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use core::cell::UnsafeCell;
#[allow(unused)]
use core::convert::TryFrom;
use core::mem;
use error_code::PosixError;
pub struct Sem {
handle: UnsafeCell<libc::sem_t>,
}
impl super::CountingSemaphore for Sem {
fn new(init: u32) -> Option<Self> {
let mut handle = mem::MaybeUninit::uninit();
let res = unsafe {
libc::sem_init(handle.as_mut_ptr(), 0, init as libc::c_uint)
};
match res {
0 => Some(Self {
handle: UnsafeCell::new(unsafe {
handle.assume_init()
})
}),
_ => None,
}
}
fn wait(&self) {
loop {
let res = unsafe {
libc::sem_wait(self.handle.get())
};
if res == -1 {
let errno = PosixError::last();
debug_assert_eq!(errno.raw_code(), libc::EINTR, "Unexpected error");
continue;
}
break
}
}
fn try_wait(&self) -> bool {
loop {
let res = unsafe {
libc::sem_trywait(self.handle.get())
};
if res == -1 {
let errno = PosixError::last();
if errno.is_would_block() {
break false;
}
debug_assert_eq!(errno.raw_code(), libc::EINTR, "Unexpected error");
continue;
}
break true
}
}
fn wait_timeout(&self, timeout: core::time::Duration) -> bool {
let timeout = libc::timespec {
tv_sec: timeout.as_secs() as libc::time_t,
#[cfg(target_pointer_width = "64")]
tv_nsec: libc::suseconds_t::from(timeout.subsec_nanos()),
#[cfg(not(target_pointer_width = "64"))]
tv_nsec: libc::suseconds_t::try_from(timeout.subsec_nanos()).unwrap_or(libc::suseconds_t::max_value()),
};
loop {
let res = unsafe {
libc::sem_timedwait(self.handle.get(), &timeout)
};
if res == -1 {
let errno = PosixError::last();
if errno.is_would_block() || errno.raw_code() == libc::ETIMEDOUT {
break false;
}
debug_assert_eq!(errno.raw_code(), libc::EINTR, "Unexpected error");
continue;
}
break true
}
}
fn signal(&self) {
let res = unsafe {
libc::sem_post(self.handle.get())
};
debug_assert_eq!(res, 0);
}
}
impl Drop for Sem {
fn drop(&mut self) {
unsafe {
libc::sem_destroy(self.handle.get());
}
}
}
unsafe impl Send for Sem {}
unsafe impl Sync for Sem {}