public void respondIfNewNode(String machineName, String sellerName, Uri machine)
{
// Clear the cache because the system changed -> the data changed
cache.clear();
//Barrier - Create, Enter, BLOCK -> Leave when Balancing ends
var barrier = AirlineReplicationModule.Instance.barrier();
// Get the cuurent snapshot of the system - including the new machine that came up!
//not included the sellers that it holds.
Dictionary <string, ZNodesDataStructures.MachineNode> machines = AirlineReplicationModule.Instance.Machines;
// in the ZK tree: If a machine holds a seller that has return to live - drop it!
foreach (string smachine in machines.Keys)
{
if (!smachine.Equals(machineName))
{
machines[smachine].primaryOf.Remove(sellerName);
machines[smachine].backsUp.Remove(sellerName);
}
}
// this is the oldest legal view of the tree. necessary to enable sellers transfers
Dictionary <string, ZNodesDataStructures.MachineNode> machinesOldVersion = copyMachines(machines);
// in the local data: If a this machine holds an old version of the seller - drop it!!
if (!machineName.Equals(myName))
{
primaries.RemoveAll(delegate(Seller candidate)
{
return(candidate.name.Equals(sellerName));
});
backups.RemoveAll(delegate(Seller candidate)
{
return(candidate.name.Equals(sellerName));
});
}
// the new machine holds the new seller
// If there is only a single machine there is no need to backup the seller and load balancing
if (machines.Count == 1)
{
try
{
ServiceEndpoint sellerSearchEndPoint =
new ServiceEndpoint(ContractDescription.GetContract(
typeof(IAirSellerRegisteration)),
new WebHttpBinding(),
new EndpointAddress
(mysearchServerAddress));
using (WebChannelFactory <IAirSellerRegisteration> cf = new WebChannelFactory <IAirSellerRegisteration>(sellerSearchEndPoint))
{
IAirSellerRegisteration registerChannel = cf.CreateChannel();
//Register the channel in the server
registerChannel.RegisterSeller(new Uri(myAddress), clusterName);
}
}
catch (ProtocolException e)
{
Console.WriteLine("Bad Protocol: " + e.Message);
}
catch (Exception e)
{
if (e.InnerException is WebException)
{
HttpWebResponse resp = (HttpWebResponse)((WebException)e.InnerException).Response;
Console.WriteLine("Failed, {0}", resp.StatusDescription);
}
else
{
Console.WriteLine("Advertisement connection kicked the bucket, quitting because:");
Console.WriteLine(e.Message.ToString());
}
return;
}
}
else
{
// if there are 2 machines - it means that before the current machine has joined there were no backups!
if (machines.Count == 2)
{
// get the oldest machine
string oldMachine = machines.Keys.Where(delegate(string str)
{
return(!str.Equals(machineName));
}).First();
// backup all the sellers in the old machine
foreach (string sell in machines[oldMachine].primaryOf)
{
machines[machineName].backsUp.Add(sell);
if (machineName.Equals(myName))
{
ServiceEndpoint endPoint = new ServiceEndpoint(ContractDescription.GetContract(typeof(ISellerClusterService)), new BasicHttpBinding(), new EndpointAddress(machines[oldMachine].uri));
using (ChannelFactory <ISellerClusterService> httpFactory = new ChannelFactory <ISellerClusterService>(endPoint))
{
ISellerClusterService sellerCluster = httpFactory.CreateChannel();
try
{
Seller sellerToBackup = sellerCluster.sendPrimarySeller(sell);
if (sellerToBackup == null)
{
sellerToBackup = sellerCluster.sendBackupSeller(sellerName);
}
backups.Add(sellerToBackup);
}
catch (FaultException fe)
{
Console.WriteLine("Failure in getting seller. Because: " + fe.Message);
return;
}
}
}
}
}
// find a deterministic victim to hold the backup of the new seller
string victim = (from p in machines where !p.Key.Equals(machineName) orderby p.Value.primaryOf.Count ascending, p.Key ascending select p.Key).First();
// if the victim is this machine - follow the command and ask a clone from the new machine that owns the primary replica
if (victim.Equals(myName))
{
Uri uri = machine;
ServiceEndpoint endPoint = new ServiceEndpoint(
ContractDescription.GetContract(typeof(ISellerClusterService)), new BasicHttpBinding(), new EndpointAddress(machines[machineName].uri));
using (ChannelFactory <ISellerClusterService> httpFactory = new ChannelFactory <ISellerClusterService>(endPoint))
{
ISellerClusterService sellerCluster = httpFactory.CreateChannel();
try
{
Seller sellerToBackup = sellerCluster.sendPrimarySeller(sellerName);
if (sellerToBackup == null)
{
sellerToBackup = sellerCluster.sendBackupSeller(sellerName);
}
backups.Add(sellerToBackup);
}
catch (FaultException fe)
{
Console.WriteLine("Failure in getting seller. Because: " + fe.Message);
return;
}
}
}
// update it in the ZK tree
machines[victim].backsUp.Add(sellerName);
}
// execute a deterministic load-balancing algorithm
if (machines.Keys.Count > 1)
{
Console.WriteLine("\t** BALANCING ALGORITHM STARTED **");
balanceTheTreeAfterJoined(machines, machinesOldVersion, machineName, machine);
// this lock makes sure that no search server will serviced while sellers are removed from the machine.
Console.WriteLine("\t** BALANCING ALGORITHM FINISHED **");
}
//// barrier: in order to prevent losing replicas at same time that other machines asks for them
barrier.Leave();
// update the ZK server!!
AirlineReplicationModule.Instance.updateMachineData(machines);
// update the primaries and backups lists - now we can remove the not needed replicas
primaries.RemoveAll(delegate(Seller p) { return(!machines[myName].primaryOf.Contains(p.name)); });
backups.RemoveAll(delegate(Seller p) { return(!machines[myName].backsUp.Contains(p.name)); });
// print replicas status
print(machines);
}
private void balanceTheTreeAfterLeft(Dictionary <string, ZNodesDataStructures.MachineNode> machines, Dictionary <string, ZNodesDataStructures.MachineNode> machinesOldView, List <string> backupsToAssign, List <string> primariesToAssign)
{
// calculate the average number of sellers (separately primaries and backups)
// that each machine has to hold approximately in order to keep load balancing
int averageP = 0, averageB = 0;
foreach (string mac in machines.Keys)
{
averageP += machines[mac].primaryOf.Count;
averageB += machines[mac].backsUp.Count;
}
averageP = Convert.ToInt32(Math.Ceiling((Convert.ToDecimal(averageP) + primariesToAssign.Count) / machines.Count));
averageB = Convert.ToInt32(Math.Ceiling((Convert.ToDecimal(averageB) + backupsToAssign.Count) / machines.Count));
// we want a deterministic list of the machines order by their availability
// so we reverese the list
List <string> reverseBusy = getTheMostBusyMachineOrderByPrimaries(machines);
reverseBusy.Reverse();
primariesToAssign.Sort();
List <string> backupsThatShouldBeMoved = new List <string>();
foreach (string lightMachine in reverseBusy)
{
// no primaries to assign
if (primariesToAssign.Count == 0)
{
break;
}
// move primaries to the light machine
while (machines[lightMachine].primaryOf.Count < averageP)
{
if (primariesToAssign.Count == 0)
{
break;
}
// do the transfer
string primaryToTransfer = primariesToAssign.First();
machines[lightMachine].primaryOf.Add(primaryToTransfer);
if (machines[lightMachine].backsUp.Contains(primaryToTransfer))
{
machines[lightMachine].backsUp.Remove(primaryToTransfer);
backupsToAssign.Add(primaryToTransfer);
backupsThatShouldBeMoved.Add(primaryToTransfer);
}
// ask for the seller from another machine
if (lightMachine.Equals(myName))
{
Uri uri = FindBackupOfSeller(primaryToTransfer, machinesOldView);
ServiceEndpoint endPoint = new ServiceEndpoint(ContractDescription.GetContract(typeof(ISellerClusterService)), new BasicHttpBinding(), new EndpointAddress(uri));
using (ChannelFactory <ISellerClusterService> httpFactory = new ChannelFactory <ISellerClusterService>(endPoint))
{
try
{
ISellerClusterService sellerCluster = httpFactory.CreateChannel();
Seller sellerToPrimary = sellerCluster.sendBackupSeller(primaryToTransfer);
primaries.Add(sellerToPrimary);
}
catch (FaultException fe)
{
Console.WriteLine("Failure in getting seller. Because: " + fe.Message);
return;
}
}
}
primariesToAssign.Remove(primaryToTransfer);
}
}
// this phase load balance the backup
List <string> idles = getTheMostBusyMachineOrderByBackups(machines);
idles.Reverse();
backupsToAssign.Sort();
// balance the machines order by backups
foreach (string lightMachine in idles)
{
if (backupsToAssign.Count == 0)
{
break;
}
// move until machine get to the average amount of backups
while (machines[lightMachine].backsUp.Count < averageB)
{
if (backupsToAssign.Except(machines[lightMachine].primaryOf).Count() == 0)
{
break;
}
List <string> bs = backupsToAssign.Except(machines[lightMachine].primaryOf).ToList();
bs.Sort();
string backupToTransfer = bs.First();
machines[lightMachine].backsUp.Add(backupToTransfer);
// we distinct between 2 cases: backups that have been removed from another machine, and backups that
// came from the dropped machine
if (lightMachine.Equals(myName))
{
if (backupsThatShouldBeMoved.Contains(backupToTransfer))
{
Uri uri = FindBackupOfSeller(backupToTransfer, machinesOldView);
ServiceEndpoint endPoint = new ServiceEndpoint(ContractDescription.GetContract(typeof(ISellerClusterService)), new BasicHttpBinding(), new EndpointAddress(uri));
using (ChannelFactory <ISellerClusterService> httpFactory = new ChannelFactory <ISellerClusterService>(endPoint))
{
try
{
Seller sellerToPrimary;
ISellerClusterService sellerCluster = httpFactory.CreateChannel();
sellerToPrimary = sellerCluster.sendBackupSeller(backupToTransfer);
backups.Add(sellerToPrimary);
}
catch (FaultException fe)
{
Console.WriteLine("Failure in getting seller. Because: " + fe.Message);
return;
}
}
}
else
{
Uri uri = FindPrimaryOfSeller(backupToTransfer, machinesOldView);
ServiceEndpoint endPoint = new ServiceEndpoint(ContractDescription.GetContract(typeof(ISellerClusterService)), new BasicHttpBinding(), new EndpointAddress(uri));
using (ChannelFactory <ISellerClusterService> httpFactory = new ChannelFactory <ISellerClusterService>(endPoint))
{
try
{
Seller sellerToPrimary;
ISellerClusterService sellerCluster = httpFactory.CreateChannel();
sellerToPrimary = sellerCluster.sendPrimarySeller(backupToTransfer);
backups.Add(sellerToPrimary);
}
catch (FaultException fe)
{
Console.WriteLine("Failure in getting seller. Because: " + fe.Message);
return;
}
}
}
}
backupsToAssign.Remove(backupToTransfer);
}
}
}