Add VisibilityService to improve tick performance with many online pairs

MareSynchronos/Services/VisibilityService.cs

@@ -0,0 +1,51 @@
+using MareSynchronos.Services.Mediator;
+using Microsoft.Extensions.Logging;
+using System.Collections.Concurrent;
+
+namespace MareSynchronos.Services;
+
+// Detect when players of interest are visible
+public class VisibilityService : DisposableMediatorSubscriberBase
+{
+    private readonly DalamudUtilService _dalamudUtil;
+    private ConcurrentDictionary<string, bool> _trackedPlayerVisibility = new();
+    private ConcurrentQueue<string> _removedPlayerMessageQueue = new();
+
+    public VisibilityService(ILogger<PairAnalyzer> logger, MareMediator mediator, DalamudUtilService dalamudUtil)
+        : base(logger, mediator)
+    {
+        _dalamudUtil = dalamudUtil;
+        Mediator.Subscribe<FrameworkUpdateMessage>(this, (_) => FrameworkUpdate());
+    }
+
+    public void StartTracking(string ident)
+    {
+        _trackedPlayerVisibility.TryAdd(ident, false);
+    }
+
+    public void StopTracking(string ident)
+    {
+        // No PairVisibilityMessage is emitted if the player was visible when removed
+        _trackedPlayerVisibility.TryRemove(ident, out _);
+    }
+
+    private void FrameworkUpdate()
+    {
+        foreach (var player in _trackedPlayerVisibility)
+        {
+            string ident = player.Key;
+            var findResult = _dalamudUtil.FindPlayerByNameHash(ident);
+
+            if (!player.Value && findResult.ObjectId != 0)
+            {
+                if (_trackedPlayerVisibility.TryUpdate(ident, newValue: true, comparisonValue: false))
+                    Mediator.Publish<PlayerVisibilityMessage>(new(ident, IsVisible: true));
+            }
+            else if (player.Value && findResult.ObjectId == 0)
+            {
+                if (_trackedPlayerVisibility.TryUpdate(ident, newValue: false, comparisonValue: true))
+                    Mediator.Publish<PlayerVisibilityMessage>(new(ident, IsVisible: false));
+            }
+        }
+    }
+}