Struct ste::Thread

#[must_use =
  "The thread should be joined with Thread::join once no longer used, \
    otherwise it will block while being dropped."]pub struct Thread { /* fields omitted */ }

The handle for a background thread.

The background thread can be interacted with in a couple of ways:

• submit - for submitted tasks, the call will block until it has been executed on the thread (or the thread has panicked).
• submit_async - for submitting asynchronous tasks, the call will block until it has been executed on the thread (or the thread has panicked).
• drop - for dropping value on the background thread. This is necessary for Tag values that requires drop.

Examples

use std::sync::Arc;

let thread = Arc::new(ste::Thread::new()?);
let mut threads = Vec::new();

for n in 0..10 {
    let thread = thread.clone();

    threads.push(std::thread::spawn(move || {
        thread.submit(move || n)
    }));
}

let mut result = 0;

for t in threads {
    result += t.join().unwrap()?;
}

assert_eq!(result, (0..10).sum());

// Unwrap the thread.
let thread = Arc::try_unwrap(thread).map_err(|_| "unwrap failed").unwrap();

let value = thread.submit(|| {
    panic!("Background thread: {:?}", std::thread::current().id());
});

println!("Main thread: {:?}", std::thread::current().id());
assert!(value.is_err());

assert!(thread.join().is_err());

Implementations

impl Thread

pub fn new() -> Result<Self>

Construct a default background thread executor.

These both do the same thing:

let thread1 = ste::Thread::new()?;
let thread2 = ste::Builder::new().build()?;

pub async fn submit_async<F>(&self, future: F) -> Result<F::Output, Panicked> where
    F: Send + Future,
    F::Output: Send, 

Run the given future on the background thread. The future can reference memory outside of the current scope, but in order to do so, every time it is polled it has to be perfectly synchronized with a remote poll happening on the background thread.

Safety

This function is unsafe as heck right now. Polling it without it having been called w/ wake_by_ref will cause a data race.

The above will be fixed.

Examples

This method supports panics the same way as other threads:

let audio_thread = ste::Thread::new()?;

let result = audio_thread
    .submit_async(async move { panic!("woops") })
    .await;

assert!(result.is_err());
assert!(audio_thread.join().is_err());

pub fn submit<F, T>(&self, task: F) -> Result<T, Panicked> where
    F: Send + FnOnce() -> T,
    T: Send, 

Submit a task to run on the background thread.

The call will block until it has been executed on the thread (or the thread has panicked).

Because this function blocks until completion, it can safely access values which are outside of the scope of the provided closure.

If you however need to store and access things which are !Send, you can wrap them in a container that ensures their thread-locality with Tag and then safely implement Send for it.

Examples

let thread = ste::Thread::new()?;

let mut n = 10;
thread.submit(|| n += 10)?;
assert_eq!(20, n);

thread.join()?;

pub fn drop<T>(&self, value: T) -> Result<(), Panicked> where
    T: Send, 

Move the provided value onto the background thread and drop it.

This is necessary for values which uses Tag to ensure that a type is not dropped incorrectly.

Examples

struct Foo(ste::Tag);

impl Drop for Foo {
    fn drop(&mut self) {
        self.0.ensure_on_thread();
    }
}

let thread = ste::Thread::new()?;

let foo = thread.submit(|| Foo(ste::Tag::current_thread()));
thread.drop(foo);

thread.join()?;

pub fn join(self) -> Result<(), Panicked>

Join the background thread.

Will block until the background thread is joined.

This is the clean way to join a background thread, the alternative is to let Thread drop and this will be performed in the drop handler instead.

Examples

let thread = ste::Thread::new()?;

let mut n = 10;
thread.submit(|| n += 10)?;
assert_eq!(20, n);

thread.join()?;

pub fn tag(&self) -> Tag

Construct the tag that is associated with the current thread externally from the thread.

Examples

struct Foo(ste::Tag);

impl Foo {
    fn say_hello(&self) {
        self.0.ensure_on_thread();
        println!("Hello World");
    }
}

let thread = ste::Thread::new()?;

let foo = Foo(thread.tag());

thread.submit(|| {
    foo.say_hello();
})?;

thread.join()?;

Trait Implementations

impl Drop for Thread

fn drop(&mut self)

Executes the destructor for this type.

impl Send for Thread

Safety: The handle is both send and sync because it joins the background thread which keeps track of the state of shared and cleans it up once it’s no longer needed.

impl Sync for Thread