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Types ¶
type EvaluationContext ¶
type EvaluationContext struct {
UserKey string `json:"user_key"`
Attributes map[string]string `json:"attributes,omitempty"`
}
EvaluationContext holds the contextual data used to evaluate a feature flag. The UserKey uniquely identifies the subject (user, service, etc.). Attributes carry additional targeting information such as email, groups, plan, etc.
type FlagCache ¶
type FlagCache struct {
// contains filtered or unexported fields
}
FlagCache is a thread-safe in-memory TTL cache for evaluated flag values. A TTL of zero disables caching (every Get returns a miss).
func NewFlagCache ¶
NewFlagCache creates a cache with the given TTL. Pass 0 to disable caching.
func (*FlagCache) Invalidate ¶
Invalidate removes a single entry from the cache.
func (*FlagCache) InvalidateFlag ¶
InvalidateFlag removes all entries for the given flag key.
type FlagChangeEvent ¶
type FlagChangeEvent struct {
Key string `json:"key"`
Value any `json:"value"`
Type FlagType `json:"type"`
Source string `json:"source"`
}
FlagChangeEvent is emitted when a flag value changes within a provider.
type FlagMeta ¶
type FlagMeta struct {
Key string `json:"key"`
Type FlagType `json:"type"`
Description string `json:"description,omitempty"`
Enabled bool `json:"enabled"`
Tags []string `json:"tags,omitempty"`
CreatedAt time.Time `json:"created_at"`
UpdatedAt time.Time `json:"updated_at"`
}
FlagMeta describes a flag definition without evaluating it.
type FlagValue ¶
type FlagValue struct {
Key string `json:"key"`
Value any `json:"value"`
Type FlagType `json:"type"`
Source string `json:"source"` // provider name that produced the value
Reason string `json:"reason,omitempty"` // why this value was selected
Metadata json.RawMessage `json:"metadata,omitempty"` // provider-specific extra data
}
FlagValue represents the evaluated result of a single feature flag.
type Provider ¶
type Provider interface {
// Name returns a unique identifier for this provider (e.g. "generic", "launchdarkly").
Name() string
// Evaluate returns the resolved flag value for the given key and context.
// Returns an error if the flag does not exist or evaluation fails.
Evaluate(ctx context.Context, key string, evalCtx EvaluationContext) (FlagValue, error)
// AllFlags returns the evaluated values for every flag visible to the given context.
AllFlags(ctx context.Context, evalCtx EvaluationContext) ([]FlagValue, error)
// Subscribe registers a callback that is invoked whenever a flag changes.
// The returned function cancels the subscription.
Subscribe(fn func(FlagChangeEvent)) (cancel func())
}
Provider is the interface that all feature-flag backends must implement.
type Service ¶
type Service struct {
// contains filtered or unexported fields
}
Service is a caching proxy that sits between consumers and a Provider. It adds an in-memory cache, SSE broadcasting, and audit logging.
func NewService ¶
NewService creates a Service wrapping the given provider and cache.
func (*Service) AllFlags ¶
AllFlags delegates to the provider (cache is per-key, so we don't cache AllFlags).
func (*Service) Evaluate ¶
func (s *Service) Evaluate(ctx context.Context, key string, evalCtx EvaluationContext) (FlagValue, error)
Evaluate returns the flag value for the given key. Cache is checked first; on a miss the provider is queried and the result is cached.
func (*Service) SSEHandler ¶
func (s *Service) SSEHandler() http.HandlerFunc
SSEHandler returns an HTTP handler that streams flag change events to clients. Events are formatted as:
event: flag.updated
data: {"key":"my-flag","value":true,"type":"boolean","source":"generic"}
func (*Service) SubscriberCount ¶
SubscriberCount returns the number of active SSE subscribers.
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