$ModuleOnly$

// A gate for starting, stopping, and canceling thread processes.
@value interface ThreadGate {
  // Start the thread(s).
  start () -> (#self)

  // Stop the thread(s).
  stop () -> (#self)

  // Returns true iff the thread(s) should be running.
  getEnabled () -> (Bool)

  // Permanently cancel the thread(s).
  cancel () -> (#self)
}


// Determine if a thread should continue or exit.
@value interface ThreadContinue {
  // Blocks until a start or cancel signal is received. If false is returned,
  // the thread should clean up and exit.
  shouldContinue () -> (Bool)
}

// Implementation of thread gating with a flag.
concrete ThreadFlag {
  refines ThreadGate
  refines ThreadContinue

  @type new () -> (ThreadFlag)
}