Struct Context 

pub struct Context { /* private fields */ }

A metric context.

Implementations

impl Context

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

Creates a new Context from the given static name.

pub fn from_static_parts(name: &'static str, tags: &[&'static str]) -> Self

Creates a new Context from the given static name and given static tags.

pub fn from_parts<S: Into<MetaString>>(name: S, tags: impl Into<TagSet>) -> Self

Creates a new Context from the given name and given tags.

pub fn with_name<S: Into<MetaString>>(&self, name: S) -> Self

Clones this context, and uses the given name for the cloned context.

pub fn with_tags(&self, tags: impl Into<TagSet>) -> Self

Clones this context, and uses the given tags for the cloned context.

The name and origin tags of this context are preserved.

pub fn with_origin_tags(&self, origin_tags: impl Into<TagSet>) -> Self

Clones this context, and uses the given origin tags for the cloned context.

The name and instrumented tags of this context are preserved.

pub fn with_tags_and_origin_tags( &self, tags: impl Into<TagSet>, origin_tags: impl Into<TagSet>, ) -> Self

Clones this context, replacing both instrumented tags and origin tags in a single allocation.

Preferred over two separate with_tags / with_origin_tags calls when both sets need to be replaced, as it halves the number of Arc allocations.

pub fn name(&self) -> &MetaString

Returns the name of this context.

pub fn tags(&self) -> &TagSet

Returns the instrumented tags of this context.

pub fn origin_tags(&self) -> &TagSet

Returns the origin tags of this context.

pub fn mutate_tags(&mut self, f: impl FnOnce(&mut TagSet))

Mutates the instrumented tags of this context via a closure.

Uses copy-on-write semantics: if this context shares its inner data with other clones, the inner data is cloned first so that mutations do not affect other holders. If this context is the sole owner, the mutation happens in place.

The context key is automatically recomputed after the closure returns.

pub fn mutate_origin_tags(&mut self, f: impl FnOnce(&mut TagSet))

Mutates the origin tags of this context via a closure.

Uses copy-on-write semantics: if this context shares its inner data with other clones, the inner data is cloned first so that mutations do not affect other holders. If this context is the sole owner, the mutation happens in place.

The context key is automatically recomputed after the closure returns.

pub fn with_tag_sets_mut(&mut self, f: impl FnOnce(&mut TagSet, &mut TagSet))

Mutates both instrumented tags and origin tags via a single closure.

Uses copy-on-write semantics: if this context shares its inner data with other clones, the inner data is cloned first so that mutations do not affect other holders. If this context is the sole owner, the mutation happens in place.

The context key is recomputed once after the closure returns.

pub fn tags_mut_view<'a, 'b>( &'a mut self, state: &'b mut TagSetMutViewState, ) -> TagSetMutView<'a, 'b>

Creates a lazy copy-on-write mutable view over this context’s tag sets.

The returned view supports mutations (e.g. retain_tags) without immediately triggering an Arc clone. The actual clone, mutation, and context key recomputation only happen when TagSetMutView::finish is called, and only if changes were actually recorded.

state provides reusable scratch space for tracking pending changes. Holding a long-lived TagSetMutViewState across calls amortizes any vector allocations.

pub fn size_of(&self) -> usize

Returns the size of this context in bytes.

A context’s size is the sum of the sizes of its fields and the size of the Context struct itself, and includes:

• the context name
• the context tags (both instrumented and origin)

Since origin tags can potentially be expensive to calculate, this method will cache the size of the origin tags when this method is first called.

Additionally, the value returned by this method does not compensate for externalities such as origin tags potentially being shared by multiple contexts, or whether or not tags are inlined, interned, or heap allocated. This means that the value returned is essentially the worst-case usage, and should be used as a rough estimate.

Trait Implementations

impl Clone for Context

fn clone(&self) -> Context

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Context

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

Formats the value using the given formatter.

impl Display for Context

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

Formats the value using the given formatter.

impl From<&'static str> for Context

fn from(name: &'static str) -> Self

Converts to this type from the input type.

impl<'a> From<(&'static str, &'a [&'static str])> for Context

fn from((name, tags): (&'static str, &'a [&'static str])) -> Self

Converts to this type from the input type.

impl Hash for Context

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

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 PartialEq for Context

fn eq(&self, other: &Context) -> 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 Eq for Context

impl StructuralPartialEq for Context