Struct PollReport 

pub struct PollReport { /* private fields */ }

What has been measured on one subscription: the samples taken, the moving average and the 99th percentile of the time its handler spent in one poll.

Examples

use ruststream::runtime::PollDiagnostics;

/// A report the operators read: the tail next to the average, and how many polls they rest on.
fn describe(diagnostics: &PollDiagnostics, subscription: &str) -> Option<String> {
    let report = diagnostics.report(subscription)?;
    Some(format!(
        "{}: average {:?}, p99 {:?}, {} polls",
        report.subscription(),
        report.average(),
        report.p99(),
        report.samples(),
    ))
}

Implementations

impl PollReport

pub fn subscription(&self) -> &str

The subscription measured.

Examples

use ruststream::runtime::PollDiagnostics;

fn log_reports(diagnostics: &PollDiagnostics) {
    for report in diagnostics.reports() {
        let subscription = report.subscription();
        tracing::info!(subscription, average = ?report.average(), "poll time");
    }
}

pub const fn samples(&self) -> u64

How many polls were timed.

Examples

use ruststream::runtime::PollDiagnostics;

/// How many polls the whole app has timed so far.
fn timed(diagnostics: &PollDiagnostics) -> u64 {
    diagnostics
        .reports()
        .iter()
        .map(|report| report.samples())
        .sum()
}

pub const fn average(&self) -> Duration

The exponential moving average of the time in one poll: each sample moves it by a sixteenth of the difference.

Examples

use std::time::Duration;

use ruststream::runtime::PollDiagnostics;

/// The subscriptions whose handler averages over a budget: candidates for `threads(n)`.
fn over_budget(diagnostics: &PollDiagnostics, budget: Duration) -> Vec<String> {
    diagnostics
        .reports()
        .into_iter()
        .filter(|report| report.average() > budget)
        .map(|report| report.subscription().to_owned())
        .collect()
}

pub const fn p99(&self) -> Duration

The 99th percentile of the time in one poll over every sample, read off the histogram.

Examples

use ruststream::runtime::PollDiagnostics;

/// The tail, which an average hides: one slow poll in a hundred is still a stalled runtime.
fn log_tails(diagnostics: &PollDiagnostics) {
    for report in diagnostics.reports() {
        let subscription = report.subscription();
        tracing::info!(subscription, p99 = ?report.p99(), "poll tail");
    }
}

Trait Implementations

impl Clone for PollReport

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PollReport

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

Formats the value using the given formatter.

impl Eq for PollReport

impl Hash for PollReport

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 PollReport

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

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for PollReport