WIP: Limit number of datapoints client subscribes to

src/ism7mqtt/ISM7/Ism7Client.cs

@@ -3,6 +3,7 @@
 using System.Buffers.Binary;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Globalization;
 using System.IO;
 using System.IO.Pipelines;
 using System.Linq;
@@ -237,6 +238,35 @@ private static string HexEncode(ReadOnlySpan<byte> data)
             return s.ToString();
         }
 
+        #region Debug
+
+        private static int GetEnvInt32(string name, int defaultValue = default)
+        {
+            var value = Environment.GetEnvironmentVariable(name, EnvironmentVariableTarget.Process);
+            if (value is null) return defaultValue;
+            if (Int32.TryParse(value, NumberStyles.None, CultureInfo.InvariantCulture, out var parsed))
+                return parsed;
+            return defaultValue;
+        }
+
+        private int _subscriptionLimit = -1;
+
+        private int SubscriptionLimit
+        {
+            get
+            {
+                if (_subscriptionLimit < 0)
+                {
+                    _subscriptionLimit = GetEnvInt32("ISM7_SUBSCR_LIMIT");
+                }
+                return _subscriptionLimit;
+            }
+        }
+
+        private int _subscriptionCount;
+
+        #endregion
+
         private async Task SubscribeAsync(string busAddress, CancellationToken cancellationToken)
         {
             var infoReads = _config.GetInfoReadForDevice(busAddress).ToList();
@@ -247,6 +277,20 @@ private async Task SubscribeAsync(string busAddress, CancellationToken cancellat
                 infoRead.BusAddress = busAddress;
                 infoRead.Intervall = Interval;
             }
+            if (SubscriptionLimit > 0)
+            {
+                int remaining = SubscriptionLimit - _subscriptionCount;
+                if (remaining == 0)
+                {
+                    return;
+                }
+                if (remaining < infoReads.Count)
+                {
+                    infoReads = infoReads.Take(remaining).ToList();
+                }
+                _subscriptionCount += infoReads.Count;
+                Console.WriteLine($"Total subscribed infopoints: {_subscriptionCount}");
+            }
             await SendAsync(new TelegramBundleReq
             {
                 AbortOnError = false,

src/ism7mqtt/ISM7/Ism7Config.cs

@@ -91,7 +91,7 @@ public void AddDevice(string ip, string ba)
         public IEnumerable<InfoRead> GetInfoReadForDevice(string ba)
         {
             var devices = _devices[Converter.FromHex(ba)];
-            return devices.SelectMany(x => x.InfoReads);
+            return devices.SelectMany(x => x.InfoReads).DistinctBy(ir => ir.InfoNumber);
         }
 
         public bool ProcessData(IEnumerable<InfonumberReadResp> data)