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Diffstat (limited to '')
-rw-r--r-- | library/std/src/sys/unix/thread_parker/netbsd.rs | 113 |
1 files changed, 0 insertions, 113 deletions
diff --git a/library/std/src/sys/unix/thread_parker/netbsd.rs b/library/std/src/sys/unix/thread_parker/netbsd.rs deleted file mode 100644 index 7657605b5..000000000 --- a/library/std/src/sys/unix/thread_parker/netbsd.rs +++ /dev/null @@ -1,113 +0,0 @@ -use crate::ffi::{c_int, c_void}; -use crate::pin::Pin; -use crate::ptr::{null, null_mut}; -use crate::sync::atomic::{ - AtomicU64, - Ordering::{Acquire, Relaxed, Release}, -}; -use crate::time::Duration; -use libc::{_lwp_self, clockid_t, lwpid_t, time_t, timespec, CLOCK_MONOTONIC}; - -extern "C" { - fn ___lwp_park60( - clock_id: clockid_t, - flags: c_int, - ts: *mut timespec, - unpark: lwpid_t, - hint: *const c_void, - unparkhint: *const c_void, - ) -> c_int; - fn _lwp_unpark(lwp: lwpid_t, hint: *const c_void) -> c_int; -} - -/// The thread is not parked and the token is not available. -/// -/// Zero cannot be a valid LWP id, since it is used as empty value for the unpark -/// argument in _lwp_park. -const EMPTY: u64 = 0; -/// The token is available. Do not park anymore. -const NOTIFIED: u64 = u64::MAX; - -pub struct Parker { - /// The parker state. Contains either one of the two state values above or the LWP - /// id of the parked thread. - state: AtomicU64, -} - -impl Parker { - pub unsafe fn new(parker: *mut Parker) { - parker.write(Parker { state: AtomicU64::new(EMPTY) }) - } - - // Does not actually need `unsafe` or `Pin`, but the pthread implementation does. - pub unsafe fn park(self: Pin<&Self>) { - // If the token has already been made available, we can skip - // a bit of work, so check for it here. - if self.state.load(Acquire) != NOTIFIED { - let parked = _lwp_self() as u64; - let hint = self.state.as_mut_ptr().cast(); - if self.state.compare_exchange(EMPTY, parked, Relaxed, Acquire).is_ok() { - // Loop to guard against spurious wakeups. - loop { - ___lwp_park60(0, 0, null_mut(), 0, hint, null()); - if self.state.load(Acquire) == NOTIFIED { - break; - } - } - } - } - - // At this point, the change to NOTIFIED has always been observed with acquire - // ordering, so we can just use a relaxed store here (instead of a swap). - self.state.store(EMPTY, Relaxed); - } - - // Does not actually need `unsafe` or `Pin`, but the pthread implementation does. - pub unsafe fn park_timeout(self: Pin<&Self>, dur: Duration) { - if self.state.load(Acquire) != NOTIFIED { - let parked = _lwp_self() as u64; - let hint = self.state.as_mut_ptr().cast(); - let mut timeout = timespec { - // Saturate so that the operation will definitely time out - // (even if it is after the heat death of the universe). - tv_sec: dur.as_secs().try_into().ok().unwrap_or(time_t::MAX), - tv_nsec: dur.subsec_nanos().into(), - }; - - if self.state.compare_exchange(EMPTY, parked, Relaxed, Acquire).is_ok() { - // Timeout needs to be mutable since it is modified on NetBSD 9.0 and - // above. - ___lwp_park60(CLOCK_MONOTONIC, 0, &mut timeout, 0, hint, null()); - // Use a swap to get acquire ordering even if the token was set after - // the timeout occurred. - self.state.swap(EMPTY, Acquire); - return; - } - } - - self.state.store(EMPTY, Relaxed); - } - - // Does not actually need `Pin`, but the pthread implementation does. - pub fn unpark(self: Pin<&Self>) { - let state = self.state.swap(NOTIFIED, Release); - if !matches!(state, EMPTY | NOTIFIED) { - let lwp = state as lwpid_t; - let hint = self.state.as_mut_ptr().cast(); - - // If the parking thread terminated and did not actually park, this will - // probably return an error, which is OK. In the worst case, another - // thread has received the same LWP id. It will then receive a spurious - // wakeup, but those are allowable per the API contract. The same reasoning - // applies if a timeout occurred before this call, but the state was not - // yet reset. - - // SAFETY: - // The syscall has no invariants to hold. Only unsafe because it is an - // extern function. - unsafe { - _lwp_unpark(lwp, hint); - } - } - } -} |