Struct LimitsConfig 

pub struct LimitsConfig {
    pub max_connections: usize,
    pub max_subscriptions_per_connection: usize,
    pub max_conversations_per_connection: usize,
    pub max_pending_pushes_per_connection: usize,
    pub max_pending_conversation_replies_per_connection: usize,
    pub max_pending_replies_per_conversation: usize,
    pub max_connection_inbox_bytes: usize,
    pub max_subscription_inbox_depth: usize,
    pub max_channels: Option<usize>,
}

Operational bounds (§5, scout Q4 — rule-2 items).

Each field is a hard per-scope cap with a typed refusal and a certifying-pair-signed default (the numbers below are §5’s). The struct is the single wire surface for [limits]; [LimitsConfig::validate] rejects any zero value as a typed config error (a zero cap would gate nothing — the exact unlimited-by-silence state §5 outlaws). Defaults come from the default_* free functions so an absent key resolves to the signed number, not zero.

Fields

max_connections: usize

Total live connections the listener admits before refusing (§5: 256 — a worker-bus, an order of magnitude above any observed fleet).

max_subscriptions_per_connection: usize

Subscriptions one connection may hold (§5: 32).

max_conversations_per_connection: usize

Open conversations one connection may hold (§5: 32).

max_pending_pushes_per_connection: usize

In-flight server→client correlated pushes per connection (§5: 32).

max_pending_conversation_replies_per_connection: usize

Entries in the per-connection pending-reply table (§1.2(3b)/§5: 32 — distinct from server-push slots).

max_pending_replies_per_conversation: usize

Per-conversation sub-cap that confines tombstone ambiguity to its own conversation (§1.2(3b)/§5: 8). Pending entries count against BOTH this and the connection table; tombstones against THIS alone.

max_connection_inbox_bytes: usize

One shared inbox-byte budget per connection, spent across ALL its subscription inboxes (§5: 4 MiB — deliberately mirroring the outbound 4 MiB bound). Accounting unit: serialized envelope bytes as admitted, charged at enqueue and released at dequeue.

max_subscription_inbox_depth: usize

Per-inbox envelope-count secondary fairness trip (§5: 256) — stops one subscription starving its siblings inside the shared byte budget; no longer load-bearing for the signed bound.

max_channels: Option<usize>

Runtime-registered channels this deployment admits.

Why this cap departs the uniform pattern

Every other field here carries #[serde(default = "…")] naming a §5 constant, because each of those numbers is a signed §5 bound. There is no signed §5 bound for channel count, and inventing one is barred: a number nobody certified, presented in the same shape as eight numbers somebody did, is a forged citation. So the type is Option<usize> and the serde default is the ABSENCE itself (None), never a value — #[serde(default)] here resolves a missing key to “no bound declared”, which is a different statement from any number.

Nor may this be a usize with a large default: unbounded-by-default is not a bound, it is the gap wearing a number.

None refuses every runtime channel registration with a typed error naming this key, so a deployment that wants runtime registration declares its own bound and a deployment that never registers needs no config change at all. The cap bounds RUNTIME-registered channels only: [[channels]] entries are the bound the operator already wrote.

Some(0) is a validation error like every other zero cap here — see LimitsConfig::collect_errors.

Implementations

impl LimitsConfig

pub const DEFAULT_MAX_CONNECTIONS: usize = 256

§5 default: total live connections before the listener refuses.

pub const DEFAULT_MAX_SUBSCRIPTIONS_PER_CONNECTION: usize = 32

§5 default: subscriptions per connection.

pub const DEFAULT_MAX_CONVERSATIONS_PER_CONNECTION: usize = 32

§5 default: open conversations per connection.

pub const DEFAULT_MAX_PENDING_PUSHES_PER_CONNECTION: usize = 32

§5 default: in-flight server pushes per connection.

pub const DEFAULT_MAX_PENDING_CONVERSATION_REPLIES_PER_CONNECTION: usize = 32

§5 default: pending-reply table entries per connection.

pub const DEFAULT_MAX_PENDING_REPLIES_PER_CONVERSATION: usize = 8

§5 default: per-conversation pending-reply sub-cap.

pub const DEFAULT_MAX_CONNECTION_INBOX_BYTES: usize

§5 default: shared per-connection inbox byte budget (4 MiB).

pub const DEFAULT_MAX_SUBSCRIPTION_INBOX_DEPTH: usize = 256

§5 default: per-inbox envelope-count fairness trip.

Trait Implementations

impl Clone for LimitsConfig

fn clone(&self) -> LimitsConfig

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for LimitsConfig

impl Debug for LimitsConfig

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

Formats the value using the given formatter.

impl Default for LimitsConfig

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for LimitsConfig

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.