package com.sptmobile.endpoint

import java.util.concurrent.ConcurrentHashMap

/**
 * Process-lifetime endpoint id → serving-host node cache for the digest route
 * (DESIGN.md ruling 4). The route is decided by a ~2s `listEndpoints` call,
 * yet it almost never changes, so caching it lets a repeat open of an endpoint
 * paint its digest immediately instead of re-paying the routing round-trip.
 *
 * A stale entry (the endpoint moved, or the serving host went away) self-heals:
 * [EndpointViewModel] invalidates on any digest RPC failure, then re-routes
 * from a fresh listing. Small and unbounded — the paired-host fleet is tiny.
 */
object DigestRouteCache {
    private val routes = ConcurrentHashMap<String, String>()

    fun get(endpointId: String): String? = routes[endpointId]

    fun put(endpointId: String, node: String) {
        routes[endpointId] = node
    }

    fun invalidate(endpointId: String) {
        routes.remove(endpointId)
    }
}