ff4k-core/com.yonatankarp.ff4k.core/FlippingStrategy

FlippingStrategy

Defines a strategy for determining whether a feature should be enabled.

A flipping strategy encapsulates the logic that controls feature activation based on runtime conditions, configuration parameters, and execution context. Common use cases include:

Gradual rollout: Enable features for a percentage of users
Region-based: Enable features only in specific geographical regions
Time-based: Enable features during specific time windows
User-based: Enable features for specific user segments or roles
Custom logic: Any business-specific activation rules

Example implementations:

// Percentage-based rollout
class PercentageStrategy(override val initParams: Map<String, String>) : FlippingStrategy {
    override suspend fun evaluate(
        featureId: String,
        store: FeatureStore?,
        context: FlippingExecutionContext
    ): Boolean {
        val percentage = initParams["percentage"]?.toInt() ?: 0
        val userId = context.get<String>(ContextKeys.USER_ID) ?: return false
        return userId.hashCode() % 100 < percentage
    }
}

// Region-based strategy
class RegionStrategy(override val initParams: Map<String, String>) : FlippingStrategy {
    override suspend fun evaluate(
        featureId: String,
        store: FeatureStore?,
        context: FlippingExecutionContext
    ): Boolean {
        val allowedRegions = initParams["regions"]?.split(",") ?: emptyList()
        val userRegion = context.get<String>(ContextKeys.REGION) ?: return false
        return userRegion in allowedRegions
    }
}