core: Rename SharedMutableState to UnsafeAtomicRcBox

Author: brson

src/libcore/unstable/global.rs

@@ -37,8 +37,7 @@ use unstable::intrinsics::atomic_cxchg;
 use hashmap::HashMap;
 use sys::Closure;
 
-#[cfg(test)] use unstable::sync::{SharedMutableState, shared_mutable_state};
-#[cfg(test)] use unstable::sync::get_shared_immutable_state;
+#[cfg(test)] use unstable::sync::{UnsafeAtomicRcBox};
 #[cfg(test)] use task::spawn;
 #[cfg(test)] use uint;
 
@@ -234,35 +233,31 @@ extern {
 
 #[test]
 fn test_clone_rc() {
-    type MyType = SharedMutableState<int>;
-
-    fn key(_v: SharedMutableState<int>) { }
+    fn key(_v: UnsafeAtomicRcBox<int>) { }
 
     for uint::range(0, 100) |_| {
         do spawn {
             unsafe {
                 let val = do global_data_clone_create(key) {
-                    ~shared_mutable_state(10)
+                    ~UnsafeAtomicRcBox::new(10)
                 };
 
-                assert!(get_shared_immutable_state(&val) == &10);
+                assert!(val.get() == &10);
             }
         }
     }
 }
 
 #[test]
 fn test_modify() {
-    type MyType = SharedMutableState<int>;
-
-    fn key(_v: SharedMutableState<int>) { }
+    fn key(_v: UnsafeAtomicRcBox<int>) { }
 
     unsafe {
         do global_data_modify(key) |v| {
             match v {
                 None => {
                     unsafe {
-                        Some(~shared_mutable_state(10))
+                        Some(~UnsafeAtomicRcBox::new(10))
                     }
                 }
                 _ => fail!()
@@ -272,7 +267,7 @@ fn test_modify() {
         do global_data_modify(key) |v| {
             match v {
                 Some(sms) => {
-                    let v = get_shared_immutable_state(sms);
+                    let v = sms.get();
                     assert!(*v == 10);
                     None
                 },
@@ -284,7 +279,7 @@ fn test_modify() {
             match v {
                 None => {
                     unsafe {
-                        Some(~shared_mutable_state(10))
+                        Some(~UnsafeAtomicRcBox::new(10))
                     }
                 }
                 _ => fail!()

src/libcore/unstable/sync.rs

@@ -19,98 +19,103 @@ use ops::Drop;
 use clone::Clone;
 use kinds::Owned;
 
-/****************************************************************************
- * Shared state & exclusive ARC
- ****************************************************************************/
-
-struct ArcData<T> {
-    count:     libc::intptr_t,
-    // FIXME(#3224) should be able to make this non-option to save memory
-    data:      Option<T>,
+/// An atomically reference counted pointer.
+///
+/// Enforces no shared-memory safety.
+pub struct UnsafeAtomicRcBox<T> {
+    data: *mut libc::c_void,
 }
 
-struct ArcDestruct<T> {
-    data: *libc::c_void,
+struct AtomicRcBoxData<T> {
+    count: int,
+    data: Option<T>,
 }
 
-#[unsafe_destructor]
-impl<T> Drop for ArcDestruct<T>{
-    fn finalize(&self) {
+impl<T: Owned> UnsafeAtomicRcBox<T> {
+    pub fn new(data: T) -> UnsafeAtomicRcBox<T> {
         unsafe {
-            do task::unkillable {
-                let mut data: ~ArcData<T> = cast::transmute(self.data);
-                let new_count =
-                    intrinsics::atomic_xsub(&mut data.count, 1) - 1;
-                assert!(new_count >= 0);
-                if new_count == 0 {
-                    // drop glue takes over.
-                } else {
-                    cast::forget(data);
-                }
-            }
+            let data = ~AtomicRcBoxData { count: 1, data: Some(data) };
+            let ptr = cast::transmute(data);
+            return UnsafeAtomicRcBox { data: ptr };
         }
     }
-}
 
-fn ArcDestruct<T>(data: *libc::c_void) -> ArcDestruct<T> {
-    ArcDestruct {
-        data: data
+    #[inline(always)]
+    #[cfg(stage0)]
+    pub unsafe fn get(&self) -> *mut T
+    {
+        let mut data: ~AtomicRcBoxData<T> = cast::transmute(self.data);
+        assert!(data.count > 0);
+        let r: *mut T = cast::transmute(data.data.get_mut_ref());
+        cast::forget(data);
+        return r;
     }
-}
 
-/**
- * COMPLETELY UNSAFE. Used as a primitive for the safe versions in std::arc.
- *
- * Data races between tasks can result in crashes and, with sufficient
- * cleverness, arbitrary type coercion.
- */
-pub type SharedMutableState<T> = ArcDestruct<T>;
+    #[inline(always)]
+    #[cfg(not(stage0))]
+    pub unsafe fn get(&self) -> *mut T
+    {
+        let mut data: ~AtomicRcBoxData<T> = cast::transmute(self.data);
+        assert!(data.count > 0);
+        let r: *mut T = data.data.get_mut_ref();
+        cast::forget(data);
+        return r;
+    }
 
-pub unsafe fn shared_mutable_state<T:Owned>(data: T) ->
-        SharedMutableState<T> {
-    let data = ~ArcData { count: 1, data: Some(data) };
-    let ptr = cast::transmute(data);
-    ArcDestruct(ptr)
-}
+    #[inline(always)]
+    #[cfg(stage0)]
+    pub unsafe fn get_immut(&self) -> *T
+    {
+        let mut data: ~AtomicRcBoxData<T> = cast::transmute(self.data);
+        assert!(data.count > 0);
+        let r: *T = cast::transmute(data.data.get_mut_ref());
+        cast::forget(data);
+        return r;
+    }
 
-#[inline(always)]
-pub unsafe fn get_shared_mutable_state<T:Owned>(
-    rc: *SharedMutableState<T>) -> *mut T
-{
-    let ptr: ~ArcData<T> = cast::transmute((*rc).data);
-    assert!(ptr.count > 0);
-    let r = cast::transmute(ptr.data.get_ref());
-    cast::forget(ptr);
-    return r;
-}
-#[inline(always)]
-pub unsafe fn get_shared_immutable_state<'a,T:Owned>(
-        rc: &'a SharedMutableState<T>) -> &'a T {
-    let ptr: ~ArcData<T> = cast::transmute((*rc).data);
-    assert!(ptr.count > 0);
-    // Cast us back into the correct region
-    let r = cast::transmute_region(ptr.data.get_ref());
-    cast::forget(ptr);
-    return r;
+    #[inline(always)]
+    #[cfg(not(stage0))]
+    pub unsafe fn get_immut(&self) -> *T
+    {
+        let mut data: ~AtomicRcBoxData<T> = cast::transmute(self.data);
+        assert!(data.count > 0);
+        let r: *T = cast::transmute_immut(data.data.get_mut_ref());
+        cast::forget(data);
+        return r;
+    }
 }
 
-pub unsafe fn clone_shared_mutable_state<T:Owned>(rc: &SharedMutableState<T>)
-        -> SharedMutableState<T> {
-    let mut ptr: ~ArcData<T> = cast::transmute((*rc).data);
-    let new_count = intrinsics::atomic_xadd(&mut ptr.count, 1) + 1;
-    assert!(new_count >= 2);
-    cast::forget(ptr);
-    ArcDestruct((*rc).data)
+impl<T: Owned> Clone for UnsafeAtomicRcBox<T> {
+    fn clone(&self) -> UnsafeAtomicRcBox<T> {
+        unsafe {
+            let mut data: ~AtomicRcBoxData<T> = cast::transmute(self.data);
+            let new_count = intrinsics::atomic_xadd(&mut data.count, 1) + 1;
+            assert!(new_count >= 2);
+            cast::forget(data);
+            return UnsafeAtomicRcBox { data: self.data };
+        }
+    }
 }
 
-impl<T:Owned> Clone for SharedMutableState<T> {
-    fn clone(&self) -> SharedMutableState<T> {
+#[unsafe_destructor]
+impl<T> Drop for UnsafeAtomicRcBox<T>{
+    fn finalize(&self) {
         unsafe {
-            clone_shared_mutable_state(self)
+            do task::unkillable {
+                let mut data: ~AtomicRcBoxData<T> = cast::transmute(self.data);
+                let new_count = intrinsics::atomic_xsub(&mut data.count, 1) - 1;
+                assert!(new_count >= 0);
+                if new_count == 0 {
+                    // drop glue takes over.
+                } else {
+                    cast::forget(data);
+                }
+            }
         }
     }
 }
 
+
 /****************************************************************************/
 
 #[allow(non_camel_case_types)] // runtime type
@@ -160,7 +165,7 @@ struct ExData<T> {
  * An arc over mutable data that is protected by a lock. For library use only.
  */
 pub struct Exclusive<T> {
-    x: SharedMutableState<ExData<T>>
+    x: UnsafeAtomicRcBox<ExData<T>>
 }
 
 pub fn exclusive<T:Owned>(user_data: T) -> Exclusive<T> {
@@ -170,16 +175,14 @@ pub fn exclusive<T:Owned>(user_data: T) -> Exclusive<T> {
         data: user_data
     };
     Exclusive {
-        x: unsafe {
-            shared_mutable_state(data)
-        }
+        x: UnsafeAtomicRcBox::new(data)
     }
 }
 
 impl<T:Owned> Clone for Exclusive<T> {
     // Duplicate an exclusive ARC, as std::arc::clone.
     fn clone(&self) -> Exclusive<T> {
-        Exclusive { x: unsafe { clone_shared_mutable_state(&self.x) } }
+        Exclusive { x: self.x.clone() }
     }
 }
 
@@ -192,7 +195,7 @@ pub impl<T:Owned> Exclusive<T> {
     // the exclusive. Supporting that is a work in progress.
     #[inline(always)]
     unsafe fn with<U>(&self, f: &fn(x: &mut T) -> U) -> U {
-        let rec = get_shared_mutable_state(&self.x);
+        let rec = self.x.get();
         do (*rec).lock.lock {
             if (*rec).failed {
                 fail!(