imported signalr 1.1.3 into NzbDrone.

src/Microsoft.AspNet.SignalR.Core/Configuration/ConfigurationExtensions.cs

@@ -0,0 +1,61 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.md in the project root for license information.
+
+using System;
+
+namespace Microsoft.AspNet.SignalR.Configuration
+{
+    internal static class ConfigurationExtensions
+    {
+        public const int MissedTimeoutsBeforeClientReconnect = 2;
+        public const int HeartBeatsPerKeepAlive = 2;
+        public const int HeartBeatsPerDisconnectTimeout = 6;
+
+        /// <summary>
+        /// The amount of time the client should wait without seeing a keep alive before trying to reconnect.
+        /// </summary>
+        public static TimeSpan? KeepAliveTimeout(this IConfigurationManager config)
+        {
+            if (config.KeepAlive != null)
+            {
+                return TimeSpan.FromTicks(config.KeepAlive.Value.Ticks * MissedTimeoutsBeforeClientReconnect);
+            }
+            else
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// The interval between successively checking connection states.
+        /// </summary>
+        public static TimeSpan HeartbeatInterval(this IConfigurationManager config)
+        {
+            if (config.KeepAlive != null)
+            {
+                return TimeSpan.FromTicks(config.KeepAlive.Value.Ticks / HeartBeatsPerKeepAlive);
+            }
+            else
+            {
+                // If KeepAlives are disabled, have the heartbeat run at the same rate it would if the KeepAlive was
+                // kept at the default value.
+                return TimeSpan.FromTicks(config.DisconnectTimeout.Ticks / HeartBeatsPerDisconnectTimeout);
+            }
+        }
+
+        /// <summary>
+        /// The amount of time a Topic should stay in memory after its last subscriber is removed.
+        /// </summary>
+        /// <param name="config"></param>
+        /// <returns></returns>
+        public static TimeSpan TopicTtl(this IConfigurationManager config)
+        {
+            // If the deep-alive is disabled, don't take it into account when calculating the topic TTL.
+            var keepAliveTimeout = config.KeepAliveTimeout() ?? TimeSpan.Zero;
+
+            // Keep topics alive for twice as long as we let connections to reconnect. (The DisconnectTimeout)
+            // Also add twice the keep-alive timeout since clients might take a while to notice they are disconnected.
+            // This should be a very conservative estimate for how long we must wait before considering a topic dead.
+            return TimeSpan.FromTicks((config.DisconnectTimeout.Ticks + keepAliveTimeout.Ticks) * 2);
+        }
+    }
+}