Struct Retention 

pub struct Retention {
    pub depth: usize,
    pub release_when_idle: bool,
}

How long a shared dataflow keeps what a subscriber might still ask for.

docs/26-arrangement-sharing-report.md §26.9 recorded both of these as constants that should have been policies: the history was 64 versions “because a subscriber further behind than that is not the bottleneck”, and the arrangements were never dropped at all.

Fields

depth: usize

The ceiling on retained change history, in versions. The reader frontiers are the floor, and they are usually far lower — this bounds what one subscriber that has stopped rendering can pin.

release_when_idle: bool

Whether to give up the arrangements when the last subscriber goes.

On, the process holds nothing between fanouts and the next subscriber pays a cold start. Off, they stay warm for a reconnection that may not come. The trade is a real one and it belongs to a deployment rather than to this file, which is why it is here and not a const.

Trait Implementations

impl Clone for Retention

fn clone(&self) -> Retention

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Retention

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

Formats the value using the given formatter.

impl Default for Retention

fn default() -> Retention

Returns the “default value” for a type.

impl PartialEq for Retention

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for Retention

impl Eq for Retention

impl StructuralPartialEq for Retention