In-flight job caching with cancellation support

InFlightJobCache.kt

class InFlightJobCache<T> {
      private val jobs = mutableMapOf<String, Deferred<T>>()
      private val mux = Mutex()

      suspend fun getOrFetch(key: String, factory: suspend () -> T): Deferred<T> = mux.withLock {
          val request = jobs.getOrDefault(key, async(start = CoroutineStart.LAZY) { factory() })
          jobs[key] = request
          return request
      }

      suspend fun get(key: String): Deferred<T>? = mux.withLock { jobs[key] }

      suspend fun cancel(key: String): Boolean? = mux.withLock {
          val result = jobs[key]?.cancel()
          jobs.remove(key)
          return result
      }
}