pub struct Parker { /* private fields */ }
Expand description

A thread parking primitive.

Conceptually, each Parker has an associated token which is initially not present:

  • The park method blocks the current thread unless or until the token is available, at which point it automatically consumes the token.

  • The park_timeout and park_deadline methods work the same as park, but block for a specified maximum time.

  • The unpark method atomically makes the token available if it wasn’t already. Because the token is initially absent, unpark followed by park will result in the second call returning immediately.

In other words, each Parker acts a bit like a spinlock that can be locked and unlocked using park and unpark.

Examples

use std::thread;
use std::time::Duration;
use crossbeam_utils::sync::Parker;

let p = Parker::new();
let u = p.unparker().clone();

// Make the token available.
u.unpark();
// Wakes up immediately and consumes the token.
p.park();

thread::spawn(move || {
    thread::sleep(Duration::from_millis(500));
    u.unpark();
});

// Wakes up when `u.unpark()` provides the token.
p.park();

Implementations

Creates a new Parker.

Examples
use crossbeam_utils::sync::Parker;

let p = Parker::new();

Blocks the current thread until the token is made available.

Examples
use crossbeam_utils::sync::Parker;

let p = Parker::new();
let u = p.unparker().clone();

// Make the token available.
u.unpark();

// Wakes up immediately and consumes the token.
p.park();

Blocks the current thread until the token is made available, but only for a limited time.

Examples
use std::time::Duration;
use crossbeam_utils::sync::Parker;

let p = Parker::new();

// Waits for the token to become available, but will not wait longer than 500 ms.
p.park_timeout(Duration::from_millis(500));

Blocks the current thread until the token is made available, or until a certain deadline.

Examples
use std::time::{Duration, Instant};
use crossbeam_utils::sync::Parker;

let p = Parker::new();
let deadline = Instant::now() + Duration::from_millis(500);

// Waits for the token to become available, but will not wait longer than 500 ms.
p.park_deadline(deadline);

Returns a reference to an associated Unparker.

The returned Unparker doesn’t have to be used by reference - it can also be cloned.

Examples
use crossbeam_utils::sync::Parker;

let p = Parker::new();
let u = p.unparker().clone();

// Make the token available.
u.unpark();
// Wakes up immediately and consumes the token.
p.park();

Converts a Parker into a raw pointer.

Examples
use crossbeam_utils::sync::Parker;

let p = Parker::new();
let raw = Parker::into_raw(p);

Converts a raw pointer into a Parker.

Safety

This method is safe to use only with pointers returned by Parker::into_raw.

Examples
use crossbeam_utils::sync::Parker;

let p = Parker::new();
let raw = Parker::into_raw(p);
let p = unsafe { Parker::from_raw(raw) };

Trait Implementations

Formats the value using the given formatter. Read more
Returns the “default value” for a type. Read more

Auto Trait Implementations

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Returns the argument unchanged.

Creates Self using data from the given [World]
Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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Initializes a with the given initializer. Read more
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Should always be Self
The inverse inclusion map: attempts to construct self from the equivalent element of its superset. Read more
Checks if self is actually part of its subset T (and can be converted to it).
Use with care! Same as self.to_subset but without any property checks. Always succeeds.
The inclusion map: converts self to the equivalent element of its superset.
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Performs the conversion.
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