}
    }

    return isRunning
  }

  /** Used by [Call.execute] to signal it is in-flight. */
  internal fun executed(call: RealCall) =
    this.withLock {
      runningSyncCalls.add(call)
    }

  /** Used by [AsyncCall.run] to signal completion. */
  internal fun finished(call: AsyncCall) {
    call.callsPerHost.decrementAndGet()