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Use futex-based locks and thread parker on NetBSD.

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This commit is contained in:
Mara Bos 2022-04-28 11:03:30 +02:00
parent afe1a256ce
commit 2dfad1e3f8
3 changed files with 53 additions and 24 deletions
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75
library/std/src/sys/unix/futex.rs
View File

@ -3,17 +3,21 @@
target_os = "android",
all(target_os = "emscripten", target_feature = "atomics"),
target_os = "openbsd",
target_os = "netbsd",
))]
use crate::sync::atomic::AtomicU32;
use crate::time::Duration;
#[cfg(target_os = "netbsd")]
pub const SYS___futex: i32 = 166;
/// Wait for a futex_wake operation to wake us.
///
/// Returns directly if the futex doesn't hold the expected value.
///
/// Returns false on timeout, and true in all other cases.
#[cfg(any(target_os = "linux", target_os = "android"))]
#[cfg(any(target_os = "linux", target_os = "android", target_os = "netbsd"))]
pub fn futex_wait(futex: &AtomicU32, expected: u32, timeout: Option<Duration>) -> bool {
use super::time::Timespec;
use crate::ptr::null;
@ -34,15 +38,32 @@ pub fn futex_wait(futex: &AtomicU32, expected: u32, timeout: Option<Duration>) -
// Use FUTEX_WAIT_BITSET rather than FUTEX_WAIT to be able to give an
// absolute time rather than a relative time.
let r = unsafe {
libc::syscall(
libc::SYS_futex,
futex as *const AtomicU32,
libc::FUTEX_WAIT_BITSET | libc::FUTEX_PRIVATE_FLAG,
expected,
timespec.as_ref().map_or(null(), |t| &t.t as *const libc::timespec),
null::<u32>(), // This argument is unused for FUTEX_WAIT_BITSET.
!0u32, // A full bitmask, to make it behave like a regular FUTEX_WAIT.
)
cfg_if::cfg_if! {
if #[cfg(target_os = "netbsd")] {
// Netbsd's futex syscall takes addr2 and val2 as separate arguments.
// (Both are unused for FUTEX_WAIT[_BITSET].)
libc::syscall(
SYS___futex,
futex as *const AtomicU32,
libc::FUTEX_WAIT_BITSET | libc::FUTEX_PRIVATE_FLAG,
expected,
timespec.as_ref().map_or(null(), |t| &t.t as *const libc::timespec),
null::<u32>(), // addr2: This argument is unused for FUTEX_WAIT_BITSET.
0, // val2: This argument is unused for FUTEX_WAIT_BITSET.
!0u32, // val3 / bitmask: A full bitmask, to make it behave like a regular FUTEX_WAIT.
)
} else {
libc::syscall(
libc::SYS_futex,
futex as *const AtomicU32,
libc::FUTEX_WAIT_BITSET | libc::FUTEX_PRIVATE_FLAG,
expected,
timespec.as_ref().map_or(null(), |t| &t.t as *const libc::timespec),
null::<u32>(), // This argument is unused for FUTEX_WAIT_BITSET.
!0u32, // A full bitmask, to make it behave like a regular FUTEX_WAIT.
)
}
}
};
match (r < 0).then(super::os::errno) {
@ -57,28 +78,34 @@ pub fn futex_wait(futex: &AtomicU32, expected: u32, timeout: Option<Duration>) -
///
/// Returns true if this actually woke up such a thread,
/// or false if no thread was waiting on this futex.
#[cfg(any(target_os = "linux", target_os = "android"))]
#[cfg(any(target_os = "linux", target_os = "android", target_os = "netbsd"))]
pub fn futex_wake(futex: &AtomicU32) -> bool {
let ptr = futex as *const AtomicU32;
let op = libc::FUTEX_WAKE | libc::FUTEX_PRIVATE_FLAG;
unsafe {
libc::syscall(
libc::SYS_futex,
futex as *const AtomicU32,
libc::FUTEX_WAKE | libc::FUTEX_PRIVATE_FLAG,
1,
) > 0
cfg_if::cfg_if! {
if #[cfg(target_os = "netbsd")] {
libc::syscall(SYS___futex, ptr, op, 1) > 0
} else {
libc::syscall(libc::SYS_futex, ptr, op, 1) > 0
}
}
}
}
/// Wake up all threads that are waiting on futex_wait on this futex.
#[cfg(any(target_os = "linux", target_os = "android"))]
#[cfg(any(target_os = "linux", target_os = "android", target_os = "netbsd"))]
pub fn futex_wake_all(futex: &AtomicU32) {
let ptr = futex as *const AtomicU32;
let op = libc::FUTEX_WAKE | libc::FUTEX_PRIVATE_FLAG;
unsafe {
libc::syscall(
libc::SYS_futex,
futex as *const AtomicU32,
libc::FUTEX_WAKE | libc::FUTEX_PRIVATE_FLAG,
i32::MAX,
);
cfg_if::cfg_if! {
if #[cfg(target_os = "netbsd")] {
libc::syscall(SYS___futex, ptr, op, i32::MAX);
} else {
libc::syscall(libc::SYS_futex, ptr, op, i32::MAX);
}
}
}
}

1
library/std/src/sys/unix/locks/mod.rs
View File

@ -4,6 +4,7 @@ cfg_if::cfg_if! {
target_os = "android",
all(target_os = "emscripten", target_feature = "atomics"),
target_os = "openbsd",
target_os = "netbsd",
))] {
mod futex;
mod futex_rwlock;

1
library/std/src/sys_common/thread_parker/mod.rs
View File

@ -4,6 +4,7 @@ cfg_if::cfg_if! {
target_os = "android",
all(target_arch = "wasm32", target_feature = "atomics"),
target_os = "openbsd",
target_os = "netbsd",
))] {
mod futex;
pub use futex::Parker;