// PathExists verifies if a path exists and does not raise an exception if the
// path does not exist
func PathExists(conn client.Connection, p string) (bool, error) {
exists, err := conn.Exists(p)
if err == client.ErrNoNode {
return false, nil
}
return exists, err
}
func (s *Server) Run(shutdown <-chan interface{}, conn client.Connection) error {
node := &Node{
Host: *s.host,
ExportPath: fmt.Sprintf("%s:%s", s.host.IPAddr, s.driver.ExportPath()),
ExportTime: strconv.FormatInt(time.Now().UnixNano(), 16),
}
// Create the storage leader and client nodes
if exists, _ := conn.Exists("/storage/leader"); !exists {
conn.CreateDir("/storage/leader")
}
storageClientsPath := "/storage/clients"
if exists, _ := conn.Exists(storageClientsPath); !exists {
conn.CreateDir(storageClientsPath)
}
leader := conn.NewLeader("/storage/leader", node)
leaderW, err := leader.TakeLead()
if err != zookeeper.ErrDeadlock && err != nil {
glog.Errorf("Could not take storage lead: %s", err)
return err
}
// monitor dfs; log warnings each cycle; restart dfs if needed
go s.monitor.MonitorDFSVolume(path.Join("/exports", s.driver.ExportPath()), s.host.IPAddr, node.ExportTime, shutdown, s.monitor.DFSVolumeMonitorPollUpdateFunc)
// loop until shutdown event
defer leader.ReleaseLead()
for {
clients, clientW, err := conn.ChildrenW(storageClientsPath)
if err != nil {
glog.Errorf("Could not set up watch for storage clients: %s", err)
return err
}
s.monitor.SetMonitorStorageClients(conn, storageClientsPath)
s.driver.SetClients(clients...)
if err := s.driver.Sync(); err != nil {
glog.Errorf("Error syncing driver: %s", err)
return err
}
select {
case e := <-clientW:
glog.Info("storage.server: receieved event: %s", e)
case <-leaderW:
err := fmt.Errorf("storage.server: lost lead")
return err
case <-shutdown:
return nil
}
}
}
// updateInstance updates the service state and host instances
func updateInstance(conn client.Connection, hostID, stateID string, mutate func(*HostState, *ss.ServiceState)) error {
glog.V(2).Infof("Updating instance %s", stateID)
// do not lock if parent lock does not exist
if exists, err := conn.Exists(path.Join(zkInstanceLock, stateID)); err != nil && err != client.ErrNoNode {
glog.Errorf("Could not check for lock on instance %s: %s", stateID, err)
return err
} else if !exists {
glog.Errorf("Lock not found for instance %s", stateID)
return ErrLockNotFound
}
lock := newInstanceLock(conn, stateID)
if err := lock.Lock(); err != nil {
glog.Errorf("Could not set lock for service instance %s on host %s: %s", stateID, hostID, err)
return err
}
defer lock.Unlock()
glog.V(2).Infof("Acquired lock for instance %s", stateID)
hpath := hostpath(hostID, stateID)
var hsdata HostState
if err := conn.Get(hpath, &hsdata); err != nil {
glog.Errorf("Could not get instance %s for host %s: %s", stateID, hostID, err)
return err
}
serviceID := hsdata.ServiceID
spath := servicepath(serviceID, stateID)
var ssnode ServiceStateNode
if err := conn.Get(spath, &ssnode); err != nil {
glog.Errorf("Could not get instance %s for service %s: %s", stateID, serviceID, err)
return err
}
mutate(&hsdata, ssnode.ServiceState)
if err := conn.Set(hpath, &hsdata); err != nil {
glog.Errorf("Could not update instance %s for host %s: %s", stateID, hostID, err)
return err
}
if err := conn.Set(spath, &ssnode); err != nil {
glog.Errorf("Could not update instance %s for service %s: %s", stateID, serviceID, err)
return err
}
glog.V(2).Infof("Releasing lock for instance %s", stateID)
return nil
}