Create observables and consume only between events

Question

Imagine the following scenario:

I have the following events:

• Afterlogin
• Beforelogoff

And AfterLogin, I have other events based on new / other objects available.

When the user makes a login, I need to create a new subscription and subscribe or process it (using other events).
When the user logs out, I need to send these subscriptions and wait for AfterLogin again

It is very similar to: Between values ​​with Rx The
big difference is that to create a subscription and host a later version of "factory" I cannot listen to the source at the beginning.

How can I handle this?

Answer 1

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public class LoggedInActivity
{
    [Test]
    public void TestLoggingIn()
    {
        var sessionManager = new SessionManager();

        var afterLogIn = Observable.FromEventPattern<SessionEventArgs>(
            h => sessionManager.AfterLogin += h,
            h => sessionManager.AfterLogin -= h)
            .Select(x => x.EventArgs.UserId);

        var beforeLogOff = Observable.FromEventPattern<SessionEventArgs>(
            h => sessionManager.BeforeLogoff += h,
            h => sessionManager.BeforeLogoff -= h)
            .Select(x => x.EventArgs.UserId);

        var loggedIn = afterLogIn.GroupByUntil(
            userId => userId,
            login => beforeLogOff.Where(y => y == login.Key));

        Func<IGroupedObservable<int, int>, IObservable<string>> whileLoggedIn = login =>
            Observable.Using(
                () => sessionManager.AddSession(new Session(login.Key)),
                session => Observable.FromEventPattern(
                    h => session.SomeEvent += h,
                    h => session.SomeEvent -= h)
                    .Select(x => "User " + login.Key + " had SomeEvent!")
                    .TakeUntil(login.LastAsync()));

        // Single non-terminating stream that captures
        // all events occuring during any login 
        var loggedInEvents = loggedIn.SelectMany(whileLoggedIn);

        loggedInEvents.Subscribe(Console.WriteLine);

        sessionManager.Login(1);
        sessionManager.Sessions[1].RaiseSomeEvent();
        sessionManager.Login(2);
        sessionManager.Sessions[1].RaiseSomeEvent();
        sessionManager.Sessions[2].RaiseSomeEvent();
        sessionManager.Logoff(2);
        sessionManager.Logoff(1);

    }
}

public class SessionManager
{
    public event EventHandler<SessionEventArgs> AfterLogin;
    public event EventHandler<SessionEventArgs> BeforeLogoff;

    private readonly Dictionary<int, Session> _sessions = new Dictionary<int, Session>();
    public Dictionary<int, Session> Sessions { get { return _sessions; } }

    public void Login(int userId)
    {
        var temp = AfterLogin;
        if (temp != null)
        {
            AfterLogin(this, new SessionEventArgs(userId));
        }
    }

    public Session AddSession(Session session)
    {
        _sessions.Add(session.UserId, session);
        return session;
    }

    public void Logoff(int userId)
    {
        var temp = BeforeLogoff;
        if (temp != null)
        {
            BeforeLogoff(this, new SessionEventArgs(userId));
        }

        Sessions.Remove(userId);

    }
}

public class Session : IDisposable
{
    private readonly int _userId;

    public int UserId { get { return _userId; } }

    public Session(int userId)
    {
        _userId = userId;
        Console.WriteLine("User " + _userId + " logged in.");
    }

    public event EventHandler SomeEvent;

    public void RaiseSomeEvent()
    {
        var temp = SomeEvent;
        if (temp != null)
        {
            SomeEvent(this, EventArgs.Empty);
        }
    }

    public void Dispose()
    {
        Console.WriteLine("User " + _userId + " logged out.");
    }
}

public class SessionEventArgs : EventArgs
{
    private readonly int _userId;

    public SessionEventArgs(int userId)
    {
        _userId = userId;
    }

    public int UserId { get { return _userId; } }
}

.

:

User 1 logged in.
User 1 had SomeEvent!
User 2 logged in.
User 1 had SomeEvent!
User 2 had SomeEvent!
User 2 logged out.
User 1 logged out.