Assorted fixes about tasks and selecting in libstd

src/libstd/cell.rs

@@ -13,6 +13,7 @@
 #[missing_doc];
 
 use cast::transmute_mut;
+use unstable::finally::Finally;
 use prelude::*;
 
 /*
@@ -65,18 +66,17 @@ impl<T> Cell<T> {
 
     /// Calls a closure with a reference to the value.
     pub fn with_ref<R>(&self, op: &fn(v: &T) -> R) -> R {
-        let v = self.take();
-        let r = op(&v);
-        self.put_back(v);
-        r
+        do self.with_mut_ref |ptr| { op(ptr) }
     }
 
     /// Calls a closure with a mutable reference to the value.
     pub fn with_mut_ref<R>(&self, op: &fn(v: &mut T) -> R) -> R {
-        let mut v = self.take();
-        let r = op(&mut v);
-        self.put_back(v);
-        r
+        let mut v = Some(self.take());
+        do (|| {
+            op(v.get_mut_ref())
+        }).finally {
+            self.put_back(v.take_unwrap());
+        }
     }
 }
 

src/libstd/rt/comm.rs

@@ -18,7 +18,8 @@ use kinds::Send;
 use rt;
 use rt::sched::Scheduler;
 use rt::local::Local;
-use rt::select::{Select, SelectPort};
+use rt::select::{SelectInner, SelectPortInner};
+use select::{Select, SelectPort};
 use unstable::atomics::{AtomicUint, AtomicOption, Acquire, Relaxed, SeqCst};
 use unstable::sync::UnsafeAtomicRcBox;
 use util::Void;
@@ -113,7 +114,9 @@ impl<T> ChanOne<T> {
     // 'do_resched' configures whether the scheduler immediately switches to
     // the receiving task, or leaves the sending task still running.
     fn try_send_inner(self, val: T, do_resched: bool) -> bool {
-        rtassert!(!rt::in_sched_context());
+        if do_resched {
+            rtassert!(!rt::in_sched_context());
+        }
 
         let mut this = self;
         let mut recvr_active = true;
@@ -215,7 +218,7 @@ impl<T> PortOne<T> {
     }
 }
 
-impl<T> Select for PortOne<T> {
+impl<T> SelectInner for PortOne<T> {
     #[inline] #[cfg(not(test))]
     fn optimistic_check(&mut self) -> bool {
         unsafe { (*self.packet()).state.load(Acquire) == STATE_ONE }
@@ -318,7 +321,9 @@ impl<T> Select for PortOne<T> {
     }
 }
 
-impl<T> SelectPort<T> for PortOne<T> {
+impl<T> Select for PortOne<T> { }
+
+impl<T> SelectPortInner<T> for PortOne<T> {
     fn recv_ready(self) -> Option<T> {
         let mut this = self;
         let packet = this.packet();
@@ -349,6 +354,8 @@ impl<T> SelectPort<T> for PortOne<T> {
     }
 }
 
+impl<T> SelectPort<T> for PortOne<T> { }
+
 impl<T> Peekable<T> for PortOne<T> {
     fn peek(&self) -> bool {
         unsafe {
@@ -513,7 +520,7 @@ impl<T> Peekable<T> for Port<T> {
 // of them, but a &Port<T> should also be selectable so you can select2 on it
 // alongside a PortOne<U> without passing the port by value in recv_ready.
 
-impl<'self, T> Select for &'self Port<T> {
+impl<'self, T> SelectInner for &'self Port<T> {
     #[inline]
     fn optimistic_check(&mut self) -> bool {
         do self.next.with_mut_ref |pone| { pone.optimistic_check() }
@@ -531,7 +538,9 @@ impl<'self, T> Select for &'self Port<T> {
     }
 }
 
-impl<T> Select for Port<T> {
+impl<'self, T> Select for &'self Port<T> { }
+
+impl<T> SelectInner for Port<T> {
     #[inline]
     fn optimistic_check(&mut self) -> bool {
         (&*self).optimistic_check()
@@ -548,7 +557,9 @@ impl<T> Select for Port<T> {
     }
 }
 
-impl<'self, T> SelectPort<T> for &'self Port<T> {
+impl<T> Select for Port<T> { }
+
+impl<'self, T> SelectPortInner<T> for &'self Port<T> {
     fn recv_ready(self) -> Option<T> {
         match self.next.take().recv_ready() {
             Some(StreamPayload { val, next }) => {
@@ -560,6 +571,8 @@ impl<'self, T> SelectPort<T> for &'self Port<T> {
     }
 }
 
+impl<'self, T> SelectPort<T> for &'self Port<T> { }
+
 pub struct SharedChan<T> {
     // Just like Chan, but a shared AtomicOption instead of Cell
     priv next: UnsafeAtomicRcBox<AtomicOption<StreamChanOne<T>>>

src/libstd/rt/kill.rs

@@ -488,8 +488,8 @@ impl Death {
         rtassert!(self.unkillable == 0);
         self.unkillable = 1;
 
-        // FIXME(#7544): See corresponding fixme at the callsite in task.rs.
-        // NB(#8192): Doesn't work with "let _ = ..."
+        // NB. See corresponding comment at the callsite in task.rs.
+        // FIXME(#8192): Doesn't work with "let _ = ..."
         { use util; util::ignore(group); }
 
         // Step 1. Decide if we need to collect child failures synchronously.

src/libstd/rt/mod.rs

@@ -142,8 +142,7 @@ pub mod tube;
 /// Simple reimplementation of core::comm
 pub mod comm;
 
-/// Routines for select()ing on pipes.
-pub mod select;
+mod select;
 
 // FIXME #5248 shouldn't be pub
 /// The runtime needs to be able to put a pointer into thread-local storage.