Merge branch 'bench'

Cargo.toml

@@ -22,7 +22,7 @@ default = ["builtin-lua"]
 #   * LUA_NUMBER as double
 #   * LUA_EXTRASPACE is sizeof(void*)
 #   * LUAI_MAXSTACK is 1000000
-builtin-lua = ["gcc"]
+builtin-lua = ["cc"]
 
 [dependencies]
 libc = { version = "0.2" }
@@ -30,7 +30,12 @@ failure = { version = "0.1.1" }
 compiletest_rs = { version = "0.3", optional = true }
 
 [build-dependencies]
-gcc = { version = "0.3.52", optional = true }
+cc = { version = "1.0", optional = true }
 
 [dev-dependencies]
-rustyline = "1.0.0"
+rustyline = "1.0.0"
+criterion = "0.2.0"
+
+[[bench]]
+name = "benchmark"
+harness = false

benches/benchmark.rs

@@ -0,0 +1,187 @@
+#[macro_use]
+extern crate criterion;
+extern crate rlua;
+
+use criterion::Criterion;
+use rlua::prelude::*;
+
+fn create_table(c: &mut Criterion) {
+    c.bench_function("create table", |b| {
+        b.iter_with_setup(
+            || Lua::new(),
+            |lua| -> Lua {
+                lua.create_table().unwrap();
+                lua
+            },
+        );
+    });
+}
+
+fn create_array(c: &mut Criterion) {
+    c.bench_function("create array 10", |b| {
+        b.iter_with_setup(
+            || Lua::new(),
+            |lua| -> Lua {
+                {
+                    let table = lua.create_table().unwrap();
+                    for i in 1..11 {
+                        table.set(i, i).unwrap();
+                    }
+                }
+                lua
+            },
+        );
+    });
+}
+
+fn create_string_table(c: &mut Criterion) {
+    c.bench_function("create string table 10", |b| {
+        b.iter_with_setup(
+            || Lua::new(),
+            |lua| -> Lua {
+                {
+                    let table = lua.create_table().unwrap();
+                    for &s in &["1", "2", "3", "4", "5", "6", "7", "8", "9", "10"] {
+                        let s = lua.create_string(s).unwrap();
+                        table.set(s.clone(), s).unwrap();
+                    }
+                }
+                lua
+            },
+        );
+    });
+}
+
+fn call_add_function(c: &mut Criterion) {
+    c.bench_function("call add function 3 10", |b| {
+        b.iter_with_setup(
+            || {
+                let lua = Lua::new();
+                let f = {
+                    let f: LuaFunction = lua.eval(
+                        r#"
+                            function(a, b, c)
+                                return a + b + c
+                            end
+                        "#,
+                        None,
+                    ).unwrap();
+                    lua.create_registry_value(f).unwrap()
+                };
+                (lua, f)
+            },
+            |(lua, f)| -> Lua {
+                {
+                    let add_function: LuaFunction = lua.registry_value(&f).unwrap();
+                    for i in 0..10 {
+                        let _result: i64 = add_function.call((i, i + 1, i + 2)).unwrap();
+                    }
+                }
+                lua
+            },
+        );
+    });
+}
+
+fn call_add_callback(c: &mut Criterion) {
+    c.bench_function("call callback add 2 10", |b| {
+        b.iter_with_setup(
+            || {
+                let lua = Lua::new();
+                let f = {
+                    let c: LuaFunction = lua.create_function(|_, (a, b, c): (i64, i64, i64)| {
+                        Ok(a + b + c)
+                    }).unwrap();
+                    lua.globals().set("callback", c).unwrap();
+                    let f: LuaFunction = lua.eval(
+                        r#"
+                            function()
+                                for i = 1,10 do
+                                    callback(i, i, i)
+                                end
+                            end
+                        "#,
+                        None,
+                    ).unwrap();
+                    lua.create_registry_value(f).unwrap()
+                };
+                (lua, f)
+            },
+            |(lua, f)| -> Lua {
+                {
+                    let entry_function: LuaFunction = lua.registry_value(&f).unwrap();
+                    entry_function.call::<_, ()>(()).unwrap();
+                }
+                lua
+            },
+        );
+    });
+}
+
+fn call_append_callback(c: &mut Criterion) {
+    c.bench_function("call callback append 10", |b| {
+        b.iter_with_setup(
+            || {
+                let lua = Lua::new();
+                let f = {
+                    let c: LuaFunction =
+                        lua.create_function(|_, (a, b): (LuaString, LuaString)| {
+                            Ok(format!("{}{}", a.to_str()?, b.to_str()?))
+                        }).unwrap();
+                    lua.globals().set("callback", c).unwrap();
+                    let f: LuaFunction = lua.eval(
+                        r#"
+                            function()
+                                for _ = 1,10 do
+                                    callback("a", "b")
+                                end
+                            end
+                        "#,
+                        None,
+                    ).unwrap();
+                    lua.create_registry_value(f).unwrap()
+                };
+                (lua, f)
+            },
+            |(lua, f)| -> Lua {
+                {
+                    let entry_function: LuaFunction = lua.registry_value(&f).unwrap();
+                    entry_function.call::<_, ()>(()).unwrap();
+                }
+                lua
+            },
+        );
+    });
+}
+
+fn create_registry_values(c: &mut Criterion) {
+    c.bench_function("create registry 10", |b| {
+        b.iter_with_setup(
+            || Lua::new(),
+            |lua| -> Lua {
+                for _ in 0..10 {
+                    lua.create_registry_value(lua.pack(true).unwrap()).unwrap();
+                }
+                lua.expire_registry_values();
+                lua
+            },
+        );
+    });
+}
+
+criterion_group! {
+    name = benches;
+    config = Criterion::default()
+        .sample_size(200)
+        .noise_threshold(0.02);
+    targets =
+        create_table,
+        create_array,
+        create_string_table,
+        call_add_function,
+        call_add_callback,
+        call_append_callback,
+        create_registry_values
+}
+
+criterion_main!(benches);

build.rs

@@ -1,5 +1,5 @@
 #[cfg(feature = "builtin-lua")]
-extern crate gcc;
+extern crate cc;
 
 fn main() {
     #[cfg(feature = "builtin-lua")]
@@ -9,7 +9,7 @@ fn main() {
         let target_os = env::var("CARGO_CFG_TARGET_OS");
         let target_family = env::var("CARGO_CFG_TARGET_FAMILY");
 
-        let mut config = gcc::Build::new();
+        let mut config = cc::Build::new();
 
         if target_os == Ok("linux".to_string()) {
             config.define("LUA_USE_LINUX", None);

src/conversion.rs

@@ -2,7 +2,7 @@ use std::collections::{BTreeMap, HashMap};
 use std::hash::{BuildHasher, Hash};
 use std::string::String as StdString;
 
-use error::*;
+use error::{Error, Result};
 use types::{Integer, LightUserData, Number};
 use string::String;
 use table::Table;

src/ffi.rs

@@ -123,6 +123,7 @@ extern "C" {
     pub fn lua_rotate(state: *mut lua_State, index: c_int, n: c_int);
     pub fn lua_copy(state: *mut lua_State, from: c_int, to: c_int);
     pub fn lua_absindex(state: *mut lua_State, index: c_int) -> c_int;
+    pub fn lua_xmove(from: *mut lua_State, to: *mut lua_State, n: c_int);
 
     pub fn lua_isinteger(state: *mut lua_State, index: c_int) -> c_int;
     pub fn lua_isnumber(state: *mut lua_State, index: c_int) -> c_int;

src/function.rs

@@ -2,8 +2,9 @@ use std::ptr;
 use std::os::raw::c_int;
 
 use ffi;
-use error::*;
+use error::{Error, Result};
-use util::*;
+use util::{check_stack, check_stack_err, error_traceback, pop_error, protect_lua_closure,
+           stack_guard};
 use types::LuaRef;
 use value::{FromLuaMulti, MultiValue, ToLuaMulti};
 
@@ -63,16 +64,16 @@ impl<'lua> Function<'lua> {
     pub fn call<A: ToLuaMulti<'lua>, R: FromLuaMulti<'lua>>(&self, args: A) -> Result<R> {
         let lua = self.0.lua;
         unsafe {
-            stack_err_guard(lua.state, || {
+            stack_guard(lua.state, || {
                 let args = args.to_lua_multi(lua)?;
                 let nargs = args.len() as c_int;
                 check_stack_err(lua.state, nargs + 3)?;
 
                 ffi::lua_pushcfunction(lua.state, error_traceback);
                 let stack_start = ffi::lua_gettop(lua.state);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
                 for arg in args {
-                    lua.push_value(lua.state, arg);
+                    lua.push_value(arg);
                 }
                 let ret = ffi::lua_pcall(lua.state, nargs, ffi::LUA_MULTRET, stack_start);
                 if ret != ffi::LUA_OK {
@@ -82,7 +83,7 @@ impl<'lua> Function<'lua> {
                 let mut results = MultiValue::new();
                 check_stack(lua.state, 2);
                 for _ in 0..nresults {
-                    results.push_front(lua.pop_value(lua.state));
+                    results.push_front(lua.pop_value());
                 }
                 ffi::lua_pop(lua.state, 1);
                 R::from_lua_multi(results, lua)
@@ -144,7 +145,7 @@ impl<'lua> Function<'lua> {
 
         let lua = self.0.lua;
         unsafe {
-            stack_err_guard(lua.state, || {
+            stack_guard(lua.state, || {
                 let args = args.to_lua_multi(lua)?;
                 let nargs = args.len() as c_int;
 
@@ -152,18 +153,18 @@ impl<'lua> Function<'lua> {
                     return Err(Error::BindError);
                 }
 
-                check_stack_err(lua.state, nargs + 3)?;
+                check_stack_err(lua.state, nargs + 5)?;
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
                 ffi::lua_pushinteger(lua.state, nargs as ffi::lua_Integer);
                 for arg in args {
-                    lua.push_value(lua.state, arg);
+                    lua.push_value(arg);
                 }
 
-                protect_lua_call(lua.state, nargs + 2, 1, |state| {
+                protect_lua_closure(lua.state, nargs + 2, 1, |state| {
                     ffi::lua_pushcclosure(state, bind_call_impl, nargs + 2);
                 })?;
 
-                Ok(Function(lua.pop_ref(lua.state)))
+                Ok(Function(lua.pop_ref()))
             })
         }
     }

src/multi.rs

@@ -2,9 +2,9 @@ use std::ops::{Deref, DerefMut};
 use std::iter::FromIterator;
 use std::result::Result as StdResult;
 
-use error::*;
+use error::Result;
-use value::*;
+use value::{FromLua, FromLuaMulti, MultiValue, Nil, ToLua, ToLuaMulti};
-use lua::*;
+use lua::Lua;
 
 /// Result is convertible to `MultiValue` following the common Lua idiom of returning the result
 /// on success, or in the case of an error, returning `nil` and an error message.
@@ -13,10 +13,10 @@ impl<'lua, T: ToLua<'lua>, E: ToLua<'lua>> ToLuaMulti<'lua> for StdResult<T, E>
         let mut result = MultiValue::new();
 
         match self {
-            Ok(v) => result.push_back(v.to_lua(lua)?),
+            Ok(v) => result.push_front(v.to_lua(lua)?),
             Err(e) => {
-                result.push_back(Nil);
+                result.push_front(e.to_lua(lua)?);
-                result.push_back(e.to_lua(lua)?);
+                result.push_front(Nil);
             }
         }
 
@@ -27,7 +27,7 @@ impl<'lua, T: ToLua<'lua>, E: ToLua<'lua>> ToLuaMulti<'lua> for StdResult<T, E>
 impl<'lua, T: ToLua<'lua>> ToLuaMulti<'lua> for T {
     fn to_lua_multi(self, lua: &'lua Lua) -> Result<MultiValue<'lua>> {
         let mut v = MultiValue::new();
-        v.push_back(self.to_lua(lua)?);
+        v.push_front(self.to_lua(lua)?);
         Ok(v)
     }
 }

src/string.rs

@@ -71,7 +71,7 @@ impl<'lua> String<'lua> {
         unsafe {
             stack_guard(lua.state, || {
                 check_stack(lua.state, 1);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
                 rlua_assert!(
                     ffi::lua_type(lua.state, -1) == ffi::LUA_TSTRING,
                     "string ref is not string type"
@@ -82,7 +82,6 @@ impl<'lua> String<'lua> {
                 // string type
                 let data = ffi::lua_tolstring(lua.state, -1, &mut size);
 
-                ffi::lua_pop(lua.state, 1);
                 slice::from_raw_parts(data as *const u8, size + 1)
             })
         }

src/table.rs

@@ -1,9 +1,10 @@
 use std::marker::PhantomData;
+use std::os::raw::c_int;
 
 use ffi;
 use error::Result;
-use util::*;
+use util::{check_stack, protect_lua, protect_lua_closure, stack_guard};
-use types::{Integer, LuaRef};
+use types::{Integer, LuaRef, RefType};
 use value::{FromLua, ToLua};
 
 /// Handle to an internal Lua table.
@@ -51,14 +52,17 @@ impl<'lua> Table<'lua> {
     pub fn set<K: ToLua<'lua>, V: ToLua<'lua>>(&self, key: K, value: V) -> Result<()> {
         let lua = self.0.lua;
         unsafe {
-            stack_err_guard(lua.state, || {
+            stack_guard(lua.state, || {
                 check_stack(lua.state, 6);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
-                lua.push_value(lua.state, key.to_lua(lua)?);
+                lua.push_value(key.to_lua(lua)?);
-                lua.push_value(lua.state, value.to_lua(lua)?);
+                lua.push_value(value.to_lua(lua)?);
-                protect_lua_call(lua.state, 3, 0, |state| {
+
+                unsafe extern "C" fn set_table(state: *mut ffi::lua_State) -> c_int {
                     ffi::lua_settable(state, -3);
-                })
+                    1
+                }
+                protect_lua(lua.state, 3, set_table)
             })
         }
     }
@@ -94,12 +98,18 @@ impl<'lua> Table<'lua> {
     pub fn get<K: ToLua<'lua>, V: FromLua<'lua>>(&self, key: K) -> Result<V> {
         let lua = self.0.lua;
         unsafe {
-            stack_err_guard(lua.state, || {
+            stack_guard(lua.state, || {
                 check_stack(lua.state, 5);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
-                lua.push_value(lua.state, key.to_lua(lua)?);
+                lua.push_value(key.to_lua(lua)?);
-                protect_lua_call(lua.state, 2, 1, |state| ffi::lua_gettable(state, -2))?;
+
-                V::from_lua(lua.pop_value(lua.state), lua)
+                unsafe extern "C" fn get_table(state: *mut ffi::lua_State) -> c_int {
+                    ffi::lua_gettable(state, -2);
+                    1
+                }
+                protect_lua(lua.state, 2, get_table)?;
+
+                V::from_lua(lua.pop_value(), lua)
             })
         }
     }
@@ -108,13 +118,18 @@ impl<'lua> Table<'lua> {
     pub fn contains_key<K: ToLua<'lua>>(&self, key: K) -> Result<bool> {
         let lua = self.0.lua;
         unsafe {
-            stack_err_guard(lua.state, || {
+            stack_guard(lua.state, || {
                 check_stack(lua.state, 5);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
-                lua.push_value(lua.state, key.to_lua(lua)?);
+                lua.push_value(key.to_lua(lua)?);
-                protect_lua_call(lua.state, 2, 1, |state| ffi::lua_gettable(state, -2))?;
+
+                unsafe extern "C" fn get_table(state: *mut ffi::lua_State) -> c_int {
+                    ffi::lua_gettable(state, -2);
+                    1
+                }
+                protect_lua(lua.state, 2, get_table)?;
+
                 let has = ffi::lua_isnil(lua.state, -1) == 0;
-                ffi::lua_pop(lua.state, 1);
                 Ok(has)
             })
         }
@@ -124,14 +139,18 @@ impl<'lua> Table<'lua> {
     pub fn raw_set<K: ToLua<'lua>, V: ToLua<'lua>>(&self, key: K, value: V) -> Result<()> {
         let lua = self.0.lua;
         unsafe {
-            stack_err_guard(lua.state, || {
+            stack_guard(lua.state, || {
                 check_stack(lua.state, 6);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
-                lua.push_value(lua.state, key.to_lua(lua)?);
+                lua.push_value(key.to_lua(lua)?);
-                lua.push_value(lua.state, value.to_lua(lua)?);
+                lua.push_value(value.to_lua(lua)?);
-                protect_lua_call(lua.state, 3, 0, |state| {
+
+                unsafe extern "C" fn raw_set(state: *mut ffi::lua_State) -> c_int {
                     ffi::lua_rawset(state, -3);
-                })?;
+                    0
+                }
+                protect_lua(lua.state, 3, raw_set)?;
+
                 Ok(())
             })
         }
@@ -141,13 +160,12 @@ impl<'lua> Table<'lua> {
     pub fn raw_get<K: ToLua<'lua>, V: FromLua<'lua>>(&self, key: K) -> Result<V> {
         let lua = self.0.lua;
         unsafe {
-            stack_err_guard(lua.state, || {
+            stack_guard(lua.state, || {
                 check_stack(lua.state, 3);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
-                lua.push_value(lua.state, key.to_lua(lua)?);
+                lua.push_value(key.to_lua(lua)?);
                 ffi::lua_rawget(lua.state, -2);
-                let res = V::from_lua(lua.pop_value(lua.state), lua)?;
+                let res = V::from_lua(lua.pop_value(), lua)?;
-                ffi::lua_pop(lua.state, 1);
                 Ok(res)
             })
         }
@@ -161,10 +179,10 @@ impl<'lua> Table<'lua> {
     pub fn len(&self) -> Result<Integer> {
         let lua = self.0.lua;
         unsafe {
-            stack_err_guard(lua.state, || {
+            stack_guard(lua.state, || {
                 check_stack(lua.state, 4);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
-                protect_lua_call(lua.state, 1, 0, |state| ffi::luaL_len(state, -1))
+                protect_lua_closure(lua.state, 1, 0, |state| ffi::luaL_len(state, -1))
             })
         }
     }
@@ -175,9 +193,8 @@ impl<'lua> Table<'lua> {
         unsafe {
             stack_guard(lua.state, || {
                 check_stack(lua.state, 1);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
                 let len = ffi::lua_rawlen(lua.state, -1);
-                ffi::lua_pop(lua.state, 1);
                 len as Integer
             })
         }
@@ -191,13 +208,11 @@ impl<'lua> Table<'lua> {
         unsafe {
             stack_guard(lua.state, || {
                 check_stack(lua.state, 1);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
                 if ffi::lua_getmetatable(lua.state, -1) == 0 {
-                    ffi::lua_pop(lua.state, 1);
                     None
                 } else {
-                    let table = Table(lua.pop_ref(lua.state));
+                    let table = Table(lua.pop_ref());
-                    ffi::lua_pop(lua.state, 1);
                     Some(table)
                 }
             })
@@ -213,14 +228,13 @@ impl<'lua> Table<'lua> {
         unsafe {
             stack_guard(lua.state, move || {
                 check_stack(lua.state, 1);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
                 if let Some(metatable) = metatable {
-                    lua.push_ref(lua.state, &metatable.0);
+                    lua.push_ref(&metatable.0);
                 } else {
                     ffi::lua_pushnil(lua.state);
                 }
                 ffi::lua_setmetatable(lua.state, -2);
-                ffi::lua_pop(lua.state, 1);
             })
         }
     }
@@ -265,8 +279,7 @@ impl<'lua> Table<'lua> {
     pub fn pairs<K: FromLua<'lua>, V: FromLua<'lua>>(self) -> TablePairs<'lua, K, V> {
         let next_key = Some(LuaRef {
             lua: self.0.lua,
-            registry_id: ffi::LUA_REFNIL,
+            ref_type: RefType::Nil,
-            drop_unref: true,
         });
 
         TablePairs {
@@ -349,26 +362,18 @@ where
                 stack_guard(lua.state, || {
                     check_stack(lua.state, 6);
 
-                    lua.push_ref(lua.state, &self.table);
+                    lua.push_ref(&self.table);
-                    lua.push_ref(lua.state, &next_key);
+                    lua.push_ref(&next_key);
 
-                    match protect_lua_call(lua.state, 2, ffi::LUA_MULTRET, |state| {
+                    match protect_lua_closure(lua.state, 2, ffi::LUA_MULTRET, |state| {
-                        if ffi::lua_next(state, -2) == 0 {
+                        ffi::lua_next(state, -2) != 0
-                            0
-                        } else {
-                            1
-                        }
                     }) {
-                        Ok(0) => {
+                        Ok(false) => None,
-                            ffi::lua_pop(lua.state, 1);
+                        Ok(true) => {
-                            None
-                        }
-                        Ok(_) => {
                             ffi::lua_pushvalue(lua.state, -2);
-                            let key = lua.pop_value(lua.state);
+                            let key = lua.pop_value();
-                            let value = lua.pop_value(lua.state);
+                            let value = lua.pop_value();
-                            self.next_key = Some(lua.pop_ref(lua.state));
+                            self.next_key = Some(lua.pop_ref());
-                            ffi::lua_pop(lua.state, 1);
 
                             Some((|| {
                                 let key = K::from_lua(key, lua)?;
@@ -411,15 +416,13 @@ where
                 stack_guard(lua.state, || {
                     check_stack(lua.state, 5);
 
-                    lua.push_ref(lua.state, &self.table);
+                    lua.push_ref(&self.table);
-                    match protect_lua_call(lua.state, 1, 1, |state| ffi::lua_geti(state, -1, index))
+                    match protect_lua_closure(lua.state, 1, 1, |state| {
-                    {
+                        ffi::lua_geti(state, -1, index)
-                        Ok(ffi::LUA_TNIL) => {
+                    }) {
-                            ffi::lua_pop(lua.state, 1);
+                        Ok(ffi::LUA_TNIL) => None,
-                            None
-                        }
                         Ok(_) => {
-                            let value = lua.pop_value(lua.state);
+                            let value = lua.pop_value();
                             self.index = Some(index + 1);
                             Some(V::from_lua(value, lua))
                         }

src/tests/mod.rs

@@ -744,3 +744,38 @@ fn too_many_binds() {
             .is_err()
     );
 }
+
+#[test]
+fn large_args() {
+    let lua = Lua::new();
+    let globals = lua.globals();
+
+    globals
+        .set(
+            "c",
+            lua.create_function(|_, args: Variadic<usize>| {
+                let mut s = 0;
+                for i in 0..args.len() {
+                    s += i;
+                    assert_eq!(i, args[i]);
+                }
+                Ok(s)
+            }).unwrap(),
+        )
+        .unwrap();
+
+    let f: Function = lua.eval(
+        r#"
+            return function(...)
+                return c(...)
+            end
+        "#,
+        None,
+    ).unwrap();
+
+    assert_eq!(
+        f.call::<_, usize>((0..100).collect::<Variadic<usize>>())
+            .unwrap(),
+        4950
+    );
+}

src/thread.rs

@@ -1,8 +1,8 @@
 use std::os::raw::c_int;
 
 use ffi;
-use error::*;
+use error::{Error, Result};
-use util::*;
+use util::{check_stack, check_stack_err, error_traceback, pop_error, stack_guard};
 use types::LuaRef;
 use value::{FromLuaMulti, MultiValue, ToLuaMulti};
 
@@ -78,10 +78,10 @@ impl<'lua> Thread<'lua> {
     {
         let lua = self.0.lua;
         unsafe {
-            stack_err_guard(lua.state, || {
+            stack_guard(lua.state, || {
                 check_stack(lua.state, 1);
 
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
                 let thread_state = ffi::lua_tothread(lua.state, -1);
 
                 let status = ffi::lua_status(thread_state);
@@ -93,11 +93,13 @@ impl<'lua> Thread<'lua> {
 
                 let args = args.to_lua_multi(lua)?;
                 let nargs = args.len() as c_int;
+                check_stack_err(lua.state, nargs)?;
                 check_stack_err(thread_state, nargs + 1)?;
 
                 for arg in args {
-                    lua.push_value(thread_state, arg);
+                    lua.push_value(arg);
                 }
+                ffi::lua_xmove(lua.state, thread_state, nargs);
 
                 let ret = ffi::lua_resume(thread_state, lua.state, nargs);
                 if ret != ffi::LUA_OK && ret != ffi::LUA_YIELD {
@@ -107,9 +109,11 @@ impl<'lua> Thread<'lua> {
 
                 let nresults = ffi::lua_gettop(thread_state);
                 let mut results = MultiValue::new();
-                check_stack(thread_state, 2);
+                ffi::lua_xmove(thread_state, lua.state, nresults);
+
+                check_stack(lua.state, 2);
                 for _ in 0..nresults {
-                    results.push_front(lua.pop_value(thread_state));
+                    results.push_front(lua.pop_value());
                 }
                 R::from_lua_multi(results, lua)
             })
@@ -123,7 +127,7 @@ impl<'lua> Thread<'lua> {
             stack_guard(lua.state, || {
                 check_stack(lua.state, 1);
 
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
                 let thread_state = ffi::lua_tothread(lua.state, -1);
                 ffi::lua_pop(lua.state, 1);
 

src/types.rs

@@ -1,4 +1,4 @@
-use std::fmt;
+use std::{fmt, mem, ptr};
 use std::os::raw::{c_int, c_void};
 use std::sync::{Arc, Mutex};
 
@@ -16,6 +16,9 @@ pub type Number = ffi::lua_Number;
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct LightUserData(pub *mut c_void);
 
+pub(crate) type Callback<'lua, 'a> =
+    Box<Fn(&'lua Lua, MultiValue<'lua>) -> Result<MultiValue<'lua>> + 'a>;
+
 /// An auto generated key into the Lua registry.
 ///
 /// This is a handle into a value stored inside the Lua registry, similar to the normal handle types
@@ -32,57 +35,54 @@ pub struct LightUserData(pub *mut c_void);
 pub struct RegistryKey {
     pub(crate) registry_id: c_int,
     pub(crate) unref_list: Arc<Mutex<Option<Vec<c_int>>>>,
-    pub(crate) drop_unref: bool,
 }
 
 impl Drop for RegistryKey {
     fn drop(&mut self) {
-        if self.drop_unref {
+        if let Some(list) = self.unref_list.lock().unwrap().as_mut() {
-            if let Some(list) = self.unref_list.lock().unwrap().as_mut() {
+            list.push(self.registry_id);
-                list.push(self.registry_id);
-            }
         }
     }
 }
 
-pub(crate) type Callback<'lua, 'a> =
+impl RegistryKey {
-    Box<Fn(&'lua Lua, MultiValue<'lua>) -> Result<MultiValue<'lua>> + 'a>;
+    // Destroys the RegistryKey without adding to the drop list
+    pub(crate) fn take(self) -> c_int {
+        let registry_id = self.registry_id;
+        unsafe {
+            ptr::read(&self.unref_list);
+            mem::forget(self);
+        }
+        registry_id
+    }
+}
+
+#[derive(Debug)]
+pub(crate) enum RefType {
+    Nil,
+    Stack { stack_slot: c_int },
+    Registry { registry_id: c_int },
+}
 
 pub(crate) struct LuaRef<'lua> {
-    pub lua: &'lua Lua,
+    pub(crate) lua: &'lua Lua,
-    pub registry_id: c_int,
+    pub(crate) ref_type: RefType,
-    pub drop_unref: bool,
 }
 
 impl<'lua> fmt::Debug for LuaRef<'lua> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "LuaRef({})", self.registry_id)
+        write!(f, "{:?}", self.ref_type)
     }
 }
 
 impl<'lua> Clone for LuaRef<'lua> {
     fn clone(&self) -> Self {
-        if self.drop_unref {
+        self.lua.clone_ref(self)
-            unsafe {
-                self.lua.push_ref(self.lua.state, self);
-                self.lua.pop_ref(self.lua.state)
-            }
-        } else {
-            LuaRef {
-                lua: self.lua,
-                registry_id: self.registry_id,
-                drop_unref: self.drop_unref,
-            }
-        }
     }
 }
 
 impl<'lua> Drop for LuaRef<'lua> {
     fn drop(&mut self) {
-        if self.drop_unref {
+        self.lua.drop_ref(self)
-            unsafe {
-                ffi::luaL_unref(self.lua.state, ffi::LUA_REGISTRYINDEX, self.registry_id);
-            }
-        }
     }
 }

src/userdata.rs

@@ -4,8 +4,8 @@ use std::collections::HashMap;
 use std::string::String as StdString;
 
 use ffi;
-use error::*;
+use error::{Error, Result};
-use util::*;
+use util::{check_stack, get_userdata, stack_guard};
 use types::{Callback, LuaRef};
 use value::{FromLua, FromLuaMulti, ToLua, ToLuaMulti};
 use lua::Lua;
@@ -415,10 +415,10 @@ impl<'lua> AnyUserData<'lua> {
     {
         unsafe {
             let lua = self.0.lua;
-            stack_err_guard(lua.state, move || {
+            stack_guard(lua.state, move || {
                 check_stack(lua.state, 3);
 
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
 
                 rlua_assert!(
                     ffi::lua_getmetatable(lua.state, -1) != 0,
@@ -432,11 +432,9 @@ impl<'lua> AnyUserData<'lua> {
                 );
 
                 if ffi::lua_rawequal(lua.state, -1, -2) == 0 {
-                    ffi::lua_pop(lua.state, 3);
                     Err(Error::UserDataTypeMismatch)
                 } else {
                     let res = func(&*get_userdata::<RefCell<T>>(lua.state, -3));
-                    ffi::lua_pop(lua.state, 3);
                     res
                 }
             })
@@ -451,12 +449,11 @@ impl<'lua> AnyUserData<'lua> {
     pub fn set_user_value<V: ToLua<'lua>>(&self, v: V) -> Result<()> {
         let lua = self.0.lua;
         unsafe {
-            stack_err_guard(lua.state, || {
+            stack_guard(lua.state, || {
                 check_stack(lua.state, 2);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
-                lua.push_value(lua.state, v.to_lua(lua)?);
+                lua.push_value(v.to_lua(lua)?);
                 ffi::lua_setuservalue(lua.state, -2);
-                ffi::lua_pop(lua.state, 1);
                 Ok(())
             })
         }
@@ -468,12 +465,11 @@ impl<'lua> AnyUserData<'lua> {
     pub fn get_user_value<V: FromLua<'lua>>(&self) -> Result<V> {
         let lua = self.0.lua;
         unsafe {
-            stack_err_guard(lua.state, || {
+            stack_guard(lua.state, || {
                 check_stack(lua.state, 3);
-                lua.push_ref(lua.state, &self.0);
+                lua.push_ref(&self.0);
                 ffi::lua_getuservalue(lua.state, -1);
-                let res = V::from_lua(lua.pop_value(lua.state), lua)?;
+                let res = V::from_lua(lua.pop_value(), lua)?;
-                ffi::lua_pop(lua.state, 1);
                 Ok(res)
             })
         }

src/util.rs

@@ -27,74 +27,71 @@ pub unsafe fn check_stack_err(state: *mut ffi::lua_State, amount: c_int) -> Resu
     }
 }
 
-// Run an operation on a lua_State and ensure that there are no stack leaks and the stack is
+pub struct StackGuard {
-// restored on panic.
+    state: *mut ffi::lua_State,
+    top: c_int,
+}
+
+impl StackGuard {
+    // Creates a StackGuard instance with wa record of the stack size, and on Drop will check the
+    // stack size and drop any extra elements.  If the stack size at the end is *smaller* than at
+    // the beginning, this is considered a fatal logic error and will result in an abort.
+    pub unsafe fn new(state: *mut ffi::lua_State) -> StackGuard {
+        StackGuard {
+            state,
+            top: ffi::lua_gettop(state),
+        }
+    }
+}
+
+impl Drop for StackGuard {
+    fn drop(&mut self) {
+        unsafe {
+            let top = ffi::lua_gettop(self.state);
+            if top > self.top {
+                ffi::lua_settop(self.state, self.top);
+            } else if top < self.top {
+                rlua_panic!("{} too many stack values popped", self.top - top);
+            }
+        }
+    }
+}
+
+// Run an operation on a lua_State and restores the stack state at the end, using `StackGuard`.
 pub unsafe fn stack_guard<F, R>(state: *mut ffi::lua_State, op: F) -> R
 where
     F: FnOnce() -> R,
 {
-    let begin = ffi::lua_gettop(state);
+    let _stack_guard = StackGuard::new(state);
-
+    op()
-    let res = match catch_unwind(AssertUnwindSafe(op)) {
-        Ok(r) => r,
-        Err(p) => {
-            let top = ffi::lua_gettop(state);
-            if top > begin {
-                ffi::lua_settop(state, begin);
-            }
-            resume_unwind(p);
-        }
-    };
-
-    let top = ffi::lua_gettop(state);
-    if top > begin {
-        ffi::lua_settop(state, begin);
-        rlua_panic!("expected stack to be {}, got {}", begin, top);
-    } else if top < begin {
-        rlua_abort!("{} too many stack values popped", begin - top);
-    }
-
-    res
 }
 
-// Run an operation on a lua_State and automatically clean up the stack on error.  Takes the
+// Call a function that calls into the Lua API and may trigger a Lua error (longjmp) in a safe way.
-// lua_State and an operation to run.  If the operation results in success, then the stack is
+// Wraps the inner function in a call to `lua_pcall`, so the inner function only has access to a
-// inspected to make sure there is not a stack leak, and otherwise this is a logic error and will
+// limited lua stack.  `nargs` is the same as the the parameter to `lua_pcall`, and `nresults` is
-// panic.  If the operation results in an error, or if the operation panics, the stack is shrunk to
+// always LUA_MULTRET.  Internally uses 2 extra stack spaces, and does not call checkstack.
-// the value before the call.
+// Provided function must *never* panic.
-pub unsafe fn stack_err_guard<F, R>(state: *mut ffi::lua_State, op: F) -> Result<R>
+pub unsafe fn protect_lua(
-where
+    state: *mut ffi::lua_State,
-    F: FnOnce() -> Result<R>,
+    nargs: c_int,
-{
+    f: unsafe extern "C" fn(*mut ffi::lua_State) -> c_int,
-    let begin = ffi::lua_gettop(state);
+) -> Result<()> {
+    let stack_start = ffi::lua_gettop(state) - nargs;
 
-    let res = match catch_unwind(AssertUnwindSafe(op)) {
+    ffi::lua_pushcfunction(state, error_traceback);
-        Ok(r) => r,
+    ffi::lua_pushcfunction(state, f);
-        Err(p) => {
+    if nargs > 0 {
-            let top = ffi::lua_gettop(state);
+        ffi::lua_rotate(state, stack_start + 1, 2);
-            if top > begin {
+    }
-                ffi::lua_settop(state, begin);
+
-            }
+    let ret = ffi::lua_pcall(state, nargs, ffi::LUA_MULTRET, stack_start + 1);
-            resume_unwind(p);
+    ffi::lua_remove(state, stack_start + 1);
-        }
+
-    };
+    if ret == ffi::LUA_OK {
-
+        Ok(())
-    let top = ffi::lua_gettop(state);
+    } else {
-    if res.is_ok() {
+        Err(pop_error(state, ret))
-        if top > begin {
-            ffi::lua_settop(state, begin);
-            rlua_panic!("expected stack to be {}, got {}", begin, top);
-        } else if top < begin {
-            rlua_abort!("{} too many stack values popped", begin - top);
-        }
-    } else {
-        if top > begin {
-            ffi::lua_settop(state, begin);
-        } else if top < begin {
-            rlua_abort!("{} too many stack values popped", begin - top);
-        }
     }
-    res
 }
 
 // Call a function that calls into the Lua API and may trigger a Lua error (longjmp) in a safe way.
@@ -104,7 +101,7 @@ where
 // values are assumed to match the `nresults` param.  Internally uses 3 extra stack spaces, and does
 // not call checkstack.  Provided function must *not* panic, and since it will generally be
 // lonjmping, should not contain any values that implement Drop.
-pub unsafe fn protect_lua_call<F, R>(
+pub unsafe fn protect_lua_closure<F, R>(
     state: *mut ffi::lua_State,
     nargs: c_int,
     nresults: c_int,
@@ -115,7 +112,7 @@ where
     R: Copy,
 {
     struct Params<F, R> {
-        function: *const F,
+        function: F,
         result: R,
         nresults: c_int,
     }
@@ -127,7 +124,7 @@ where
         let params = ffi::lua_touserdata(state, -1) as *mut Params<F, R>;
         ffi::lua_pop(state, 1);
 
-        (*params).result = (*(*params).function)(state);
+        (*params).result = ((*params).function)(state);
 
         if (*params).nresults == ffi::LUA_MULTRET {
             ffi::lua_gettop(state)
@@ -140,10 +137,12 @@ where
 
     ffi::lua_pushcfunction(state, error_traceback);
     ffi::lua_pushcfunction(state, do_call::<F, R>);
-    ffi::lua_rotate(state, stack_start + 1, 2);
+    if nargs > 0 {
+        ffi::lua_rotate(state, stack_start + 1, 2);
+    }
 
     let mut params = Params {
-        function: &f,
+        function: f,
         result: mem::uninitialized(),
         nresults,
     };
@@ -173,8 +172,9 @@ pub unsafe fn pop_error(state: *mut ffi::lua_State, err_code: c_int) -> Error {
         "pop_error called with non-error return code"
     );
 
-    if let Some(err) = pop_wrapped_error(state) {
+    if let Some(err) = get_wrapped_error(state, -1).as_ref() {
-        err
+        ffi::lua_pop(state, 1);
+        err.clone()
     } else if is_wrapped_panic(state, -1) {
         let panic = get_userdata::<WrappedPanic>(state, -1);
         if let Some(p) = (*panic).0.take() {
@@ -212,7 +212,7 @@ pub unsafe fn pop_error(state: *mut ffi::lua_State, err_code: c_int) -> Error {
             ffi::LUA_ERRMEM => {
                 // This should be impossible, as we set the lua allocator to one that aborts
                 // instead of failing.
-                rlua_abort!("impossible Lua allocation error, aborting!")
+                rlua_abort!("impossible Lua allocation error")
             }
             ffi::LUA_ERRGCMM => Error::GarbageCollectorError(err_string),
             _ => rlua_panic!("unrecognized lua error code"),
@@ -222,14 +222,14 @@ pub unsafe fn pop_error(state: *mut ffi::lua_State, err_code: c_int) -> Error {
 
 // Internally uses 4 stack spaces, does not call checkstack
 pub unsafe fn push_string(state: *mut ffi::lua_State, s: &str) -> Result<()> {
-    protect_lua_call(state, 0, 1, |state| {
+    protect_lua_closure(state, 0, 1, |state| {
         ffi::lua_pushlstring(state, s.as_ptr() as *const c_char, s.len());
     })
 }
 
 // Internally uses 4 stack spaces, does not call checkstack
 pub unsafe fn push_userdata<T>(state: *mut ffi::lua_State, t: T) -> Result<()> {
-    let ud = protect_lua_call(state, 0, 1, move |state| {
+    let ud = protect_lua_closure(state, 0, 1, move |state| {
         ffi::lua_newuserdata(state, mem::size_of::<T>()) as *mut T
     })?;
     ptr::write(ud, t);
@@ -300,7 +300,7 @@ pub unsafe extern "C" fn error_traceback(state: *mut ffi::lua_State) -> c_int {
 
     if ffi::lua_checkstack(state, 2) == 0 {
         // If we don't have enough stack space to even check the error type, do nothing
-    } else if is_wrapped_error(state, 1) {
+    } else if let Some(error) = get_wrapped_error(state, 1).as_ref() {
         let traceback = if ffi::lua_checkstack(state, LUA_TRACEBACK_STACK) != 0 {
             gc_guard(state, || {
                 ffi::luaL_traceback(state, state, ptr::null(), 0);
@@ -314,7 +314,9 @@ pub unsafe extern "C" fn error_traceback(state: *mut ffi::lua_State) -> c_int {
             "not enough stack space for traceback".to_owned()
         };
 
-        let error = pop_wrapped_error(state).unwrap();
+        let error = error.clone();
+        ffi::lua_pop(state, 1);
+
         push_wrapped_error(
             state,
             Error::CallbackError {
@@ -404,14 +406,6 @@ pub unsafe extern "C" fn safe_xpcall(state: *mut ffi::lua_State) -> c_int {
     }
 }
 
-// Does not call lua_checkstack, uses 1 stack space.
-pub unsafe fn main_state(state: *mut ffi::lua_State) -> *mut ffi::lua_State {
-    ffi::lua_rawgeti(state, ffi::LUA_REGISTRYINDEX, ffi::LUA_RIDX_MAINTHREAD);
-    let main_state = ffi::lua_tothread(state, -1);
-    ffi::lua_pop(state, 1);
-    main_state
-}
-
 // Pushes a WrappedError::Error to the top of the stack.  Uses two stack spaces and does not call
 // lua_checkstack.
 pub unsafe fn push_wrapped_error(state: *mut ffi::lua_State, err: Error) {
@@ -424,18 +418,26 @@ pub unsafe fn push_wrapped_error(state: *mut ffi::lua_State, err: Error) {
     ffi::lua_setmetatable(state, -2);
 }
 
-// Pops a WrappedError off of the top of the stack, if it is a WrappedError.  If it is not a
+// Checks if the value at the given index is a WrappedError, and if it is returns a pointer to it,
-// WrappedError, returns None and does not pop anything.  Uses 2 stack spaces and does not call
+// otherwise returns null.  Uses 2 stack spaces and does not call lua_checkstack.
-// lua_checkstack.
+pub unsafe fn get_wrapped_error(state: *mut ffi::lua_State, index: c_int) -> *const Error {
-pub unsafe fn pop_wrapped_error(state: *mut ffi::lua_State) -> Option<Error> {
+    let userdata = ffi::lua_touserdata(state, index);
-    if !is_wrapped_error(state, -1) {
+    if userdata.is_null() {
-        None
+        return ptr::null();
+    }
+
+    if ffi::lua_getmetatable(state, index) == 0 {
+        return ptr::null();
+    }
+
+    get_error_metatable(state);
+    let res = ffi::lua_rawequal(state, -1, -2) != 0;
+    ffi::lua_pop(state, 2);
+
+    if res {
+        &(*get_userdata::<WrappedError>(state, -1)).0
     } else {
-        let err = &*get_userdata::<WrappedError>(state, -1);
+        ptr::null()
-        // We are assuming here that Error::clone() cannot panic.
-        let err = err.0.clone();
-        ffi::lua_pop(state, 1);
-        Some(err)
     }
 }
 
@@ -466,9 +468,8 @@ pub unsafe fn init_error_metatables(state: *mut ffi::lua_State) {
         ffi::luaL_checkstack(state, 2, ptr::null());
 
         callback_error(state, || {
-            if is_wrapped_error(state, -1) {
+            if let Some(error) = get_wrapped_error(state, -1).as_ref() {
-                let error = get_userdata::<WrappedError>(state, -1);
+                let error_str = error.to_string();
-                let error_str = (*error).0.to_string();
                 gc_guard(state, || {
                     ffi::lua_pushlstring(
                         state,
@@ -587,24 +588,6 @@ unsafe fn push_wrapped_panic(state: *mut ffi::lua_State, panic: Box<Any + Send>)
     ffi::lua_setmetatable(state, -2);
 }
 
-// Checks if the value at the given index is a WrappedError, uses 2 stack spaces and does not call
-// lua_checkstack.
-unsafe fn is_wrapped_error(state: *mut ffi::lua_State, index: c_int) -> bool {
-    let userdata = ffi::lua_touserdata(state, index);
-    if userdata.is_null() {
-        return false;
-    }
-
-    if ffi::lua_getmetatable(state, index) == 0 {
-        return false;
-    }
-
-    get_error_metatable(state);
-    let res = ffi::lua_rawequal(state, -1, -2) != 0;
-    ffi::lua_pop(state, 2);
-    res
-}
-
 // Checks if the value at the given index is a WrappedPanic.  Uses 2 stack spaces and does not call
 // lua_checkstack.
 unsafe fn is_wrapped_panic(state: *mut ffi::lua_State, index: c_int) -> bool {

src/value.rs

@@ -1,9 +1,7 @@
-use std::str;
+use std::{slice, str, vec};
-use std::ops::{Deref, DerefMut};
+use std::iter::{self, FromIterator};
-use std::iter::FromIterator;
-use std::collections::VecDeque;
 
-use error::*;
+use error::{Error, Result};
 use types::{Integer, LightUserData, Number};
 use string::String;
 use table::Table;
@@ -76,41 +74,77 @@ pub trait FromLua<'lua>: Sized {
 
 /// Multiple Lua values used for both argument passing and also for multiple return values.
 #[derive(Debug, Clone)]
-pub struct MultiValue<'lua>(VecDeque<Value<'lua>>);
+pub struct MultiValue<'lua>(Vec<Value<'lua>>);
 
 impl<'lua> MultiValue<'lua> {
     /// Creates an empty `MultiValue` containing no values.
     pub fn new() -> MultiValue<'lua> {
-        MultiValue(VecDeque::new())
+        MultiValue(Vec::new())
     }
 }
 
 impl<'lua> FromIterator<Value<'lua>> for MultiValue<'lua> {
     fn from_iter<I: IntoIterator<Item = Value<'lua>>>(iter: I) -> Self {
-        MultiValue(VecDeque::from_iter(iter))
+        MultiValue::from_vec(Vec::from_iter(iter))
     }
 }
 
 impl<'lua> IntoIterator for MultiValue<'lua> {
     type Item = Value<'lua>;
-    type IntoIter = <VecDeque<Value<'lua>> as IntoIterator>::IntoIter;
+    type IntoIter = iter::Rev<vec::IntoIter<Value<'lua>>>;
 
     fn into_iter(self) -> Self::IntoIter {
-        self.0.into_iter()
+        self.0.into_iter().rev()
     }
 }
 
-impl<'lua> Deref for MultiValue<'lua> {
+impl<'a, 'lua> IntoIterator for &'a MultiValue<'lua> {
-    type Target = VecDeque<Value<'lua>>;
+    type Item = &'a Value<'lua>;
+    type IntoIter = iter::Rev<slice::Iter<'a, Value<'lua>>>;
 
-    fn deref(&self) -> &Self::Target {
+    fn into_iter(self) -> Self::IntoIter {
-        &self.0
+        (&self.0).into_iter().rev()
     }
 }
 
-impl<'lua> DerefMut for MultiValue<'lua> {
+impl<'lua> MultiValue<'lua> {
-    fn deref_mut(&mut self) -> &mut Self::Target {
+    pub fn from_vec(mut v: Vec<Value<'lua>>) -> MultiValue<'lua> {
-        &mut self.0
+        v.reverse();
+        MultiValue(v)
+    }
+
+    pub fn into_vec(self) -> Vec<Value<'lua>> {
+        let mut v = self.0;
+        v.reverse();
+        v
+    }
+
+    pub fn from_vec_rev(v: Vec<Value<'lua>>) -> MultiValue<'lua> {
+        MultiValue(v)
+    }
+
+    pub fn into_vec_rev(self) -> Vec<Value<'lua>> {
+        self.0
+    }
+
+    pub fn reserve(&mut self, size: usize) {
+        self.0.reserve(size);
+    }
+
+    pub fn push_front(&mut self, value: Value<'lua>) {
+        self.0.push(value);
+    }
+
+    pub fn pop_front(&mut self) -> Option<Value<'lua>> {
+        self.0.pop()
+    }
+
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    pub fn iter(&self) -> iter::Rev<slice::Iter<Value<'lua>>> {
+        self.0.iter().rev()
     }
 }