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);
}