Struct abi_stable::external_types::parking_lot::once::ROnce
source · #[repr(C)]pub struct ROnce { /* private fields */ }
Expand description
A synchronization primitive for running global initialization once.
Example
use abi_stable::external_types::{RMutex, ROnce};
static MUTEX: RMutex<usize> = RMutex::new(0);
static ONCE: ROnce = ROnce::new();
let guards = std::iter::repeat_with(|| {
std::thread::spawn(|| {
ONCE.call_once(|| {
*MUTEX.lock() += 1;
})
})
})
.take(20)
.collect::<Vec<_>>();
for guard in guards {
guard.join().unwrap();
}
assert_eq!(*MUTEX.lock(), 1);
Implementations§
source§impl ROnce
impl ROnce
sourcepub const NEW: Self = _
pub const NEW: Self = _
Constructs an ROnce.
Example
use abi_stable::external_types::ROnce;
static ONCE: ROnce = ROnce::NEW;
sourcepub fn state(&self) -> ROnceState
pub fn state(&self) -> ROnceState
Gets the running state of this ROnce.
Example
use abi_stable::external_types::parking_lot::once::{ROnce, ROnceState};
use std::panic::AssertUnwindSafe;
let once = ROnce::new();
assert_eq!(once.state(), ROnceState::New);
let _ = std::panic::catch_unwind(AssertUnwindSafe(|| {
once.call_once(|| panic!());
}));
assert!(once.state().poisoned());
once.call_once_force(|_| ());
assert!(once.state().done());
sourcepub fn call_once<F>(&self, f: F)where
F: FnOnce(),
pub fn call_once<F>(&self, f: F)where
F: FnOnce(),
Runs an initialization function.
f
will be run only if this is the first time this method has been called
on this ROnce.
Once this function returns it is guaranteed that some closure passed to this method has run to completion.
Panics
Panics in the closure will cause this ROnce to become poisoned, and any future calls to this method will panic.
Example
use abi_stable::external_types::ROnce;
let once = ROnce::new();
let mut counter = 0usize;
once.call_once(|| counter += 1);
once.call_once(|| counter += 1);
once.call_once(|| counter += 1);
once.call_once(|| counter += 1);
assert_eq!(counter, 1);
sourcepub fn call_once_force<F>(&self, f: F)where
F: FnOnce(ROnceState),
pub fn call_once_force<F>(&self, f: F)where
F: FnOnce(ROnceState),
Runs an initialization function,even if the ROnce is poisoned.
This will keep trying to run different closures until one of them doesn’t panic.
The ROnceState parameter describes whether the ROnce is New or Poisoned.
Example
use abi_stable::external_types::ROnce;
use std::panic::{self, AssertUnwindSafe};
let once = ROnce::new();
let mut counter = 0usize;
for i in 0..100 {
let _ = panic::catch_unwind(AssertUnwindSafe(|| {
once.call_once_force(|_| {
if i < 6 {
panic!();
}
counter = i;
})
}));
}
assert_eq!(counter, 6);
Trait Implementations§
source§impl GetStaticEquivalent_ for ROnce
impl GetStaticEquivalent_ for ROnce
§type StaticEquivalent = _static_ROnce
type StaticEquivalent = _static_ROnce
The
'static
equivalent of Self
source§impl StableAbi for ROnce
impl StableAbi for ROnce
§type IsNonZeroType = False
type IsNonZeroType = False
Whether this type has a single invalid bit-pattern. Read more
source§const LAYOUT: &'static TypeLayout = _
const LAYOUT: &'static TypeLayout = _
The layout of the type provided by implementors.
source§const ABI_CONSTS: AbiConsts = _
const ABI_CONSTS: AbiConsts = _
const
-equivalents of the associated types.impl Send for ROnce
impl Sync for ROnce
Auto Trait Implementations§
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source§impl<T> AlignerFor<1> for T
impl<T> AlignerFor<1> for T
source§impl<T> AlignerFor<1024> for T
impl<T> AlignerFor<1024> for T
§type Aligner = AlignTo1024<T>
type Aligner = AlignTo1024<T>
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AlignTo*
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.source§impl<T> AlignerFor<128> for T
impl<T> AlignerFor<128> for T
§type Aligner = AlignTo128<T>
type Aligner = AlignTo128<T>
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AlignTo*
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.source§impl<T> AlignerFor<16> for T
impl<T> AlignerFor<16> for T
source§impl<T> AlignerFor<16384> for T
impl<T> AlignerFor<16384> for T
§type Aligner = AlignTo16384<T>
type Aligner = AlignTo16384<T>
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AlignTo*
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.source§impl<T> AlignerFor<2> for T
impl<T> AlignerFor<2> for T
source§impl<T> AlignerFor<2048> for T
impl<T> AlignerFor<2048> for T
§type Aligner = AlignTo2048<T>
type Aligner = AlignTo2048<T>
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AlignTo*
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.source§impl<T> AlignerFor<256> for T
impl<T> AlignerFor<256> for T
§type Aligner = AlignTo256<T>
type Aligner = AlignTo256<T>
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AlignTo*
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impl<T> AlignerFor<32> for T
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impl<T> AlignerFor<32768> for T
§type Aligner = AlignTo32768<T>
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§type Aligner = AlignTo4096<T>
type Aligner = AlignTo4096<T>
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.source§impl<T> AlignerFor<512> for T
impl<T> AlignerFor<512> for T
§type Aligner = AlignTo512<T>
type Aligner = AlignTo512<T>
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.source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
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source§fn borrow_mut(&mut self) -> &mut T
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source§impl<S> ROExtAcc for S
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source§fn f_get<F>(&self, offset: FieldOffset<S, F, Aligned>) -> &F
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