Redis distributed cache: add HybridCache usage signal

src/Caching/StackExchangeRedis/src/RedisCache.cs

@@ -53,6 +53,8 @@ private static RedisValue[] GetHashFields(bool getData) => getData
     private long _firstErrorTimeTicks;
     private long _previousErrorTimeTicks;
 
+    internal bool HybridCacheActive { get; set; }
+
     // StackExchange.Redis will also be trying to reconnect internally,
     // so limit how often we recreate the ConnectionMultiplexer instance
     // in an attempt to reconnect
@@ -375,6 +377,11 @@ private void TryAddSuffix(IConnectionMultiplexer connection)
         {
             connection.AddLibraryNameSuffix("aspnet");
             connection.AddLibraryNameSuffix("DC");
+
+            if (HybridCacheActive)
+            {
+                connection.AddLibraryNameSuffix("HC");
+            }
         }
         catch (Exception ex)
         {

src/Caching/StackExchangeRedis/src/RedisCacheImpl.cs

@@ -1,20 +1,29 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System;
+using Microsoft.Extensions.Caching.Hybrid;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 
 namespace Microsoft.Extensions.Caching.StackExchangeRedis;
 
 internal sealed class RedisCacheImpl : RedisCache
 {
-    public RedisCacheImpl(IOptions<RedisCacheOptions> optionsAccessor, ILogger<RedisCache> logger)
+    public RedisCacheImpl(IOptions<RedisCacheOptions> optionsAccessor, ILogger<RedisCache> logger, IServiceProvider services)
         : base(optionsAccessor, logger)
     {
+        HybridCacheActive = IsHybridCacheDefined(services);
     }
 
-    public RedisCacheImpl(IOptions<RedisCacheOptions> optionsAccessor)
+    public RedisCacheImpl(IOptions<RedisCacheOptions> optionsAccessor, IServiceProvider services)
         : base(optionsAccessor)
     {
+        HybridCacheActive = IsHybridCacheDefined(services);
     }
+
+    // HybridCache optionally uses IDistributedCache; if we're here, then *we are* the DC
+    private static bool IsHybridCacheDefined(IServiceProvider services)
+        => services.GetService<HybridCache>() is not null;
 }

src/Caching/StackExchangeRedis/test/CacheServiceExtensionsTests.cs

@@ -1,9 +1,15 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System;
+using System.Collections.Generic;
 using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
 using Microsoft.Extensions.Caching.Distributed;
+using Microsoft.Extensions.Caching.Hybrid;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
 using Moq;
@@ -121,4 +127,41 @@ public void AddStackExchangeRedisCache_UsesLoggerFactoryAlreadyRegisteredWithSer
 
         loggerFactory.Verify();
     }
+
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public void AddStackExchangeRedisCache_HybridCacheDetected(bool hybridCacheActive)
+    {
+        // Arrange
+        var services = new ServiceCollection();
+
+        services.AddLogging();
+
+        // Act
+        services.AddStackExchangeRedisCache(options => { });
+        if (hybridCacheActive)
+        {
+            services.TryAddSingleton<HybridCache>(new DummyHybridCache());
+        }
+
+        using var provider = services.BuildServiceProvider();
+        var cache = Assert.IsAssignableFrom<RedisCache>(provider.GetRequiredService<IDistributedCache>());
+        Assert.Equal(hybridCacheActive, cache.HybridCacheActive);
+    }
+
+    sealed class DummyHybridCache : HybridCache
+    {
+        public override ValueTask<T> GetOrCreateAsync<TState, T>(string key, TState state, Func<TState, CancellationToken, ValueTask<T>> factory, HybridCacheEntryOptions options = null, IEnumerable<string> tags = null, CancellationToken cancellationToken = default)
+            => throw new NotSupportedException();
+
+        public override ValueTask RemoveAsync(string key, CancellationToken cancellationToken = default)
+            => throw new NotSupportedException();
+
+        public override ValueTask RemoveByTagAsync(string tag, CancellationToken cancellationToken = default)
+            => throw new NotSupportedException();
+
+        public override ValueTask SetAsync<T>(string key, T value, HybridCacheEntryOptions options = null, IEnumerable<string> tags = null, CancellationToken cancellationToken = default)
+            => throw new NotSupportedException();
+    }
 }