Optimize async functionality:

Rewrite using the new `push_into_stack()`/`from_stack()` methods.
Also store thread state (pointer) in `Thread` struct to avoid getting it every time.
Async userdata methods still need to have arguments stored in ref thread as stack is empty on every poll().

1 files changed, 5 insertions, 0 deletions

diff --git a/src/util/mod.rs b/src/util/mod.rs
index d52119f..1351fbf 100644
--- a/src/util/mod.rs
+++ b/src/util/mod.rs
@@ -63,6 +63,11 @@ impl StackGuard {
             top: ffi::lua_gettop(state),
         }
     }
+
+    // Same as `new()`, but allows specifying the expected stack size at the end of the scope.
+    pub const fn with_top(state: *mut ffi::lua_State, top: c_int) -> StackGuard {
+        StackGuard { state, top }
+    }
 }
 
 impl Drop for StackGuard {