Struct CreditHeader 

pub struct CreditHeader {
    pub endpoint: String,
    pub filter: String,
    pub limit: u64,
}

CREDIT header (kind 5).

The L2 credit of decisions/0003 §4.2-§4.3: which subscription, and how many messages that subscription will accept in total. Three keys, all required — a subscription is (endpoint, filter) on the connection the frame arrives on, and an absent limit would be indistinguishable from a limit of zero, which is the pause.

The limit is absolute and cumulative, not a delta. It counts messages delivered on that subscription since it was created, so a lost frame costs nothing and a duplicated one changes nothing. It is also monotone at the receiver: a broker keeps the highest limit it has seen, which is what makes a reordered frame harmless on a transport that does not order the streams control frames ride. Monotone is the whole rule: a receiver ignores any limit that is not strictly greater than the standing one, so restating a number already delivered changes nothing unless the subscription had exhausted its credit anyway. v0 offers no way to lower a standing limit. The only pause is the 0 a fresh subscription starts at, so a consumer that wants to stay in control grants in increments it is willing to receive. AMQP 1.0 can shrink link-credit against an absolute baseline [amqp10 §5.1]; this frame cannot, and a peer that reads it as if it could would wait for a stop no broker can deliver.

Fields

endpoint: String

Endpoint path of the queue the subscription is on.

filter: String

Topic filter of the subscription. A decoded header’s filter has passed filter::validate.

limit: u64

Messages this subscription will accept in total, counted from its creation.

Implementations

impl CreditHeader

pub fn new( endpoint: impl Into<String>, filter: impl Into<String>, limit: u64, ) -> CreditHeader

A header granting limit to the subscription (endpoint, filter).

pub fn encode(&self) -> Vec<u8>

Encodes the header.

pub fn encode_into(&self, out: &mut Vec<u8>)

Appends the encoded header to out, for a send path that reuses a buffer (B-250). The canonical form has one implementation and this is it; Self::encode is a wrapper.

pub fn decode(bytes: &[u8]) -> Result<CreditHeader, HeaderError>

Decodes the header.

Trait Implementations

impl Clone for CreditHeader

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 CreditHeader

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

Formats the value using the given formatter.

impl Eq for CreditHeader

impl PartialEq for CreditHeader

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for CreditHeader