Merge pull request #245 from hulkhan22/fix/duplicate-ids-during-inventory-lootgen

fix: Ensure unique MongoIDs

Libraries/SPTarkov.Server.Core/Utils/HashUtil.cs

@@ -28,7 +28,7 @@ public partial class HashUtil(RandomUtil _randomUtil)
         objectId[3] = (byte) timestamp;
 
         // Random value (5 bytes)
-        _randomUtil.Random.NextBytes(objectId.Slice(4, 5));
+        _randomUtil.NextBytes(objectId.Slice(4, 5));
 
         // Incrementing counter (3 bytes)
         // 24-bit counter

Libraries/SPTarkov.Server.Core/Utils/RandomUtil.cs

@@ -35,7 +35,7 @@ public class RandomUtil(ISptLogger<RandomUtil> _logger, ICloner _cloner)
             max -= 1;
         }
 
-        return max > min ? Random.Next(min, exclusive ? max : max + 1) : min;
+        return max > min ? Random.Shared.Next(min, exclusive ? max : max + 1) : min;
     }
 
     /// <summary>
@@ -64,6 +64,11 @@ public class RandomUtil(ISptLogger<RandomUtil> _logger, ICloner _cloner)
         return Random.Next(0, 2) == 1;
     }
 
+    public void NextBytes(Span<byte> bytes)
+    {
+        Random.Shared.NextBytes(bytes);
+    }
+
     /// <summary>
     ///     Calculates the percentage of a given number and returns the result.
     /// </summary>

UnitTests/Tests/Utils/HashUtilTests.cs

@@ -1,3 +1,5 @@
+using System.Collections.Concurrent;
+using System.Diagnostics;
 using SPTarkov.Server.Core.Utils;
 using SPTarkov.Server.Core.Utils.Cloners;
 using UnitTests.Mock;
@@ -63,4 +65,30 @@ public class HashUtilTests
             failMessage
         );
     }
+
+    [TestMethod]
+    public void MultiThreadedMongoIDGenerationTest()
+    {
+        var concurrentBag = new ConcurrentBag<string>();
+        var random = new Random();
+        var stopwatch = new Stopwatch();
+        stopwatch.Start();
+
+        Parallel.For(0, 1000, i =>
+        {
+            Thread.Sleep(random.Next(0, 10));
+            var mongoId = _hashUtil.Generate();
+            concurrentBag.Add(mongoId);
+        });
+
+        stopwatch.Stop();
+        Console.WriteLine($"Elapsed time: {stopwatch.ElapsedMilliseconds} ms");
+        var uniqueCount = concurrentBag.Distinct().Count();
+        var totalCount = concurrentBag.Count;
+        Assert.AreEqual(
+            totalCount,
+            uniqueCount,
+            $"Expected all generated MongoId's to be unique, but found {totalCount - uniqueCount} duplicates."
+        );
+    }
 }