Struct MetricsView 

#[non_exhaustive]
pub struct MetricsView { /* private fields */ }

A live, read-only view of the metrics of a client, indexed by metric name: what Java’s clients return from metrics() as Collections.unmodifiableMap(metrics.metrics()).

Every lookup reads the registry as it is at the time of the call, so a metric registered after the view was returned is visible through it and a removed one is not. Self::snapshot gives the whole map as it is now, to iterate without blocking the registry, as Java’s weakly consistent iteration does. A view stays valid after its client is closed.

A view can also stand alone, built from a map (From) or empty (Default), for a test double or a user implementation of Producer or Consumer.

A clone is a second view of the same map, as copying a Java reference is.

Java’s Map interface lets unmodifiableMap stand for a live map; Rust has no read-only map trait in its standard library, and returning a HashMap would copy the registry on every call.

Implementations

impl MetricsView

pub fn get(&self, name: &MetricName) -> Option<Arc<KafkaMetric>>

Returns the metric registered under name, if any, as the registry is at the time of the call.

Arguments

• name - the name of the metric

pub fn contains_key(&self, name: &MetricName) -> bool

Returns whether a metric is registered under name, as the registry is at the time of the call.

Arguments

• name - the name of the metric

pub fn len(&self) -> usize

Returns how many metrics the registry holds at the time of the call.

pub fn is_empty(&self) -> bool

Returns whether the registry holds no metric at the time of the call.

pub fn snapshot(&self) -> Arc<HashMap<MetricName, Arc<KafkaMetric>>>

Returns the map as it is now, indexed by metric name.

The returned map never changes: a metric registered or removed later shows in the view, not in the snapshot. Taking it copies no entry and never blocks the registry; a later registration copies the map once while a snapshot of the old version is held.

Trait Implementations

impl Clone for MetricsView

fn clone(&self) -> MetricsView

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MetricsView

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

Formats the value using the given formatter.

impl Default for MetricsView

fn default() -> MetricsView

Returns the “default value” for a type.

impl From<HashMap<MetricName, Arc<KafkaMetric>>> for MetricsView

fn from(metrics: HashMap<MetricName, Arc<KafkaMetric>>) -> Self

A view of metrics, tied to no registry.

Arguments

• metrics - the metrics the view holds, indexed by metric name