Struct Meter 

pub struct Meter { /* private fields */ }

What the open on screen cost, as measured; shared with reading threads (Arc, written through &self). Never cleared: each open builds a new one, since an abandoned load’s reads still run and would add to the next dataset’s figures.

Implementations

impl Meter

pub fn listed(&self, took: Duration, files: Option<usize>, over_the_wire: bool)

Finding the files took took and found files. over_the_wire is always false today (local walks make no requests; remote listings page inside the object store), kept so both stretches record alike.

pub fn read_footers( &self, took: Duration, files: Option<usize>, over_the_wire: bool, )

A pass over files footers took took. over_the_wire publishes requests counted by Self::footer_request; a disk pass passes false (no requests, not zero).

pub fn counted_rows( &self, took: Duration, files: Option<usize>, wire: Option<OverTheWire>, ) -> bool

A count pass over files footers took took: recorded once only (the return says whether), since counts rerun on every invalidation and would inflate the open’s cost.

pub fn read_page(&self, took: Duration, files: Option<usize>)

The page on screen took took and read files files (None when Polars chose). Replaces rather than adds: the page being viewed. No byte figure: Polars does not report what it fetched, and row-group sizes would overstate it.

pub fn last_page(&self) -> Option<Cost>

What the page now on screen cost, or None before one has been read.

pub fn footer_request(&self, bytes: u64)

One footer request, and the bytes it returned. Counted as the reads happen; what they come to is published when the pass ends.

pub fn listing(&self) -> Option<Cost>

What finding the files cost, or None if no listing has been measured.

pub fn footers(&self) -> Option<Cost>

What reading the footers cost, or None if no footer pass has been measured.

pub fn total(&self) -> Option<Total>

Everything measured, added; None until something is. No file count (listing counts files, footer passes count footers). Wire figures sum the stretches that counted them, None when none did.

Trait Implementations

impl Debug for Meter

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

Formats the value using the given formatter.

impl Default for Meter

fn default() -> Self

Returns the “default value” for a type.