Implement #506 - event for a keep-alive being received on a stream

Author: JoshKeegan

Tweetinvi.Core/Core/Streaming/IStreamResultGenerator.cs

@@ -32,6 +32,12 @@ public interface IStreamResultGenerator
         /// </summary>
         event EventHandler<StreamExceptionEventArgs> StreamStopped;
 
+        /// <summary>
+        /// A keep-alive message has been received.
+        /// Twitter sends these every 30s so we know the stream's still working.
+        /// </summary>
+        event EventHandler KeepAliveReceived;
+
         /// <summary>
         /// Get the current state of the stream analysis
         /// </summary>

Tweetinvi.Core/Core/Streaming/ITwitterStream.cs

@@ -29,6 +29,12 @@ public interface ITwitterStream
         /// </summary>
         event EventHandler<StreamExceptionEventArgs> StreamStopped;
 
+        /// <summary>
+        /// A keep-alive message has been received.
+        /// Twitter sends these every 30s so we know the stream's still working.
+        /// </summary>
+        event EventHandler KeepAliveReceived;
+
         /// <summary>
         /// A tweet has been deleted.
         /// </summary>

Tweetinvi.Streams/Helpers/StreamResultGenerator.cs

@@ -21,6 +21,7 @@ public class StreamResultGenerator : IStreamResultGenerator
         public event EventHandler StreamResumed;
         public event EventHandler StreamPaused;
         public event EventHandler<StreamExceptionEventArgs> StreamStopped;
+        public event EventHandler KeepAliveReceived;
 
         private IStreamTask _currentStreamTask;
         private readonly IFactory<IStreamTask> _streamTaskFactory;
@@ -84,6 +85,7 @@ public async Task StartStreamAsync(Func<string, bool> processObject, Func<ITwitt
                 _currentStreamTask = streamTask;
                 _currentStreamTask.StreamStarted += StreamTaskStarted;
                 _currentStreamTask.StreamStateChanged += StreamTaskStateChanged;
+                _currentStreamTask.KeepAliveReceived += KeepAliveReceived;
             }
 #if NET_CORE
             await Task.Run(() =>
@@ -190,6 +192,7 @@ private StreamExceptionEventArgs StopStreamAndUnsubscribeFromEvents()
             {
                 streamTask.StreamStarted -= StreamTaskStarted;
                 streamTask.StreamStateChanged -= StreamTaskStateChanged;
+                streamTask.KeepAliveReceived -= KeepAliveReceived;
                 streamTask.Stop();
 
                 if (_currentStreamTask == streamTask)

Tweetinvi.Streams/StreamTask.cs

@@ -21,6 +21,7 @@ public interface IStreamTask
     {
         event EventHandler StreamStarted;
         event EventHandler<GenericEventArgs<StreamState>> StreamStateChanged;
+        event EventHandler KeepAliveReceived;
 
         StreamState StreamState { get; }
         Exception LastException { get; }
@@ -35,6 +36,7 @@ public class StreamTask : IStreamTask
     {
         public event EventHandler StreamStarted;
         public event EventHandler<GenericEventArgs<StreamState>> StreamStateChanged;
+        public event EventHandler KeepAliveReceived;
 
         // https://dev.twitter.com/streaming/overview/connecting#stalls
         private const int STREAM_DISCONNECTED_DELAY = 90000;
@@ -122,6 +124,7 @@ public void Start()
                     {
                         if (json == string.Empty)
                         {
+                            this.Raise(KeepAliveReceived);
                             continue;
                         }
 

Tweetinvi.Streams/TwitterStream.cs

@@ -91,6 +91,11 @@ public event EventHandler<StreamExceptionEventArgs> StreamStopped
             add { _streamResultGenerator.StreamStopped += value; }
             remove { _streamResultGenerator.StreamStopped -= value; }
         }
+        public event EventHandler KeepAliveReceived
+        {
+            add { _streamResultGenerator.KeepAliveReceived += value; }
+            remove { _streamResultGenerator.KeepAliveReceived -= value; }
+        }
 
         public event EventHandler<TweetDeletedEventArgs> TweetDeleted;
         public event EventHandler<TweetLocationDeletedEventArgs> TweetLocationInfoRemoved;