add new AddLibraryNameSuffix API for annotating connections with usage

docs/ReleaseNotes.md

@@ -9,6 +9,7 @@ Current package versions:
 ## Unreleased
 
 - Support `HeartbeatConsistencyChecks` and `HeartbeatInterval` in `Clone()` ([#2658 by mgravell](https://github.com/StackExchange/StackExchange.Redis/pull/2658))
+- Add `AddLibraryNameSuffix` to multiplexer; allows usage-specific tokens to be appended *after connect*
 
 ## 2.7.23
 

src/StackExchange.Redis/ConfigurationOptions.cs

@@ -260,7 +260,7 @@ public bool SetClientLibrary
         /// Gets or sets the library name to use for CLIENT SETINFO lib-name calls to Redis during handshake.
         /// Defaults to "SE.Redis".
         /// </summary>
-        /// <remarks>If the value is null, empty or whitespace, then the value from the options-provideer is used;
+        /// <remarks>If the value is null, empty or whitespace, then the value from the options-provider is used;
         /// to disable the library name feature, use <see cref="SetClientLibrary"/> instead.</remarks>
         public string? LibraryName { get; set; }
 

src/StackExchange.Redis/ConnectionMultiplexer.LibraryName.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Threading;
+
+namespace StackExchange.Redis;
+
+public partial class ConnectionMultiplexer
+{
+    private readonly HashSet<string> _libraryNameSuffixHash = new();
+    private string _libraryNameSuffixCombined = "";
+
+    /// <inheritdoc cref="IConnectionMultiplexer.AddLibraryNameSuffix(string)" />
+    public void AddLibraryNameSuffix(string suffix)
+    {
+        if (string.IsNullOrWhiteSpace(suffix)) return; // trivial
+
+        // sanitize and re-check
+        suffix = ServerEndPoint.ClientInfoSanitize(suffix ?? "").Trim();
+        if (string.IsNullOrWhiteSpace(suffix)) return; // trivial
+
+        lock (_libraryNameSuffixHash)
+        {
+            if (!_libraryNameSuffixHash.Add(suffix)) return; // already cited; nothing to do
+
+            _libraryNameSuffixCombined = "-" + string.Join("-", _libraryNameSuffixHash.OrderBy(_ => _));
+        }
+
+        // if we get here, we *actually changed something*; we can retroactively fixup the connections
+        var libName = GetFullLibraryName(); // note this also checks SetClientLibrary
+        if (string.IsNullOrWhiteSpace(libName) || !CommandMap.IsAvailable(RedisCommand.CLIENT)) return; // disabled on no lib name
+
+        // note that during initial handshake we use raw Message; this is low frequency - no
+        // concern over overhead of Execute here
+        var args = new object[] { RedisLiterals.SETINFO, RedisLiterals.lib_name, libName };
+        foreach (var server in GetServers())
+        {
+            try
+            {
+                // note we can only fixup the *interactive* channel; that's tolerable here
+                if (server.IsConnected)
+                {
+                    // best effort only
+                    server.Execute("CLIENT", args, CommandFlags.FireAndForget);
+                }
+            }
+            catch (Exception ex)
+            {
+                // if an individual server trips, that's fine - best effort; note we're using
+                // F+F here anyway, so we don't *expect* any failures
+                Debug.WriteLine(ex.Message);
+            }
+        }
+    }
+
+    internal string GetFullLibraryName()
+    {
+        var config = RawConfig;
+        if (!config.SetClientLibrary) return ""; // disabled
+
+        var libName = config.LibraryName;
+        if (string.IsNullOrWhiteSpace(libName))
+        {
+            // defer to provider if missing (note re null vs blank; if caller wants to disable
+            // it, they should set SetClientLibrary to false, not set the name to empty string)
+            libName = config.Defaults.LibraryName;
+        }
+
+        libName = ServerEndPoint.ClientInfoSanitize(libName);
+        // if no primary name, return nothing, even if suffixes exist
+        if (string.IsNullOrWhiteSpace(libName)) return "";
+
+        return libName + Volatile.Read(ref _libraryNameSuffixCombined);
+    }
+}

src/StackExchange.Redis/Interfaces/IConnectionMultiplexer.cs

@@ -294,5 +294,13 @@ public interface IConnectionMultiplexer : IDisposable, IAsyncDisposable
         /// <param name="destination">The destination stream to write the export to.</param>
         /// <param name="options">The options to use for this export.</param>
         void ExportConfiguration(Stream destination, ExportOptions options = ExportOptions.All);
+
+        /// <summary>
+        /// Append a usage-specific modifier to the advertised library name; suffixes are de-duplicated
+        /// and sorted alphabetically (so adding 'a', 'b' and 'a' will result in suffix '-a-b').
+        /// Connections will be updated as necessary (RESP2 subscription
+        /// connections will not show updates until those connections next connect).
+        /// </summary>
+        void AddLibraryNameSuffix(string suffix);
     }
 }

src/StackExchange.Redis/PublicAPI/PublicAPI.Shipped.txt

@@ -1845,4 +1845,6 @@ StackExchange.Redis.ResultType.VerbatimString = 12 -> StackExchange.Redis.Result
 static StackExchange.Redis.RedisResult.Create(StackExchange.Redis.RedisResult![]! values, StackExchange.Redis.ResultType resultType) -> StackExchange.Redis.RedisResult!
 static StackExchange.Redis.RedisResult.Create(StackExchange.Redis.RedisValue[]! values, StackExchange.Redis.ResultType resultType) -> StackExchange.Redis.RedisResult!
 virtual StackExchange.Redis.RedisResult.Length.get -> int
-virtual StackExchange.Redis.RedisResult.this[int index].get -> StackExchange.Redis.RedisResult!
+virtual StackExchange.Redis.RedisResult.this[int index].get -> StackExchange.Redis.RedisResult!
+StackExchange.Redis.ConnectionMultiplexer.AddLibraryNameSuffix(string! suffix) -> void
+StackExchange.Redis.IConnectionMultiplexer.AddLibraryNameSuffix(string! suffix) -> void

src/StackExchange.Redis/ServerEndPoint.cs

@@ -930,7 +930,7 @@ private async Task HandshakeAsync(PhysicalConnection connection, ILogger? log)
             var config = Multiplexer.RawConfig;
             string? user = config.User;
             string password = config.Password ?? "";
-            
+
             string clientName = Multiplexer.ClientName;
             if (!string.IsNullOrWhiteSpace(clientName))
             {
@@ -1017,15 +1017,7 @@ private async Task HandshakeAsync(PhysicalConnection connection, ILogger? log)
                     // server version, so we will use this speculatively and hope for the best
                     log?.LogInformation($"{Format.ToString(this)}: Setting client lib/ver");
 
-                    var libName = config.LibraryName;
-                    if (string.IsNullOrWhiteSpace(libName))
-                    {
-                        // defer to provider if missing (note re null vs blank; if caller wants to disable
-                        // it, they should set SetClientLibrary to false, not set the name to empty string)
-                        libName = config.Defaults.LibraryName;
-                    }
-
-                    libName = ClientInfoSanitize(libName);
+                    var libName = Multiplexer.GetFullLibraryName();
                     if (!string.IsNullOrWhiteSpace(libName))
                     {
                         msg = Message.Create(-1, CommandFlags.FireAndForget, RedisCommand.CLIENT,

tests/StackExchange.Redis.Tests/ConfigTests.cs

@@ -279,6 +279,41 @@ public void ClientName()
         Assert.Equal("TestRig", name);
     }
 
+    [Fact]
+    public async Task ClientLibraryName()
+    {
+        using var conn = Create(allowAdmin: true, shared: false);
+        var server = GetAnyPrimary(conn);
+
+        await server.PingAsync();
+        var possibleId = conn.GetConnectionId(server.EndPoint, ConnectionType.Interactive);
+
+        if (possibleId is null)
+        {
+            Log("(client id not available)");
+            return;
+        }
+        var id = possibleId.Value;
+        var libName = server.ClientList().Single(x => x.Id == id).LibraryName;
+        if (libName is not null) // server-version dependent
+        {
+            Log("library name: {0}", libName);
+            Assert.Equal("SE.Redis", libName);
+
+            conn.AddLibraryNameSuffix("foo");
+            conn.AddLibraryNameSuffix("bar");
+            conn.AddLibraryNameSuffix("foo");
+
+            libName = (await server.ClientListAsync()).Single(x => x.Id == id).LibraryName;
+            Log("library name: {0}", libName);
+            Assert.Equal("SE.Redis-bar-foo", libName);
+        }
+        else
+        {
+            Log("(library name not available)");
+        }
+    }
+
     [Fact]
     public void DefaultClientName()
     {

tests/StackExchange.Redis.Tests/Helpers/SharedConnectionFixture.cs

@@ -98,6 +98,8 @@ public bool IgnoreConnect
         public int GetSubscriptionsCount() => _inner.GetSubscriptionsCount();
         public ConcurrentDictionary<RedisChannel, ConnectionMultiplexer.Subscription> GetSubscriptions() => _inner.GetSubscriptions();
 
+        public void AddLibraryNameSuffix(string suffix) => _inner.AddLibraryNameSuffix(suffix);
+
         public string ClientName => _inner.ClientName;
 
         public string Configuration => _inner.Configuration;