Enum WatchCapability 

#[non_exhaustive]
pub enum WatchCapability {
    Native,
    Conditional,
    Interval,
}

How a store finds out that its document changed.

What a store answers here is a fact about the protocol, not a promise about the implementation: it tells a caller what a watch is going to cost, so an agent can decide whether to run one at all and an operator can read why a change took as long as it did.

Native       the store says so         a blocking query, a stream, a subscription
Conditional  the store answers cheaply a version, an ETag, a revision — a header, not a document
Interval     nothing but re-reading    the whole document, on a timer

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Native

The store pushes. A change is delivered as soon as it happens, and the interval is only a resync — a stream can stall without saying so.

Conditional

The store answers “has it changed?” without sending the document. A poll costs a round trip and almost no bytes.

Interval

Nothing but re-reading the whole document on a timer.

Trait Implementations

impl Clone for WatchCapability

fn clone(&self) -> WatchCapability

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for WatchCapability

impl Debug for WatchCapability

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

Formats the value using the given formatter.

impl Display for WatchCapability

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

Formats the value using the given formatter.

impl Eq for WatchCapability

impl Hash for WatchCapability

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 WatchCapability

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for WatchCapability