Signalr-闲置一段时间后运行任务

Question

I want to call a function after a period of inactivity (regardless of whether the client is connected or not) to clean up / dispose of data. Basically, I am creating a new instance of a class for each client that is connected and storing it in a Dictionary, but I don't want to keep that instance there if the client is inactive / disconnected for a period of time (eg 30 minutes) to free up memory. Is this possible with Signalr?

Answer 1

You can use the OnDisconnected event in your Hub to know when your client is not active , and clear up your memory.

public override Task OnDisconnected() { // Free Your memory here return base.OnDisconnected(); }

and you can configure the disconnect event time period

Answer 2

Found my answer here . Basically, you can create a variable like so:

static public Dictionary<string, DateTime> LastConnectionTime = new Dictionary<string, DateTime>();

Whenever the user accesses a function, you can update the last time like so:

LastConnectionTime[Context.User.Identity.Name] = DateTime.Now;

Then, in your Globals.asax:

    protected void Application_Start()
    {
        // ...

        AddTask("HubInactivity", 120);
    }

    private void AddTask(string name, int seconds)
    {
        OnCacheRemove = new CacheItemRemovedCallback(CacheItemRemoved);
        HttpRuntime.Cache.Insert(name, seconds, null,
            DateTime.Now.AddSeconds(seconds), Cache.NoSlidingExpiration,
            CacheItemPriority.NotRemovable, OnCacheRemove);
    }

    public void CacheItemRemoved(string k, object v, CacheItemRemovedReason r)
    {
        if (k == "HubInactivity")
        {
            var time = DateTime.Now;

            // HubHelpers is where I kept the dictionary in my case
            foreach (var identity in Hubs.HubHelpers.LastConnectionTime.Keys)
            {
                var lastConnection = Hubs.HubHelpers.LastConnectionTime[identity];

                if ((time - lastConnection).TotalMinutes > 30.0)
                {
                    // Do stuff.
                }
            }
        }

        // re-add our task so it recurs
        AddTask(k, Convert.ToInt32(v));
    }