// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package appcycle defines interfaces for managing application processes.
package appcycle

// TODO(caprita): Implement AppCycle server in runtime.

// Task is streamed by Stop to provide the client with a sense of the progress
// of the shutdown.
// The meaning of Progress and Goal are up to the developer (the server provides
// the framework with values for these).  The recommended meanings are:
// - Progress: how far along the shutdown sequence the server is.  This should
//   be a monotonically increasing number.
// - Goal: when Progress reaches this value, the shutdown is expected to
//   complete.  This should not change during a stream, but could change if
//   e.g. new shutdown tasks are triggered that were not forseen at the outset
//   of the shutdown.
type Task struct {
	Progress, Goal int32
}

// AppCycle interfaces with the process running a vanadium runtime.
type AppCycle interface{
	// Stop initiates shutdown of the server.  It streams back periodic
	// updates to give the client an idea of how the shutdown is
	// progressing.
	Stop() stream<_, Task> error
	// ForceStop tells the server to shut down right away.  It can be issued
	// while a Stop is outstanding if for example the client does not want
	// to wait any longer.
	ForceStop() error
}