// WatchServiceLock waits for a service lock to be enabled/disabled
func WaitServiceLock(shutdown <-chan interface{}, conn client.Connection, enabled bool) error {
for {
// make sure the parent exists
if err := zzk.Ready(shutdown, conn, zkServiceLock); err != nil {
return err
}
// check if the lock is enabled
nodes, event, err := conn.ChildrenW(zkServiceLock)
if err != nil {
return err
}
// check that the states match
if locked := len(nodes) > 0; locked == enabled {
return nil
}
// wait to reach the desired state or shutdown
select {
case <-event:
// pass
case <-shutdown:
return zzk.ErrTimeout
}
}
}
func MonitorResourcePool(shutdown <-chan interface{}, conn client.Connection, poolID string) <-chan *pool.ResourcePool {
monitor := make(chan *pool.ResourcePool)
go func() {
defer close(monitor)
if err := zzk.Ready(shutdown, conn, poolpath(poolID)); err != nil {
glog.V(2).Infof("Could not watch pool %s: %s", poolID, err)
return
}
for {
var node PoolNode
event, err := conn.GetW(poolpath(poolID), &node)
if err != nil {
glog.V(2).Infof("Could not get pool %s: %s", poolID, err)
return
}
select {
case monitor <- node.ResourcePool:
case <-shutdown:
return
}
select {
case <-event:
case <-shutdown:
return
}
}
}()
return monitor
}
func (l *ServiceLockListener) Spawn(shutdown <-chan interface{}, poolID string) {
lock := l.conn.NewLock(l.GetPath(poolID, zkServiceLock))
defer lock.Unlock()
for {
if err := zzk.Ready(shutdown, l.conn, zkServiceLock); err != nil {
glog.V(2).Infof("Could not monitor lock: %s", err)
return
}
nodes, lockEvent, err := l.conn.ChildrenW(zkServiceLock)
if err != nil {
glog.V(2).Infof("Could not monitor lock: %s", err)
return
}
poolEvent, err := l.conn.GetW(l.GetPath(poolID), &PoolNode{})
if err != nil {
glog.V(2).Infof("Could not look up node for pool %s: %s", poolID, err)
return
}
if len(nodes) > 0 {
glog.V(3).Infof("Engaging service lock for %s", poolID)
lock.Lock()
} else {
glog.V(3).Infof("Disengaging service lock for %s", poolID)
lock.Unlock()
}
select {
case <-lockEvent:
// pass
case e := <-poolEvent:
if e.Type == client.EventNodeDeleted {
return
}
case <-shutdown:
return
}
}
}