// Set the sucessor replica of the worker
internal static void SetReplica(string worker_url, string sucessor, string predecessor)
{
IMasterWorker remote = (IMasterWorker)Activator.GetObject(typeof(IMasterWorker),
worker_url + "MasterWorker");
remote.setReplica(sucessor, predecessor);
}
// Status operation
internal static void status()
{
foreach (String server_url in availableServers.Values)
{
if (!isFailedServer(server_url) || !isFreezedServer(server_url))
{
IMasterWorker worker = (IMasterWorker)Activator.GetObject(typeof(IMasterWorker),
server_url + "MasterWorker");
worker.status();
}
}
}
public static void Main(string[] args)
{
try
{
IUnityContainer unityContainer = UnityHelper.RegisterUnityContainer();
IMasterWorker worker = unityContainer.Resolve <IMasterWorker>(WORKER_ON_DUTY);
worker.Do();
Console.ReadKey();
}
catch (Exception e)
{
Console.Write(e.StackTrace);
}
Console.ReadKey();
}
// Master tells the worker to freeze itself
internal static bool freeze(string url)
{
if (isFailedServer(url) || isFreezedServer(url))
{
return(false);
}
IMasterWorker worker = (IMasterWorker)Activator.GetObject(
typeof(IMasterWorker), url + "MasterWorker");
int id = getAvailableID(url);
freezedServers.Add(id, url);
worker.freeze();
return(true);
}
internal static bool recover(string url)
{
if (isFailedServer(url))
{
int failed_id = getFailedID(url);
failedServers.Remove(failed_id);
// Sets the original URL
availableServers[failed_id] = url;
string failed_sucessorURL = getWorkerSucessor(failed_id);
string failed_predecessorURL = getWorkerPredecessor(failed_id);
IMasterWorker failed_predecessor = (IMasterWorker)Activator.GetObject(
typeof(IMasterWorker), failed_predecessorURL + "MasterWorker");
IMasterWorker datastore = (IMasterWorker)Activator.GetObject(
typeof(IMasterWorker), url + "MasterWorker");
// Set sucessor of the failed predecessor to the recovered server
failed_predecessor.setSucessor(url);
// Fetch data from from failed predecessor to put in his list of updates
datastore.fetch_data(failed_predecessorURL);
// Fetch recover data to recovered server to fetch the primary data of his sucessor
// also sets his sucessor
datastore.fetch_recover_data(failed_sucessorURL);
return(true);
}
if (isFreezedServer(url))
{
int freeze_id = getFreezeID(url);
freezedServers.Remove(freeze_id);
availableServers[freeze_id] = url;
IMasterWorker worker = (IMasterWorker)Activator.GetObject(typeof(IMasterWorker), url + "MasterWorker");
worker.recover();
return(true);
}
return(false);
}
// Master tells the worker to fail itself and stabilizes the system
internal static bool fail(string url)
{
if (isFailedServer(url))
{
return(false);
}
int id = getAvailableID(url);
if (isFreezedServer(url))
{
freezedServers.Remove(id);
}
failedServers.Add(id, url);
string failed_sucessorURL = getWorkerSucessor(id);
string failed_predecessorURL = getWorkerPredecessor(id);
IMasterWorker failed_sucessor = (IMasterWorker)Activator.GetObject(
typeof(IMasterWorker), failed_sucessorURL + "MasterWorker");
IMasterWorker failed_predecessor = (IMasterWorker)Activator.GetObject(
typeof(IMasterWorker), failed_predecessorURL + "MasterWorker");
// Na posicao original dos available trocar o url pelo sucessor
availableServers[id] = failed_sucessorURL;
//Set sucessor of failed_predecessor to failed_sucessor -> Problema de concorrencia entre estas 2 operções?
failed_predecessor.setSucessor(failed_sucessorURL);
//Tell the sucessor to substitute the failed server
failed_sucessor.substituteFailedServer();
//Tell the sucessor to fetch the original data from the failed_predecessor and put it in his the list of updates
failed_sucessor.fetch_data(failed_predecessorURL);
IMasterWorker datastore = (IMasterWorker)Activator.GetObject(
typeof(IMasterWorker), url + "MasterWorker");
// Last thing to do is change the state, so that the library can continue working
datastore.fail();
return(true);
}
// Sets the detected url to failed
internal static string setFailedServer(string url)
{
// simple sanity check
if (!failedServers.ContainsValue(url))
{
// if the server was available do the following
if (availableServers.ContainsValue(url))
{
lock (availableServers)
{
int id = getAvailableID(url);
int sucessorID = id + 1;
if (sucessorID >= availableServers.Count)
{
sucessorID = 0;
}
int predecessorID = id - 1;
if (predecessorID < 0)
{
predecessorID = availableServers.Count;
}
string predecessorURL = availableServers[predecessorID];
string sucessorURL = availableServers[sucessorID];
string failedURL = availableServers[id];
IMasterWorker sucessor =
(IMasterWorker)Activator.GetObject(typeof(IMasterWorker),
sucessorURL + "MasterWorker");
IMasterWorker predecessor =
(IMasterWorker)Activator.GetObject(typeof(IMasterWorker),
predecessorURL + "MasterWorker");
IMasterWorker failed =
(IMasterWorker)Activator.GetObject(typeof(IMasterWorker),
failedURL + "MasterWorker");
availableServers[id] = sucessorURL; // same as availableServers[successorID]
sucessor.setPredecessor(predecessorURL);
predecessor.setSucessor(sucessorURL);
sucessor.substituteFailedServer();
failed.fail();
failedServers.Add(id, url);
return(sucessorURL);
}
}
else if (freezedServers.ContainsValue(url))
{
lock (freezedServers)
{
int id = getFreezeID(url);
int sucessorID = id + 1;
if (sucessorID >= freezedServers.Count)
{
sucessorID = 0;
}
int predecessorID = id - 1;
if (predecessorID < 0)
{
predecessorID = freezedServers.Count;
}
string predecessorURL = freezedServers[predecessorID];
string sucessorURL = freezedServers[sucessorID];
string failedURL = freezedServers[id];
IMasterWorker sucessor =
(IMasterWorker)Activator.GetObject(typeof(IMasterWorker),
sucessorURL + "MasterWorker");
IMasterWorker predecessor =
(IMasterWorker)Activator.GetObject(typeof(IMasterWorker),
predecessorURL + "MasterWorker");
IMasterWorker failed =
(IMasterWorker)Activator.GetObject(typeof(IMasterWorker),
failedURL + "MasterWorker");
// the server was both in available and freezed servers
availableServers[id] = sucessorURL;
sucessor.setPredecessor(predecessorURL);
predecessor.setSucessor(sucessorURL);
sucessor.substituteFailedServer();
failed.fail();
freezedServers.Remove(id);
failedServers.Add(id, url);
return(sucessorURL);
}
}
}
return(null);
}
