Struct metriken::Lazy

pub struct Lazy<T, F = fn() -> T> { /* private fields */ }

A value which is initialized on the first access.

This type is thread-safe and can be used in statics.

Example

In this example, Heatmap does not have a const new function so it must be constructed using Lazy.

#[metric]
static HEATMAP: Lazy<Heatmap> = Lazy::new(|| {
    Heatmap::new(
        100,
        2,
        Duration::<Nanoseconds<u64>>::from_secs(30),
        Duration::<Nanoseconds<u64>>::from_secs(1),
    )
});

Implementations

impl<T, F> Lazy<T, F>

pub const fn new(func: F) -> Self

Create a new lazy value with the given initializing function.

pub fn get(this: &Self) -> Option<&T>

If this lazy has been initialized, then return a reference to the contained value.

pub fn get_mut(this: &mut Self) -> Option<&mut T>

If this lazy has been initialized, then return a reference to the contained value.

impl<T, F: FnOnce() -> T> Lazy<T, F>

pub fn force(this: &Self) -> &T

Force the evaluation of this lazy value and return a reference to the result. This is equivalent to the Deref impl.

Trait Implementations

impl<T: Default> Default for Lazy<T>

fn default() -> Self

Create a new lazy value using default as the initializing function.

impl<T, F: FnOnce() -> T> Deref for Lazy<T, F>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T, F: FnOnce() -> T> DerefMut for Lazy<T, F>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<T: Metric, F: Send + 'static> Metric for Lazy<T, F>

fn is_enabled(&self) -> bool

Indicate whether this metric has been set up.

fn as_any(&self) -> Option<&dyn Any>

Get the current metric as an Any instance. This is meant to allow custom processing for known metric types.

fn value(&self) -> Option<Value<'_>>

Get the value of the current metric, should it be enabled.

impl<T, F: Send> Sync for Lazy<T, F>

where OnceCell<T>: Sync,