct fixtureudata
 {
 	// Reference to arbitrary data.
-	Reference *ref;
+	Reference *ref = nullptr;
 };
 
 /**

src/modules/physics/box2d/Joint.cpp

@@ -193,15 +193,7 @@ int Joint::setUserData(lua_State *L)
 {
 	love::luax_assert_argc(L, 1, 1);
 
-	if (udata->ref != nullptr)
-	{
-		// We set the Reference's lua_State to this one before deleting it, so
-		// it unrefs using the current lua_State's stack. This is necessary
-		// if setUserData is called in a coroutine.
-		udata->ref->setL(L);
-		delete udata->ref;
-	}
-
+	delete udata->ref;
 	udata->ref = new Reference(L);
 
 	return 0;

src/modules/physics/box2d/Joint.h

@@ -46,7 +46,7 @@ class World;
 struct jointudata
 {
     // Reference to arbitrary data.
-    Reference *ref;
+    Reference *ref = nullptr;
 };
 
 /**

src/modules/physics/box2d/World.cpp

@@ -36,6 +36,7 @@ namespace box2d
 
 World::ContactCallback::ContactCallback()
 	: ref(nullptr)
+	, L(nullptr)
 {
 }
 
@@ -48,10 +49,9 @@ World::ContactCallback::~ContactCallback()
 void World::ContactCallback::process(b2Contact *contact, const b2ContactImpulse *impulse)
 {
 	// Process contacts.
-	if (ref != nullptr)
+	if (ref != nullptr && L != nullptr)
 	{
-		lua_State *L = ref->getL();
-		ref->push();
+		ref->push(L);
 
 		// Push first fixture.
 		{
@@ -97,6 +97,7 @@ void World::ContactCallback::process(b2Contact *contact, const b2ContactImpulse
 
 World::ContactFilter::ContactFilter()
 	: ref(nullptr)
+	, L(nullptr)
 {
 }
 
@@ -124,10 +125,9 @@ bool World::ContactFilter::process(Fixture *a, Fixture *b)
 		(filterB[1] & filterA[0]) == 0)
 		return false; // A and B aren't set to collide
 
-	if (ref != nullptr)
+	if (ref != nullptr && L != nullptr)
 	{
-		lua_State *L = ref->getL();
-		ref->push();
+		ref->push(L);
 		luax_pushtype(L, PHYSICS_FIXTURE_ID, a);
 		luax_pushtype(L, PHYSICS_FIXTURE_ID, b);
 		lua_call(L, 2, 1);
@@ -136,50 +136,51 @@ bool World::ContactFilter::process(Fixture *a, Fixture *b)
 	return true;
 }
 
-World::QueryCallback::QueryCallback()
-	: ref(nullptr)
+World::QueryCallback::QueryCallback(lua_State *L, int idx)
+	: L(L)
+	, funcidx(idx)
 {
+	luaL_checktype(L, funcidx, LUA_TFUNCTION);
 }
 
 World::QueryCallback::~QueryCallback()
 {
-	if (ref != nullptr)
-		delete ref;
 }
 
 bool World::QueryCallback::ReportFixture(b2Fixture *fixture)
 {
-	if (ref != nullptr)
+	if (L != nullptr)
 	{
-		lua_State *L = ref->getL();
-		ref->push();
+		lua_pushvalue(L, funcidx);
 		Fixture *f = (Fixture *)Memoizer::find(fixture);
 		if (!f)
 			throw love::Exception("A fixture has escaped Memoizer!");
 		luax_pushtype(L, PHYSICS_FIXTURE_ID, f);
 		lua_call(L, 1, 1);
-		return luax_toboolean(L, -1);
+		bool cont = luax_toboolean(L, -1);
+		lua_pop(L, 1);
+		return cont;
 	}
+
 	return true;
 }
 
-World::RayCastCallback::RayCastCallback()
-	: ref(nullptr)
+World::RayCastCallback::RayCastCallback(lua_State *L, int idx)
+	: L(L)
+	, funcidx(idx)
 {
+	luaL_checktype(L, funcidx, LUA_TFUNCTION);
 }
 
 World::RayCastCallback::~RayCastCallback()
 {
-	if (ref != nullptr)
-		delete ref;
 }
 
 float32 World::RayCastCallback::ReportFixture(b2Fixture *fixture, const b2Vec2 &point, const b2Vec2 &normal, float32 fraction)
 {
-	if (ref != nullptr)
+	if (L != nullptr)
 	{
-		lua_State *L = ref->getL();
-		ref->push();
+		lua_pushvalue(L, funcidx);
 		Fixture *f = (Fixture *)Memoizer::find(fixture);
 		if (!f)
 			throw love::Exception("A fixture has escaped Memoizer!");
@@ -193,8 +194,11 @@ float32 World::RayCastCallback::ReportFixture(b2Fixture *fixture, const b2Vec2 &
 		lua_call(L, 6, 1);
 		if (!lua_isnumber(L, -1))
 			luaL_error(L, "Raycast callback didn't return a number!");
-		return (float32)lua_tonumber(L, -1);
+		float32 fraction = (float32) lua_tonumber(L, -1);
+		lua_pop(L, 1);
+		return fraction;
 	}
+
 	return 0;
 }
 
@@ -345,24 +349,28 @@ int World::setCallbacks(lua_State *L)
 	{
 		lua_pushvalue(L, 1);
 		begin.ref = luax_refif(L, LUA_TFUNCTION);
+		begin.L = L;
 	}
 
 	if (nargs >= 2)
 	{
 		lua_pushvalue(L, 2);
 		end.ref = luax_refif(L, LUA_TFUNCTION);
+		end.L = L;
 	}
 
 	if (nargs >= 3)
 	{
 		lua_pushvalue(L, 3);
 		presolve.ref = luax_refif(L, LUA_TFUNCTION);
+		presolve.L = L;
 	}
 
 	if (nargs >= 4)
 	{
 		lua_pushvalue(L, 4);
 		postsolve.ref = luax_refif(L, LUA_TFUNCTION);
+		postsolve.L = L;
 	}
 
 	return 0;
@@ -377,6 +385,11 @@ int World::getCallbacks(lua_State *L)
 	return 4;
 }
 
+void World::setCallbacksL(lua_State *L)
+{
+	begin.L = end.L = presolve.L = postsolve.L = filter.L = L;
+}
+
 int World::setContactFilter(lua_State *L)
 {
 	if (!lua_isnoneornil(L, 1))
@@ -385,6 +398,7 @@ int World::setContactFilter(lua_State *L)
 	if (filter.ref)
 		delete filter.ref;
 	filter.ref = luax_refif(L, LUA_TFUNCTION);
+	filter.L = L;
 	return 0;
 }
 
@@ -519,8 +533,7 @@ int World::queryBoundingBox(lua_State *L)
 	box.lowerBound = Physics::scaleDown(b2Vec2(lx, ly));
 	box.upperBound = Physics::scaleDown(b2Vec2(ux, uy));
 	luaL_checktype(L, 5, LUA_TFUNCTION);
-	if (query.ref) delete query.ref;
-	query.ref = luax_refif(L, LUA_TFUNCTION);
+	QueryCallback query(L, 5);
 	world->QueryAABB(&query, box);
 	return 0;
 }
@@ -534,9 +547,7 @@ int World::rayCast(lua_State *L)
 	b2Vec2 v1 = Physics::scaleDown(b2Vec2(x1, y1));
 	b2Vec2 v2 = Physics::scaleDown(b2Vec2(x2, y2));
 	luaL_checktype(L, 5, LUA_TFUNCTION);
-	if (raycast.ref)
-		delete raycast.ref;
-	raycast.ref = luax_refif(L, LUA_TFUNCTION);
+	RayCastCallback raycast(L, 5);
 	world->RayCast(&raycast, v1, v2);
 	return 0;
 }

src/modules/physics/box2d/World.h

@@ -70,6 +70,7 @@ public:
 	{
 	public:
 		Reference *ref;
+		lua_State *L;
 		ContactCallback();
 		~ContactCallback();
 		void process(b2Contact *contact, const b2ContactImpulse *impulse = NULL);
@@ -79,6 +80,7 @@ public:
 	{
 	public:
 		Reference *ref;
+		lua_State *L;
 		ContactFilter();
 		~ContactFilter();
 		bool process(Fixture *a, Fixture *b);
@@ -87,19 +89,23 @@ public:
 	class QueryCallback : public b2QueryCallback
 	{
 	public:
-		Reference *ref;
-		QueryCallback();
+		QueryCallback(lua_State *L, int idx);
 		~QueryCallback();
 		virtual bool ReportFixture(b2Fixture *fixture);
+	private:
+		lua_State *L;
+		int funcidx;
 	};
 
 	class RayCastCallback : public b2RayCastCallback
 	{
 	public:
-		Reference *ref;
-		RayCastCallback();
+		RayCastCallback(lua_State *L, int idx);
 		~RayCastCallback();
 		virtual float32 ReportFixture(b2Fixture *fixture, const b2Vec2 &point, const b2Vec2 &normal, float32 fraction);
+	private:
+		lua_State *L;
+		int funcidx;
 	};
 
 	/**
@@ -157,6 +163,13 @@ public:
 	 **/
 	int getCallbacks(lua_State *L);
 
+	/**
+	 * Updates the Lua thread/coroutine used when callbacks are executed in
+	 * the update method. This should be called in the same Lua function which
+	 * calls update().
+	 **/
+	void setCallbacksL(lua_State *L);
+
 	/**
 	 * Sets the ContactFilter callback.
 	 **/
@@ -281,8 +294,6 @@ private:
 	// Contact callbacks.
 	ContactCallback begin, end, presolve, postsolve;
 	ContactFilter filter;
-	QueryCallback query;
-	RayCastCallback	raycast;
 };
 
 } // box2d

src/modules/physics/box2d/wrap_World.cpp

@@ -39,6 +39,8 @@ int w_World_update(lua_State *L)
 {
 	World *t = luax_checkworld(L, 1);
 	float dt = (float)luaL_checknumber(L, 2);
+	// Make sure the world callbacks are using the calling Lua thread.
+	t->setCallbacksL(L);
 	luax_catchexcept(L, [&](){ t->update(dt); });
 	return 0;
 }