Struct TracingMiddleware 

pub struct TracingMiddleware {
    pub sampling_strategy: SamplingStrategy,
    pub sampling_rate: f64,
    /* private fields */
}

Middleware that creates tracing spans around module execution.

Uses a stack-based approach (Vec of Spans per trace_id) to correctly handle nested module-to-module calls with proper parent-child span relationships.

Lock ordering: always acquire ctx.data before self.state to prevent deadlocks.

Fields

sampling_strategy: SamplingStrategy

sampling_rate: f64

Implementations

impl TracingMiddleware

pub fn new(exporter: Box<dyn SpanExporter>) -> Self

Create a new tracing middleware with the given exporter (Always sampling).

pub fn with_sampling( exporter: Box<dyn SpanExporter>, strategy: SamplingStrategy, rate: f64, ) -> Self

Create with explicit sampling configuration.

Trait Implementations

impl Debug for TracingMiddleware

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

Formats the value using the given formatter.

impl Middleware for TracingMiddleware

fn name(&self) -> &'static str

Name of this middleware for logging/debugging.

fn before<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, module_id: &'life1 str, _inputs: Value, ctx: &'life2 Context<Value>, ) -> Pin<Box<dyn Future<Output = Result<Option<Value>, ModuleError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called before module execution. Can modify input. Return Ok(None) to pass through unchanged, Ok(Some(v)) to modify.

fn after<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, _module_id: &'life1 str, _inputs: Value, _output: Value, ctx: &'life2 Context<Value>, ) -> Pin<Box<dyn Future<Output = Result<Option<Value>, ModuleError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called after successful module execution. Can modify output. inputs is the original (post-before) input for correlation. Return Ok(None) to pass through unchanged, Ok(Some(v)) to modify.

fn on_error<'life0, 'life1, 'life2, 'life3, 'async_trait>( &'life0 self, _module_id: &'life1 str, _inputs: Value, error: &'life2 ModuleError, ctx: &'life3 Context<Value>, ) -> Pin<Box<dyn Future<Output = Result<Option<Value>, ModuleError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait, 'life3: 'async_trait,

Called when module execution fails. inputs is the original (post-before) input for correlation. Return Ok(Some(v)) to signal recovery (retry with those inputs), or Ok(None) to let the error propagate.

fn priority(&self) -> u16

Priority of this middleware (higher runs first). Default is 100. Valid range: 0-1000 (enforced by MiddlewareManager::add). When two middlewares have the same priority, registration order is preserved.