# ephemeral(cacheDirectory:) Returns a fully self-cleaning ephemeral configuration, optionally keeping a warm cache. ``` static func ephemeral(cacheDirectory: String? = nil) -> TorConfiguration ``` ## Parameters `cacheDirectory` Optional persistent cache path. The cache is **not** removed on stop, so this is the single most effective way to drop subsequent bootstrap times from ~40s to ~5–10s. ## Return Value A `TorConfiguration` that fully disposes of its data directory on shutdown while optionally reusing a warm cache. ## Discussion Intended for per-session embedded Tor usage where the caller wants zero residual state on disk after [`stop()`](/documentation/Tor/TorClient/stop()) returns. Internally: UUID-suffixed temp directory, [`ownsDataDirectory`](/documentation/Tor/TorConfiguration/ownsDataDirectory) set to `true`, and [`cacheDirectory`](/documentation/Tor/TorConfiguration/cacheDirectory) optionally pointed at a caller-owned warm cache. > Important: The cache directory is shared across sessions and > must survive process death. Store it under a stable > app-scoped path (not `tmp`).