Enum metrics::Key

pub enum Key {
    Borrowed(&'static KeyData),
    Owned(KeyData),
}

A metric identifier.

While KeyData holds the actual name and label data for a metric, Key works similar to std::borrow::Cow in that we can either hold an owned version of the key data, or a static reference to key data initialized elsewhere.

This allows for flexibility in the ways that KeyData can be passed around and reused, which allows us to enable performance optimizations in specific circumstances.

Variants

Borrowed(&'static KeyData)

A statically borrowed KeyData.

If you are capable of keeping a static KeyData around, this variant can be used to reduce allocations and improve performance.

Owned(KeyData)

An owned KeyData.

Useful when you need to modify a borrowed KeyData in-flight, or when there's no way to keep around a static KeyData reference.

Implementations

impl Key

pub fn into_owned(self) -> KeyData

Converts any kind of Key into an owned KeyData.

If this key is owned, the value is returned as is, otherwise, the contents are cloned.

Methods from Deref<Target = KeyData>

pub fn name(&self) -> &NameParts

Name parts of this key.

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

Labels of this key, if they exist.

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

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

Trait Implementations

impl AsRef<KeyData> for Key

#[must_use]fn as_ref(&self) -> &KeyData

Performs the conversion.

impl Clone for Key

fn clone(&self) -> Key

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Key

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

Formats the value using the given formatter.

impl Deref for Key

type Target = KeyData

The resulting type after dereferencing.

#[must_use]fn deref(&self) -> &Self::Target

Dereferences the value.

impl Display for Key

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

Formats the value using the given formatter.

impl Eq for Key

impl From<&'static KeyData> for Key

fn from(key_data: &'static KeyData) -> Self

Performs the conversion.

impl From<KeyData> for Key

fn from(key_data: KeyData) -> Self

Performs the conversion.

impl Hash for Key

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

Feeds this value into the given Hasher.

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

Feeds a slice of this type into the given Hasher.

impl PartialEq<Key> for Key

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

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.