/// <summary>
/// Event raise every heartbeat
/// </summary>
/// <param name="source"></param>
/// <param name="e"></param>
private static void Heartbeat(Object source, ElapsedEventArgs e)
{
IHubContext hub = GlobalHost.ConnectionManager.GetHubContext <DatabaseHub>();
if (hub == null)
{
return;
}
Info("Running heartbeat ...");
using (Module.Administration.DatabaseContext requester = new Module.Administration.DatabaseContext())
{
Debug("Ping all clients connected ...");
foreach (ConnectionRecord connection in requester._Connection.Where(c => c.Allow && c.Status).ToList())
{
try
{
Verbose($"Ping the client {connection}");
hub.Clients.Client(connection.ConnectionId).ping();
}
catch (System.Exception exception)
{
Exception("Unable to ping the client", exception);
}
}
Debug("Disconnect all clients without any updates since a while ...");
foreach (ConnectionRecord connection in requester._Connection.Where(c => c.Allow && c.Status).ToList())
{
if (connection.ConnectionLast < DateTime.Now.AddSeconds(-ConfigurationManager.ClientHubTimeout))
{
try
{
Info($"Disconnecting the client {connection} ...");
hub.Clients.Client(connection.ConnectionId).stop();
connection.Allow = false;
requester.SaveChanges();
}
catch (System.Exception exception)
{
Exception("Unable to disconnect the client", exception);
}
}
}
}
}
/// <summary>
/// Launch the heartbeat of the application if it is enabled
/// </summary>
public static void StartHeartbeat()
{
// Start Heartbeat to disconnect client if no updated done since a while
if (ConfigurationManager.HeartbeatDelay <= 0 || ConfigurationManager.ClientHubTimeout <= 0)
{
return;
}
Info($"Launching heartbeat every {ConfigurationManager.HeartbeatDelay} seconds and disconnect clients after {ConfigurationManager.ClientHubTimeout} seconds without response ...");
// Disconnect all connections if no updates done since a while ...
IHubContext hub = GlobalHost.ConnectionManager.GetHubContext <DatabaseHub>();
using (Module.Administration.DatabaseContext requester = new Module.Administration.DatabaseContext())
foreach (ConnectionRecord connection in requester._Connection.Where(c => c.Allow && c.Status).ToList())
{
if (connection.ConnectionLast < DateTime.Now.AddSeconds(-ConfigurationManager.ClientHubTimeout))
{
try
{
Info($"Disconnecting the client {connection} ...");
if (hub != null)
{
hub.Clients.Client(connection.ConnectionId).stop();
}
connection.Allow = false;
requester.SaveChanges();
}
catch (System.Exception exception)
{
Exception("Unable to disconnect the client", exception);
}
}
}
// Run the heartbeat
Debug("Starting heartbeat ...");
Timer heartbeat = new Timer(ConfigurationManager.HeartbeatDelay * 1000);
heartbeat.Elapsed += Heartbeat;
heartbeat.Start();
}
/// <summary>
/// The client tests if the server if up ... this call generally occurs on connection on an existing account!
/// </summary>
public void Ping()
{
try
{
DateTime now = DateTime.Now;
Debug($"Ping from '{Context.ConnectionId}'");
using (Module.Administration.DatabaseContext database = new Module.Administration.DatabaseContext())
{
// receive the ping from the client
PingRecord existingPing = database._Ping.Find(Context.ConnectionId);
if (existingPing != null)
{
existingPing.Date = now;
}
else
{
database._Ping.Add(new PingRecord {
ConnectionId = Context.ConnectionId
});
}
// update the last connection time of the client
ConnectionRecord currentConnection = database._Connection.Find(Context.ConnectionId);
if (currentConnection != null)
{
currentConnection.ConnectionLast = now;
}
database.SaveChanges();
}
}
catch (System.Exception ex)
{
Exception($"An exception occurs on pinging of the connection '{Context.ConnectionId}'", ex);
Warn("This exception is ignored ... may be the connection was previously deleted or disconnected!");
}
}
/// <summary>
/// Check if the given user is already connected through hub
/// </summary>
/// <param name="userId"></param>
/// <returns></returns>
public static bool IsAlreadyConnected(int userId)
{
// the user exists, check if it's already connected
// In case of reloading page, the connection can't be disconnected as quick as expected ...
IHubContext hub = GlobalHost.ConnectionManager.GetHubContext <DatabaseHub>();
if (hub == null)
{
// no hub ... disconnect the user and go to the index page
Common.Logger.LoggerManager.Instance.Info(MODULE, $"Cleaning up all connections for the user {userId} ...");
using (Module.Administration.DatabaseContext database = new Module.Administration.DatabaseContext())
{
ConnectionRecord currentConnection = database._Connection.FirstOrDefault(c => c.UserId == userId && c.Allow);
while (currentConnection != null)
{
Common.Logger.LoggerManager.Instance.Debug(MODULE, $"Connection {currentConnection} removed ...");
try { database._Connection.Remove(currentConnection); } catch { }
currentConnection = database._Connection.FirstOrDefault(c => c.UserId == userId && c.Allow);
}
database.SaveChanges();
}
return(false);
}
// DatabaseCommonContext is frequently open/close here to clean up the cache of the database (else the ping record is never updated) ...
bool alreadyConnected = true;
DateTime pingDate = DateTime.Now;
int count = 0;
while (count < ConfigurationManager.ConnectionMaxWaiting && alreadyConnected)
{
count++;
ConnectionRecord currentConnection = null;
using (Module.Administration.DatabaseContext database = new Module.Administration.DatabaseContext())
currentConnection = database._Connection.FirstOrDefault(c => c.UserId == userId && c.Allow);
if (currentConnection != null && count < ConfigurationManager.ConnectionMaxWaiting)
{
// Ping the client and wait 1 secondes to check if the client responses
if (count == 1)
{
Thread.Sleep(1000);
Common.Logger.LoggerManager.Instance.Debug(MODULE, $"Ping to '{currentConnection.ConnectionId}'");
hub.Clients.Client(currentConnection.ConnectionId).ping();
}
// Did the client answer to the ping ?
PingRecord currentPing = null;
using (Module.Administration.DatabaseContext database = new Module.Administration.DatabaseContext())
currentPing = database._Ping.Find(currentConnection.ConnectionId);
// The client has answered to the ping ... So, it already exists
if (currentPing != null && DateTime.Compare(currentPing.Date, pingDate) >= 0)
{
break;
}
// The client didn't answer ... wait a few more second
if (count > 1)
{
Thread.Sleep(1000);
}
}
else if (currentConnection != null)
{
// The max seconds has expired ... it means that no client is already connected ... disconnect it
alreadyConnected = false;
try
{
hub.Clients.Client(currentConnection.ConnectionId).stop();
Common.Logger.LoggerManager.Instance.Info(MODULE, $"The connection '{currentConnection.ConnectionId}' is disconnected");
}
catch (System.Exception ex)
{
Common.Logger.LoggerManager.Instance.Exception(MODULE, $"(Warning) Unable to disconnect '{currentConnection.ConnectionId}' due to an exception", ex);
}
using (Module.Administration.DatabaseContext database = new Module.Administration.DatabaseContext())
{
currentConnection = database._Connection.Find(currentConnection.ConnectionId);
currentConnection.Allow = false;
database.SaveChanges();
}
}
else
{
alreadyConnected = false;
Common.Logger.LoggerManager.Instance.Info(MODULE, $"No connection already existing or the previous connection is disconnected ...");
}
}
if (alreadyConnected)
{
Common.Logger.LoggerManager.Instance.Debug(MODULE, $"The user '{userId}' is already connected on another support");
return(true);
}
return(false);
}