Changed luax_pushtype to retain the pushed object itself, but only if the object isn't in the Lua state already.

Previously, calling e.g. love.graphics.getFont() 10,000 times would retain the object 10,000 times (and release it 10,000 times when the Font object was garbage-collected in the Lua state.) Now it will only retain it once and release it once.

src/common/runtime.cpp

@@ -36,8 +36,7 @@
 namespace love
 {
 
-static thread::Mutex *gcmutex = 0;
-void *_gcmutex = 0;
+static thread::Mutex *gcmutex = nullptr;
 
 /**
  * Called when an object is collected. The object is released
@@ -46,25 +45,16 @@ void *_gcmutex = 0;
 static int w__gc(lua_State *L)
 {
 	if (!gcmutex)
-	{
 		gcmutex = thread::newMutex();
-		_gcmutex = (void *) gcmutex;
-	}
 
-	Proxy *p = (Proxy *)lua_touserdata(L, 1);
-	Object *t = (Object *)p->data;
+	Proxy *p = (Proxy *) lua_touserdata(L, 1);
+	Object *object = (Object *) p->data;
 
 	thread::Lock lock(gcmutex);
 
-	int numretains = p->retains;
-	if (numretains >= 0)
-		numretains = std::min(numretains, t->getReferenceCount());
+	if (p->own)
+		object->release();
 
-	for (int i = numretains; i > 0; i--)
-		t->release();
-
-	// Signal that this Proxy is dead.
-	p->retains = -1;
 	return 0;
 }
 
@@ -228,7 +218,7 @@ int luax_register_module(lua_State *L, const WrappedModule &m)
 	luax_insistregistry(L, REGISTRY_MODULES);
 
 	Proxy *p = (Proxy *)lua_newuserdata(L, sizeof(Proxy));
-	p->retains = 1;
+	p->own = true;
 	p->data = m.module;
 	p->flags = m.flags;
 
@@ -394,20 +384,26 @@ int luax_register_searcher(lua_State *L, lua_CFunction f, int pos)
 	return 0;
 }
 
-void luax_rawnewtype(lua_State *L, const char *name, bits flags, love::Object *data, bool own)
+void luax_rawnewtype(lua_State *L, const char *name, bits flags, love::Object *object, bool own)
 {
 	Proxy *u = (Proxy *)lua_newuserdata(L, sizeof(Proxy));
 
-	u->data = (void *) data;
+	if (own)
+		object->retain();
+
+	u->data = (void *) object;
 	u->flags = flags;
-	u->retains = own ? 1 : 0;
+	u->own = own;
 
 	luaL_newmetatable(L, name);
 	lua_setmetatable(L, -2);
 }
 
-void luax_pushtype(lua_State *L, const char *name, bits flags, love::Object *data, bool own)
+void luax_pushtype(lua_State *L, const char *name, bits flags, love::Object *object, bool own)
 {
+	if (object == nullptr)
+		lua_pushnil(L);
+
 	// Fetch the registry table of instantiated types.
 	luax_getregistry(L, REGISTRY_TYPES);
 
@@ -415,11 +411,11 @@ void luax_pushtype(lua_State *L, const char *name, bits flags, love::Object *dat
 	if (!lua_istable(L, -1))
 	{
 		lua_pop(L, 1);
-		return luax_rawnewtype(L, name, flags, data, own);
+		return luax_rawnewtype(L, name, flags, object, own);
 	}
 
 	// Get the value of lovetypes[data] on the stack.
-	lua_pushlightuserdata(L, (void *) data);
+	lua_pushlightuserdata(L, (void *) object);
 	lua_gettable(L, -2);
 
 	// If the Proxy userdata isn't in the instantiated types table yet, add it.
@@ -427,38 +423,18 @@ void luax_pushtype(lua_State *L, const char *name, bits flags, love::Object *dat
 	{
 		lua_pop(L, 1);
 
-		luax_rawnewtype(L, name, flags, data, own);
+		luax_rawnewtype(L, name, flags, object, own);
 
-		lua_pushlightuserdata(L, (void *) data);
+		lua_pushlightuserdata(L, (void *) object);
 		lua_pushvalue(L, -2);
 
 		// lovetypes[data] = Proxy.
 		lua_settable(L, -4);
-
-		// Remove the lovetypes table from the stack.
-		lua_remove(L, -2);
-
-		// The Proxy userdata remains at the top of the stack.
-		return;
 	}
 
 	// Remove the lovetypes table from the stack.
 	lua_remove(L, -2);
 
-	// If the object should be released on GC and we already have a stored
-	// Proxy, we should tell the Proxy that the object was retained again.
-	if (own)
-	{
-		Proxy *p = (Proxy *) lua_touserdata(L, -1);
-
-		thread::EmptyLock lock;
-		if (gcmutex)
-			lock.setLock(gcmutex);
-
-		if (p->retains >= 0)
-			++(p->retains);
-	}
-
 	// Keep the Proxy userdata on the stack.
 }