leadership

type Manager interface {

	// ClaimLeadership claims leadership of the named service on behalf of the
	// named unit. If no error is returned, leadership will be guaranteed for
	// at least the supplied duration from the point when the call was made.
	ClaimLeadership(serviceName, unitName string, duration time.Duration) error

	// CheckLeadership verifies that the named unit is leader of the named
	// service, and returns a Token attesting to that fact for use building
	// mgo/txn transactions that depend upon it.
	CheckLeadership(serviceName, unitName string) (Token, error)

	// BlockUntilLeadershipReleased blocks until the named service is known
	// to have no leader, in which case it returns no error; or until the
	// manager is stopped, in which case it will fail.
	BlockUntilLeadershipReleased(serviceName string) error
}

type ManagerConfig struct {
	Client lease.Client
	Clock  lease.Clock
}

type ManagerWorker interface {
	worker.Worker
	Manager
}

type Token interface {

	// AssertOps returns mgo/txn operations that will abort if some fact no
	// longer holds true.
	AssertOps() []txn.Op
}