remove allocations to keep style of surrounding code

Author: datwelk

.vscode/settings.json

@@ -11,5 +11,6 @@
     "MD025": {
       "front_matter_title": ""
     }
-  }
+  },
+  "cmake.sourceDirectory": "/Users/datwelk/Dev/LIVEOP/aspnetcore/node_modules/bare-fs"
 }

src/SignalR/server/Core/src/DefaultHubLifetimeManager.cs

@@ -225,8 +225,8 @@ public override Task SendGroupAsync(string groupName, string methodName, object?
     public override Task SendGroupsAsync(IReadOnlyList<string> groupNames, string methodName, object?[] args, CancellationToken cancellationToken = default)
     {
         // Each task represents the list of tasks for each of the writes within a group
-        List<Task>? tasks = new List<Task>();
-        var connections = new HashSet<string>();
+        List<Task>? tasks = null;
+        HashSet<string>? connections = null;
 
         foreach (var groupName in groupNames)
         {
@@ -240,14 +240,25 @@ public override Task SendGroupsAsync(IReadOnlyList<string> groupNames, string me
             {
                 foreach (var connection in group)
                 {
+                    if (connections == null)
+                    {
+                        connections = new HashSet<string>();
+                    }
                     connections.Add(connection.Key);
                 }
             }
         }
 
-        foreach (var connectionId in connections)
+        if (connections != null)
         {
-            tasks.Add(SendConnectionAsync(connectionId, methodName, args, cancellationToken));
+            foreach (var connectionId in connections)
+            {
+                if (tasks == null)
+                {
+                    tasks = new List<Task>();
+                }
+                tasks.Add(SendConnectionAsync(connectionId, methodName, args, cancellationToken));
+            }
         }
 
         if (tasks != null)

src/SignalR/server/StackExchangeRedis/src/RedisHubLifetimeManager.cs

@@ -257,7 +257,7 @@ public override Task SendConnectionsAsync(IReadOnlyList<string> connectionIds, s
     public override async Task SendGroupsAsync(IReadOnlyList<string> groupNames, string methodName, object?[] args, CancellationToken cancellationToken = default)
     {
         ArgumentNullException.ThrowIfNull(groupNames);
-        var connections = new HashSet<string>();
+        HashSet<string>? connections = null;
 
         foreach (var groupName in groupNames)
         {
@@ -271,14 +271,21 @@ public override async Task SendGroupsAsync(IReadOnlyList<string> groupNames, str
                     {
                         foreach (var connection in connectionStore)
                         {
+                            if (connections == null)
+                            {
+                                connections = new HashSet<string>();
+                            }
                             connections.Add(connection.ConnectionId);
                         }
                     }
                 }
             }
         }
 
-        await SendConnectionsAsync(connections.ToList(), methodName, args, cancellationToken);
+        if (connections != null)
+        {
+            await SendConnectionsAsync(connections.ToList(), methodName, args, cancellationToken);
+        }
     }
 
     /// <inheritdoc />