redis-blog-post-4.cs

public static class DistributedCacheExtensions
{
    public static async Task RemoveWithPrefixAsync(this IDistributedCache cache, string keyPrefix)
    {
        if (cache is RedisCache redisCache)
        {
            ConnectionMultiplexer connection = await redisCache.GetConnectionAsync();
            IDatabase db = connection.GetDatabase();
            foreach (EndPoint? endpoint in connection.GetEndPoints())
            {
                IServer redisServer = connection.GetServer(endpoint);
                List<RedisKey> keys = await redisServer
                    .KeysAsync(pattern: $"{keyPrefix}*")
                    .ToListAsync();
                foreach (RedisKey key in keys)
                {
                    await db.KeyDeleteAsync(key);
                }
            }
        }
        else
        {
            // If another IDistributedCache is registered, we skip the delete.
            // In practice this will only be the "in-memory" implementation which will clear on restarts.
        }
    }

    private static async Task<ConnectionMultiplexer> GetConnectionAsync(this RedisCache cache, CancellationToken cancellationToken = default)
    {
#nullable disable
        // Ensure connection is established
        await (Task)typeof(RedisCache).InvokeMember("ConnectAsync", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.InvokeMethod, null, cache, new object[] { cancellationToken });

        // Get connection multiplexer
        FieldInfo fi = typeof(RedisCache).GetField("_connection", BindingFlags.Instance | BindingFlags.NonPublic);
        return (ConnectionMultiplexer)fi.GetValue(cache);
#nullable disable
    }