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|
use crate::ffi::CStr;
use crate::io;
use crate::mem;
use crate::num::NonZeroUsize;
use crate::sys::unsupported;
use crate::time::Duration;
cfg_if::cfg_if! {
if #[cfg(target_feature = "atomics")] {
use crate::cmp;
use crate::ptr;
use crate::sys::os;
// Add a few symbols not in upstream `libc` just yet.
mod libc {
pub use crate::ffi;
pub use crate::mem;
pub use libc::*;
// defined in wasi-libc
// https://github.com/WebAssembly/wasi-libc/blob/a6f871343313220b76009827ed0153586361c0d5/libc-top-half/musl/include/alltypes.h.in#L108
#[repr(C)]
union pthread_attr_union {
__i: [ffi::c_int; if mem::size_of::<ffi::c_long>() == 8 { 14 } else { 9 }],
__vi: [ffi::c_int; if mem::size_of::<ffi::c_long>() == 8 { 14 } else { 9 }],
__s: [ffi::c_ulong; if mem::size_of::<ffi::c_long>() == 8 { 7 } else { 9 }],
}
#[repr(C)]
pub struct pthread_attr_t {
__u: pthread_attr_union,
}
#[allow(non_camel_case_types)]
pub type pthread_t = *mut ffi::c_void;
extern "C" {
pub fn pthread_create(
native: *mut pthread_t,
attr: *const pthread_attr_t,
f: extern "C" fn(*mut ffi::c_void) -> *mut ffi::c_void,
value: *mut ffi::c_void,
) -> ffi::c_int;
pub fn pthread_join(native: pthread_t, value: *mut *mut ffi::c_void) -> ffi::c_int;
pub fn pthread_attr_init(attrp: *mut pthread_attr_t) -> ffi::c_int;
pub fn pthread_attr_setstacksize(
attr: *mut pthread_attr_t,
stack_size: libc::size_t,
) -> ffi::c_int;
pub fn pthread_attr_destroy(attr: *mut pthread_attr_t) -> ffi::c_int;
pub fn pthread_detach(thread: pthread_t) -> ffi::c_int;
}
}
pub struct Thread {
id: libc::pthread_t,
}
impl Drop for Thread {
fn drop(&mut self) {
let ret = unsafe { libc::pthread_detach(self.id) };
debug_assert_eq!(ret, 0);
}
}
} else {
pub struct Thread(!);
}
}
pub const DEFAULT_MIN_STACK_SIZE: usize = 4096;
impl Thread {
// unsafe: see thread::Builder::spawn_unchecked for safety requirements
cfg_if::cfg_if! {
if #[cfg(target_feature = "atomics")] {
pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
let p = Box::into_raw(Box::new(p));
let mut native: libc::pthread_t = mem::zeroed();
let mut attr: libc::pthread_attr_t = mem::zeroed();
assert_eq!(libc::pthread_attr_init(&mut attr), 0);
let stack_size = cmp::max(stack, DEFAULT_MIN_STACK_SIZE);
match libc::pthread_attr_setstacksize(&mut attr, stack_size) {
0 => {}
n => {
assert_eq!(n, libc::EINVAL);
// EINVAL means |stack_size| is either too small or not a
// multiple of the system page size. Because it's definitely
// >= PTHREAD_STACK_MIN, it must be an alignment issue.
// Round up to the nearest page and try again.
let page_size = os::page_size();
let stack_size =
(stack_size + page_size - 1) & (-(page_size as isize - 1) as usize - 1);
assert_eq!(libc::pthread_attr_setstacksize(&mut attr, stack_size), 0);
}
};
let ret = libc::pthread_create(&mut native, &attr, thread_start, p as *mut _);
// Note: if the thread creation fails and this assert fails, then p will
// be leaked. However, an alternative design could cause double-free
// which is clearly worse.
assert_eq!(libc::pthread_attr_destroy(&mut attr), 0);
return if ret != 0 {
// The thread failed to start and as a result p was not consumed. Therefore, it is
// safe to reconstruct the box so that it gets deallocated.
drop(Box::from_raw(p));
Err(io::Error::from_raw_os_error(ret))
} else {
Ok(Thread { id: native })
};
extern "C" fn thread_start(main: *mut libc::c_void) -> *mut libc::c_void {
unsafe {
// Finally, let's run some code.
Box::from_raw(main as *mut Box<dyn FnOnce()>)();
}
ptr::null_mut()
}
}
} else {
pub unsafe fn new(_stack: usize, _p: Box<dyn FnOnce()>) -> io::Result<Thread> {
unsupported()
}
}
}
pub fn yield_now() {
let ret = unsafe { 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 as u128);
const USERDATA: wasi::Userdata = 0x0123_45678;
let clock = wasi::SubscriptionClock {
id: wasi::CLOCKID_MONOTONIC,
timeout: nanos as u64,
precision: 0,
flags: 0,
};
let in_ = wasi::Subscription {
userdata: USERDATA,
u: wasi::SubscriptionU { tag: 0, u: wasi::SubscriptionUU { clock } },
};
unsafe {
let mut event: wasi::Event = mem::zeroed();
let res = wasi::poll_oneoff(&in_, &mut event, 1);
match (res, event) {
(
Ok(1),
wasi::Event {
userdata: USERDATA,
error: wasi::ERRNO_SUCCESS,
type_: wasi::EVENTTYPE_CLOCK,
..
},
) => {}
_ => panic!("thread::sleep(): unexpected result of poll_oneoff"),
}
}
}
pub fn join(self) {
cfg_if::cfg_if! {
if #[cfg(target_feature = "atomics")] {
unsafe {
let ret = libc::pthread_join(self.id, ptr::null_mut());
mem::forget(self);
if ret != 0 {
rtabort!("failed to join thread: {}", io::Error::from_raw_os_error(ret));
}
}
} else {
self.0
}
}
}
}
pub fn available_parallelism() -> io::Result<NonZeroUsize> {
unsupported()
}
pub mod guard {
pub type Guard = !;
pub unsafe fn current() -> Option<Guard> {
None
}
pub unsafe fn init() -> Option<Guard> {
None
}
}
|
