Thread fixes + module update

1 files changed, 197 insertions, 72 deletions

diff --git a/ctr-std/src/thread/local.rs b/ctr-std/src/thread/local.rs
index 5166ddf..0172f89 100644
--- a/ctr-std/src/thread/local.rs
+++ b/ctr-std/src/thread/local.rs
@@ -19,17 +19,17 @@ use mem;
 /// A thread local storage key which owns its contents.
 ///
 /// This key uses the fastest possible implementation available to it for the
-/// target platform. It is instantiated with the `thread_local!` macro and the
-/// primary method is the `with` method.
+/// target platform. It is instantiated with the [`thread_local!`] macro and the
+/// primary method is the [`with`] method.
 ///
-/// The `with` method yields a reference to the contained value which cannot be
+/// The [`with`] method yields a reference to the contained value which cannot be
 /// sent across threads or escape the given closure.
 ///
 /// # Initialization and Destruction
 ///
-/// Initialization is dynamically performed on the first call to `with()`
-/// within a thread, and values support destructors which will be run when a
-/// thread exits.
+/// Initialization is dynamically performed on the first call to [`with`]
+/// within a thread, and values that implement [`Drop`] get destructed when a
+/// thread exits. Some caveats apply, which are explained below.
 ///
 /// # Examples
 ///
@@ -74,9 +74,13 @@ use mem;
 ///    destroyed, but not all platforms have this guard. Those platforms that do
 ///    not guard typically have a synthetic limit after which point no more
 ///    destructors are run.
-/// 3. On OSX, initializing TLS during destruction of other TLS slots can
+/// 3. On macOS, initializing TLS during destruction of other TLS slots can
 ///    sometimes cancel *all* destructors for the current thread, whether or not
 ///    the slots have already had their destructors run or not.
+///
+/// [`with`]: ../../std/thread/struct.LocalKey.html#method.with
+/// [`thread_local!`]: ../../std/macro.thread_local.html
+/// [`Drop`]: ../../std/ops/trait.Drop.html
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct LocalKey<T: 'static> {
     // This outer `LocalKey<T>` type is what's going to be stored in statics,
@@ -106,12 +110,12 @@ impl<T: 'static> fmt::Debug for LocalKey<T> {
     }
 }
 
-/// Declare a new thread local storage key of type `std::thread::LocalKey`.
+/// Declare a new thread local storage key of type [`std::thread::LocalKey`].
 ///
 /// # Syntax
 ///
 /// The macro wraps any number of static declarations and makes them thread local.
-/// Each static may be public or private, and attributes are allowed. Example:
+/// Publicity and attributes for each static are allowed. Example:
 ///
 /// ```
 /// use std::cell::RefCell;
@@ -124,37 +128,26 @@ impl<T: 'static> fmt::Debug for LocalKey<T> {
 /// # fn main() {}
 /// ```
 ///
-/// See [LocalKey documentation](thread/struct.LocalKey.html) for more
+/// See [LocalKey documentation][`std::thread::LocalKey`] for more
 /// information.
+///
+/// [`std::thread::LocalKey`]: ../std/thread/struct.LocalKey.html
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[allow_internal_unstable]
 macro_rules! thread_local {
-    // rule 0: empty (base case for the recursion)
+    // empty (base case for the recursion)
     () => {};
 
-    // rule 1: process multiple declarations where the first one is private
-    ($(#[$attr:meta])* static $name:ident: $t:ty = $init:expr; $($rest:tt)*) => (
-        thread_local!($(#[$attr])* static $name: $t = $init); // go to rule 2
-        thread_local!($($rest)*);
-    );
-
-    // rule 2: handle a single private declaration
-    ($(#[$attr:meta])* static $name:ident: $t:ty = $init:expr) => (
-        $(#[$attr])* static $name: $crate::thread::LocalKey<$t> =
-            __thread_local_inner!($t, $init);
-    );
-
-    // rule 3: handle multiple declarations where the first one is public
-    ($(#[$attr:meta])* pub static $name:ident: $t:ty = $init:expr; $($rest:tt)*) => (
-        thread_local!($(#[$attr])* pub static $name: $t = $init); // go to rule 4
+    // process multiple declarations
+    ($(#[$attr:meta])* $vis:vis static $name:ident: $t:ty = $init:expr; $($rest:tt)*) => (
+        __thread_local_inner!($(#[$attr])* $vis $name, $t, $init);
         thread_local!($($rest)*);
     );
 
-    // rule 4: handle a single public declaration
-    ($(#[$attr:meta])* pub static $name:ident: $t:ty = $init:expr) => (
-        $(#[$attr])* pub static $name: $crate::thread::LocalKey<$t> =
-            __thread_local_inner!($t, $init);
+    // handle a single declaration
+    ($(#[$attr:meta])* $vis:vis static $name:ident: $t:ty = $init:expr) => (
+        __thread_local_inner!($(#[$attr])* $vis $name, $t, $init);
     );
 }
 
@@ -165,27 +158,29 @@ macro_rules! thread_local {
 #[macro_export]
 #[allow_internal_unstable]
 macro_rules! __thread_local_inner {
-    ($t:ty, $init:expr) => {{
-        fn __init() -> $t { $init }
-
-        fn __getit() -> $crate::option::Option<
-            &'static $crate::cell::UnsafeCell<
-                $crate::option::Option<$t>>>
-        {
-            #[thread_local]
-            #[cfg(target_thread_local)]
-            static __KEY: $crate::thread::__FastLocalKeyInner<$t> =
-                $crate::thread::__FastLocalKeyInner::new();
-
-            #[cfg(not(target_thread_local))]
-            static __KEY: $crate::thread::__OsLocalKeyInner<$t> =
-                $crate::thread::__OsLocalKeyInner::new();
-
-            __KEY.get()
-        }
+    ($(#[$attr:meta])* $vis:vis $name:ident, $t:ty, $init:expr) => {
+        $(#[$attr])* $vis static $name: $crate::thread::LocalKey<$t> = {
+            fn __init() -> $t { $init }
+
+            fn __getit() -> $crate::option::Option<
+                &'static $crate::cell::UnsafeCell<
+                    $crate::option::Option<$t>>>
+            {
+                #[thread_local]
+                #[cfg(target_thread_local)]
+                static __KEY: $crate::thread::__FastLocalKeyInner<$t> =
+                    $crate::thread::__FastLocalKeyInner::new();
+
+                #[cfg(not(target_thread_local))]
+                static __KEY: $crate::thread::__OsLocalKeyInner<$t> =
+                    $crate::thread::__OsLocalKeyInner::new();
+
+                __KEY.get()
+            }
 
-        $crate::thread::LocalKey::new(__getit, __init)
-    }}
+            $crate::thread::LocalKey::new(__getit, __init)
+        };
+    }
 }
 
 /// Indicator of the state of a thread local storage key.
@@ -195,11 +190,13 @@ macro_rules! __thread_local_inner {
 #[derive(Debug, Eq, PartialEq, Copy, Clone)]
 pub enum LocalKeyState {
     /// All keys are in this state whenever a thread starts. Keys will
-    /// transition to the `Valid` state once the first call to `with` happens
+    /// transition to the `Valid` state once the first call to [`with`] happens
     /// and the initialization expression succeeds.
     ///
     /// Keys in the `Uninitialized` state will yield a reference to the closure
-    /// passed to `with` so long as the initialization routine does not panic.
+    /// passed to [`with`] so long as the initialization routine does not panic.
+    ///
+    /// [`with`]: ../../std/thread/struct.LocalKey.html#method.with
     Uninitialized,
 
     /// Once a key has been accessed successfully, it will enter the `Valid`
@@ -208,7 +205,9 @@ pub enum LocalKeyState {
     /// `Destroyed` state.
     ///
     /// Keys in the `Valid` state will be guaranteed to yield a reference to the
-    /// closure passed to `with`.
+    /// closure passed to [`with`].
+    ///
+    /// [`with`]: ../../std/thread/struct.LocalKey.html#method.with
     Valid,
 
     /// When a thread exits, the destructors for keys will be run (if
@@ -216,10 +215,38 @@ pub enum LocalKeyState {
     /// destructor has run, a key is in the `Destroyed` state.
     ///
     /// Keys in the `Destroyed` states will trigger a panic when accessed via
-    /// `with`.
+    /// [`with`].
+    ///
+    /// [`with`]: ../../std/thread/struct.LocalKey.html#method.with
     Destroyed,
 }
 
+/// An error returned by [`LocalKey::try_with`](struct.LocalKey.html#method.try_with).
+#[unstable(feature = "thread_local_state",
+           reason = "state querying was recently added",
+           issue = "27716")]
+pub struct AccessError {
+    _private: (),
+}
+
+#[unstable(feature = "thread_local_state",
+           reason = "state querying was recently added",
+           issue = "27716")]
+impl fmt::Debug for AccessError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("AccessError").finish()
+    }
+}
+
+#[unstable(feature = "thread_local_state",
+           reason = "state querying was recently added",
+           issue = "27716")]
+impl fmt::Display for AccessError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Display::fmt("already destroyed", f)
+    }
+}
+
 impl<T: 'static> LocalKey<T> {
     #[doc(hidden)]
     #[unstable(feature = "thread_local_internals",
@@ -246,15 +273,8 @@ impl<T: 'static> LocalKey<T> {
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with<F, R>(&'static self, f: F) -> R
                       where F: FnOnce(&T) -> R {
-        unsafe {
-            let slot = (self.inner)();
-            let slot = slot.expect("cannot access a TLS value during or \
-                                    after it is destroyed");
-            f(match *slot.get() {
-                Some(ref inner) => inner,
-                None => self.init(slot),
-            })
-        }
+        self.try_with(f).expect("cannot access a TLS value during or \
+                                 after it is destroyed")
     }
 
     unsafe fn init(&self, slot: &UnsafeCell<Option<T>>) -> &T {
@@ -283,23 +303,26 @@ impl<T: 'static> LocalKey<T> {
     /// Query the current state of this key.
     ///
     /// A key is initially in the `Uninitialized` state whenever a thread
-    /// starts. It will remain in this state up until the first call to `with`
+    /// starts. It will remain in this state up until the first call to [`with`]
     /// within a thread has run the initialization expression successfully.
     ///
     /// Once the initialization expression succeeds, the key transitions to the
-    /// `Valid` state which will guarantee that future calls to `with` will
+    /// `Valid` state which will guarantee that future calls to [`with`] will
     /// succeed within the thread.
     ///
     /// When a thread exits, each key will be destroyed in turn, and as keys are
     /// destroyed they will enter the `Destroyed` state just before the
     /// destructor starts to run. Keys may remain in the `Destroyed` state after
     /// destruction has completed. Keys without destructors (e.g. with types
-    /// that are `Copy`), may never enter the `Destroyed` state.
+    /// that are [`Copy`]), may never enter the `Destroyed` state.
     ///
     /// Keys in the `Uninitialized` state can be accessed so long as the
     /// initialization does not panic. Keys in the `Valid` state are guaranteed
     /// to be able to be accessed. Keys in the `Destroyed` state will panic on
-    /// any call to `with`.
+    /// any call to [`with`].
+    ///
+    /// [`with`]: ../../std/thread/struct.LocalKey.html#method.with
+    /// [`Copy`]: ../../std/marker/trait.Copy.html
     #[unstable(feature = "thread_local_state",
                reason = "state querying was recently added",
                issue = "27716")]
@@ -316,6 +339,108 @@ impl<T: 'static> LocalKey<T> {
             }
         }
     }
+
+    /// Acquires a reference to the value in this TLS key.
+    ///
+    /// This will lazily initialize the value if this thread has not referenced
+    /// this key yet. If the key has been destroyed (which may happen if this is called
+    /// in a destructor), this function will return a ThreadLocalError.
+    ///
+    /// # Panics
+    ///
+    /// This function will still `panic!()` if the key is uninitialized and the
+    /// key's initializer panics.
+    #[unstable(feature = "thread_local_state",
+               reason = "state querying was recently added",
+               issue = "27716")]
+    pub fn try_with<F, R>(&'static self, f: F) -> Result<R, AccessError>
+                      where F: FnOnce(&T) -> R {
+        unsafe {
+            let slot = (self.inner)().ok_or(AccessError {
+                _private: (),
+            })?;
+            Ok(f(match *slot.get() {
+                Some(ref inner) => inner,
+                None => self.init(slot),
+            }))
+        }
+    }
+}
+
+#[doc(hidden)]
+#[cfg(target_thread_local)]
+pub mod fast {
+    use cell::{Cell, UnsafeCell};
+    use fmt;
+    use mem;
+    use ptr;
+    use sys::fast_thread_local::{register_dtor, requires_move_before_drop};
+
+    pub struct Key<T> {
+        inner: UnsafeCell<Option<T>>,
+
+        // Metadata to keep track of the state of the destructor. Remember that
+        // these variables are thread-local, not global.
+        dtor_registered: Cell<bool>,
+        dtor_running: Cell<bool>,
+    }
+
+    impl<T> fmt::Debug for Key<T> {
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+            f.pad("Key { .. }")
+        }
+    }
+
+    unsafe impl<T> ::marker::Sync for Key<T> { }
+
+    impl<T> Key<T> {
+        pub const fn new() -> Key<T> {
+            Key {
+                inner: UnsafeCell::new(None),
+                dtor_registered: Cell::new(false),
+                dtor_running: Cell::new(false)
+            }
+        }
+
+        pub fn get(&'static self) -> Option<&'static UnsafeCell<Option<T>>> {
+            unsafe {
+                if mem::needs_drop::<T>() && self.dtor_running.get() {
+                    return None
+                }
+                self.register_dtor();
+            }
+            Some(&self.inner)
+        }
+
+        unsafe fn register_dtor(&self) {
+            if !mem::needs_drop::<T>() || self.dtor_registered.get() {
+                return
+            }
+
+            register_dtor(self as *const _ as *mut u8,
+                          destroy_value::<T>);
+            self.dtor_registered.set(true);
+        }
+    }
+
+    unsafe extern fn destroy_value<T>(ptr: *mut u8) {
+        let ptr = ptr as *mut Key<T>;
+        // Right before we run the user destructor be sure to flag the
+        // destructor as running for this thread so calls to `get` will return
+        // `None`.
+        (*ptr).dtor_running.set(true);
+
+        // Some implementations may require us to move the value before we drop
+        // it as it could get re-initialized in-place during destruction.
+        //
+        // Hence, we use `ptr::read` on those platforms (to move to a "safe"
+        // location) instead of drop_in_place.
+        if requires_move_before_drop() {
+            ptr::read((*ptr).inner.get());
+        } else {
+            ptr::drop_in_place((*ptr).inner.get());
+        }
+    }
 }
 
 #[doc(hidden)]
@@ -363,8 +488,8 @@ pub mod os {
                     return Some(&(*ptr).value);
                 }
 
-                // If the lookup returned null, we haven't initialized our own local
-                // copy, so do that now.
+                // If the lookup returned null, we haven't initialized our own
+                // local copy, so do that now.
                 let ptr: Box<Value<T>> = box Value {
                     key: self,
                     value: UnsafeCell::new(None),
@@ -376,7 +501,7 @@ pub mod os {
         }
     }
 
-    pub unsafe extern fn destroy_value<T: 'static>(ptr: *mut u8) {
+    unsafe extern fn destroy_value<T: 'static>(ptr: *mut u8) {
         // The OS TLS ensures that this key contains a NULL value when this
         // destructor starts to run. We set it back to a sentinel value of 1 to
         // ensure that any future calls to `get` for this thread will return
@@ -524,9 +649,9 @@ mod tests {
     }
 
     // Note that this test will deadlock if TLS destructors aren't run (this
-    // requires the destructor to be run to pass the test). OSX has a known bug
+    // requires the destructor to be run to pass the test). macOS has a known bug
     // where dtors-in-dtors may cancel other destructors, so we just ignore this
-    // test on OSX.
+    // test on macOS.
     #[test]
     #[cfg_attr(target_os = "macos", ignore)]
     fn dtors_in_dtors_in_dtors() {