imported signalr 1.1.3 into NzbDrone.

src/Microsoft.AspNet.SignalR.Core/Infrastructure/AckHandler.cs

@@ -0,0 +1,112 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.md in the project root for license information.
+
+using System;
+using System.Collections.Concurrent;
+using System.Diagnostics.CodeAnalysis;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNet.SignalR.Infrastructure
+{
+    public class AckHandler : IAckHandler, IDisposable
+    {
+        private readonly ConcurrentDictionary<string, AckInfo> _acks = new ConcurrentDictionary<string, AckInfo>();
+
+        // REVIEW: Consider making this pluggable
+        private readonly TimeSpan _ackThreshold;
+
+        // REVIEW: Consider moving this logic to the transport heartbeat
+        private Timer _timer;
+
+        public AckHandler()
+            : this(completeAcksOnTimeout: true,
+                   ackThreshold: TimeSpan.FromSeconds(30),
+                   ackInterval: TimeSpan.FromSeconds(5))
+        {
+        }
+
+        [SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Acks", Justification = "Ack is a well known term")]
+        public AckHandler(bool completeAcksOnTimeout, TimeSpan ackThreshold, TimeSpan ackInterval)
+        {
+            if (completeAcksOnTimeout)
+            {
+                _timer = new Timer(_ => CheckAcks(), state: null, dueTime: ackInterval, period: ackInterval);
+            }
+
+            _ackThreshold = ackThreshold;
+        }
+
+        public Task CreateAck(string id)
+        {
+            return _acks.GetOrAdd(id, _ => new AckInfo()).Tcs.Task;
+        }
+
+        public bool TriggerAck(string id)
+        {
+            AckInfo info;
+            if (_acks.TryRemove(id, out info))
+            {
+                info.Tcs.TrySetResult(null);
+                return true;
+            }
+
+            return false;
+        }
+
+        private void CheckAcks()
+        {
+            foreach (var pair in _acks)
+            {
+                TimeSpan elapsed = DateTime.UtcNow - pair.Value.Created;
+                if (elapsed > _ackThreshold)
+                {
+                    AckInfo info;
+                    if (_acks.TryRemove(pair.Key, out info))
+                    {
+                        // If we have a pending ack for longer than the threshold
+                        // cancel it.
+                        info.Tcs.TrySetCanceled();
+                    }
+                }
+            }
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                if (_timer != null)
+                {
+                    _timer.Dispose();
+                }
+
+                // Trip all pending acks
+                foreach (var pair in _acks)
+                {
+                    AckInfo info;
+                    if (_acks.TryRemove(pair.Key, out info))
+                    {
+                        info.Tcs.TrySetCanceled();
+                    }
+                }
+            }
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+        }
+
+        private class AckInfo
+        {
+            public TaskCompletionSource<object> Tcs { get; private set; }
+            public DateTime Created { get; private set; }
+
+            public AckInfo()
+            {
+                Tcs = new TaskCompletionSource<object>();
+                Created = DateTime.UtcNow;
+            }
+        }
+    }
+}