pub struct OnceBox<T> { /* private fields */ }
Expand description
A thread-safe cell which can be written to only once.
Implementations
impl<T> OnceBox<T>
impl<T> OnceBox<T>
pub fn set(&self, value: Box<T, Global>) -> Result<(), Box<T, Global>>
pub fn set(&self, value: Box<T, Global>) -> Result<(), Box<T, Global>>
Sets the contents of this cell to value
.
Returns Ok(())
if the cell was empty and Err(value)
if it was
full.
pub fn get_or_init<F>(&self, f: F) -> &T where
F: FnOnce() -> Box<T, Global>,
pub fn get_or_init<F>(&self, f: F) -> &T where
F: FnOnce() -> Box<T, Global>,
Gets the contents of the cell, initializing it with f
if the cell was
empty.
If several threads concurrently run get_or_init
, more than one f
can
be called. However, all threads will return the same value, produced by
some f
.
pub fn get_or_try_init<F, E>(&self, f: F) -> Result<&T, E> where
F: FnOnce() -> Result<Box<T, Global>, E>,
pub fn get_or_try_init<F, E>(&self, f: F) -> Result<&T, E> where
F: FnOnce() -> Result<Box<T, Global>, E>,
Gets the contents of the cell, initializing it with f
if
the cell was empty. If the cell was empty and f
failed, an
error is returned.
If several threads concurrently run get_or_init
, more than one f
can
be called. However, all threads will return the same value, produced by
some f
.
Trait Implementations
impl<T> Sync for OnceBox<T> where
T: Sync + Send,
Auto Trait Implementations
impl<T> RefUnwindSafe for OnceBox<T> where
T: RefUnwindSafe,
impl<T> Send for OnceBox<T> where
T: Send,
impl<T> Unpin for OnceBox<T>
impl<T> UnwindSafe for OnceBox<T> where
T: UnwindSafe + RefUnwindSafe,
Blanket Implementations
impl<T> ArchivePointee for T
impl<T> ArchivePointee for T
type ArchivedMetadata = ()
type ArchivedMetadata = ()
The archived version of the pointer metadata for this type.
fn pointer_metadata(
&<T as ArchivePointee>::ArchivedMetadata
) -> <T as Pointee>::Metadata
fn pointer_metadata(
&<T as ArchivePointee>::ArchivedMetadata
) -> <T as Pointee>::Metadata
Converts some archived metadata to the pointer metadata for itself.
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
impl<F, W, T, D> Deserialize<With<T, W>, D> for F where
W: DeserializeWith<F, T, D>,
D: Fallible + ?Sized,
F: ?Sized,
impl<F, W, T, D> Deserialize<With<T, W>, D> for F where
W: DeserializeWith<F, T, D>,
D: Fallible + ?Sized,
F: ?Sized,
fn deserialize(
&self,
deserializer: &mut D
) -> Result<With<T, W>, <D as Fallible>::Error>
fn deserialize(
&self,
deserializer: &mut D
) -> Result<With<T, W>, <D as Fallible>::Error>
Deserializes using the given deserializer
sourceimpl<T> Instrument for T
impl<T> Instrument for T
sourcefn instrument(self, span: Span) -> Instrumented<Self>
fn instrument(self, span: Span) -> Instrumented<Self>
sourcefn in_current_span(self) -> Instrumented<Self>
fn in_current_span(self) -> Instrumented<Self>
sourceimpl<T> WithSubscriber for T
impl<T> WithSubscriber for T
sourcefn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> where
S: Into<Dispatch>,
fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> where
S: Into<Dispatch>,
Attaches the provided Subscriber
to this type, returning a
WithDispatch
wrapper. Read more
sourcefn with_current_subscriber(self) -> WithDispatch<Self>
fn with_current_subscriber(self) -> WithDispatch<Self>
Attaches the current default Subscriber
to this type, returning a
WithDispatch
wrapper. Read more