Struct RetractableCountAccumulator 

pub struct RetractableCountAccumulator { /* private fields */ }

Retractable count accumulator.

Uses signed integer to support negative counts from retractions. In a correct pipeline, the count should never go negative.

Implementations

impl RetractableCountAccumulator

pub fn new() -> Self

Creates a new count accumulator.

pub fn count(&self) -> i64

Returns the current count (may be negative during retraction).

Trait Implementations

impl Archive for RetractableCountAccumulator

where i64: Archive,

const COPY_OPTIMIZATION: CopyOptimization<Self>

An optimization flag that allows the bytes of this type to be copied directly to a writer instead of calling serialize.

type Archived = ArchivedRetractableCountAccumulator

The archived representation of this type.

type Resolver = RetractableCountAccumulatorResolver

The resolver for this type. It must contain all the additional information from serializing needed to make the archived type from the normal type.

fn resolve(&self, resolver: Self::Resolver, out: Place<Self::Archived>)

Creates the archived version of this value at the given position and writes it to the given output.

impl Clone for RetractableCountAccumulator

fn clone(&self) -> RetractableCountAccumulator

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for RetractableCountAccumulator

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

Formats the value using the given formatter.

impl Default for RetractableCountAccumulator

fn default() -> RetractableCountAccumulator

Returns the “default value” for a type.

impl<__D: Fallible + ?Sized> Deserialize<RetractableCountAccumulator, __D> for Archived<RetractableCountAccumulator>

where i64: Archive, <i64 as Archive>::Archived: Deserialize<i64, __D>,

fn deserialize( &self, deserializer: &mut __D, ) -> Result<RetractableCountAccumulator, <__D as Fallible>::Error>

Deserializes using the given deserializer

impl RetractableAccumulator for RetractableCountAccumulator

type Input = ()

The input type for the aggregation.

type Output = i64

The output type produced by the aggregation.

fn add(&mut self, _value: ())

Adds a value to the accumulator.

fn retract(&mut self, _value: &())

Retracts (un-applies) a value from the accumulator.

fn merge(&mut self, other: &Self)

Merges another accumulator into this one.

fn result(&self) -> i64

Extracts the final result from the accumulator.

fn is_empty(&self) -> bool

Returns true if the accumulator is empty (no values added).

fn reset(&mut self)

Resets the accumulator to its initial state.

fn supports_efficient_retraction(&self) -> bool

Returns true if this accumulator can efficiently retract.

impl<__S: Fallible + ?Sized> Serialize<__S> for RetractableCountAccumulator

where i64: Serialize<__S>,

fn serialize( &self, serializer: &mut __S, ) -> Result<<Self as Archive>::Resolver, <__S as Fallible>::Error>

Writes the dependencies for the object and returns a resolver that can create the archived type.