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) -> &Twhere
F: FnOnce() -> Box<T, Global>,
pub fn get_or_init<F>(&self, f: F) -> &Twhere 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§
source§impl<T> Instrument for T
impl<T> Instrument for T
source§fn instrument(self, span: Span) -> Instrumented<Self> ⓘ
fn instrument(self, span: Span) -> Instrumented<Self> ⓘ
source§fn in_current_span(self) -> Instrumented<Self> ⓘ
fn in_current_span(self) -> Instrumented<Self> ⓘ
§impl<T> RoundFrom<T> for T
impl<T> RoundFrom<T> for T
§fn round_from(x: T) -> T
fn round_from(x: T) -> T
Performs the conversion.
§impl<T, U> RoundInto<U> for Twhere
U: RoundFrom<T>,
impl<T, U> RoundInto<U> for Twhere U: RoundFrom<T>,
§fn round_into(self) -> U
fn round_into(self) -> U
Performs the conversion.