state

type Cursor interface {
	Save(state *State, configWriter io.WriterTo) error
	Destroy(id app.ID) error
	Load() (Entries, error)
	Len() (int, error)
}

type Entries map[app.ID]*State

type Joiner interface{ Join() (Entries, error) }

type State struct {
	// fortify instance id
	ID app.ID `json:"instance"`
	// child process PID value
	PID int `json:"pid"`
	// sealed app configuration
	Config *fst.Config `json:"config"`

	// process start time
	Time time.Time `json:"time"`
}

type Store interface {
	// Do calls f exactly once and ensures store exclusivity until f returns.
	// Returns whether f is called and any errors during the locking process.
	// Cursor provided to f becomes invalid as soon as f returns.
	Do(aid int, f func(c Cursor)) (ok bool, err error)

	// List queries the store and returns a list of aids known to the store.
	// Note that some or all returned aids might not have any active apps.
	List() (aids []int, err error)

	// Close releases any resources held by Store.
	Close() error
}