From 9c10b89fa83220194c8814043ef7b662aaee656c Mon Sep 17 00:00:00 2001
From: David Fowler <davidfowl@gmail.com>
Date: Fri, 4 Nov 2016 01:50:55 -0700
Subject: [PATCH] Small tweaks to sample - Fix redis issues with removing while
 - Use string interpolation in the Chat hub

---
 samples/SocketsSample/Hubs/Chat.cs            | 12 ++++++------
 .../RedisHubLifetimeManager.cs                | 19 ++++++++++++++++---
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/samples/SocketsSample/Hubs/Chat.cs b/samples/SocketsSample/Hubs/Chat.cs
index 0d05dcde30..8ca2ba3ac3 100644
--- a/samples/SocketsSample/Hubs/Chat.cs
+++ b/samples/SocketsSample/Hubs/Chat.cs
@@ -8,27 +8,27 @@ namespace SocketsSample.Hubs
     {
         public override async Task OnConnectedAsync()
         {
-            await Clients.All.InvokeAsync("Send", Context.Connection.ConnectionId + " joined");
+            await Clients.All.InvokeAsync("Send", $"{Context.Connection.ConnectionId} joined");
         }
 
         public override async Task OnDisconnectedAsync()
         {
-            await Clients.All.InvokeAsync("Send", Context.Connection.ConnectionId + " left");
+            await Clients.All.InvokeAsync("Send", $"{Context.Connection.ConnectionId} left");
         }
 
         public Task Send(string message)
         {
-            return Clients.All.InvokeAsync("Send", Context.ConnectionId + ": " + message);
+            return Clients.All.InvokeAsync("Send", $"{Context.ConnectionId}: {message}");
         }
 
         public Task SendToGroup(string groupName, string message)
         {
-            return Clients.Group(groupName).InvokeAsync("Send", Context.ConnectionId + ": " + message);
+            return Clients.Group(groupName).InvokeAsync("Send", $"{Context.ConnectionId}@{groupName}: {message}");
         }
 
         public async Task JoinGroup(string groupName)
         {
-            await Clients.Group(groupName).InvokeAsync("Send", Context.Connection.ConnectionId + " joined " + groupName);
+            await Clients.Group(groupName).InvokeAsync("Send", $"{Context.Connection.ConnectionId} joined {groupName}");
 
             await Groups.AddAsync(groupName);
         }
@@ -37,7 +37,7 @@ namespace SocketsSample.Hubs
         {
             await Groups.RemoveAsync(groupName);
 
-            await Clients.Group(groupName).InvokeAsync("Send", Context.Connection.ConnectionId + " left " + groupName);
+            await Clients.Group(groupName).InvokeAsync("Send", $"{Context.Connection.ConnectionId} left {groupName}");
         }
     }
 }
diff --git a/src/Microsoft.AspNetCore.SignalR.Redis/RedisHubLifetimeManager.cs b/src/Microsoft.AspNetCore.SignalR.Redis/RedisHubLifetimeManager.cs
index 07eb67c0fb..8df2468090 100644
--- a/src/Microsoft.AspNetCore.SignalR.Redis/RedisHubLifetimeManager.cs
+++ b/src/Microsoft.AspNetCore.SignalR.Redis/RedisHubLifetimeManager.cs
@@ -2,6 +2,7 @@
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
@@ -170,7 +171,9 @@ namespace Microsoft.AspNetCore.SignalR.Redis
 
             if (groupNames != null)
             {
-                foreach (var group in groupNames)
+                // Copy the groups to an array here because they get removed from this collection
+                // in RemoveGroupAsync
+                foreach (var group in groupNames.ToArray())
                 {
                     tasks.Add(RemoveGroupAsync(connection, group));
                 }
@@ -184,7 +187,11 @@ namespace Microsoft.AspNetCore.SignalR.Redis
             var groupChannel = typeof(THub).FullName + "." + groupName;
 
             var groupNames = connection.Metadata.GetOrAdd("group", _ => new HashSet<string>());
-            groupNames.Add(groupName);
+
+            lock (groupNames)
+            {
+                groupNames.Add(groupName);
+            }
 
             var group = _groups.GetOrAdd(groupChannel, _ => new GroupData());
 
@@ -234,7 +241,13 @@ namespace Microsoft.AspNetCore.SignalR.Redis
             }
 
             var groupNames = connection.Metadata.Get<HashSet<string>>("group");
-            groupNames?.Remove(groupName);
+            if (groupNames != null)
+            {
+                lock (groupNames)
+                {
+                    groupNames.Remove(groupName);
+                }
+            }
 
             await group.Lock.WaitAsync();
             try