not having a bridge is no excuse not to complete something; if the bridge is...

not having a bridge is no excuse not to complete something; if the bridge is unavailable, complete things on the shared manager (which will defer to the thread-pool if disposed)

StackExchange.Redis/StackExchange/Redis/CompletionManager.cs

 using System;
-using System.Collections.Generic;
-using System.Text;
 using System.Threading;
 
 namespace StackExchange.Redis
@@ -18,6 +16,14 @@ public CompletionManager(ConnectionMultiplexer multiplexer, string name)
             this.name = name;
         }
 
+        internal static void SharedCompleteSyncOrAsync(ICompletable operation)
+        {
+            if (operation == null) return;
+            if (!operation.TryComplete(false))
+            {
+                SocketManager.Shared.ScheduleTask(s_AnyOrderCompletionHandler, operation);
+            }
+        }
         public void CompleteSyncOrAsync(ICompletable operation)
         {
             if (operation == null) return;

StackExchange.Redis/StackExchange/Redis/PhysicalBridge.cs

@@ -9,6 +9,11 @@
 
 namespace StackExchange.Redis
 {
+    internal static class PhysicalBridgeHelpers
+    {
+        public static void CompleteSyncOrAsync(this PhysicalBridge bridge, ICompletable operation)
+            => PhysicalBridge.CompleteSyncOrAsyncImpl(bridge, operation);
+    }
     internal sealed partial class PhysicalBridge : IDisposable
     {
         internal readonly string Name;
@@ -86,9 +91,11 @@ public long SubscriptionCount
 
         internal long OperationCount => Interlocked.Read(ref operationCount);
 
-        public void CompleteSyncOrAsync(ICompletable operation)
+        internal static void CompleteSyncOrAsyncImpl(PhysicalBridge bridge, ICompletable operation)
         {
-            completionManager.CompleteSyncOrAsync(operation);
+            var manager = bridge?.completionManager;
+            if (manager != null) manager.CompleteSyncOrAsync(operation);
+            else CompletionManager.SharedCompleteSyncOrAsync(operation);
         }
 
         public void Dispose()
@@ -347,7 +354,7 @@ private void AbandonPendingBacklog(Exception ex)
                 if(next != null)
                 {
                     next.SetException(ex);
-                    CompleteSyncOrAsync(next);
+                    this.CompleteSyncOrAsync(next);
                 }
             } while (next != null);
         }
@@ -541,7 +548,7 @@ internal WriteResult WriteMessageTakingWriteLock(PhysicalConnection physical, Me
                             // killed the underlying connection
                             Trace("Unable to write to server");
                             next.Fail(ConnectionFailureType.ProtocolFailure, null, "failure before write: " + result.ToString());
-                            CompleteSyncOrAsync(next);
+                            this.CompleteSyncOrAsync(next);
                             return result;
                         }
                         //The parent message (next) may be returned from GetMessages
@@ -741,7 +748,7 @@ private WriteResult WriteMessageToServerInsideWriteLock(PhysicalConnection conne
             {
                 Trace("Write failed: " + ex.Message);
                 message.Fail(ConnectionFailureType.InternalFailure, ex, null);
-                CompleteSyncOrAsync(message);
+                this.CompleteSyncOrAsync(message);
                 // this failed without actually writing; we're OK with that... unless there's a transaction
 
                 if (connection?.TransactionActive == true)
@@ -756,7 +763,7 @@ private WriteResult WriteMessageToServerInsideWriteLock(PhysicalConnection conne
             {
                 Trace("Write failed: " + ex.Message);
                 message.Fail(ConnectionFailureType.InternalFailure, ex, null);
-                CompleteSyncOrAsync(message);
+                this.CompleteSyncOrAsync(message);
 
                 // we're not sure *what* happened here; probably an IOException; kill the connection
                 connection?.RecordConnectionFailed(ConnectionFailureType.InternalFailure, ex);

StackExchange.Redis/StackExchange/Redis/PhysicalConnection.cs

@@ -377,7 +377,7 @@ void add(string lk, string sk, string v)
                     var next = _writtenAwaitingResponse.Dequeue();
                     BridgeCouldBeNull?.Trace("Failing: " + next);
                     next.SetException(innerException is RedisException ? innerException : outerException);
-                    BridgeCouldBeNull?.CompleteSyncOrAsync(next);
+                    BridgeCouldBeNull.CompleteSyncOrAsync(next);
                 }
             }
 
@@ -1229,7 +1229,7 @@ private void MatchResult(RawResult result)
             Trace("Response to: " + msg);
             if (msg.ComputeResult(this, result))
             {
-                BridgeCouldBeNull?.CompleteSyncOrAsync(msg);
+                BridgeCouldBeNull.CompleteSyncOrAsync(msg);
             }
         }
 

StackExchange.Redis/StackExchange/Redis/RedisSubscriber.cs

@@ -86,7 +86,7 @@ internal Task RemoveAllSubscriptions(CommandFlags flags, object asyncState)
                 foreach (var pair in subscriptions)
                 {
                     var msg = pair.Value.ForSyncShutdown();
-                    if(msg != null) UnprocessableCompletionManager?.CompleteSyncOrAsync(msg);
+                    if(msg != null) UnprocessableCompletionManager.CompleteSyncOrAsync(msg);
                     pair.Value.Remove(true, null);
                     pair.Value.Remove(false, null);
 

StackExchange.Redis/StackExchange/Redis/RedisTransaction.cs

@@ -341,7 +341,7 @@ public IEnumerable<Message> GetMessages(PhysicalConnection connection)
                     foreach (var op in InnerOperations)
                     {
                         op.Wrapped.Cancel();
-                        bridge?.CompleteSyncOrAsync(op.Wrapped);
+                        bridge.CompleteSyncOrAsync(op.Wrapped);
                     }
                 }
                 connection.Trace("End of transaction: " + Command);
@@ -387,7 +387,7 @@ public override bool SetResult(PhysicalConnection connection, Message message, R
                     foreach (var op in tran.InnerOperations)
                     {
                         ServerFail(op.Wrapped, error);
-                        bridge?.CompleteSyncOrAsync(op.Wrapped);
+                        bridge.CompleteSyncOrAsync(op.Wrapped);
                     }
                 }
                 return base.SetResult(connection, message, result);
@@ -416,7 +416,7 @@ protected override bool SetResultCore(PhysicalConnection connection, Message mes
                                 foreach (var op in wrapped)
                                 {
                                     op.Wrapped.Cancel();
-                                    bridge?.CompleteSyncOrAsync(op.Wrapped);
+                                    bridge.CompleteSyncOrAsync(op.Wrapped);
                                 }
                                 SetResult(message, false);
                                 return true;
@@ -432,7 +432,7 @@ protected override bool SetResultCore(PhysicalConnection connection, Message mes
                                     foreach (var op in wrapped)
                                     {
                                         op.Wrapped.Cancel();
-                                        bridge?.CompleteSyncOrAsync(op.Wrapped);
+                                        bridge.CompleteSyncOrAsync(op.Wrapped);
                                     }
                                     SetResult(message, false);
                                     return true;
@@ -444,7 +444,7 @@ protected override bool SetResultCore(PhysicalConnection connection, Message mes
                                     {
                                         if (wrapped[i].Wrapped.ComputeResult(connection, arr[i]))
                                         {
-                                            bridge?.CompleteSyncOrAsync(wrapped[i].Wrapped);
+                                            bridge.CompleteSyncOrAsync(wrapped[i].Wrapped);
                                         }
                                     }
                                     SetResult(message, true);