Struct FeatureFlagService 

pub struct FeatureFlagService { /* private fields */ }

The main feature-flag service.

Wrap a FlagStore (for persistence) and an optional GroupResolver (for named-group membership). The service is cheaply clone-able and intended to be stored as an AppState extension:

state.insert_extension(FeatureFlagService::new(Arc::new(InMemoryFlagStore::new())));

Store failures

When the store returns an error, the service uses the last value that it read for that flag (the last-known value). With no last-known value, it uses the declared default (with_default), or false. Clones share the last-known values and the error count.

Implementations

impl FeatureFlagService

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

Create a new service wrapping the given store.

pub fn with_default(self, flag_key: impl Into<String>, default: bool) -> Self

Declare the value of flag_key when the store does not hold the flag, or cannot read it and no last-known value exists.

Without a declared default, that value is false.

pub fn store_errors(&self) -> u64

Number of failed store reads since the service was made.

pub fn preload(&self) -> Result<(), FlagStoreError>

Load the store before the first read. This can block.

Errors

Propagates FlagStoreError from the backing store.

pub fn with_group_resolver(self, resolver: GroupResolver) -> Self

Attach a group resolver so named-group gates are evaluated.

pub fn is_enabled(&self, flag_key: &str, actor_id: Option<&str>) -> bool

Return true if flag_key is enabled for actor_id.

An unknown flag gets its declared default, or false. A store error gets the last-known value (see Store failures).

pub fn enable( &self, flag_key: &str, actor: Option<&str>, ) -> Result<(), FlagStoreError>

Enable flag_key for all actors.

Errors

Propagates FlagStoreError from the backing store.

pub fn disable( &self, flag_key: &str, actor: Option<&str>, ) -> Result<(), FlagStoreError>

Disable flag_key globally.

Errors

Propagates FlagStoreError from the backing store.

pub fn set_rollout( &self, flag_key: &str, pct: u8, actor: Option<&str>, ) -> Result<(), FlagStoreError>

Set the percent-rollout gate for flag_key to pct (0–100).

Errors

Propagates FlagStoreError from the backing store.

pub fn allow_actor( &self, flag_key: &str, actor_id: &str, actor: Option<&str>, ) -> Result<(), FlagStoreError>

Add actor_id to the explicit allowlist for flag_key.

Errors

Propagates FlagStoreError from the backing store.

pub fn add_group( &self, flag_key: &str, group: &str, actor: Option<&str>, ) -> Result<(), FlagStoreError>

Add group to the named-group allowlist for flag_key.

Errors

Propagates FlagStoreError from the backing store.

pub fn list(&self) -> Result<Vec<FlagConfig>, FlagStoreError>

Return all known flags, sorted by key.

Errors

Propagates FlagStoreError from the backing store.

pub fn history( &self, flag_key: &str, limit: usize, ) -> Result<Vec<FlagChangeRecord>, FlagStoreError>

Return the most recent limit change records for flag_key.

Errors

Propagates FlagStoreError from the backing store.

Trait Implementations

impl Clone for FeatureFlagService

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FeatureFlagService

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

Formats the value using the given formatter.