Support Alibaba pseudo-cluster configurations (#2646)

* fix #2642 1: don't treat trivial clusters as clusters - Alibaba uses this config 2: report synchronous failures immidiately and accurately * instead of using node count, use explicit tracking of the DB count * release notes
StackExchange · Feb 13, 2024 · 39eac01 · 39eac01
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diff --git a/docs/ReleaseNotes.md b/docs/ReleaseNotes.md
@@ -7,7 +7,8 @@ Current package versions:
 | [![StackExchange.Redis](https://img.shields.io/nuget/v/StackExchange.Redis.svg)](https://www.nuget.org/packages/StackExchange.Redis/) | [![StackExchange.Redis](https://img.shields.io/nuget/vpre/StackExchange.Redis.svg)](https://www.nuget.org/packages/StackExchange.Redis/) | [![StackExchange.Redis MyGet](https://img.shields.io/myget/stackoverflow/vpre/StackExchange.Redis.svg)](https://www.myget.org/feed/stackoverflow/package/nuget/StackExchange.Redis) |
 
 ## Unreleased
-No unreleased changes
+
+- Fix [#2642](https://github.com/StackExchange/StackExchange.Redis/issues/2642): Detect and support multi-DB pseudo-cluster/proxy scenarios ([#2646](https://github.com/StackExchange/StackExchange.Redis/pull/2646) by mgravell)
 
 ## 2.7.17
 

diff --git a/src/StackExchange.Redis/ConnectionMultiplexer.cs b/src/StackExchange.Redis/ConnectionMultiplexer.cs
@@ -1,4 +1,7 @@
-using System;
+using Microsoft.Extensions.Logging;
+using Pipelines.Sockets.Unofficial;
+using StackExchange.Redis.Profiling;
+using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.ComponentModel;
@@ -11,9 +14,6 @@
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.Extensions.Logging;
-using Pipelines.Sockets.Unofficial;
-using StackExchange.Redis.Profiling;
 
 namespace StackExchange.Redis
 {
@@ -2078,19 +2078,22 @@ internal static void ThrowFailed<T>(TaskCompletionSource<T>? source, Exception u
 #pragma warning disable CS0618 // Type or member is obsolete
                     result = TryPushMessageToBridgeSync(message, processor, source, ref server);
 #pragma warning restore CS0618
-                    if (result != WriteResult.Success)
+                    if (!source.IsFaulted) // if we faulted while writing, we don't need to wait
                     {
-                        throw GetException(result, message, server);
-                    }
+                        if (result != WriteResult.Success)
+                        {
+                            throw GetException(result, message, server);
+                        }
 
-                    if (Monitor.Wait(source, TimeoutMilliseconds))
-                    {
-                        Trace("Timely response to " + message);
-                    }
-                    else
-                    {
-                        Trace("Timeout performing " + message);
-                        timeout = true;
+                        if (Monitor.Wait(source, TimeoutMilliseconds))
+                        {
+                            Trace("Timely response to " + message);
+                        }
+                        else
+                        {
+                            Trace("Timeout performing " + message);
+                            timeout = true;
+                        }
                     }
                 }
 

diff --git a/src/StackExchange.Redis/PhysicalConnection.cs b/src/StackExchange.Redis/PhysicalConnection.cs
@@ -95,6 +95,9 @@ public PhysicalConnection(PhysicalBridge bridge)
             OnCreateEcho();
         }
 
+        // *definitely* multi-database; this can help identify some unusual config scenarios
+        internal bool MultiDatabasesOverride { get; set; } // switch to flags-enum if more needed later
+
         internal async Task BeginConnectAsync(ILogger? log)
         {
             var bridge = BridgeCouldBeNull;
@@ -262,6 +265,7 @@ private enum ReadMode : byte
 
         private RedisProtocol _protocol; // note starts at **zero**, not RESP2
         public RedisProtocol? Protocol => _protocol == 0 ? null : _protocol;
+
         internal void SetProtocol(RedisProtocol value) => _protocol = value;
 
         [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2202:Do not dispose objects multiple times")]

diff --git a/src/StackExchange.Redis/ResultProcessor.cs b/src/StackExchange.Redis/ResultProcessor.cs
@@ -929,6 +929,10 @@ protected override bool SetResultCore(PhysicalConnection connection, Message mes
                                     int dbCount = checked((int)i64);
                                     Log?.LogInformation($"{Format.ToString(server)}: Auto-configured (CONFIG) databases: " + dbCount);
                                     server.Databases = dbCount;
+                                    if (dbCount > 1)
+                                    {
+                                        connection.MultiDatabasesOverride = true;
+                                    }
                                 }
                                 else if (key.IsEqual(CommonReplies.slave_read_only) || key.IsEqual(CommonReplies.replica_read_only))
                                 {
@@ -1108,8 +1112,13 @@ protected override bool SetResultCore(PhysicalConnection connection, Message mes
                     case ResultType.BulkString:
                         string nodes = result.GetString()!;
                         var bridge = connection.BridgeCouldBeNull;
-                        if (bridge != null) bridge.ServerEndPoint.ServerType = ServerType.Cluster;
                         var config = Parse(connection, nodes);
+
+                        // re multi-db: https://github.com/StackExchange/StackExchange.Redis/issues/2642
+                        if (bridge != null && !connection.MultiDatabasesOverride)
+                        {
+                            bridge.ServerEndPoint.ServerType = ServerType.Cluster;
+                        }
                         SetResult(message, config);
                         return true;
                 }

diff --git a/src/StackExchange.Redis/ServerEndPoint.cs b/src/StackExchange.Redis/ServerEndPoint.cs
@@ -415,6 +415,10 @@ internal async Task AutoConfigureAsync(PhysicalConnection? connection, ILogger?
                 lastInfoReplicationCheckTicks = Environment.TickCount;
                 if (features.InfoSections)
                 {
+                    // note: Redis 7.0 has a multi-section usage, but we don't know
+                    // the server version at this point; we *could* use the optional
+                    // value on the config, but let's keep things simple: these
+                    // commands are suitably cheap
                     msg = Message.Create(-1, flags, RedisCommand.INFO, RedisLiterals.replication);
                     msg.SetInternalCall();
                     await WriteDirectOrQueueFireAndForgetAsync(connection, msg, autoConfigProcessor).ForAwait();