Struct UsageEvent 

pub struct UsageEvent {
    pub timestamp: SystemTime,
    pub request_id: String,
    pub principal: Option<String>,
    pub model: String,
    pub provider: String,
    pub endpoint: &'static str,
    pub usage: Usage,
    pub duration_ms: u64,
    pub status: u16,
    pub error: Option<String>,
}

Per-request event emitted after a request completes. Embedders subscribe to the AppState::usage_events broadcast channel to observe live traffic without scraping the Prometheus endpoint.

Fields

timestamp: SystemTime

request_id: String

principal: Option<String>

model: String

provider: String

endpoint: &'static str

Logical endpoint: "chat.completions", "embeddings", "images.generations", "audio.speech", "audio.transcriptions".

usage: Usage

Full canonical usage with all axes (input, cache_read, cache_write, output, reasoning, audio, per-call tools). Embeds the same type that drives billing in crabllm_core::ModelInfo::cost, so subscribers see exactly what was charged for.

duration_ms: u64

status: u16

The wire HTTP status the client observed, or 0 when a streaming chat response sent 200 OK headers and then broke mid-stream. 0 is a sentinel meaning “not a real HTTP response” — consumers branching on status alone can distinguish a clean 200 from a failed stream without having to inspect Self::error. For non-streaming requests status is always the real HTTP code the client saw.

error: Option<String>

Some(msg) if the request failed. Set alongside status == 0 for mid-stream streaming failures; set alongside a real error status (4xx/5xx) for pre-stream and non-streaming failures.

Trait Implementations

impl Clone for UsageEvent

fn clone(&self) -> UsageEvent

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for UsageEvent

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

Formats the value using the given formatter.