Fix data race in ProfileExManager (#10388)

* Fix data race in ProfileExManager

Parallel speed tests over many profiles corrupt the save queue of test results: IndexIdEnqueue touches a plain Queue<string> from every test thread, so Contains plus Enqueue race - the same profile gets queued twice, and Queue.Contains can even throw ArgumentOutOfRangeException out of SetTestDelay, losing the result. SaveQueueIndexIds has the same class of bug: it snapshots Count and then dequeues in a loop, so concurrent enqueues throw or lose entries. GetProfileExItem could create duplicate rows for the same index the same way.

Guard the queue and the profile lookup with a lock and drain a snapshot instead of a stale count. No behavior change besides correctness.

* Fix data race in ProfileExManager

Parallel speed tests over many profiles corrupt the save queue of test results: IndexIdEnqueue touches a plain Queue<string> from every test thread, so Contains plus Enqueue race - the same profile gets queued twice, and Queue.Contains can even throw ArgumentOutOfRangeException out of SetTestDelay, losing the result. SaveQueueIndexIds has the same class of bug: it snapshots Count and then dequeues in a loop, so concurrent enqueues throw or lose entries.

Switch the queue to ConcurrentQueue and drain it with TryDequeue. As suggested in review, duplicates are not filtered anymore: this is a helper, and the save loop just writes the same row more than once.

v2rayN/ServiceLib.Tests/Manager/ProfileExManagerConcurrencyTests.cs

@@ -0,0 +1,91 @@
+namespace ServiceLib.Tests.Manager;
+
+public class ProfileExManagerConcurrencyTests
+{
+    [Test]
+    public async Task SetTestDelay_FromManyThreads_ShouldNotThrow()
+    {
+        var manager = CreateManager();
+        var exceptions = new List<Exception>();
+        var threads = Environment.ProcessorCount * 2;
+
+        //Hammer the same manager from several streams at once: the queue is mutated while
+        //other threads keep pushing into it
+        var barrier = new Barrier(threads);
+        Parallel.For(0, threads, t =>
+        {
+            barrier.SignalAndWait();
+            for (var i = 0; i < 5000; i++)
+            {
+                try
+                {
+                    manager.SetTestDelay($"index{i % 500}", i);
+                }
+                catch (Exception ex)
+                {
+                    lock (exceptions)
+                    {
+                        exceptions.Add(ex);
+                    }
+                }
+            }
+        });
+
+        await exceptions.Count.Should().BeEqualTo(0);
+    }
+
+    [Test]
+    public async Task SetTestDelay_FromManyThreads_ShouldNotLoseQueuedIds()
+    {
+        var manager = CreateManager();
+        var ids = 500;
+
+        Parallel.For(0, Environment.ProcessorCount * 2, t =>
+        {
+            for (var i = 0; i < 5000; i++)
+            {
+                manager.SetTestDelay($"id{i % ids}", i);
+            }
+        });
+
+        var drained = Drain(manager);
+        await drained.Count.Should().BeGreaterThanOrEqualTo(ids);
+        await drained.Distinct().Count().Should().BeEqualTo(ids);
+    }
+
+    [Test]
+    public async Task SetTestDelay_ShouldCreateOneEntryPerIndex()
+    {
+        var manager = CreateManager();
+
+        await Parallel.ForEachAsync(Enumerable.Range(0, 500), new ParallelOptions { MaxDegreeOfParallelism = 32 },
+            async (i, ct) =>
+            {
+                manager.SetTestDelay($"same{i % 10}", i);
+                await Task.CompletedTask;
+            });
+
+        var items = await manager.GetProfileExs();
+        await items.Count.Should().BeEqualTo(10);
+        await items.Select(t => t.IndexId).Distinct().Count().Should().BeEqualTo(10);
+    }
+
+    private static ProfileExManager CreateManager()
+    {
+        return (ProfileExManager)Activator.CreateInstance(typeof(ProfileExManager), nonPublic: true)!;
+    }
+
+    private static List<string> Drain(ProfileExManager manager)
+    {
+        var queue = (System.Collections.Concurrent.ConcurrentQueue<string>)typeof(ProfileExManager)
+            .GetField("_queIndexIds", BindingFlags.Instance | BindingFlags.NonPublic)!
+            .GetValue(manager)!;
+
+        var result = new List<string>();
+        while (queue.TryDequeue(out var id))
+        {
+            result.Add(id);
+        }
+        return result;
+    }
+}

v2rayN/ServiceLib/Manager/ProfileExManager.cs

@@ -4,7 +4,7 @@ public class ProfileExManager
 {
     private static readonly Lazy<ProfileExManager> _instance = new(() => new());
     private ConcurrentBag<ProfileExItem> _lstProfileEx = [];
-    private readonly Queue<string> _queIndexIds = new();
+    private readonly ConcurrentQueue<string> _queIndexIds = new();
     public static ProfileExManager Instance => _instance.Value;
     private static readonly string _tag = "ProfileExHandler";
 
@@ -32,24 +32,30 @@ public class ProfileExManager
 
     private void IndexIdEnqueue(string indexId)
     {
-        if (indexId.IsNotEmpty() && !_queIndexIds.Contains(indexId))
+        if (indexId.IsNotEmpty())
         {
+            //Speed tests touch this from many threads; duplicates are harmless here since
+            //the save loop just writes the same row more than once
             _queIndexIds.Enqueue(indexId);
         }
     }
 
     private async Task SaveQueueIndexIds()
     {
-        var cnt = _queIndexIds.Count;
+        var lstIds = new List<string>();
-        if (cnt > 0)
+        while (_queIndexIds.TryDequeue(out var id))
+        {
+            lstIds.Add(id);
+        }
+
+        if (lstIds.Count > 0)
         {
             var lstExists = await SQLiteHelper.Instance.TableAsync<ProfileExItem>().ToListAsync();
             List<ProfileExItem> lstInserts = [];
             List<ProfileExItem> lstUpdates = [];
 
-            for (var i = 0; i < cnt; i++)
+            foreach (var id in lstIds)
             {
-                var id = _queIndexIds.Dequeue();
                 var item = lstExists.FirstOrDefault(t => t.IndexId == id);
                 var itemNew = _lstProfileEx?.FirstOrDefault(t => t.IndexId == id);
                 if (itemNew is null)