Struct objc2_foundation::MainThreadMarker

pub struct MainThreadMarker { /* private fields */ }

A marker type taken by functions that can only be executed on the main thread.

By design, this is neither Send nor Sync, and can only be created on the main thread, meaning that if you’re holding this, you know you’re running on the main thread.

See the following links for more information on main-thread-only APIs:

• Main Thread Only APIs on OS X
• Thread Safety Summary
• Are the Cocoa Frameworks Thread Safe?
• Technical Note TN2028 - Threading Architectures
• Thread Management
• Mike Ash’ article on thread safety

Examples

Use when designing APIs that are only safe to use on the main thread:

use objc2::msg_send;
use objc2::runtime::Object;
use objc2_foundation::MainThreadMarker;

// This action requires the main thread, so we take a marker as parameter.
// It signals clearly to users "this requires the main thread".
unsafe fn do_thing(obj: *const Object, _mtm: MainThreadMarker) {
    msg_send![obj, someActionThatRequiresTheMainThread]
}

// Usage
let mtm = MainThreadMarker::new().unwrap();
unsafe { do_thing(obj, mtm) }

Implementations

impl MainThreadMarker

pub fn new() -> Option<Self>

Construct a new MainThreadMarker.

Returns None if the current thread was not the main thread.

pub unsafe fn new_unchecked() -> Self

Construct a new MainThreadMarker without first checking whether the current thread is the main one.

Safety

The current thread must be the main thread.

Trait Implementations

impl Clone for MainThreadMarker

fn clone(&self) -> MainThreadMarker

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for MainThreadMarker

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

Formats the value using the given formatter.

impl Hash for MainThreadMarker

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, 

Feeds a slice of this type into the given Hasher.

impl Ord for MainThreadMarker

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

This method returns an Ordering between self and other.

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

Compares and returns the maximum of two values.

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

Compares and returns the minimum of two values.

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

Restrict a value to a certain interval.

impl PartialEq<MainThreadMarker> for MainThreadMarker

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

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

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

This method tests for !=.

impl PartialOrd<MainThreadMarker> for MainThreadMarker

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

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

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

This method tests less than (for self and other) and is used by the < operator.

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

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

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

This method tests greater than (for self and other) and is used by the > operator.

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

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

impl Copy for MainThreadMarker

impl Eq for MainThreadMarker

impl StructuralEq for MainThreadMarker

impl StructuralPartialEq for MainThreadMarker