std: Second pass stabilization of sync

This pass performs a second pass of stabilization through the `std::sync`
module, avoiding modules/types that are being handled in other PRs (e.g.
mutexes, rwlocks, condvars, and channels).

The following items are now stable

* `sync::atomic`
* `sync::atomic::ATOMIC_BOOL_INIT` (was `INIT_ATOMIC_BOOL`)
* `sync::atomic::ATOMIC_INT_INIT` (was `INIT_ATOMIC_INT`)
* `sync::atomic::ATOMIC_UINT_INIT` (was `INIT_ATOMIC_UINT`)
* `sync::Once`
* `sync::ONCE_INIT`
* `sync::Once::call_once` (was `doit`)
  * C == `pthread_once(..)`
  * Boost == `call_once(..)`
  * Windows == `InitOnceExecuteOnce`
* `sync::Barrier`
* `sync::Barrier::new`
* `sync::Barrier::wait` (now returns a `bool`)
* `sync::Semaphore::new`
* `sync::Semaphore::acquire`
* `sync::Semaphore::release`

The following items remain unstable

* `sync::SemaphoreGuard`
* `sync::Semaphore::access` - it's unclear how this relates to the poisoning
                              story of mutexes.
* `sync::TaskPool` - the semantics of a failing task and whether a thread is
                     re-attached to a thread pool are somewhat unclear, and the
                     utility of this type in `sync` is question with respect to
                     the jobs of other primitives. This type will likely become
                     stable or move out of the standard library over time.
* `sync::Future` - futures as-is have yet to be deeply re-evaluated with the
                   recent core changes to Rust's synchronization story, and will
                   likely become stable in the future but are unstable until
                   that time comes.

[breaking-change]

4 files changed, 12 insertions, 131 deletions

diff --git a/src/libstd/rt/backtrace.rs b/src/libstd/rt/backtrace.rs
index 3eeb0ad3968..0b69486129a 100644
--- a/src/libstd/rt/backtrace.rs
+++ b/src/libstd/rt/backtrace.rs
@@ -22,7 +22,7 @@ pub use sys::backtrace::write;
 // For now logging is turned off by default, and this function checks to see
 // whether the magical environment variable is present to see if it's turned on.
 pub fn log_enabled() -> bool {
-    static ENABLED: atomic::AtomicInt = atomic::INIT_ATOMIC_INT;
+    static ENABLED: atomic::AtomicInt = atomic::ATOMIC_INT_INIT;
     match ENABLED.load(atomic::SeqCst) {
         1 => return false,
         2 => return true,
diff --git a/src/libstd/rt/exclusive.rs b/src/libstd/rt/exclusive.rs
deleted file mode 100644
index 88bdb29caec..00000000000
--- a/src/libstd/rt/exclusive.rs
+++ /dev/null
@@ -1,119 +0,0 @@
-// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-use core::prelude::*;
-
-use cell::UnsafeCell;
-use rt::mutex;
-
-/// An OS mutex over some data.
-///
-/// This is not a safe primitive to use, it is unaware of the libgreen
-/// scheduler, as well as being easily susceptible to misuse due to the usage of
-/// the inner NativeMutex.
-///
-/// > **Note**: This type is not recommended for general use. The mutex provided
-/// >           as part of `libsync` should almost always be favored.
-pub struct Exclusive<T> {
-    lock: mutex::NativeMutex,
-    data: UnsafeCell<T>,
-}
-
-unsafe impl<T:Send> Send for Exclusive<T> { }
-
-unsafe impl<T:Send> Sync for Exclusive<T> { }
-
-/// An RAII guard returned via `lock`
-pub struct ExclusiveGuard<'a, T:'a> {
-    // FIXME #12808: strange name to try to avoid interfering with
-    // field accesses of the contained type via Deref
-    _data: &'a mut T,
-    _guard: mutex::LockGuard<'a>,
-}
-
-impl<T: Send> Exclusive<T> {
-    /// Creates a new `Exclusive` which will protect the data provided.
-    pub fn new(user_data: T) -> Exclusive<T> {
-        Exclusive {
-            lock: unsafe { mutex::NativeMutex::new() },
-            data: UnsafeCell::new(user_data),
-        }
-    }
-
-    /// Acquires this lock, returning a guard which the data is accessed through
-    /// and from which that lock will be unlocked.
-    ///
-    /// This method is unsafe due to many of the same reasons that the
-    /// NativeMutex itself is unsafe.
-    pub unsafe fn lock<'a>(&'a self) -> ExclusiveGuard<'a, T> {
-        let guard = self.lock.lock();
-        let data = &mut *self.data.get();
-
-        ExclusiveGuard {
-            _data: data,
-            _guard: guard,
-        }
-    }
-}
-
-impl<'a, T: Send> ExclusiveGuard<'a, T> {
-    // The unsafety here should be ok because our loan guarantees that the lock
-    // itself is not moving
-    pub fn signal(&self) {
-        unsafe { self._guard.signal() }
-    }
-    pub fn wait(&self) {
-        unsafe { self._guard.wait() }
-    }
-}
-
-impl<'a, T: Send> Deref<T> for ExclusiveGuard<'a, T> {
-    fn deref(&self) -> &T { &*self._data }
-}
-impl<'a, T: Send> DerefMut<T> for ExclusiveGuard<'a, T> {
-    fn deref_mut(&mut self) -> &mut T { &mut *self._data }
-}
-
-#[cfg(test)]
-mod tests {
-    use prelude::*;
-    use sync::Arc;
-    use super::Exclusive;
-    use task;
-
-    #[test]
-    fn exclusive_new_arc() {
-        unsafe {
-            let mut futures = Vec::new();
-
-            let num_tasks = 10;
-            let count = 10;
-
-            let total = Arc::new(Exclusive::new(box 0));
-
-            for _ in range(0u, num_tasks) {
-                let total = total.clone();
-                let (tx, rx) = channel();
-                futures.push(rx);
-
-                task::spawn(move || {
-                    for _ in range(0u, count) {
-                        **total.lock() += 1;
-                    }
-                    tx.send(());
-                });
-            };
-
-            for f in futures.iter_mut() { f.recv() }
-
-            assert_eq!(**total.lock(), num_tasks * count);
-        }
-    }
-}
diff --git a/src/libstd/rt/unwind.rs b/src/libstd/rt/unwind.rs
index e0c512706e6..a6063d0b609 100644
--- a/src/libstd/rt/unwind.rs
+++ b/src/libstd/rt/unwind.rs
@@ -84,15 +84,15 @@ pub type Callback = fn(msg: &(Any + Send), file: &'static str, line: uint);
 // For more information, see below.
 const MAX_CALLBACKS: uint = 16;
 static CALLBACKS: [atomic::AtomicUint; MAX_CALLBACKS] =
-        [atomic::INIT_ATOMIC_UINT, atomic::INIT_ATOMIC_UINT,
-         atomic::INIT_ATOMIC_UINT, atomic::INIT_ATOMIC_UINT,
-         atomic::INIT_ATOMIC_UINT, atomic::INIT_ATOMIC_UINT,
-         atomic::INIT_ATOMIC_UINT, atomic::INIT_ATOMIC_UINT,
-         atomic::INIT_ATOMIC_UINT, atomic::INIT_ATOMIC_UINT,
-         atomic::INIT_ATOMIC_UINT, atomic::INIT_ATOMIC_UINT,
-         atomic::INIT_ATOMIC_UINT, atomic::INIT_ATOMIC_UINT,
-         atomic::INIT_ATOMIC_UINT, atomic::INIT_ATOMIC_UINT];
-static CALLBACK_CNT: atomic::AtomicUint = atomic::INIT_ATOMIC_UINT;
+        [atomic::ATOMIC_UINT_INIT, atomic::ATOMIC_UINT_INIT,
+         atomic::ATOMIC_UINT_INIT, atomic::ATOMIC_UINT_INIT,
+         atomic::ATOMIC_UINT_INIT, atomic::ATOMIC_UINT_INIT,
+         atomic::ATOMIC_UINT_INIT, atomic::ATOMIC_UINT_INIT,
+         atomic::ATOMIC_UINT_INIT, atomic::ATOMIC_UINT_INIT,
+         atomic::ATOMIC_UINT_INIT, atomic::ATOMIC_UINT_INIT,
+         atomic::ATOMIC_UINT_INIT, atomic::ATOMIC_UINT_INIT,
+         atomic::ATOMIC_UINT_INIT, atomic::ATOMIC_UINT_INIT];
+static CALLBACK_CNT: atomic::AtomicUint = atomic::ATOMIC_UINT_INIT;
 
 thread_local! { static PANICKING: Cell<bool> = Cell::new(false) }
 
@@ -544,7 +544,7 @@ fn begin_unwind_inner(msg: Box<Any + Send>, file_line: &(&'static str, uint)) ->
     // Make sure the default failure handler is registered before we look at the
     // callbacks.
     static INIT: Once = ONCE_INIT;
-    INIT.doit(|| unsafe { register(failure::on_fail); });
+    INIT.call_once(|| unsafe { register(failure::on_fail); });
 
     // First, invoke call the user-defined callbacks triggered on thread panic.
     //
diff --git a/src/libstd/rt/util.rs b/src/libstd/rt/util.rs
index fee86e33455..d66d8d52be9 100644
--- a/src/libstd/rt/util.rs
+++ b/src/libstd/rt/util.rs
@@ -47,7 +47,7 @@ pub fn limit_thread_creation_due_to_osx_and_valgrind() -> bool {
 }
 
 pub fn min_stack() -> uint {
-    static MIN: atomic::AtomicUint = atomic::INIT_ATOMIC_UINT;
+    static MIN: atomic::AtomicUint = atomic::ATOMIC_UINT_INIT;
     match MIN.load(atomic::SeqCst) {
         0 => {}
         n => return n - 1,