consul/internal/controller/lease.go

30 lines
950 B
Go

package controller
// Lease is used to ensure controllers are run as singletons (i.e. one leader-
// elected instance per cluster).
//
// Currently, this is just an abstraction over Raft leadership. In the future,
// we'll build a backend-agnostic leasing system into the Resource Service which
// will allow us to balance controllers between many servers.
type Lease interface {
// Held returns whether we are the current lease-holders.
Held() bool
// Changed returns a channel on which you can receive notifications whenever
// the lease is acquired or lost.
Changed() <-chan struct{}
}
type raftLease struct {
m *Manager
ch <-chan struct{}
}
func (l *raftLease) Held() bool { return l.m.raftLeader.Load() }
func (l *raftLease) Changed() <-chan struct{} { return l.ch }
type eternalLease struct{}
func (eternalLease) Held() bool { return true }
func (eternalLease) Changed() <-chan struct{} { return nil }