Struct ExperimentService 

pub struct ExperimentService { /* private fields */ }

The main experiment service.

Wrap an ExperimentStore (for persistence) and an optional ExposureSink (default: TracingExposureSink). The service is cheaply clone-able and intended to be stored as an AppState extension.

Example

use autumn_web::experiments::{
    ExperimentConfig, ExperimentService, InMemoryExperimentStore, VariantConfig,
};
use std::sync::Arc;

let store = Arc::new(InMemoryExperimentStore::new());
let svc = ExperimentService::new(store);

svc.create(ExperimentConfig::new("onboarding_v3", vec![
    VariantConfig::new("control", 50),
    VariantConfig::new("wizard", 50),
])).unwrap();
svc.start("onboarding_v3").unwrap();

let variant = svc.assign("onboarding_v3", "user:42").unwrap();
assert!(matches!(variant.as_str(), "control" | "wizard"));

Implementations

impl ExperimentService

pub fn new(store: Arc<dyn ExperimentStore>) -> Self

Create a new service backed by store, with the default TracingExposureSink.

pub fn with_exposure_sink(self, sink: Arc<dyn ExposureSink>) -> Self

Override the default ExposureSink.

pub fn assign( &self, experiment: &str, actor: &str, ) -> Result<String, ExperimentError>

Assign a variant to actor in experiment.

Assignment rules (evaluated in order):

1. Archived → Err(Archived).
2. Concluded → Ok(winner) without emitting an exposure.
3. Draft → Err(NotRunning).
4. Staff/QA override present → return override variant (exposure emitted, tagged is_override = true).
5. Sticky assignment already recorded → return cached variant (exposure emitted each call).
6. Mutual exclusion check → if actor has any assignment in a sibling experiment in the same group, return Err(ExcludedByGroup).
7. Compute bucket → select variant by weight → store sticky → emit exposure.

Errors

• ExperimentError::NotFound — no such experiment.
• ExperimentError::Archived — experiment is archived.
• ExperimentError::NotRunning — experiment is in Draft state.
• ExperimentError::ExcludedByGroup — actor excluded by mutual exclusion.
• ExperimentError::NoVariant — all variant weights are zero.
• ExperimentError::Store — backend failure.

pub fn assign_with_request_id( &self, experiment: &str, actor: &str, request_id: Option<&str>, ) -> Result<String, ExperimentError>

Like assign but propagates a request_id into the exposure record.

Call this from HTTP handlers where a request trace ID is available.

Errors

See assign.

pub fn create(&self, config: ExperimentConfig) -> Result<(), ExperimentError>

Declare a new experiment (starts in Draft state).

Errors

Returns ExperimentError::Store on backend failure.

pub fn start(&self, name: &str) -> Result<(), ExperimentError>

Transition a Draft or Concluded experiment to Running.

Archived experiments are terminal and cannot be restarted.

Errors

Returns ExperimentError::NotFound if the experiment is unknown. Returns ExperimentError::Archived if the experiment is archived.

pub fn conclude(&self, name: &str, winner: &str) -> Result<(), ExperimentError>

Conclude a running experiment, pinning winner as the result.

After concluding, assign() returns winner for all actors without emitting new exposure events.

Errors

Returns ExperimentError::NotFound if the experiment is unknown.

pub fn archive(&self, name: &str) -> Result<(), ExperimentError>

Archive an experiment.

Archived experiments reject all new assignments with ExperimentError::Archived.

Errors

Returns ExperimentError::NotFound if the experiment is unknown.

pub fn set_weights( &self, name: &str, variants: Vec<VariantConfig>, actor: Option<&str>, ) -> Result<(), ExperimentError>

Update the variant weights for name.

Existing sticky assignments are not re-bucketed: already-assigned actors keep their variant. New actors are bucketed against the updated weights.

Errors

Returns ExperimentError::NotFound if the experiment is unknown.

pub fn set_override( &self, experiment: &str, actor: &str, variant: &str, ) -> Result<(), ExperimentError>

Pin actor to variant in experiment, bypassing weight-based bucketing.

Overrides are used by staff/QA to force a specific variant during manual testing. Exposure events include is_override: true.

Errors

Returns ExperimentError::NotFound if the experiment is unknown.

pub fn list(&self) -> Result<Vec<ExperimentConfig>, ExperimentError>

List all declared experiments.

Errors

Returns ExperimentError::Store on backend failure.

pub fn status(&self, name: &str) -> Result<ExperimentConfig, ExperimentError>

Return the current configuration for name.

Errors

Returns ExperimentError::NotFound if the experiment is unknown.

pub fn history( &self, experiment: &str, limit: usize, ) -> Result<Vec<ChangeRecord>, ExperimentError>

Return the change log for experiment (most-recent first), capped at limit.

Errors

Returns ExperimentError::Store on backend failure.

Trait Implementations

impl Clone for ExperimentService

fn clone(&self) -> ExperimentService

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ExperimentService

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

Formats the value using the given formatter.