Struct crossbeam_channel::Receiver

[+] Show declaration

pub struct Receiver<T>(_);

[−] Expand description

The receiving side of a channel.

Receivers can be cloned and shared among multiple threads.

Examples

use std::thread;
use std::time::Duration;
use crossbeam_channel as channel;

let (s, r) = channel::unbounded();

thread::spawn(move || {
    s.send("Hello world!");
    thread::sleep(Duration::from_secs(2));
    s.send("Delayed for 2 seconds");
});

println!("{}", r.recv().unwrap()); // Received immediately.
println!("Waiting...");
println!("{}", r.recv().unwrap()); // Received after 2 seconds.

Methods

impl<T> Receiver<T>

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pub fn recv(&self) -> Option<T>

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Blocks the current thread until a message is received or the channel is closed.

Returns the message if it was received, or None if the channel is closed and empty.

If called on a zero-capacity channel, this method blocks the current thread until a send operation appears on the other side of the channel or it becomes closed.

Note: r.recv() is equivalent to select! { recv(r, msg) => msg }.

Examples

use std::thread;
use std::time::Duration;
use crossbeam_channel as channel;

let (s, r) = channel::unbounded();

thread::spawn(move || {
    thread::sleep(Duration::from_secs(1));
    s.send(5);
    // `s` gets dropped, thus closing the channel.
});

assert_eq!(r.recv(), Some(5));
assert_eq!(r.recv(), None);

pub fn try_recv(&self) -> Option<T>

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Attempts to receive a message from the channel without blocking.

If there is no message ready to be received, returns None.

Note: r.try_recv() is equivalent to select! { recv(r, msg) => msg, default => None }.

Examples

use crossbeam_channel as channel;

let (s, r) = channel::unbounded();
assert_eq!(r.try_recv(), None);

s.send(5);
drop(s);

assert_eq!(r.try_recv(), Some(5));
assert_eq!(r.try_recv(), None);

pub fn is_empty(&self) -> bool

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Returns true if the channel is empty.

Note: zero-capacity channels are always empty.

Examples

use crossbeam_channel as channel;

let (s, r) = channel::unbounded();

assert!(r.is_empty());
s.send(0);
assert!(!r.is_empty());

pub fn is_full(&self) -> bool

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Returns true if the channel is full.

Note: zero-capacity channels are always full.

Examples

use crossbeam_channel as channel;

let (s, r) = channel::bounded(1);

assert!(!r.is_full());
s.send(0);
assert!(r.is_full());

pub fn len(&self) -> usize

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Returns the number of messages in the channel.

Examples

use crossbeam_channel as channel;

let (s, r) = channel::unbounded();
assert_eq!(r.len(), 0);

s.send(1);
s.send(2);
assert_eq!(r.len(), 2);

pub fn capacity(&self) -> Option<usize>

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If the channel is bounded, returns its capacity.

Examples

use crossbeam_channel as channel;

let (_, r) = channel::unbounded::<i32>();
assert_eq!(r.capacity(), None);

let (_, r) = channel::bounded::<i32>(5);
assert_eq!(r.capacity(), Some(5));

let (_, r) = channel::bounded::<i32>(0);
assert_eq!(r.capacity(), Some(0));

Trait Implementations

impl<T> PartialEq<Receiver<T>> for Sender<T>

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fn eq(&self, other: &Receiver<T>) -> bool

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This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

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This method tests for !=.

impl<T: Send> Send for Receiver<T>

impl<T: Send> Sync for Receiver<T>

impl<T> Clone for Receiver<T>

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fn clone(&self) -> Self

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Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

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Performs copy-assignment from source.

impl<T> Debug for Receiver<T>

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fn fmt(&self, f: &mut Formatter) -> Result

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Formats the value using the given formatter.

impl<T> Hash for Receiver<T>

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fn hash<H: Hasher>(&self, state: &mut H)

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Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where     H: Hasher,

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Feeds a slice of this type into the given [Hasher].

impl<T> PartialEq for Receiver<T>

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fn eq(&self, other: &Receiver<T>) -> bool

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This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

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This method tests for !=.

impl<T> Eq for Receiver<T>

impl<T> PartialEq<Sender<T>> for Receiver<T>

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fn eq(&self, other: &Sender<T>) -> bool

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This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

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This method tests for !=.

impl<T> Iterator for Receiver<T>

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type Item = T

The type of the elements being iterated over.

fn next(&mut self) -> Option<Self::Item>

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Advances the iterator and returns the next value.

fn size_hint(&self) -> (usize, Option<usize>)

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Returns the bounds on the remaining length of the iterator.

fn count(self) -> usize

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Consumes the iterator, counting the number of iterations and returning it.

fn last(self) -> Option<Self::Item>

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Consumes the iterator, returning the last element.

fn nth(&mut self, n: usize) -> Option<Self::Item>

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Returns the nth element of the iterator.

fn step_by(self, step: usize) -> StepBy<Self>

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🔬 This is a nightly-only experimental API. (iterator_step_by)

unstable replacement of Range::step_by

Creates an iterator starting at the same point, but stepping by the given amount at each iteration.

fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where     U: IntoIterator<Item = Self::Item>,

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Takes two iterators and creates a new iterator over both in sequence.

fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where     U: IntoIterator,

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'Zips up' two iterators into a single iterator of pairs.

fn map<B, F>(self, f: F) -> Map<Self, F> where     F: FnMut(Self::Item) -> B,

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Takes a closure and creates an iterator which calls that closure on each element.

fn for_each<F>(self, f: F) where     F: FnMut(Self::Item),

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Calls a closure on each element of an iterator.

fn filter<P>(self, predicate: P) -> Filter<Self, P> where     P: FnMut(&Self::Item) -> bool,

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Creates an iterator which uses a closure to determine if an element should be yielded.

fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where     F: FnMut(Self::Item) -> Option<B>,

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Creates an iterator that both filters and maps.

fn enumerate(self) -> Enumerate<Self>

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Creates an iterator which gives the current iteration count as well as the next value.

fn peekable(self) -> Peekable<Self>

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Creates an iterator which can use peek to look at the next element of the iterator without consuming it.

fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where     P: FnMut(&Self::Item) -> bool,

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Creates an iterator that [skip]s elements based on a predicate.

fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where     P: FnMut(&Self::Item) -> bool,

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Creates an iterator that yields elements based on a predicate.

fn skip(self, n: usize) -> Skip<Self>

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Creates an iterator that skips the first n elements.

fn take(self, n: usize) -> Take<Self>

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Creates an iterator that yields its first n elements.

fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> where     F: FnMut(&mut St, Self::Item) -> Option<B>,

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An iterator adaptor similar to [fold] that holds internal state and produces a new iterator.

fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where     F: FnMut(Self::Item) -> U,     U: IntoIterator,

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Creates an iterator that works like map, but flattens nested structure.

fn flatten(self) -> Flatten<Self> where     Self::Item: IntoIterator,

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🔬 This is a nightly-only experimental API. (iterator_flatten)

Creates an iterator that flattens nested structure.

fn fuse(self) -> Fuse<Self>

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Creates an iterator which ends after the first [None].

fn inspect<F>(self, f: F) -> Inspect<Self, F> where     F: FnMut(&Self::Item),

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Do something with each element of an iterator, passing the value on.

fn by_ref(&mut self) -> &mut Self

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Borrows an iterator, rather than consuming it.

fn collect<B>(self) -> B where     B: FromIterator<Self::Item>,

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Transforms an iterator into a collection.

fn partition<B, F>(self, f: F) -> (B, B) where     B: Default + Extend<Self::Item>,     F: FnMut(&Self::Item) -> bool,

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Consumes an iterator, creating two collections from it.

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where     F: FnMut(B, Self::Item) -> R,     R: Try<Ok = B>,

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An iterator method that applies a function as long as it returns successfully, producing a single, final value.

fn try_for_each<F, R>(&mut self, f: F) -> R where     F: FnMut(Self::Item) -> R,     R: Try<Ok = ()>,

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An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error.

fn fold<B, F>(self, init: B, f: F) -> B where     F: FnMut(B, Self::Item) -> B,

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An iterator method that applies a function, producing a single, final value.

fn all<F>(&mut self, f: F) -> bool where     F: FnMut(Self::Item) -> bool,

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Tests if every element of the iterator matches a predicate.

fn any<F>(&mut self, f: F) -> bool where     F: FnMut(Self::Item) -> bool,

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Tests if any element of the iterator matches a predicate.

fn find<P>(&mut self, predicate: P) -> Option<Self::Item> where     P: FnMut(&Self::Item) -> bool,

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Searches for an element of an iterator that satisfies a predicate.

fn find_map<B, F>(&mut self, f: F) -> Option<B> where     F: FnMut(Self::Item) -> Option<B>,

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🔬 This is a nightly-only experimental API. (iterator_find_map)

unstable new API

Applies function to the elements of iterator and returns the first non-none result.

fn position<P>(&mut self, predicate: P) -> Option<usize> where     P: FnMut(Self::Item) -> bool,

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Searches for an element in an iterator, returning its index.

fn rposition<P>(&mut self, predicate: P) -> Option<usize> where     P: FnMut(Self::Item) -> bool,     Self: ExactSizeIterator + DoubleEndedIterator,

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Searches for an element in an iterator from the right, returning its index.

fn max(self) -> Option<Self::Item> where     Self::Item: Ord,

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Returns the maximum element of an iterator.

fn min(self) -> Option<Self::Item> where     Self::Item: Ord,

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Returns the minimum element of an iterator.

fn max_by_key<B, F>(self, f: F) -> Option<Self::Item> where     B: Ord,     F: FnMut(&Self::Item) -> B,

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Returns the element that gives the maximum value from the specified function.

fn max_by<F>(self, compare: F) -> Option<Self::Item> where     F: FnMut(&Self::Item, &Self::Item) -> Ordering,

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Returns the element that gives the maximum value with respect to the specified comparison function.

fn min_by_key<B, F>(self, f: F) -> Option<Self::Item> where     B: Ord,     F: FnMut(&Self::Item) -> B,

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Returns the element that gives the minimum value from the specified function.

fn min_by<F>(self, compare: F) -> Option<Self::Item> where     F: FnMut(&Self::Item, &Self::Item) -> Ordering,

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Returns the element that gives the minimum value with respect to the specified comparison function.

fn rev(self) -> Rev<Self> where     Self: DoubleEndedIterator,

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Reverses an iterator's direction.

fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB) where     FromA: Default + Extend<A>,     FromB: Default + Extend<B>,     Self: Iterator<Item = (A, B)>,

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Converts an iterator of pairs into a pair of containers.

fn cloned<'a, T>(self) -> Cloned<Self> where     Self: Iterator<Item = &'a T>,     T: 'a + Clone,

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Creates an iterator which [clone]s all of its elements.

fn cycle(self) -> Cycle<Self> where     Self: Clone,

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Repeats an iterator endlessly.

fn sum<S>(self) -> S where     S: Sum<Self::Item>,

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Sums the elements of an iterator.

fn product<P>(self) -> P where     P: Product<Self::Item>,

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Iterates over the entire iterator, multiplying all the elements

fn cmp<I>(self, other: I) -> Ordering where     I: IntoIterator<Item = Self::Item>,     Self::Item: Ord,

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Lexicographically compares the elements of this Iterator with those of another.

fn partial_cmp<I>(self, other: I) -> Option<Ordering> where     I: IntoIterator,     Self::Item: PartialOrd<<I as IntoIterator>::Item>,

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Lexicographically compares the elements of this Iterator with those of another.

fn eq<I>(self, other: I) -> bool where     I: IntoIterator,     Self::Item: PartialEq<<I as IntoIterator>::Item>,

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Determines if the elements of this Iterator are equal to those of another.

fn ne<I>(self, other: I) -> bool where     I: IntoIterator,     Self::Item: PartialEq<<I as IntoIterator>::Item>,

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Determines if the elements of this Iterator are unequal to those of another.

fn lt<I>(self, other: I) -> bool where     I: IntoIterator,     Self::Item: PartialOrd<<I as IntoIterator>::Item>,

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Determines if the elements of this Iterator are lexicographically less than those of another.

fn le<I>(self, other: I) -> bool where     I: IntoIterator,     Self::Item: PartialOrd<<I as IntoIterator>::Item>,

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Determines if the elements of this Iterator are lexicographically less or equal to those of another.

fn gt<I>(self, other: I) -> bool where     I: IntoIterator,     Self::Item: PartialOrd<<I as IntoIterator>::Item>,

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Determines if the elements of this Iterator are lexicographically greater than those of another.

fn ge<I>(self, other: I) -> bool where     I: IntoIterator,     Self::Item: PartialOrd<<I as IntoIterator>::Item>,

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Determines if the elements of this Iterator are lexicographically greater than or equal to those of another.

impl<T> FusedIterator for Receiver<T>

impl<'a, T> IntoIterator for &'a Receiver<T>

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type Item = T

The type of the elements being iterated over.

type IntoIter = Receiver<T>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

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Creates an iterator from a value.

impl<T> UnwindSafe for Receiver<T>

impl<T> RefUnwindSafe for Receiver<T>