Struct Counters 

pub struct Counters {
    pub shed: ShedCounts,
    pub overload_rejections: u64,
    pub unmatched_responses: u64,
    pub retransmissions_sent: u64,
    pub oversized_request_tcp_fallbacks: u64,
    pub timeouts: TimeoutCounts,
    pub discards: DiscardCounts,
    pub unsent: UnsentCounts,
    pub capture: CaptureCounts,
    pub observation_dropped: u64,
    /* private fields */
}

Everything an endpoint will tell you about itself, at one moment (§12).

What this is not

A snapshot is not an instant. The fields are separate atomics read one after another, so a snapshot taken while traffic flows can show TransportCounts::requests_in from a later moment than TransportCounts::responses_in. Every field is individually monotonic and none is ever lost, so differences between successive snapshots are sound. Arithmetic identities across fields of a single snapshot are not, unless the endpoint is quiet.

See TransportCounts::parse_failures for the one place that surprises people: in and out do not balance, by construction.

Fields

shed: ShedCounts

What was dropped because the application was not keeping up (§10).

The same value crate::Handle::shed returns, embedded rather than recounted: two tallies of one event would eventually disagree, and then neither could be trusted.

overload_rejections: u64

Locally rejected outbound requests under RFC 7339/RFC 7415 control.

unmatched_responses: u64

Responses that matched no client transaction (RFC 3261 §16.7).

Counted whether or not anyone is watching for them through crate::Handle::watch_unmatched. A user agent is right to ignore these; a forwarding element is required to act on them, and either way the rate is worth knowing.

retransmissions_sent: u64

Retransmissions put on the wire by Timer A, E or G.

Counted where the timer fires, so a retransmission the socket then refuses is still counted as sent (§12.2). Counting after the socket call would mean a peer that stopped hearing us produced a falling count, inverting the signal this exists to give.

A rise with no matching growth in traffic is a peer that is not hearing us, which is the difference between a network problem and an application one.

oversized_request_tcp_fallbacks: u64

Oversized UDP requests for which RFC 3261 §18.1.1 selected TCP instead.

Counted at selection, including a selection whose connection attempt then fails. Consult Self::unsent and Self::discards for whether the selected send reached the wire.

timeouts: TimeoutCounts

Transactions a timer gave up on.

discards: DiscardCounts

Discards that are not backpressure (§12.1).

unsent: UnsentCounts

Requests the endpoint tried to put on the wire and could not, by method (§12.3).

Overlaps DiscardCounts::send_failures for requests on the transaction path — see UnsentCounts, which states what that does and does not let you conclude.

capture: CaptureCounts

How the capture is faring, if one is running (§13).

observation_dropped: u64

Observation events dropped because the optional bounded consumer was behind.

Implementations

impl Counters

pub fn transport(&self, transport: TransportKind) -> TransportCounts

What crossed one transport.

pub fn messages_in(&self) -> u64

Messages that arrived and parsed, over every transport.

pub fn messages_out(&self) -> u64

Messages put on the wire, over every transport.

pub fn parse_failures(&self) -> u64

Everything that arrived and could not be parsed, over every transport.

pub fn any_loss(&self) -> bool

Whether anything at all has been lost: shed, discarded, dropped from a capture, or never put on the wire.

A single question for a health check to ask. Deliberately does not include Self::parse_failures or Self::timeouts: a malformed datagram from a stranger and a peer that stopped answering are things that happened to the endpoint, not things it threw away, and folding them in here would make the number impossible to act on.

Trait Implementations

impl Clone for Counters

fn clone(&self) -> Counters

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Counters

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

Formats the value using the given formatter.

impl Default for Counters

fn default() -> Counters

Returns the “default value” for a type.

impl PartialEq for Counters

fn eq(&self, other: &Counters) -> 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 Counters

impl Eq for Counters

impl StructuralPartialEq for Counters