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Feb 26, 2015
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13 changes: 8 additions & 5 deletions src/libcollections/btree/node.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1085,7 +1085,7 @@ impl<K, V> Node<K, V> {
vals: RawItems::from_slice(self.vals()),
edges: RawItems::from_slice(self.edges()),

ptr: *self.keys as *mut u8,
ptr: Unique::new(*self.keys as *mut u8),
capacity: self.capacity(),
is_leaf: self.is_leaf()
},
Expand Down Expand Up @@ -1354,11 +1354,14 @@ struct MoveTraversalImpl<K, V> {
edges: RawItems<Node<K, V>>,

// For deallocation when we are done iterating.
ptr: *mut u8,
ptr: Unique<u8>,
capacity: usize,
is_leaf: bool
}

unsafe impl<K: Sync, V: Sync> Sync for MoveTraversalImpl<K, V> {}
unsafe impl<K: Send, V: Send> Send for MoveTraversalImpl<K, V> {}
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Ah I see what you mean about RawItems now. Could these unsafe impl blocks move onto the RawItems structure itself instead? cc @gankro (you may know more)

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So raw items has basically two functions: drain items out of an allocation, and push items into an allocation. No bounds checks. No lifetimes. It's like straight up *mut [T]/UncheckedVec.

But critically it doesn't update the source node's len field, because len is shared between three "independent" arrays. It also has no lifetimes attached, so you're free to Drop it or its backing allocation. This means that if you Send a RawItems alone to another thread, you basically have no idea what the state of your node's memory is at that point. It's not even sound to Sync RawItems since it's possible to Drop the parent node with an outstanding RawItems.

It's very much so an internal utility to make what is basically *mut [T] manipulation a bit nicer.


impl<K, V> TraversalImpl for MoveTraversalImpl<K, V> {
type Item = (K, V);
type Edge = Node<K, V>;
Expand Down Expand Up @@ -1401,7 +1404,7 @@ impl<K, V> Drop for MoveTraversalImpl<K, V> {

let (alignment, size) =
calculate_allocation_generic::<K, V>(self.capacity, self.is_leaf);
unsafe { heap::deallocate(self.ptr, size, alignment) };
unsafe { heap::deallocate(*self.ptr, size, alignment) };
}
}

Expand All @@ -1425,12 +1428,12 @@ pub enum TraversalItem<K, V, E> {
/// A traversal over a node's entries and edges
pub type Traversal<'a, K, V> = AbsTraversal<ElemsAndEdges<Zip<slice::Iter<'a, K>,
slice::Iter<'a, V>>,
slice::Iter<'a, Node<K, V>>>>;
slice::Iter<'a, Node<K, V>>>>;

/// A mutable traversal over a node's entries and edges
pub type MutTraversal<'a, K, V> = AbsTraversal<ElemsAndEdges<Zip<slice::Iter<'a, K>,
slice::IterMut<'a, V>>,
slice::IterMut<'a, Node<K, V>>>>;
slice::IterMut<'a, Node<K, V>>>>;

/// An owning traversal over a node's entries and edges
pub type MoveTraversal<K, V> = AbsTraversal<MoveTraversalImpl<K, V>>;
Expand Down
4 changes: 2 additions & 2 deletions src/libcollections/linked_list.rs
Original file line number Diff line number Diff line change
Expand Up @@ -51,8 +51,8 @@ struct Rawlink<T> {
}

impl<T> Copy for Rawlink<T> {}
unsafe impl<T:'static+Send> Send for Rawlink<T> {}
unsafe impl<T:Send+Sync> Sync for Rawlink<T> {}
unsafe impl<T:Send> Send for Rawlink<T> {}
unsafe impl<T:Sync> Sync for Rawlink<T> {}

struct Node<T> {
next: Link<T>,
Expand Down
3 changes: 3 additions & 0 deletions src/libcollections/vec.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1755,6 +1755,9 @@ pub struct Drain<'a, T:'a> {
marker: PhantomData<&'a T>,
}

unsafe impl<'a, T: Sync> Sync for Drain<'a, T> {}
unsafe impl<'a, T: Send> Send for Drain<'a, T> {}

#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Iterator for Drain<'a, T> {
type Item = T;
Expand Down
30 changes: 9 additions & 21 deletions src/libcollections/vec_deque.rs
Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,6 @@ use core::cmp::Ordering;
use core::default::Default;
use core::fmt;
use core::iter::{self, repeat, FromIterator, IntoIterator, RandomAccessIterator};
use core::marker;
use core::mem;
use core::num::{Int, UnsignedInt};
use core::ops::{Index, IndexMut};
Expand Down Expand Up @@ -59,12 +58,6 @@ pub struct VecDeque<T> {
ptr: Unique<T>,
}

#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<T: Send> Send for VecDeque<T> {}

#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<T: Sync> Sync for VecDeque<T> {}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: Clone> Clone for VecDeque<T> {
fn clone(&self) -> VecDeque<T> {
Expand Down Expand Up @@ -545,9 +538,7 @@ impl<T> VecDeque<T> {
IterMut {
tail: self.tail,
head: self.head,
cap: self.cap,
ptr: *self.ptr,
marker: marker::PhantomData,
ring: unsafe { self.buffer_as_mut_slice() },
}
}

Expand Down Expand Up @@ -1515,17 +1506,12 @@ impl<'a, T> RandomAccessIterator for Iter<'a, T> {
}
}

// FIXME This was implemented differently from Iter because of a problem
// with returning the mutable reference. I couldn't find a way to
// make the lifetime checker happy so, but there should be a way.
/// `VecDeque` mutable iterator.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct IterMut<'a, T:'a> {
ptr: *mut T,
ring: &'a mut [T],
tail: usize,
head: usize,
cap: usize,
marker: marker::PhantomData<&'a mut T>,
}

#[stable(feature = "rust1", since = "1.0.0")]
Expand All @@ -1538,16 +1524,17 @@ impl<'a, T> Iterator for IterMut<'a, T> {
return None;
}
let tail = self.tail;
self.tail = wrap_index(self.tail + 1, self.cap);
self.tail = wrap_index(self.tail + 1, self.ring.len());

unsafe {
Some(&mut *self.ptr.offset(tail as isize))
let elem = self.ring.get_unchecked_mut(tail);
Some(&mut *(elem as *mut _))
}
}

#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let len = count(self.tail, self.head, self.cap);
let len = count(self.tail, self.head, self.ring.len());
(len, Some(len))
}
}
Expand All @@ -1559,10 +1546,11 @@ impl<'a, T> DoubleEndedIterator for IterMut<'a, T> {
if self.tail == self.head {
return None;
}
self.head = wrap_index(self.head - 1, self.cap);
self.head = wrap_index(self.head - 1, self.ring.len());

unsafe {
Some(&mut *self.ptr.offset(self.head as isize))
let elem = self.ring.get_unchecked_mut(self.head);
Some(&mut *(elem as *mut _))
}
}
}
Expand Down
6 changes: 5 additions & 1 deletion src/libcore/iter.rs
Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,7 @@ use num::{ToPrimitive, Int};
use ops::{Add, Deref, FnMut};
use option::Option;
use option::Option::{Some, None};
use marker::Sized;
use marker::{Send, Sized, Sync};
use usize;

/// An interface for dealing with "external iterators". These types of iterators
Expand Down Expand Up @@ -1786,6 +1786,10 @@ pub struct Peekable<I: Iterator> {
peeked: Option<I::Item>,
}

// FIXME: after #22828 being fixed, the following unsafe impl should be removed
unsafe impl<I: Iterator> Sync for Peekable<I> where I: Sync, I::Item: Sync {}
unsafe impl<I: Iterator> Send for Peekable<I> where I: Send, I::Item: Send {}

impl<I: Iterator + Clone> Clone for Peekable<I> where I::Item: Clone {
fn clone(&self) -> Peekable<I> {
Peekable {
Expand Down
7 changes: 6 additions & 1 deletion src/libcore/slice.rs
Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,7 @@ use ptr;
use ptr::PtrExt;
use mem;
use mem::size_of;
use marker::{Sized, self};
use marker::{Send, Sized, Sync, self};
use raw::Repr;
// Avoid conflicts with *both* the Slice trait (buggy) and the `slice::raw` module.
use raw::Slice as RawSlice;
Expand Down Expand Up @@ -740,6 +740,9 @@ pub struct Iter<'a, T: 'a> {
_marker: marker::PhantomData<&'a T>,
}

unsafe impl<'a, T: Sync> Sync for Iter<'a, T> {}
unsafe impl<'a, T: Sync> Send for Iter<'a, T> {}
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T: Sync => T: Send

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Sync is correct; Iter<T> is essentially the same as &T.

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Oh wow that is subtle, looks like I should read this again.


#[unstable(feature = "core")]
impl<'a, T> ops::Index<ops::Range<usize>> for Iter<'a, T> {
type Output = [T];
Expand Down Expand Up @@ -830,6 +833,8 @@ pub struct IterMut<'a, T: 'a> {
_marker: marker::PhantomData<&'a mut T>,
}

unsafe impl<'a, T: Sync> Sync for IterMut<'a, T> {}
unsafe impl<'a, T: Send> Send for IterMut<'a, T> {}

#[unstable(feature = "core")]
impl<'a, T> ops::Index<ops::Range<usize>> for IterMut<'a, T> {
Expand Down
98 changes: 98 additions & 0 deletions src/test/run-pass/sync-send-iterators-in-libcollections.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,98 @@
// Copyright 2015 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.

#![allow(unused_mut)]
#![feature(collections)]

extern crate collections;

use collections::BinaryHeap;
use collections::{BitSet, BitVec};
use collections::{BTreeMap, BTreeSet};
use collections::EnumSet;
use collections::LinkedList;
use collections::Vec;
use collections::VecDeque;
use collections::VecMap;

use collections::Bound::Included;
use collections::enum_set::CLike;
use std::mem;

fn is_sync<T>(_: T) where T: Sync {}
fn is_send<T>(_: T) where T: Send {}

macro_rules! all_sync_send {
($ctor:expr, $($iter:ident),+) => ({
$(
let mut x = $ctor;
is_sync(x.$iter());
let mut y = $ctor;
is_send(y.$iter());
)+
})
}

macro_rules! is_sync_send {
($ctor:expr, $iter:ident($($param:expr),+)) => ({
let mut x = $ctor;
is_sync(x.$iter($( $param ),+));
let mut y = $ctor;
is_send(y.$iter($( $param ),+));
})
}

fn main() {
// The iterator "generator" list should exhaust what corresponding
// implementations have where `Sync` and `Send` semantics apply.
all_sync_send!(BinaryHeap::<usize>::new(), iter, drain, into_iter);

all_sync_send!(BitVec::new(), iter);

all_sync_send!(BitSet::new(), iter);
is_sync_send!(BitSet::new(), union(&BitSet::new()));
is_sync_send!(BitSet::new(), intersection(&BitSet::new()));
is_sync_send!(BitSet::new(), difference(&BitSet::new()));
is_sync_send!(BitSet::new(), symmetric_difference(&BitSet::new()));

all_sync_send!(BTreeMap::<usize, usize>::new(), iter, iter_mut, into_iter, keys, values);
is_sync_send!(BTreeMap::<usize, usize>::new(), range(Included(&0), Included(&9)));
is_sync_send!(BTreeMap::<usize, usize>::new(), range_mut(Included(&0), Included(&9)));

all_sync_send!(BTreeSet::<usize>::new(), iter, into_iter);
is_sync_send!(BTreeSet::<usize>::new(), range(Included(&0), Included(&9)));
is_sync_send!(BTreeSet::<usize>::new(), difference(&BTreeSet::<usize>::new()));
is_sync_send!(BTreeSet::<usize>::new(), symmetric_difference(&BTreeSet::<usize>::new()));
is_sync_send!(BTreeSet::<usize>::new(), intersection(&BTreeSet::<usize>::new()));
is_sync_send!(BTreeSet::<usize>::new(), union(&BTreeSet::<usize>::new()));

all_sync_send!(LinkedList::<usize>::new(), iter, iter_mut, into_iter);

#[derive(Copy)]
#[repr(usize)]
#[allow(dead_code)]
enum Foo { A, B, C }
impl CLike for Foo {
fn to_usize(&self) -> usize {
*self as usize
}

fn from_usize(v: usize) -> Foo {
unsafe { mem::transmute(v) }
}
}
all_sync_send!(EnumSet::<Foo>::new(), iter);

all_sync_send!(VecDeque::<usize>::new(), iter, iter_mut, drain, into_iter);

all_sync_send!(VecMap::<usize>::new(), iter, iter_mut, drain, into_iter, keys, values);

all_sync_send!(Vec::<usize>::new(), into_iter, drain);
}