v0.7.4

Relates to #127
Should be fixed in a next major release by adding support of TCDATA type.

CHANGELOG.md

@@ -1,3 +1,10 @@
+## v0.7.4
+
+- Improved `Lua::create_registry_value` to reuse previously expired registry keys.
+  No need to call `Lua::expire_registry_values` when creating/dropping registry values.
+- Added `Lua::replace_registry_value` to change value of an existing Registry Key
+- Async calls optimization
+
 ## v0.7.3
 
 - Fixed cross-compilation issue (introduced in 84a174c)

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mlua"
-version = "0.7.3" # remember to update html_root_url and mlua_derive
+version = "0.7.4" # remember to update html_root_url and mlua_derive
 authors = ["Aleksandr Orlenko <zxteam@pm.me>", "kyren <catherine@chucklefish.org>"]
 edition = "2018"
 repository = "https://github.com/khvzak/mlua"

build/find_dummy.rs

@@ -1,5 +1,5 @@
 use std::path::PathBuf;
 
-pub fn probe_lua() -> PathBuf {
+pub fn probe_lua() -> Option<PathBuf> {
     unreachable!()
 }

src/ffi/lua.rs

@@ -101,6 +101,10 @@ pub const LUA_TFUNCTION: c_int = 6;
 pub const LUA_TUSERDATA: c_int = 7;
 pub const LUA_TTHREAD: c_int = 8;
 
+// Type produced by LuaJIT FFI module
+#[cfg(feature = "luajit")]
+pub const LUA_TCDATA: c_int = 10;
+
 #[cfg(feature = "lua54")]
 pub const LUA_NUMTYPES: c_int = 9;
 #[cfg(any(feature = "lua53", feature = "lua52"))]

src/ffi/mod.rs

@@ -236,6 +236,9 @@ pub use self::lua::LUA_ERRGCMM;
 #[cfg(any(feature = "lua51", feature = "luajit"))]
 pub use self::lua::{LUA_ENVIRONINDEX, LUA_GLOBALSINDEX};
 
+#[cfg(feature = "luajit")]
+pub use self::lua::LUA_TCDATA;
+
 // constants from lauxlib.h
 pub use self::lauxlib::{LUA_ERRFILE, LUA_NOREF, LUA_REFNIL};
 

src/lib.rs

@@ -72,7 +72,7 @@
 //! [`serde::Deserialize`]: https://docs.serde.rs/serde/de/trait.Deserialize.html
 
 // mlua types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/mlua/0.7.3")]
+#![doc(html_root_url = "https://docs.rs/mlua/0.7.4")]
 // Deny warnings inside doc tests / examples. When this isn't present, rustdoc doesn't show *any*
 // warnings at all.
 #![doc(test(attr(deny(warnings))))]

src/lua.rs

@@ -1708,11 +1708,12 @@ impl Lua {
 
     /// Place a value in the Lua registry with an auto-generated key.
     ///
-    /// This value will be available to rust from all `Lua` instances which share the same main
+    /// This value will be available to Rust from all `Lua` instances which share the same main
     /// state.
     ///
     /// Be warned, garbage collection of values held inside the registry is not automatic, see
     /// [`RegistryKey`] for more details.
+    /// However, dropped [`RegistryKey`]s automatically reused to store new values.
     ///
     /// [`RegistryKey`]: crate::RegistryKey
     pub fn create_registry_value<'lua, T: ToLua<'lua>>(&'lua self, t: T) -> Result<RegistryKey> {
@@ -1721,14 +1722,29 @@ impl Lua {
             let _sg = StackGuard::new(self.state);
             check_stack(self.state, 4)?;
 
+            let unref_list = (*self.extra.get()).registry_unref_list.clone();
             self.push_value(t)?;
+
+            // Try to reuse previously allocated RegistryKey
+            let unref_list2 = unref_list.clone();
+            let mut unref_list2 = mlua_expect!(unref_list2.lock(), "unref list poisoned");
+            if let Some(registry_id) = unref_list2.as_mut().and_then(|x| x.pop()) {
+                // It must be safe to replace the value without triggering memory error
+                ffi::lua_rawseti(self.state, ffi::LUA_REGISTRYINDEX, registry_id as Integer);
+                return Ok(RegistryKey {
+                    registry_id,
+                    unref_list,
+                });
+            }
+
+            // Allocate a new RegistryKey
             let registry_id = protect_lua!(self.state, 1, 0, |state| {
                 ffi::luaL_ref(state, ffi::LUA_REGISTRYINDEX)
             })?;
 
             Ok(RegistryKey {
                 registry_id,
-                unref_list: (*self.extra.get()).registry_unref_list.clone(),
+                unref_list,
             })
         }
     }
@@ -1777,6 +1793,37 @@ impl Lua {
         Ok(())
     }
 
+    /// Replaces a value in the Lua registry by its `RegistryKey`.
+    ///
+    /// See [`create_registry_value`] for more details.
+    ///
+    /// [`create_registry_value`]: #method.create_registry_value
+    pub fn replace_registry_value<'lua, T: ToLua<'lua>>(
+        &'lua self,
+        key: &RegistryKey,
+        t: T,
+    ) -> Result<()> {
+        if !self.owns_registry_value(key) {
+            return Err(Error::MismatchedRegistryKey);
+        }
+
+        let t = t.to_lua(self)?;
+        unsafe {
+            let _sg = StackGuard::new(self.state);
+            check_stack(self.state, 2)?;
+
+            self.push_value(t)?;
+            // It must be safe to replace the value without triggering memory error
+            ffi::lua_rawseti(
+                self.state,
+                ffi::LUA_REGISTRYINDEX,
+                key.registry_id as Integer,
+            );
+
+            Ok(())
+        }
+    }
+
     /// Returns true if the given `RegistryKey` was created by a `Lua` which shares the underlying
     /// main state with this `Lua` instance.
     ///
@@ -1988,6 +2035,13 @@ impl Lua {
 
             ffi::LUA_TTHREAD => Value::Thread(Thread(self.pop_ref())),
 
+            #[cfg(feature = "luajit")]
+            ffi::LUA_TCDATA => {
+                ffi::lua_pop(state, 1);
+                // TODO: Fix this in a next major release
+                panic!("cdata objects cannot be handled by mlua yet");
+            }
+
             _ => mlua_panic!("LUA_TNONE in pop_value"),
         }
     }
@@ -2400,19 +2454,23 @@ impl Lua {
             Function(self.pop_ref())
         };
 
+        unsafe extern "C" fn unpack(state: *mut ffi::lua_State) -> c_int {
+            let len = ffi::lua_tointeger(state, 2);
+            ffi::luaL_checkstack(state, len as c_int, ptr::null());
+            for i in 1..=len {
+                ffi::lua_rawgeti(state, 1, i);
+            }
+            len as c_int
+        }
+
         let coroutine = self.globals().get::<_, Table>("coroutine")?;
 
         let env = self.create_table_with_capacity(0, 4)?;
         env.set("get_poll", get_poll)?;
         env.set("yield", coroutine.get::<_, Function>("yield")?)?;
-        env.set(
-            "unpack",
-            self.create_function(|lua, (tbl, len): (Table, Integer)| {
-                let mut values = MultiValue::new_or_cached(lua);
-                values.refill(tbl.raw_sequence_values_by_len(Some(len)))?;
-                Ok(values)
-            })?,
-        )?;
+        unsafe {
+            env.set("unpack", self.create_c_function(unpack)?)?;
+        }
         env.set("pending", {
             LightUserData(&ASYNC_POLL_PENDING as *const u8 as *mut c_void)
         })?;

src/table.rs

@@ -455,7 +455,7 @@ impl<'lua> Table<'lua> {
         }
     }
 
-    #[cfg(any(feature = "async", feature = "serialize"))]
+    #[cfg(any(feature = "serialize"))]
     pub(crate) fn raw_sequence_values_by_len<V: FromLua<'lua>>(
         self,
         len: Option<Integer>,

tests/tests.rs

@@ -800,6 +800,17 @@ fn test_drop_registry_value() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn test_replace_registry_value() -> Result<()> {
+    let lua = Lua::new();
+
+    let key = lua.create_registry_value::<i32>(42)?;
+    lua.replace_registry_value(&key, "new value")?;
+    assert_eq!(lua.registry_value::<String>(&key)?, "new value");
+
+    Ok(())
+}
+
 #[test]
 fn test_lua_registry_hash() -> Result<()> {
     let lua = Lua::new();
@@ -1256,3 +1267,24 @@ fn test_warnings() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+#[cfg(feature = "luajit")]
+#[should_panic]
+fn test_luajit_cdata() {
+    let lua = unsafe { Lua::unsafe_new() };
+    let _v: Result<Value> = lua
+        .load(
+            r#"
+        local ffi = require("ffi")
+        ffi.cdef[[
+            void *malloc(size_t size);
+            void free(void *ptr);
+        ]]
+        local ptr = ffi.C.malloc(1)
+        ffi.C.free(ptr)
+        return ptr
+    "#,
+        )
+        .eval();
+}

tests/thread.rs

@@ -130,7 +130,15 @@ fn test_thread_reset() -> Result<()> {
         assert_eq!(thread.status(), ThreadStatus::Error);
         assert_eq!(Arc::strong_count(&arc), 2);
         assert!(thread.reset(func.clone()).is_err());
-        assert_eq!(thread.status(), ThreadStatus::Error);
+        // Reset behavior has changed in Lua v5.4.4
+        // It's became possible to force reset thread by popping error object
+        assert!(matches!(
+            thread.status(),
+            ThreadStatus::Unresumable | ThreadStatus::Error
+        ));
+        // Would pass in 5.4.4
+        // assert!(thread.reset(func.clone()).is_ok());
+        // assert_eq!(thread.status(), ThreadStatus::Resumable);
     }
 
     Ok(())