Struct Key

pub struct Key { /* private fields */ }

A metric identifier.

A key represents both the name and labels of a metric.

Safety

Clippy will report any usage of Key as the key of a map/set as “mutable key type”, meaning that it believes that there is interior mutability present which could lead to a key being hashed different over time. That behavior could lead to unexpected behavior, as standard maps/sets depend on keys having stable hashes over time, related to times when they must be recomputed as the internal storage is resized and items are moved around.

In this case, the Hash implementation of Key does not depend on the fields which Clippy considers mutable (the atomics) and so it is actually safe against differing hashes being generated. We personally allow this Clippy lint in places where we store the key, such as helper types in the metrics-util crate, and you may need to do the same if you’re using it in such a way as well.

Implementations

impl Key

pub fn from_name<N>(name: N) -> Key

where N: Into<KeyName>,

Creates a Key from a name.

pub fn from_parts<N, L>(name: N, labels: L) -> Key

where N: Into<KeyName>, L: IntoLabels,

Creates a Key from a name and set of labels.

pub fn from_static_labels<N>(name: N, labels: &'static [Label]) -> Key

where N: Into<KeyName>,

Creates a Key from a non-static name and a static set of labels.

pub const fn from_static_name(name: &'static str) -> Key

Creates a Key from a static name.

This function is const, so it can be used in a static context.

pub const fn from_static_parts( name: &'static str, labels: &'static [Label], ) -> Key

Creates a Key from a static name and static set of labels.

This function is const, so it can be used in a static context.

pub fn name(&self) -> &str

Name of this key.

pub fn labels(&self) -> Iter<'_, Label>

Labels of this key, if they exist.

pub fn into_parts(self) -> (KeyName, Vec<Label>)

Consumes this Key, returning the name parts and any labels.

pub fn with_extra_labels(&self, extra_labels: Vec<Label>) -> Key

Clones this Key, and expands the existing set of labels.

pub fn get_hash(&self) -> u64

Gets the hash value for this key.

Trait Implementations

impl Clone for Key

fn clone(&self) -> Key

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Key

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Display for Key

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<N, L> From<(N, L)> for Key

where N: Into<KeyName>, L: IntoLabels,

fn from(parts: (N, L)) -> Key

Converts to this type from the input type.

impl<T> From<T> for Key

where T: Into<KeyName>,

fn from(name: T) -> Key

Converts to this type from the input type.

impl Hash for Key

fn hash<H>(&self, state: &mut H)

where H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Hashable for Key

type Hasher = KeyHasher

The hasher implementation used internally.

fn hashable(&self) -> u64

Generate the hash of this object.

impl Ord for Key

fn cmp(&self, other: &Key) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Key

fn eq(&self, other: &Key) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Key

fn partial_cmp(&self, other: &Key) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Eq for Key