mirror of
https://github.com/luau-lang/luau.git
synced 2024-12-13 13:30:40 +00:00
Add lua_getuserdatadtor (#870)
Some userdata objects may need to support manual destruction in addition to automatic GC. For example, files, threads, GPU resources and objects with large external allocations. With Lua, a finalizer can be _generically_ called by invoking the __gc metamethod manually, but this is currently not possible with tagged userdata in Luau because it's not possible to query the destructor associated with an userdata. While it is possible to workaround this by duplicating the destructor table locally on client side (*), it's more convenient to deduplicate the data and get the destructor using the API instead. (*) Note: a separate destructor table for each VM may be required if the VMs use different set of tags. Implementation notes: 1. I first considered adding a typedef for lua_Destructor but unfortunately there are two kinds of destructors, one with and one without the lua_State* argument, so I decided against it at this point. Maybe it should be added later if the destructor API is unified (by dropping the Lua state pointer argument?). 2. For some reason the conformance test produced warning "qualifier applied to function type has no meaning; ignored" on VS2017 (possibly because the test framework does not like function pointers for some reason?). I silenced this by pulling out the test expressions from those CHECKs.
This commit is contained in:
parent
ba67fb275e
commit
7345891f6b
4 changed files with 20 additions and 6 deletions
|
@ -313,7 +313,11 @@ LUA_API uintptr_t lua_encodepointer(lua_State* L, uintptr_t p);
|
||||||
LUA_API double lua_clock();
|
LUA_API double lua_clock();
|
||||||
|
|
||||||
LUA_API void lua_setuserdatatag(lua_State* L, int idx, int tag);
|
LUA_API void lua_setuserdatatag(lua_State* L, int idx, int tag);
|
||||||
LUA_API void lua_setuserdatadtor(lua_State* L, int tag, void (*dtor)(lua_State*, void*));
|
|
||||||
|
typedef void (*lua_Destructor)(lua_State* L, void* userdata);
|
||||||
|
|
||||||
|
LUA_API void lua_setuserdatadtor(lua_State* L, int tag, lua_Destructor dtor);
|
||||||
|
LUA_API lua_Destructor lua_getuserdatadtor(lua_State* L, int tag);
|
||||||
|
|
||||||
LUA_API void lua_clonefunction(lua_State* L, int idx);
|
LUA_API void lua_clonefunction(lua_State* L, int idx);
|
||||||
|
|
||||||
|
|
|
@ -1378,12 +1378,18 @@ void lua_setuserdatatag(lua_State* L, int idx, int tag)
|
||||||
uvalue(o)->tag = uint8_t(tag);
|
uvalue(o)->tag = uint8_t(tag);
|
||||||
}
|
}
|
||||||
|
|
||||||
void lua_setuserdatadtor(lua_State* L, int tag, void (*dtor)(lua_State*, void*))
|
void lua_setuserdatadtor(lua_State* L, int tag, lua_Destructor dtor)
|
||||||
{
|
{
|
||||||
api_check(L, unsigned(tag) < LUA_UTAG_LIMIT);
|
api_check(L, unsigned(tag) < LUA_UTAG_LIMIT);
|
||||||
L->global->udatagc[tag] = dtor;
|
L->global->udatagc[tag] = dtor;
|
||||||
}
|
}
|
||||||
|
|
||||||
|
lua_Destructor lua_getuserdatadtor(lua_State* L, int tag)
|
||||||
|
{
|
||||||
|
api_check(L, unsigned(tag) < LUA_UTAG_LIMIT);
|
||||||
|
return L->global->udatagc[tag];
|
||||||
|
}
|
||||||
|
|
||||||
void lua_clonefunction(lua_State* L, int idx)
|
void lua_clonefunction(lua_State* L, int idx)
|
||||||
{
|
{
|
||||||
luaC_checkGC(L);
|
luaC_checkGC(L);
|
||||||
|
|
|
@ -24,8 +24,7 @@ void luaU_freeudata(lua_State* L, Udata* u, lua_Page* page)
|
||||||
{
|
{
|
||||||
if (u->tag < LUA_UTAG_LIMIT)
|
if (u->tag < LUA_UTAG_LIMIT)
|
||||||
{
|
{
|
||||||
void (*dtor)(lua_State*, void*) = nullptr;
|
lua_Destructor dtor = L->global->udatagc[u->tag];
|
||||||
dtor = L->global->udatagc[u->tag];
|
|
||||||
// TODO: access to L here is highly unsafe since this is called during internal GC traversal
|
// TODO: access to L here is highly unsafe since this is called during internal GC traversal
|
||||||
// certain operations such as lua_getthreaddata are okay, but by and large this risks crashes on improper use
|
// certain operations such as lua_getthreaddata are okay, but by and large this risks crashes on improper use
|
||||||
if (dtor)
|
if (dtor)
|
||||||
|
|
|
@ -1352,9 +1352,14 @@ TEST_CASE("UserdataApi")
|
||||||
lua_State* L = globalState.get();
|
lua_State* L = globalState.get();
|
||||||
|
|
||||||
// setup dtor for tag 42 (created later)
|
// setup dtor for tag 42 (created later)
|
||||||
lua_setuserdatadtor(L, 42, [](lua_State* l, void* data) {
|
auto dtor = [](lua_State* l, void* data) {
|
||||||
dtorhits += *(int*)data;
|
dtorhits += *(int*)data;
|
||||||
});
|
};
|
||||||
|
bool dtorIsNull = lua_getuserdatadtor(L, 42) == nullptr;
|
||||||
|
CHECK(dtorIsNull);
|
||||||
|
lua_setuserdatadtor(L, 42, dtor);
|
||||||
|
bool dtorIsSet = lua_getuserdatadtor(L, 42) == dtor;
|
||||||
|
CHECK(dtorIsSet);
|
||||||
|
|
||||||
// light user data
|
// light user data
|
||||||
int lud;
|
int lud;
|
||||||
|
|
Loading…
Reference in a new issue