libcore: Remove mutable fields from pipes

src/libcore/comm.rs

@@ -12,6 +12,7 @@
 Message passing
 */
 
+use cast::transmute;
 use cast;
 use either::{Either, Left, Right};
 use kinds::Owned;
@@ -192,9 +193,9 @@ impl<T: Owned> Peekable<T> for Port<T> {
     fn peek(&self) -> bool {
         let mut endp = None;
         endp <-> self.endp;
-        let peek = match &endp {
-            &Some(ref endp) => peek(endp),
-            &None => fail!(~"peeking empty stream")
+        let peek = match endp {
+            Some(ref mut endp) => peek(endp),
+            None => fail!(~"peeking empty stream")
         };
         self.endp <-> endp;
         peek
@@ -202,10 +203,10 @@ fn peek(&self) -> bool {
 }
 
 impl<T: Owned> Selectable for Port<T> {
-    fn header(&self) -> *PacketHeader {
+    fn header(&mut self) -> *mut PacketHeader {
         unsafe {
             match self.endp {
-                Some(ref endp) => endp.header(),
+                Some(ref mut endp) => endp.header(),
                 None => fail!(~"peeking empty stream")
             }
         }
@@ -327,23 +328,20 @@ fn clone(&self) -> SharedChan<T> {
 #[allow(non_camel_case_types)]
 pub mod oneshot {
     priv use core::kinds::Owned;
-    use ptr::to_unsafe_ptr;
+    use ptr::to_mut_unsafe_ptr;
 
     pub fn init<T: Owned>() -> (client::Oneshot<T>, server::Oneshot<T>) {
         pub use core::pipes::HasBuffer;
 
-        let buffer =
-            ~::core::pipes::Buffer{
+        let mut buffer = ~::core::pipes::Buffer {
             header: ::core::pipes::BufferHeader(),
-            data: __Buffer{
+            data: __Buffer {
                 Oneshot: ::core::pipes::mk_packet::<Oneshot<T>>()
             },
         };
         do ::core::pipes::entangle_buffer(buffer) |buffer, data| {
-            {
-                data.Oneshot.set_buffer(buffer);
-                to_unsafe_ptr(&data.Oneshot)
-            }
+            data.Oneshot.set_buffer(buffer);
+            to_mut_unsafe_ptr(&mut data.Oneshot)
         }
     }
     #[allow(non_camel_case_types)]
@@ -497,48 +495,66 @@ pub fn try_send_one<T: Owned>(chan: ChanOne<T>, data: T) -> bool {
 
 
 /// Returns the index of an endpoint that is ready to receive.
-pub fn selecti<T: Selectable>(endpoints: &[T]) -> uint {
+pub fn selecti<T: Selectable>(endpoints: &mut [T]) -> uint {
     wait_many(endpoints)
 }
 
 /// Returns 0 or 1 depending on which endpoint is ready to receive
-pub fn select2i<A: Selectable, B: Selectable>(a: &A, b: &B) ->
-        Either<(), ()> {
-    match wait_many([a.header(), b.header()]) {
-      0 => Left(()),
-      1 => Right(()),
-      _ => fail!(~"wait returned unexpected index")
+pub fn select2i<A:Selectable, B:Selectable>(a: &mut A, b: &mut B)
+                                            -> Either<(), ()> {
+    let mut endpoints = [ a.header(), b.header() ];
+    match wait_many(endpoints) {
+        0 => Left(()),
+        1 => Right(()),
+        _ => fail!(~"wait returned unexpected index"),
     }
 }
 
 /// Receive a message from one of two endpoints.
 pub trait Select2<T: Owned, U: Owned> {
     /// Receive a message or return `None` if a connection closes.
-    fn try_select(&self) -> Either<Option<T>, Option<U>>;
+    fn try_select(&mut self) -> Either<Option<T>, Option<U>>;
     /// Receive a message or fail if a connection closes.
-    fn select(&self) -> Either<T, U>;
+    fn select(&mut self) -> Either<T, U>;
 }
 
-impl<T: Owned, U: Owned,
-     Left: Selectable + GenericPort<T>,
-     Right: Selectable + GenericPort<U>>
-    Select2<T, U> for (Left, Right) {
-
-    fn select(&self) -> Either<T, U> {
-        match *self {
-          (ref lp, ref rp) => match select2i(lp, rp) {
-            Left(()) => Left (lp.recv()),
-            Right(()) => Right(rp.recv())
-          }
+impl<T:Owned,
+     U:Owned,
+     Left:Selectable + GenericPort<T>,
+     Right:Selectable + GenericPort<U>>
+     Select2<T, U>
+     for (Left, Right) {
+    fn select(&mut self) -> Either<T, U> {
+        // XXX: Bad borrow check workaround.
+        unsafe {
+            let this: &(Left, Right) = transmute(self);
+            match *this {
+                (ref lp, ref rp) => {
+                    let lp: &mut Left = transmute(lp);
+                    let rp: &mut Right = transmute(rp);
+                    match select2i(lp, rp) {
+                        Left(()) => Left(lp.recv()),
+                        Right(()) => Right(rp.recv()),
+                    }
+                }
+            }
         }
     }
 
-    fn try_select(&self) -> Either<Option<T>, Option<U>> {
-        match *self {
-          (ref lp, ref rp) => match select2i(lp, rp) {
-            Left(()) => Left (lp.try_recv()),
-            Right(()) => Right(rp.try_recv())
-          }
+    fn try_select(&mut self) -> Either<Option<T>, Option<U>> {
+        // XXX: Bad borrow check workaround.
+        unsafe {
+            let this: &(Left, Right) = transmute(self);
+            match *this {
+                (ref lp, ref rp) => {
+                    let lp: &mut Left = transmute(lp);
+                    let rp: &mut Right = transmute(rp);
+                    match select2i(lp, rp) {
+                        Left(()) => Left (lp.try_recv()),
+                        Right(()) => Right(rp.try_recv()),
+                    }
+                }
+            }
         }
     }
 }

src/libcore/pipes.rs

@@ -111,7 +111,7 @@ enum State {
 pub struct BufferHeader {
     // Tracks whether this buffer needs to be freed. We can probably
     // get away with restricting it to 0 or 1, if we're careful.
-    mut ref_count: int,
+    ref_count: int,
 
     // We may want a drop, and to be careful about stringing this
     // thing along.
@@ -130,12 +130,12 @@ pub struct Buffer<T> {
 }
 
 pub struct PacketHeader {
-    mut state: State,
-    mut blocked_task: *rust_task,
+    state: State,
+    blocked_task: *rust_task,
 
     // This is a transmute_copy of a ~buffer, that can also be cast
     // to a buffer_header if need be.
-    mut buffer: *libc::c_void,
+    buffer: *libc::c_void,
 }
 
 pub fn PacketHeader() -> PacketHeader {
@@ -148,14 +148,14 @@ pub fn PacketHeader() -> PacketHeader {
 
 pub impl PacketHeader {
     // Returns the old state.
-    unsafe fn mark_blocked(&self, this: *rust_task) -> State {
+    unsafe fn mark_blocked(&mut self, this: *rust_task) -> State {
         rustrt::rust_task_ref(this);
         let old_task = swap_task(&mut self.blocked_task, this);
         assert!(old_task.is_null());
         swap_state_acq(&mut self.state, Blocked)
     }
 
-    unsafe fn unblock(&self) {
+    unsafe fn unblock(&mut self) {
         let old_task = swap_task(&mut self.blocked_task, ptr::null());
         if !old_task.is_null() {
             rustrt::rust_task_deref(old_task)
@@ -169,13 +169,13 @@ unsafe fn unblock(&self) {
 
     // unsafe because this can do weird things to the space/time
     // continuum. It ends making multiple unique pointers to the same
-    // thing. You'll proobably want to forget them when you're done.
-    unsafe fn buf_header(&self) -> ~BufferHeader {
+    // thing. You'll probably want to forget them when you're done.
+    unsafe fn buf_header(&mut self) -> ~BufferHeader {
         assert!(self.buffer.is_not_null());
         transmute_copy(&self.buffer)
     }
 
-    fn set_buffer<T:Owned>(&self, b: ~Buffer<T>) {
+    fn set_buffer<T:Owned>(&mut self, b: ~Buffer<T>) {
         unsafe {
             self.buffer = transmute_copy(&b);
         }
@@ -184,15 +184,15 @@ fn set_buffer<T:Owned>(&self, b: ~Buffer<T>) {
 
 pub struct Packet<T> {
     header: PacketHeader,
-    mut payload: Option<T>,
+    payload: Option<T>,
 }
 
 pub trait HasBuffer {
-    fn set_buffer(&self, b: *libc::c_void);
+    fn set_buffer(&mut self, b: *libc::c_void);
 }
 
 impl<T:Owned> HasBuffer for Packet<T> {
-    fn set_buffer(&self, b: *libc::c_void) {
+    fn set_buffer(&mut self, b: *libc::c_void) {
         self.header.buffer = b;
     }
 }
@@ -204,7 +204,7 @@ pub fn mk_packet<T:Owned>() -> Packet<T> {
     }
 }
 fn unibuffer<T>() -> ~Buffer<Packet<T>> {
-    let b = ~Buffer {
+    let mut b = ~Buffer {
         header: BufferHeader(),
         data: Packet {
             header: PacketHeader(),
@@ -218,22 +218,25 @@ fn unibuffer<T>() -> ~Buffer<Packet<T>> {
     b
 }
 
-pub fn packet<T>() -> *Packet<T> {
-    let b = unibuffer();
-    let p = ptr::to_unsafe_ptr(&(b.data));
+pub fn packet<T>() -> *mut Packet<T> {
+    let mut b = unibuffer();
+    let p = ptr::to_mut_unsafe_ptr(&mut b.data);
     // We'll take over memory management from here.
-    unsafe { forget(b) }
+    unsafe {
+        forget(b);
+    }
     p
 }
 
 pub fn entangle_buffer<T:Owned,Tstart:Owned>(
-    buffer: ~Buffer<T>,
-    init: &fn(*libc::c_void, x: &T) -> *Packet<Tstart>)
-    -> (SendPacketBuffered<Tstart, T>, RecvPacketBuffered<Tstart, T>)
-{
-    let p = init(unsafe { transmute_copy(&buffer) }, &buffer.data);
-    unsafe { forget(buffer) }
-    (SendPacketBuffered(p), RecvPacketBuffered(p))
+    mut buffer: ~Buffer<T>,
+    init: &fn(*libc::c_void, x: &mut T) -> *mut Packet<Tstart>)
+    -> (SendPacketBuffered<Tstart, T>, RecvPacketBuffered<Tstart, T>) {
+    unsafe {
+        let p = init(transmute_copy(&buffer), &mut buffer.data);
+        forget(buffer);
+        (SendPacketBuffered(p), RecvPacketBuffered(p))
+    }
 }
 
 pub fn swap_task(dst: &mut *rust_task, src: *rust_task) -> *rust_task {
@@ -292,7 +295,7 @@ fn swap_state_rel(dst: &mut State, src: State) -> State {
     }
 }
 
-pub unsafe fn get_buffer<T>(p: *PacketHeader) -> ~Buffer<T> {
+pub unsafe fn get_buffer<T>(p: *mut PacketHeader) -> ~Buffer<T> {
     transmute((*p).buf_header())
 }
 
@@ -306,10 +309,14 @@ struct BufferResource<T> {
 impl<T> Drop for BufferResource<T> {
     fn finalize(&self) {
         unsafe {
-            let b = move_it!(self.buffer);
+            let this: &mut BufferResource<T> = transmute(self);
+
+            let mut b = move_it!(this.buffer);
             //let p = ptr::to_unsafe_ptr(*b);
             //error!("drop %?", p);
-            let old_count = intrinsics::atomic_xsub_rel(&mut b.header.ref_count, 1);
+            let old_count = intrinsics::atomic_xsub_rel(
+                &mut b.header.ref_count,
+                1);
             //let old_count = atomic_xchng_rel(b.header.ref_count, 0);
             if old_count == 1 {
                 // The new count is 0.
@@ -323,10 +330,12 @@ fn finalize(&self) {
     }
 }
 
-fn BufferResource<T>(b: ~Buffer<T>) -> BufferResource<T> {
+fn BufferResource<T>(mut b: ~Buffer<T>) -> BufferResource<T> {
     //let p = ptr::to_unsafe_ptr(*b);
     //error!("take %?", p);
-    unsafe { intrinsics::atomic_xadd_acq(&mut b.header.ref_count, 1) };
+    unsafe {
+        intrinsics::atomic_xadd_acq(&mut b.header.ref_count, 1);
+    }
 
     BufferResource {
         // tjc: ????
@@ -334,10 +343,12 @@ fn BufferResource<T>(b: ~Buffer<T>) -> BufferResource<T> {
     }
 }
 
-pub fn send<T,Tbuffer>(p: SendPacketBuffered<T,Tbuffer>, payload: T) -> bool {
+pub fn send<T,Tbuffer>(mut p: SendPacketBuffered<T,Tbuffer>,
+                       payload: T)
+                       -> bool {
     let header = p.header();
-    let p_ = p.unwrap();
-    let p = unsafe { &*p_ };
+    let mut p_ = p.unwrap();
+    let p = unsafe { &mut *p_ };
     assert!(ptr::to_unsafe_ptr(&(p.header)) == header);
     assert!(p.payload.is_none());
     p.payload = Some(payload);
@@ -391,11 +402,12 @@ pub fn recv<T:Owned,Tbuffer:Owned>(
 a message, or `Some(T)` if a message was received.
 
 */
-pub fn try_recv<T:Owned,Tbuffer:Owned>(p: RecvPacketBuffered<T, Tbuffer>)
-    -> Option<T>
-{
-    let p_ = p.unwrap();
-    let p = unsafe { &*p_ };
+pub fn try_recv<T:Owned,Tbuffer:Owned>(mut p: RecvPacketBuffered<T, Tbuffer>)
+                                       -> Option<T> {
+    let mut p_ = p.unwrap();
+    let mut p = unsafe {
+        &mut *p_
+    };
 
     do (|| {
         try_recv_(p)
@@ -412,7 +424,7 @@ pub fn try_recv<T:Owned,Tbuffer:Owned>(p: RecvPacketBuffered<T, Tbuffer>)
     }
 }
 
-fn try_recv_<T:Owned>(p: &Packet<T>) -> Option<T> {
+fn try_recv_<T:Owned>(p: &mut Packet<T>) -> Option<T> {
     // optimistic path
     match p.header.state {
       Full => {
@@ -498,16 +510,20 @@ fn try_recv_<T:Owned>(p: &Packet<T>) -> Option<T> {
 }
 
 /// Returns true if messages are available.
-pub fn peek<T:Owned,Tb:Owned>(p: &RecvPacketBuffered<T, Tb>) -> bool {
-    match unsafe {(*p.header()).state} {
-      Empty | Terminated => false,
-      Blocked => fail!(~"peeking on blocked packet"),
-      Full => true
+pub fn peek<T:Owned,Tb:Owned>(p: &mut RecvPacketBuffered<T, Tb>) -> bool {
+    unsafe {
+        match (*p.header()).state {
+            Empty | Terminated => false,
+            Blocked => fail!(~"peeking on blocked packet"),
+            Full => true
+        }
     }
 }
 
-fn sender_terminate<T:Owned>(p: *Packet<T>) {
-    let p = unsafe { &*p };
+fn sender_terminate<T:Owned>(p: *mut Packet<T>) {
+    let p = unsafe {
+        &mut *p
+    };
     match swap_state_rel(&mut p.header.state, Terminated) {
       Empty => {
         // The receiver will eventually clean up.
@@ -536,8 +552,10 @@ fn sender_terminate<T:Owned>(p: *Packet<T>) {
     }
 }
 
-fn receiver_terminate<T:Owned>(p: *Packet<T>) {
-    let p = unsafe { &*p };
+fn receiver_terminate<T:Owned>(p: *mut Packet<T>) {
+    let p = unsafe {
+        &mut *p
+    };
     match swap_state_rel(&mut p.header.state, Terminated) {
       Empty => {
         assert!(p.header.blocked_task.is_null());
@@ -569,8 +587,10 @@ fn receiver_terminate<T:Owned>(p: *Packet<T>) {
 closed by the sender or has a message waiting to be received.
 
 */
-pub fn wait_many<T: Selectable>(pkts: &[T]) -> uint {
-    let this = unsafe { rustrt::rust_get_task() };
+pub fn wait_many<T: Selectable>(pkts: &mut [T]) -> uint {
+    let this = unsafe {
+        rustrt::rust_get_task()
+    };
 
     unsafe {
         rustrt::task_clear_event_reject(this);
@@ -578,19 +598,19 @@ pub fn wait_many<T: Selectable>(pkts: &[T]) -> uint {
 
     let mut data_avail = false;
     let mut ready_packet = pkts.len();
-    for pkts.eachi |i, p| {
+    for vec::eachi_mut(pkts) |i, p| {
         unsafe {
-            let p = &*p.header();
+            let p = &mut *p.header();
             let old = p.mark_blocked(this);
             match old {
-              Full | Terminated => {
-                data_avail = true;
-                ready_packet = i;
-                (*p).state = old;
-                break;
-              }
-              Blocked => fail!(~"blocking on blocked packet"),
-              Empty => ()
+                Full | Terminated => {
+                    data_avail = true;
+                    ready_packet = i;
+                    (*p).state = old;
+                    break;
+                }
+                Blocked => fail!(~"blocking on blocked packet"),
+                Empty => ()
             }
         }
     }
@@ -598,7 +618,14 @@ pub fn wait_many<T: Selectable>(pkts: &[T]) -> uint {
     while !data_avail {
         debug!("sleeping on %? packets", pkts.len());
         let event = wait_event(this) as *PacketHeader;
-        let pos = vec::position(pkts, |p| p.header() == event);
+
+        let mut pos = None;
+        for vec::eachi_mut(pkts) |i, p| {
+            if p.header() == event {
+                pos = Some(i);
+                break;
+            }
+        };
 
         match pos {
           Some(i) => {
@@ -609,11 +636,15 @@ pub fn wait_many<T: Selectable>(pkts: &[T]) -> uint {
         }
     }
 
-    debug!("%?", pkts[ready_packet]);
+    debug!("%?", &mut pkts[ready_packet]);
 
-    for pkts.each |p| { unsafe{ (*p.header()).unblock()} }
+    for vec::each_mut(pkts) |p| {
+        unsafe {
+            (*p.header()).unblock()
+        }
+    }
 
-    debug!("%?, %?", ready_packet, pkts[ready_packet]);
+    debug!("%?, %?", ready_packet, &mut pkts[ready_packet]);
 
     unsafe {
         assert!((*pkts[ready_packet].header()).state == Full
@@ -629,65 +660,58 @@ pub fn wait_many<T: Selectable>(pkts: &[T]) -> uint {
 */
 pub type SendPacket<T> = SendPacketBuffered<T, Packet<T>>;
 
-pub fn SendPacket<T>(p: *Packet<T>) -> SendPacket<T> {
+pub fn SendPacket<T>(p: *mut Packet<T>) -> SendPacket<T> {
     SendPacketBuffered(p)
 }
 
 pub struct SendPacketBuffered<T, Tbuffer> {
-    mut p: Option<*Packet<T>>,
-    mut buffer: Option<BufferResource<Tbuffer>>,
+    p: Option<*mut Packet<T>>,
+    buffer: Option<BufferResource<Tbuffer>>,
 }
 
 #[unsafe_destructor]
 impl<T:Owned,Tbuffer:Owned> Drop for SendPacketBuffered<T,Tbuffer> {
     fn finalize(&self) {
-        //if self.p != none {
-        //    debug!("drop send %?", option::get(self.p));
-        //}
-        if self.p != None {
-            let mut p = None;
-            p <-> self.p;
-            sender_terminate(p.unwrap())
+        unsafe {
+            let this: &mut SendPacketBuffered<T,Tbuffer> = transmute(self);
+            if this.p != None {
+                let mut p = None;
+                p <-> this.p;
+                sender_terminate(p.unwrap())
+            }
         }
-        //unsafe { error!("send_drop: %?",
-        //                if self.buffer == none {
-        //                    "none"
-        //                } else { "some" }); }
     }
 }
 
-pub fn SendPacketBuffered<T,Tbuffer>(p: *Packet<T>)
-    -> SendPacketBuffered<T, Tbuffer> {
-        //debug!("take send %?", p);
+pub fn SendPacketBuffered<T,Tbuffer>(p: *mut Packet<T>)
+                                     -> SendPacketBuffered<T,Tbuffer> {
     SendPacketBuffered {
         p: Some(p),
         buffer: unsafe {
-            Some(BufferResource(
-                get_buffer(ptr::to_unsafe_ptr(&((*p).header)))))
+            Some(BufferResource(get_buffer(&mut (*p).header)))
         }
     }
 }
 
 pub impl<T,Tbuffer> SendPacketBuffered<T,Tbuffer> {
-    fn unwrap(&self) -> *Packet<T> {
+    fn unwrap(&mut self) -> *mut Packet<T> {
         let mut p = None;
         p <-> self.p;
         p.unwrap()
     }
 
-    fn header(&self) -> *PacketHeader {
+    fn header(&mut self) -> *mut PacketHeader {
         match self.p {
-          Some(packet) => unsafe {
-            let packet = &*packet;
-            let header = ptr::to_unsafe_ptr(&(packet.header));
-            //forget(packet);
-            header
-          },
-          None => fail!(~"packet already consumed")
+            Some(packet) => unsafe {
+                let packet = &mut *packet;
+                let header = ptr::to_mut_unsafe_ptr(&mut packet.header);
+                header
+            },
+            None => fail!(~"packet already consumed")
         }
     }
 
-    fn reuse_buffer(&self) -> BufferResource<Tbuffer> {
+    fn reuse_buffer(&mut self) -> BufferResource<Tbuffer> {
         //error!("send reuse_buffer");
         let mut tmp = None;
         tmp <-> self.buffer;
@@ -699,41 +723,37 @@ fn reuse_buffer(&self) -> BufferResource<Tbuffer> {
 /// message.
 pub type RecvPacket<T> = RecvPacketBuffered<T, Packet<T>>;
 
-pub fn RecvPacket<T>(p: *Packet<T>) -> RecvPacket<T> {
+pub fn RecvPacket<T>(p: *mut Packet<T>) -> RecvPacket<T> {
     RecvPacketBuffered(p)
 }
+
 pub struct RecvPacketBuffered<T, Tbuffer> {
-    mut p: Option<*Packet<T>>,
-    mut buffer: Option<BufferResource<Tbuffer>>,
+    p: Option<*mut Packet<T>>,
+    buffer: Option<BufferResource<Tbuffer>>,
 }
 
 #[unsafe_destructor]
 impl<T:Owned,Tbuffer:Owned> Drop for RecvPacketBuffered<T,Tbuffer> {
     fn finalize(&self) {
-        //if self.p != none {
-        //    debug!("drop recv %?", option::get(self.p));
-        //}
-        if self.p != None {
-            let mut p = None;
-            p <-> self.p;
-            receiver_terminate(p.unwrap())
+        unsafe {
+            let this: &mut RecvPacketBuffered<T,Tbuffer> = transmute(self);
+            if this.p != None {
+                let mut p = None;
+                p <-> this.p;
+                receiver_terminate(p.unwrap())
+            }
         }
-        //unsafe { error!("recv_drop: %?",
-        //                if self.buffer == none {
-        //                    "none"
-        //                } else { "some" }); }
     }
 }
 
 pub impl<T:Owned,Tbuffer:Owned> RecvPacketBuffered<T, Tbuffer> {
-    fn unwrap(&self) -> *Packet<T> {
+    fn unwrap(&mut self) -> *mut Packet<T> {
         let mut p = None;
         p <-> self.p;
         p.unwrap()
     }
 
-    fn reuse_buffer(&self) -> BufferResource<Tbuffer> {
-        //error!("recv reuse_buffer");
+    fn reuse_buffer(&mut self) -> BufferResource<Tbuffer> {
         let mut tmp = None;
         tmp <-> self.buffer;
         tmp.unwrap()
@@ -741,27 +761,24 @@ fn reuse_buffer(&self) -> BufferResource<Tbuffer> {
 }
 
 impl<T:Owned,Tbuffer:Owned> Selectable for RecvPacketBuffered<T, Tbuffer> {
-    fn header(&self) -> *PacketHeader {
+    fn header(&mut self) -> *mut PacketHeader {
         match self.p {
-          Some(packet) => unsafe {
-            let packet = &*packet;
-            let header = ptr::to_unsafe_ptr(&(packet.header));
-            //forget(packet);
-            header
-          },
-          None => fail!(~"packet already consumed")
+            Some(packet) => unsafe {
+                let packet = &mut *packet;
+                let header = ptr::to_mut_unsafe_ptr(&mut packet.header);
+                header
+            },
+            None => fail!(~"packet already consumed")
         }
     }
 }
 
-pub fn RecvPacketBuffered<T,Tbuffer>(p: *Packet<T>)
-    -> RecvPacketBuffered<T,Tbuffer> {
-    //debug!("take recv %?", p);
+pub fn RecvPacketBuffered<T,Tbuffer>(p: *mut Packet<T>)
+                                     -> RecvPacketBuffered<T,Tbuffer> {
     RecvPacketBuffered {
         p: Some(p),
         buffer: unsafe {
-            Some(BufferResource(
-                get_buffer(ptr::to_unsafe_ptr(&((*p).header)))))
+            Some(BufferResource(get_buffer(&mut (*p).header)))
         }
     }
 }
@@ -800,51 +817,55 @@ pub fn entangle<T>() -> (SendPacket<T>, RecvPacket<T>) {
 
 */
 pub fn select2<A:Owned,Ab:Owned,B:Owned,Bb:Owned>(
-    a: RecvPacketBuffered<A, Ab>,
-    b: RecvPacketBuffered<B, Bb>)
+    mut a: RecvPacketBuffered<A, Ab>,
+    mut b: RecvPacketBuffered<B, Bb>)
     -> Either<(Option<A>, RecvPacketBuffered<B, Bb>),
-              (RecvPacketBuffered<A, Ab>, Option<B>)>
-{
-    let i = wait_many([a.header(), b.header()]);
-
+              (RecvPacketBuffered<A, Ab>, Option<B>)> {
+    let mut endpoints = [ a.header(), b.header() ];
+    let i = wait_many(endpoints);
     match i {
-      0 => Left((try_recv(a), b)),
-      1 => Right((a, try_recv(b))),
-      _ => fail!(~"select2 return an invalid packet")
+        0 => Left((try_recv(a), b)),
+        1 => Right((a, try_recv(b))),
+        _ => fail!(~"select2 return an invalid packet")
     }
 }
 
 pub trait Selectable {
-    fn header(&self) -> *PacketHeader;
+    fn header(&mut self) -> *mut PacketHeader;
 }
 
-impl Selectable for *PacketHeader {
-    fn header(&self) -> *PacketHeader { *self }
+impl Selectable for *mut PacketHeader {
+    fn header(&mut self) -> *mut PacketHeader { *self }
 }
 
 /// Returns the index of an endpoint that is ready to receive.
-pub fn selecti<T:Selectable>(endpoints: &[T]) -> uint {
+pub fn selecti<T:Selectable>(endpoints: &mut [T]) -> uint {
     wait_many(endpoints)
 }
 
 /// Returns 0 or 1 depending on which endpoint is ready to receive
-pub fn select2i<A:Selectable,B:Selectable>(a: &A, b: &B) ->
-        Either<(), ()> {
-    match wait_many([a.header(), b.header()]) {
-      0 => Left(()),
-      1 => Right(()),
-      _ => fail!(~"wait returned unexpected index")
+pub fn select2i<A:Selectable,B:Selectable>(a: &mut A, b: &mut B)
+                                           -> Either<(), ()> {
+    let mut endpoints = [ a.header(), b.header() ];
+    match wait_many(endpoints) {
+        0 => Left(()),
+        1 => Right(()),
+        _ => fail!(~"wait returned unexpected index")
     }
 }
 
-/** Waits on a set of endpoints. Returns a message, its index, and a
- list of the remaining endpoints.
+/// Waits on a set of endpoints. Returns a message, its index, and a
+/// list of the remaining endpoints.
+pub fn select<T:Owned,Tb:Owned>(mut endpoints: ~[RecvPacketBuffered<T, Tb>])
+                                -> (uint,
+                                    Option<T>,
+                                    ~[RecvPacketBuffered<T, Tb>]) {
+    let mut endpoint_headers = ~[];
+    for vec::each_mut(endpoints) |endpoint| {
+        endpoint_headers.push(endpoint.header());
+    }
 
-*/
-pub fn select<T:Owned,Tb:Owned>(endpoints: ~[RecvPacketBuffered<T, Tb>])
-    -> (uint, Option<T>, ~[RecvPacketBuffered<T, Tb>])
-{
-    let ready = wait_many(endpoints.map(|p| p.header()));
+    let ready = wait_many(endpoint_headers);
     let mut remaining = endpoints;
     let port = remaining.swap_remove(ready);
     let result = try_recv(port);

src/libstd/comm.rs

@@ -72,7 +72,7 @@ fn peek(&self) -> bool {
 }
 
 impl<T:Owned,U:Owned> Selectable for DuplexStream<T, U> {
-    fn header(&self) -> *pipes::PacketHeader {
+    fn header(&mut self) -> *mut pipes::PacketHeader {
         self.port.header()
     }
 }

src/libstd/timer.rs

@@ -14,10 +14,11 @@
 use uv::iotask;
 use uv::iotask::IoTask;
 
-use core::libc;
-use core::libc::c_void;
 use core::cast::transmute;
+use core::cast;
 use core::comm::{stream, Chan, SharedChan, Port, select2i};
+use core::libc::c_void;
+use core::libc;
 
 /**
  * Wait for timeout period then send provided value over a channel
@@ -120,22 +121,28 @@ pub fn sleep(iotask: &IoTask, msecs: uint) {
 pub fn recv_timeout<T:Copy + Owned>(iotask: &IoTask,
                                    msecs: uint,
                                    wait_po: &Port<T>)
-                                -> Option<T> {
-    let (timeout_po, timeout_ch) = stream::<()>();
+                                   -> Option<T> {
+    let mut (timeout_po, timeout_ch) = stream::<()>();
     delayed_send(iotask, msecs, &timeout_ch, ());
-    // FIXME: This could be written clearer (#2618)
-    either::either(
-        |_| {
-            None
-        }, |_| {
-            Some(wait_po.recv())
-        }, &select2i(&timeout_po, wait_po)
-    )
+
+    // XXX: Workaround due to ports and channels not being &mut. They should
+    // be.
+    unsafe {
+        let wait_po = cast::transmute_mut(wait_po);
+
+        // FIXME: This could be written clearer (#2618)
+        either::either(
+            |_| {
+                None
+            }, |_| {
+                Some(wait_po.recv())
+            }, &select2i(&mut timeout_po, wait_po)
+        )
+    }
 }
 
 // INTERNAL API
-extern fn delayed_send_cb(handle: *uv::ll::uv_timer_t,
-                                status: libc::c_int) {
+extern fn delayed_send_cb(handle: *uv::ll::uv_timer_t, status: libc::c_int) {
     unsafe {
         debug!(
             "delayed_send_cb handle %? status %?", handle, status);