add redis for character identification

MareSynchronosServer/MareSynchronosShared/Services/DistributedClientIdentificationService.cs

@@ -0,0 +1,57 @@
+using System.Text;
+using MareSynchronosShared.Metrics;
+using Microsoft.Extensions.Caching.Distributed;
+using Microsoft.Extensions.Configuration;
+using StackExchange.Redis;
+
+namespace MareSynchronosShared.Services;
+
+public class DistributedClientIdentificationService : BaseClientIdentificationService
+{
+    private readonly IDistributedCache distributedCache;
+    private readonly IConfiguration configuration;
+    private const string RedisPrefix = "uidcache:";
+
+    public DistributedClientIdentificationService(MareMetrics metrics, IDistributedCache distributedCache, IConfiguration configuration) : base(metrics)
+    {
+        this.distributedCache = distributedCache;
+        this.configuration = configuration.GetSection("MareSynchronos");
+    }
+
+    public override int GetOnlineUsers()
+    {
+        var redis = configuration.GetValue<string>("RedisConnectionString");
+        var conn = ConnectionMultiplexer.Connect(redis);
+        var endpoint = conn.GetEndPoints().First();
+        return conn.GetServer(endpoint).Keys(pattern: RedisPrefix + "*").Count();
+    }
+
+    public override string? GetCharacterIdentForUid(string uid)
+    {
+        var localIdent = base.GetCharacterIdentForUid(uid);
+        if (localIdent != null) return localIdent;
+        var cachedIdent = distributedCache.Get(RedisPrefix + uid);
+        return cachedIdent == null ? null : Encoding.UTF8.GetString(cachedIdent);
+    }
+
+    public override void MarkUserOffline(string uid)
+    {
+        base.MarkUserOffline(uid);
+        distributedCache.Remove(RedisPrefix + uid);
+    }
+
+    public override void MarkUserOnline(string uid, string charaIdent)
+    {
+        base.MarkUserOnline(uid, charaIdent);
+        distributedCache.Set(RedisPrefix + uid, Encoding.UTF8.GetBytes(charaIdent));
+    }
+
+    public override Task StopAsync(CancellationToken cancellationToken)
+    {
+        foreach (var uid in OnlineClients)
+        {
+            distributedCache.Remove(RedisPrefix + uid.Key);
+        }
+        return base.StopAsync(cancellationToken);
+    }
+}