func (session *pcpBalancingSession) HandleServerFault() (*balancer.BackendServer, error) {
// Fencing: Stop the original node just to be sure.
// TODO more reliable fencing.
session.backgroundStopRemote()
// Check preconditions for failover
sending := session.balancingSession.SendingSession
sending2, ok := sending.(*balancer.BalancingSession)
ampSession, ok2 := sending2.Handler.(*ampBalancingSession)
if !ok || !ok2 {
return nil, fmt.Errorf("Can only handle PCP fault when sending session is *ampBalancingSession. Instead have %v (%T)", sending, sending)
}
// Find and initialize backup server
var usedBackup *balancer.BackendServer
var pcpBackup *pcp.Client
var resp *pcp.StartProxyPairResponse
for _, backup := range session.balancingSession.BackupServers {
var err error
pcpBackup, err = pcp.NewClient(backup.Client)
// TODO log errors that prevented a backup server from being used?
if err == nil {
var err error
proxyHost := pcpBackup.Server().IP().String()
// TODO The proxyHost could be different. See the comment above in NewSession.
resp, err = pcpBackup.StartProxyPair(proxyHost, session.receiverHost, session.receiverPort, session.receiverPort+1)
if err == nil {
usedBackup = backup
break
}
}
}
if usedBackup == nil {
return nil, fmt.Errorf("No valid backup server for %s!", session.client)
}
session.client = pcpBackup
session.proxyHost = resp.ProxyHost
session.proxyPort = resp.ProxyPort1
// Try to redirect the stream to the new proxy.
err := ampSession.RedirectStream(resp.ProxyHost, resp.ProxyPort1)
if err != nil {
return nil, err
}
return usedBackup, nil
}
func closeProxyPCP(client *pcp.Client, listenPort, targetPort int) {
golib.Printerr(client.StopProxy(pcpProxyAddrs(listenPort, targetPort)))
}
func makeProxyPCP(client *pcp.Client, listenPort, targetPort int) {
golib.Checkerr(client.StartProxy(pcpProxyAddrs(listenPort, targetPort)))
}
