private void StartSubscription(PubnubSubscription subscription)
{
Task.Factory.StartNew(() =>
{
int failureCount = 0;
// check if the subscription still exists in the dictionary
// if not, then end this task, otherwise, repeat.
using (var handle = new System.Threading.ManualResetEventSlim(false))
{
while (_subscriptions.ContainsKey(subscription.Channel))
{
try
{
var url = PubnubRequest.BuildUrl(PubnubConfiguration.EnableSsl,
"subscribe",
PubnubConfiguration.SubscribeKey,
subscription.Channel,
"0",
subscription.TimeToken.ToString(CultureInfo.InvariantCulture));
var request = new PubnubRequest();
string json;
request.Execute(url, out json);
var result = JsonConvert.DeserializeObject<List<object>>(json);
#if DEBUG
System.Diagnostics.Debug.WriteLine(json);
#endif
if (result[0] is JArray && result[0].ToString() != "[]")
{
// loop through each message and fire individually
for (var i = 0; i < ((JArray)result[0]).Count; i++)
{
var message = ((JArray)result[0])[i].ToString();
if (MessageRecieved != null && !string.IsNullOrEmpty(message))
try
{
MessageRecieved(null, new PubNubEventArgs
{
Channel = subscription.Channel,
Message = message
});
}
catch (Exception exp)
{
// adding this try catch because if we have multiple messages and one of
// them encouters an unhandled exception it should not impact the others
// or the subscription time token.
System.Diagnostics.Debug.WriteLine("MessageRecievedException: " + exp.Message);
}
}
}
// update the time token
PubnubSubscription retrievedSubscription;
if (_subscriptions.TryGetValue(subscription.Channel, out retrievedSubscription))
retrievedSubscription.TimeToken = Convert.ToInt64(result[1].ToString());
// reset the failure count
failureCount = 0;
}
catch (Exception exp)
{
System.Diagnostics.Debug.WriteLine("SubscriptionException: " + exp.Message);
failureCount++;
handle.Wait(GetWaitTimeForErrorCount(failureCount));
// rather than throwing the errors, we collect them for
// periodic analysis, the idea is to enhance this with error limits
// and a backoff strategy incase there is a problem with Pubnub
// or the local connection to pubnub
PubnubSubscription retrievedSubscription;
if (_subscriptions.TryGetValue(subscription.Channel, out retrievedSubscription))
retrievedSubscription.Errors.Add(exp);
}
}
}
});
}
/// <summary>
/// Starts a looping subscription request which runs on it's own
/// thread.
/// </summary>
/// <param name="channel"></param>
/// <returns></returns>
public bool Subscribe(string channel)
{
var subscription = new PubnubSubscription
{
Channel = channel,
TimeToken = 0
};
// Add a new one
if (!_subscriptions.TryAdd(channel, subscription))
return false; //Subscription already exists
StartSubscription(subscription);
return true;
}
