func (handler *pcpBalancingHandler) NewSession(balancingSession *balancer.BalancingSession, param protocols.SessionParameter) (balancer.BalancingSessionHandler, error) {
desc, ok := param.(*amp.StartStream)
if !ok {
return nil, fmt.Errorf("Illegal session parameter type for pcpBalancingHandler: %T", param)
}
client, err := pcp.NewClient(balancingSession.PrimaryServer.Client)
if err != nil {
return nil, err
}
proxyHost := client.Server().IP().String()
// TODO the address for receiving traffic could be different from the protocol-API
// Check the address of the sending session plugin..?
resp, err := client.StartProxyPair(proxyHost, desc.ReceiverHost, desc.Port, desc.Port+1)
if err != nil {
return nil, err
}
session := &pcpBalancingSession{
client: client,
balancingSession: balancingSession,
receiverHost: desc.ReceiverHost,
receiverPort: desc.Port,
proxyHost: resp.ProxyHost,
proxyPort: resp.ProxyPort1,
}
// Make sure the next plugin sends the data to the proxies instead of the actual client
desc.ReceiverHost = resp.ProxyHost
desc.Port = resp.ProxyPort1
return session, nil
}
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
}
