Enum Semantics

#[non_exhaustive]
pub enum Semantics {
    Relaxed,
    Coupled,
    Ordered,
}

Memory ordering semantics for atomic operations

Each variant represents a group of compatible orderings. They determine how value updates are synchronized between threads

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Relaxed

Relaxed semantics

No synchronization constraints and the best performance

Set this when using a value in only one thread

Coupled

Release - Acquire coupling semantics

Mild synchronization constraints and fair performance

A read will always see the preceding write (if one exists). Any operations that take place before the write will also be seen, regardless of their semantics

Set this when using a value in multiple threads, unless certain that you need different semantics

Ordered

SeqCst semantics

Maximum synchronization constraints and the worst performance

All memory operations will appear to be executed in a single, total order

Implementations

impl Semantics

pub const fn read_write(&self) -> Ordering

Returns the memory ordering for read-write operations with these semantics

Returns

• Relaxed for Relaxed semantics
• AcqRel for Coupled semantics
• SeqCst for Ordered semantics

Usage

use ptr_cell::Semantics::Coupled;
use std::sync::atomic::Ordering;

assert_eq!(Coupled.read_write(), Ordering::AcqRel)

impl Semantics

pub const fn write(&self) -> Ordering

Returns the memory ordering for write operations with these semantics

Returns

• Relaxed for Relaxed semantics
• Release for Coupled semantics
• SeqCst for Ordered semantics

Usage

use ptr_cell::Semantics::Coupled;
use std::sync::atomic::Ordering;

assert_eq!(Coupled.write(), Ordering::Release)

impl Semantics

pub const fn read(&self) -> Ordering

Returns the memory ordering for read operations with these semantics

Returns

• Relaxed for Relaxed semantics
• Acquire for Coupled semantics
• SeqCst for Ordered semantics

Usage

use ptr_cell::Semantics::Coupled;
use std::sync::atomic::Ordering;

assert_eq!(Coupled.read(), Ordering::Acquire)

Trait Implementations

impl Clone for Semantics

fn clone(&self) -> Semantics

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Semantics

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

Formats the value using the given formatter.

impl Default for Semantics

fn default() -> Semantics

Returns the “default value” for a type.

impl Hash for Semantics

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

Feeds this value into the given Hasher.

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

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Semantics

fn cmp(&self, other: &Semantics) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Semantics

fn eq(&self, other: &Semantics) -> bool

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Semantics

fn partial_cmp(&self, other: &Semantics) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for Semantics

impl Eq for Semantics

impl StructuralPartialEq for Semantics