1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36

use std::fmt;
use std::sync::atomic::{AtomicUsize, Ordering};

/// A unique identifier for a task.

///

/// # Examples

///

/// ```

/// use async_std::task;

///

/// task::block_on(async {

///     println!("id = {:?}", task::current().id());

/// })

/// ```

#[derive(Eq, PartialEq, Clone, Copy, Hash, Debug)]
pub struct TaskId(pub(crate) usize);

impl TaskId {
    /// Generates a new `TaskId`.

    pub(crate) fn generate() -> TaskId {
        // TODO: find a good version to emulate u64 atomics on 32 bit systems.

        static COUNTER: AtomicUsize = AtomicUsize::new(1);

        let id = COUNTER.fetch_add(1, Ordering::Relaxed);
        if id > usize::max_value() / 2 {
            std::process::abort();
        }
        TaskId(id)
    }
}

impl fmt::Display for TaskId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}