Struct SpanTag

source

struct SpanTag(u8);

Expand description

A span tag byte encodes a bunch of data, so that we can cut out a few extra bytes from span encodings (which are very common, for example, libcore has ~650,000 unique spans and over 1.1 million references to prior-written spans).

The byte format is split into several parts:

[ a a a a a c d d ]

a bits represent the span length. We have 5 bits, so we can store lengths up to 30 inline, with an all-1s pattern representing that the length is stored separately.

c represents whether the span context is zero (and then it is not stored as a separate varint) for direct span encodings, and whether the offset is absolute or relative otherwise (zero for absolute).

d bits represent the kind of span we are storing (local, foreign, partial, indirect).

Tuple Fields§

§0: u8

Struct SpanTagCopy item path

Tuple Fields§

Implementations§

impl SpanTag

fn new(kind: SpanKind, context: SyntaxContext, length: usize) -> SpanTag

fn indirect(relative: bool, length_bytes: u8) -> SpanTag

fn kind(self) -> SpanKind

fn is_relative_offset(self) -> bool

fn context(self) -> Option<SyntaxContext>

fn length(self) -> Option<BytePos>

Trait Implementations§

impl Clone for SpanTag

fn clone(&self) -> SpanTag

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

impl<__D: SpanDecoder> Decodable<__D> for SpanTag

fn decode(__decoder: &mut __D) -> Self

impl<__E: SpanEncoder> Encodable<__E> for SpanTag

fn encode(&self, __encoder: &mut __E)

impl Copy for SpanTag

Auto Trait Implementations§

impl Freeze for SpanTag

impl RefUnwindSafe for SpanTag

impl Send for SpanTag

impl Sync for SpanTag

impl Unpin for SpanTag

impl UnwindSafe for SpanTag

Blanket Implementations§

impl<T> Aligned for T

const ALIGN: Alignment = _

impl<T> Any for Twhere T: 'static + ?Sized,

fn type_id(&self) -> TypeId

impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for Twhere T: Copy,

fn allocate_on(self, arena: &'tcx Arena<'tcx>) -> &'tcx mut T

fn allocate_from_iter( arena: &'tcx Arena<'tcx>, iter: impl IntoIterator<Item = T>, ) -> &'tcx mut [T]

impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for Twhere T: Copy,

fn allocate_on(self, arena: &'tcx Arena<'tcx>) -> &'tcx mut T

fn allocate_from_iter( arena: &'tcx Arena<'tcx>, iter: impl IntoIterator<Item = T>, ) -> &'tcx mut [T]

impl<T> Borrow<T> for Twhere T: ?Sized,

fn borrow(&self) -> &T

impl<T> BorrowMut<T> for Twhere T: ?Sized,

fn borrow_mut(&mut self) -> &mut T

impl<T> CloneToUninit for Twhere T: Clone,

unsafe fn clone_to_uninit(&self, dst: *mut T)

impl<T, R> CollectAndApply<T, R> for T

fn collect_and_apply<I, F>(iter: I, f: F) -> Rwhere I: Iterator<Item = T>, F: FnOnce(&[T]) -> R,

type Output = R

impl<T> Filterable for T

fn filterable( self, filter_name: &'static str, ) -> RequestFilterDataProvider<T, fn(_: DataRequest<'_>) -> bool>

impl<T> From<T> for T

fn from(t: T) -> T

impl<T> Instrument for T

fn instrument(self, span: Span) -> Instrumented<Self>

fn in_current_span(self) -> Instrumented<Self>

impl<T, U> Into<U> for Twhere U: From<T>,

fn into(self) -> U

impl<T> IntoEither for T

fn into_either(self, into_left: bool) -> Either<Self, Self>

fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>where F: FnOnce(&Self) -> bool,

impl<P> IntoQueryParam<P> for P

fn into_query_param(self) -> P

impl<T> MaybeResult<T> for T

type Error = !

fn from(_: Result<T, <T as MaybeResult<T>>::Error>) -> T

fn to_result(self) -> Result<T, <T as MaybeResult<T>>::Error>

impl<T> Same for T

type Output = T

impl<T> ToOwned for Twhere T: Clone,

type Owned = T

fn to_owned(&self) -> T

fn clone_into(&self, target: &mut T)

impl<T, U> TryFrom<U> for Twhere U: Into<T>,

type Error = Infallible

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

type Error = <U as TryFrom<T>>::Error

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

impl<I, T, U> Upcast<I, U> for Twhere U: UpcastFrom<I, T>,

fn upcast(self, interner: I) -> U

impl<I, T> UpcastFrom<I, T> for T

fn upcast_from(from: T, _tcx: I) -> T

Struct SpanTag

impl<D: SpanDecoder> Decodable<D> for SpanTag

fn decode(decoder: &mut D) -> Self

impl<E: SpanEncoder> Encodable<E> for SpanTag

fn encode(&self, encoder: &mut E)

impl<T> Any for T
where T: 'static + ?Sized,

impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T
where T: Copy,

impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T
where T: Copy,

impl<T> Borrow<T> for T
where T: ?Sized,

impl<T> BorrowMut<T> for T
where T: ?Sized,

impl<T> CloneToUninit for T
where T: Clone,

fn collect_and_apply<I, F>(iter: I, f: F) -> R
where I: Iterator<Item = T>, F: FnOnce(&[T]) -> R,

impl<T, U> Into<U> for T
where U: From<T>,

fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

impl<T> ToOwned for T
where T: Clone,

impl<T, U> TryFrom<U> for T
where U: Into<T>,

impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

impl<I, T, U> Upcast<I, U> for T
where U: UpcastFrom<I, T>,

impl<V, T> VZip<V> for T
where V: MultiLane<T>,

impl<Tcx, T> Value<Tcx> for T
where Tcx: DepContext,

fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

impl<'a, T> Captures<'a> for T
where T: ?Sized,

impl<T> ErasedDestructor for T
where T: 'static,