Support multi-DB cluster usage on valkey (#3040)

* - propose new API to resolve product variant; only handles Redis, Valkey and Garnet at the moment

* - change the test-server to support multi-DB operations
- update the client to use the product-variant info to allow multi-DB operations on Valkey
- unit test with the toy-server

* naming is hard

* release notes

Author: mgravell

docs/ReleaseNotes.md

@@ -8,6 +8,8 @@ Current package versions:
 
 ## Unreleased
 
+- Add `IServer.GetProductVariant` to detect the product variant and version of the connected server, and use that internally
+  to enable multi-DB operations on Valkey clusters ([#3040 by @mgravell](https://github.com/StackExchange/StackExchange.Redis/pull/3040))
 - Ignore cluster nodes with the `handshake` flag ([#3043 by @TimLovellSmith](https://github.com/StackExchange/StackExchange.Redis/pull/3043))
 
 ## 2.12.4

src/StackExchange.Redis/AutoConfigureInfoField.cs

@@ -0,0 +1,49 @@
+using System;
+using RESPite;
+
+namespace StackExchange.Redis;
+
+/// <summary>
+/// Fields that can appear in INFO output during auto-configuration.
+/// </summary>
+internal enum AutoConfigureInfoField
+{
+    /// <summary>
+    /// Unknown or unrecognized field.
+    /// </summary>
+    [AsciiHash("")]
+    Unknown = 0,
+
+    [AsciiHash("role")]
+    Role,
+
+    [AsciiHash("master_host")]
+    MasterHost,
+
+    [AsciiHash("master_port")]
+    MasterPort,
+
+    [AsciiHash("redis_version")]
+    RedisVersion,
+
+    [AsciiHash("redis_mode")]
+    RedisMode,
+
+    [AsciiHash("run_id")]
+    RunId,
+
+    [AsciiHash("garnet_version")]
+    GarnetVersion,
+
+    [AsciiHash("valkey_version")]
+    ValkeyVersion,
+}
+
+/// <summary>
+/// Metadata and parsing methods for <see cref="AutoConfigureInfoField"/>.
+/// </summary>
+internal static partial class AutoConfigureInfoFieldMetadata
+{
+    [AsciiHash]
+    internal static partial bool TryParse(ReadOnlySpan<char> value, out AutoConfigureInfoField field);
+}

src/StackExchange.Redis/Enums/ProductVariant.cs

@@ -0,0 +1,28 @@
+// ReSharper disable once CheckNamespace
+namespace StackExchange.Redis;
+
+/// <summary>
+/// Indicates the flavor of RESP-server being used, if known. Unknown variants will be reported as <see cref="Redis"/>.
+/// Inclusion (or omission) in this list does not imply support for any given variant; nor does it indicate any specific
+/// relationship with the vendor or rights to use the name. It is provided solely for informational purposes. Identification
+/// is not guaranteed, and is based on the server's self-reporting (typically via `INFO`), which may be incomplete or misleading.
+/// </summary>
+public enum ProductVariant
+{
+    /// <summary>
+    /// The original Redis server. This is also the default value if the variant is unknown.
+    /// </summary>
+    Redis,
+
+    /// <summary>
+    /// <a href="https://valkey.io/">Valkey</a> is a fork of open-source Redis associated with AWS.
+    /// </summary>
+    Valkey,
+
+    /// <summary>
+    /// <a href="https://microsoft.github.io/garnet/">Garnet</a> is a Redis-compatible server from Microsoft.
+    /// </summary>
+    Garnet,
+
+    // if you want to add another variant here, please open an issue with the details (variant name, INFO output, etc.)
+}

src/StackExchange.Redis/Enums/ServerType.cs

@@ -1,4 +1,7 @@
-namespace StackExchange.Redis
+using System;
+using RESPite;
+
+namespace StackExchange.Redis
 {
     /// <summary>
     /// Indicates the flavor of a particular redis server.
@@ -8,29 +11,50 @@ public enum ServerType
         /// <summary>
         /// Classic redis-server server.
         /// </summary>
+        [AsciiHash("standalone")]
         Standalone,
 
         /// <summary>
         /// Monitoring/configuration redis-sentinel server.
         /// </summary>
+        [AsciiHash("sentinel")]
         Sentinel,
 
         /// <summary>
         /// Distributed redis-cluster server.
         /// </summary>
+        [AsciiHash("cluster")]
         Cluster,
 
         /// <summary>
         /// Distributed redis installation via <a href="https://github.com/twitter/twemproxy">twemproxy</a>.
         /// </summary>
+        [AsciiHash("")]
         Twemproxy,
 
         /// <summary>
         /// Redis cluster via <a href="https://github.com/envoyproxy/envoy">envoyproxy</a>.
         /// </summary>
+        [AsciiHash("")]
         Envoyproxy,
     }
 
+    /// <summary>
+    /// Metadata and parsing methods for <see cref="ServerType"/>.
+    /// </summary>
+    internal static partial class ServerTypeMetadata
+    {
+        [AsciiHash]
+        internal static partial bool TryParse(ReadOnlySpan<char> value, out ServerType serverType);
+
+        internal static bool TryParse(string? val, out ServerType serverType)
+        {
+            if (val is not null) return TryParse(val.AsSpan().Trim(), out serverType);
+            serverType = default;
+            return false;
+        }
+    }
+
     internal static class ServerTypeExtensions
     {
         /// <summary>

src/StackExchange.Redis/Format.cs

@@ -583,14 +583,8 @@ internal static bool TryParseVersion(ReadOnlySpan<char> input, [NotNullWhen(true
                 version = null;
                 return false;
             }
-            unsafe
-            {
-                fixed (char* ptr = input)
-                {
-                    string s = new(ptr, 0, input.Length);
-                    return TryParseVersion(s, out version);
-                }
-            }
+            string s = input.ToString();
+            return TryParseVersion(s, out version);
 #endif
         }
 

src/StackExchange.Redis/Interfaces/IServer.cs

@@ -72,6 +72,12 @@ public partial interface IServer : IRedis
         /// </summary>
         Version Version { get; }
 
+        /// <summary>
+        /// Attempt to identify the specific Redis product variant and version.
+        /// </summary>
+        /// <remarks>Note that it is explicitly not assumed that the version will conform to the <see cref="Version"/> format.</remarks>
+        ProductVariant GetProductVariant(out string version);
+
         /// <summary>
         /// The number of databases supported on this server.
         /// </summary>

src/StackExchange.Redis/KnownRole.cs

@@ -0,0 +1,55 @@
+using System;
+using RESPite;
+
+namespace StackExchange.Redis;
+
+/// <summary>
+/// Known role values used during auto-configuration parsing.
+/// </summary>
+internal enum KnownRole
+{
+    /// <summary>
+    /// Unknown or unrecognized role.
+    /// </summary>
+    [AsciiHash("")]
+    None = 0,
+
+    [AsciiHash("primary")]
+    Primary,
+
+    [AsciiHash("master")]
+    Master,
+
+    [AsciiHash("replica")]
+    Replica,
+
+    [AsciiHash("slave")]
+    Slave,
+}
+
+/// <summary>
+/// Metadata and parsing methods for <see cref="KnownRole"/>.
+/// </summary>
+internal static partial class KnownRoleMetadata
+{
+    [AsciiHash]
+    private static partial bool TryParseCore(ReadOnlySpan<char> value, out KnownRole role);
+
+    internal static bool TryParse(ReadOnlySpan<char> value, out bool isReplica)
+    {
+        if (!TryParseCore(value.Trim(), out var role))
+        {
+            isReplica = false;
+            return false;
+        }
+
+        isReplica = role is KnownRole.Replica or KnownRole.Slave;
+        return true;
+    }
+    internal static bool TryParse(string? val, out bool isReplica)
+    {
+        if (val is not null) return TryParse(val.AsSpan(), out isReplica);
+        isReplica = false;
+        return false;
+    }
+}

src/StackExchange.Redis/PublicAPI/PublicAPI.Unshipped.txt

@@ -1 +1,6 @@
 #nullable enable
+StackExchange.Redis.IServer.GetProductVariant(out string! version) -> StackExchange.Redis.ProductVariant
+StackExchange.Redis.ProductVariant
+StackExchange.Redis.ProductVariant.Garnet = 2 -> StackExchange.Redis.ProductVariant
+StackExchange.Redis.ProductVariant.Redis = 0 -> StackExchange.Redis.ProductVariant
+StackExchange.Redis.ProductVariant.Valkey = 1 -> StackExchange.Redis.ProductVariant

src/StackExchange.Redis/RedisServer.cs

@@ -49,6 +49,8 @@ public bool AllowReplicaWrites
 
         public ServerType ServerType => server.ServerType;
 
+        public ProductVariant GetProductVariant(out string version) => server.GetProductVariant(out version);
+
         public Version Version => server.Version;
 
         public void ClientKill(EndPoint endpoint, CommandFlags flags = CommandFlags.None)