thread.rs

use crate::cmp;
use crate::ffi::CStr;
use crate::io;
use crate::mem;
use crate::sys::{unsupported, Void};
use crate::time::Duration;
use libc;

pub struct Thread(Void);

pub const DEFAULT_MIN_STACK_SIZE: usize = 4096;

impl Thread {
    // unsafe: see thread::Builder::spawn_unchecked for safety requirements
    pub unsafe fn new(_stack: usize, _p: Box<dyn FnOnce()>)
        -> io::Result<Thread>
    {
        unsupported()
    }

    pub fn yield_now() {
        let ret = wasi::sched_yield();
        debug_assert_eq!(ret, Ok(()));
    }

    pub fn set_name(_name: &CStr) {
        // nope
    }

    pub fn sleep(dur: Duration) {
        let nanos = dur.as_nanos();
        assert!(nanos <= u64::max_value() as u128);

        let clock = wasi::raw::__wasi_subscription_u_clock_t {
            identifier: 0,
            clock_id: wasi::CLOCK_MONOTONIC,
            timeout: nanos as u64,
            precision: 0,
            flags: 0,
        };

        let in_ = [wasi::Subscription {
            userdata: 0,
            type_: wasi::EVENTTYPE_CLOCK,
            u: wasi::raw::__wasi_subscription_u { clock: clock },
        }];
        let mut out: [wasi::Event; 1] = [unsafe { mem::zeroed() }];
        let n = wasi::poll_oneoff(&in_, &mut out).unwrap();
        let wasi::Event { userdata, error, type_, .. } = out[0];
        match (n, userdata, error) {
            (1, 0, 0) if type_ == wasi::EVENTTYPE_CLOCK => {}
            _ => panic!("thread::sleep(): unexpected result of poll_oneof"),
        }
    }

    pub fn join(self) {
        match self.0 {}
    }
}

pub mod guard {
    pub type Guard = !;
    pub unsafe fn current() -> Option<Guard> { None }
    pub unsafe fn init() -> Option<Guard> { None }
}