l4 evict and swiss api improve

src/Nitload.Common/HighPerformance/Memory/L4.CacheLine.cs

@@ -71,7 +71,7 @@ namespace Nitload.Common.HighPerformance.Memory
 
             #region buffer
 
-            [FieldOffset(8)] public ulong Position;
+            [FieldOffset(8)] public nuint Position;
             [FieldOffset(16)] public uint SizeMask;
 
             #endregion

src/Nitload.Common/HighPerformance/Memory/L4.Predict.cs

@@ -16,6 +16,10 @@ namespace Nitload.Common.HighPerformance.Memory
     public unsafe partial class L4
     {
 
+        private int _active_line_count;
+
+        private int _last_evict_pos;
+
         internal partial int Predict()
         {
             if (!TryGetCurrentPredictor(out IL4Predictor? p)) {
@@ -23,12 +27,13 @@ namespace Nitload.Common.HighPerformance.Memory
             }
             int total_count = 0, count;
             Span<L4.AddressSource> as_sp = stackalloc L4.AddressSource[4];
+            SwissEnumerator e = _addressMap.GetWriteBufferEnumerator();
             Predict:
             while ((count = p.PredictMission(in as_sp)) > 0)
             {
                 for (int i = 0; i < count; i++)
                 {
-                    if (_addressMap.TryGet(as_sp[i], out ulong map_handle_adr))
+                    if (_addressMap.TryGetWrite(as_sp[i], out ulong map_handle_adr))
                     {
                         L4.CacheLineMetadata* map_handle = (L4.CacheLineMetadata*)map_handle_adr;
                         map_handle->IncreasePredictCount();
@@ -38,13 +43,31 @@ namespace Nitload.Common.HighPerformance.Memory
                         uint size = as_sp[i].Size;
                         int handle_idx = _bufferAllocator.Alloc(size);
                         L4.CacheLineMetadata* handle = _bufferAllocator.MetadataAt(handle_idx);
+                        p.Prefetch(as_sp[i], handle->Position, handle->SizeMask);
                         if (!_addressMap.TryAddOrSet(as_sp[i], (ulong)handle)) {
                             throw new InvalidOperationException();
                         }
+                        _active_line_count++;
+
+                        if (_active_line_count >= MaxActiveCacheLineCount)
+                        {
+                            int retry = 0;
+                            const int max_retry = 3;
+                            for (; retry < max_retry && EvictOnce(ref e); retry++) {
+                                e = _addressMap.GetWriteBufferEnumerator(_last_evict_pos);
+                            }
+                            if (retry >= max_retry) {
+                                throw new OverflowException("Evict failed, maybe all cache lines are in use.");
+                            }
+                            _active_line_count--;
+                        }
                     }
                 }
                 total_count += count;
-                if (total_count >= 2048) {
+                if (total_count >= 2048)
+                {
+                    _ = Interlocked.Add(ref _predict_count, total_count);
+                    _last_evict_pos = e.CurrentOffset;
                     return total_count;
                 }
             }
@@ -53,22 +76,36 @@ namespace Nitload.Common.HighPerformance.Memory
                 _ = TryGetCurrentPredictor(out p);
                 goto Predict;
             }
+            _ = Interlocked.Add(ref _predict_count, total_count);
+            _last_evict_pos = e.CurrentOffset;
             return total_count;
         }
 
+        private bool EvictOnce(
+                     ref SwissEnumerator e
+        )
+        {
+            while (e.MoveNext())
+            {
+                (AddressSource source, ulong cache_head_ptr) = e.Current;
+                L4.CacheLineMetadata* handle = (L4.CacheLineMetadata*)cache_head_ptr;
+                if (Volatile.Read(ref handle->ConsumeCount) == Volatile.Read(ref handle->ConsumeCount))
+                {
+                    // evict
+                    _ = _addressMap.TryRemove(source, out _);
+                    _bufferAllocator.Free(handle);
+                    return true;
+                }
+            }
+            return false;
+        }
+
     }
 }
 
-/*
+// Eviction follow-up:
-goto 本身没问题，但当前控制流有几个需要先确认的点：
+// 1. Compare ConsumeCount with PredictCount; reset both on TLSF slot reuse and count new predictions.
-
+// 2. Fix retry/result handling; decrement _active_line_count only after a successful eviction.
-高：换 predictor 的分支看起来反了。 MoveNextPredictor() 在 _predict 到达 _enter 时返回 true。因此 L4.Predict.cs:51 现在会在队列耗尽时再次取 predictor；TryGetCurrentPredictor 失败后仍 goto Predict，接着会用空的 p 调 PredictMission。反过来，有下一个 predictor 时它会提前返回，不再处理后续 predictor。
+// 3. Correct TLSF reverse-slab pointer validation before freeing metadata pointers.
-
+// 4. Defer TLSF Free until retired published buffers and outstanding handles can no longer reference the line.
-高：新分配的 metadata 没有增加预测计数。 现有映射分支会调用 IncreasePredictCount()，但新分配分支只分配并写入 Swiss。若该计数表示未消费预测数，新条目也需要相同的计数处理；还要确认 TLSF 重用 metadata 时会重置旧计数。
+// 5. Add Swiss TryRemoveAt(offset) to tombstone the enumerated slot without hashing and probing again.
-
-高：同一轮内重复的 AddressSource 可能重复分配。 SwissTable.TryGet 只查 published buffer，而新条目先写入 inactive buffer。后续再次预测相同 key 时会查不到，重新分配 metadata，再由 TryAddOrSet 覆盖先前 value，旧分配就失去映射。
-
-中：需要校验 PredictMission 的返回值范围。 Span 容量是 4；count > 4 会让 as_sp[i] 越界，负值则被当作本轮结束。建议契约明确要求 0..4，并在 L4 边界验证。
-
-本轮未改代码。L4.Predict.cs 的文件诊断通过，但尚未运行完整构建或运行时测试。
-*/

src/Nitload.Common/HighPerformance/Memory/L4.PredictorQueue.cs

@@ -44,8 +44,7 @@ namespace Nitload.Common.HighPerformance.Memory
                         if (ReferenceEquals(predictor, _ring[idx]))
                         {
                             int end = _predict;
-                            for (int move = i; move < end - 1; move++)
+                            for (int move = i; move < end - 1; move++) {
-                            {
                                 _ring[(byte)move] = _ring[(byte)(move + 1)];
                             }
                             _ring[(byte)(end - 1)] = default!;
@@ -64,7 +63,7 @@ namespace Nitload.Common.HighPerformance.Memory
         internal bool MoveNextPredictor()
         {
             int cur = Interlocked.Increment(ref _predict);
-            return cur == _enter;
+            return cur < _enter;
         }
 
         internal void RegistPredictor(
@@ -92,8 +91,8 @@ namespace Nitload.Common.HighPerformance.Memory
             {
                 unchecked
                 {
-                    byte idx = (byte)_consume;
+                    byte idx = (byte)_enter;
-                    _consume++;
+                    _enter++;
                     _ring[idx] = predictor;
                 }
             }

src/Nitload.Common/HighPerformance/Memory/L4.SwissTable.cs

@@ -97,16 +97,18 @@ namespace Nitload.Common.HighPerformance.Memory
         }
 
         internal unsafe struct SwissEnumerator(
-                               byte* buffer
+                               byte* buffer,
+                               int begins_at = 0
         )
         {
 
             private readonly SwissBucket* _buckets = (SwissBucket*)(buffer + IdealCount);
             private readonly Vector128<byte>* _control_bytes = (Vector128<byte>*)buffer;
-            private bool _group_loaded;
+            private bool _group_loaded = false;
-            private int _current_group;
+            private int _visited_group = 0;
-            private int _current_mask;
+            private int _current_group = (begins_at / BucketCapacity) & (GroupCount - 1);
-            private int _current_offset;
+            private int _current_mask = 0;
+            private int _current_offset = 0;
 
             public (AddressSource key, ulong value) Current
             {
@@ -119,9 +121,11 @@ namespace Nitload.Common.HighPerformance.Memory
                 }
             }
 
+            public readonly int CurrentOffset => (_current_group * BucketCapacity) + _current_offset;
+
             public bool MoveNext()
             {
-                while (_current_group < GroupCount)
+                while (_visited_group < GroupCount)
                 {
                     if (!_group_loaded)
                     {
@@ -142,7 +146,8 @@ namespace Nitload.Common.HighPerformance.Memory
                         return true;
                     }
 
-                    _current_group++;
+                    _current_group = (_current_group + 1) & (GroupCount - 1);
+                    _visited_group++;
                     _group_loaded = false;
                 }
                 return false;
@@ -218,6 +223,22 @@ namespace Nitload.Common.HighPerformance.Memory
                 throw new NotImplementedException("The Swiss backend is not implemented for this ISA.");
             }
 
+            /// <summary>
+            ///   Reads the inactive write buffer. The caller must serialize this query with all
+            ///   writes.
+            /// </summary>
+            public bool TryGetWrite(
+                        AddressSource key,
+                        out ulong value
+            )
+            {
+                if (Sse42.IsSupported) {
+                    return SwissReaderX86.TryGet(_buffer_write, key, out value);
+                }
+
+                throw new NotImplementedException("The Swiss backend is not implemented for this ISA.");
+            }
+
             public void TryRehash()
             {
                 if (_delete_count < 2048)
@@ -278,6 +299,14 @@ namespace Nitload.Common.HighPerformance.Memory
                 return new SwissTable(buffers);
             }
 
+            // Enumerates the write buffer; the caller must serialize writers and prevent swaps.
+            internal readonly SwissEnumerator GetWriteBufferEnumerator(
+                                              int begins_at = 0
+            )
+            {
+                return new SwissEnumerator(_buffer_write, begins_at);
+            }
+
             private static void InitializeBuffer(
                                 byte* buffer
             )

src/Nitload.Common/HighPerformance/Memory/L4.Tlsf.cs

@@ -6,6 +6,7 @@
 // -----------------------------------------------------------------------------
 
 using System.Numerics;
+using System.Reflection.Metadata;
 
 namespace Nitload.Common.HighPerformance.Memory
 {
@@ -23,10 +24,10 @@ namespace Nitload.Common.HighPerformance.Memory
         private unsafe struct TLSF
         {
 
-            public const int MaxCacheLineCount = 8192;
+            public const int MaxCacheLineCount = MaxActiveCacheLineCount;
 
             public static readonly nuint RequestedAllocation =
-                    ((nuint)MaxCacheLineCount + 1u) * CacheLineMetadata.SizeOf + CacheLineMetadata.SizeOf - 1u;
+                    (((nuint)MaxCacheLineCount + 1u) * CacheLineMetadata.SizeOf) + CacheLineMetadata.SizeOf - 1u;
             private readonly CacheLineMetadata* _spareMemory;
             private readonly int _align;
             private readonly int _maxLevel;
@@ -62,7 +63,7 @@ namespace Nitload.Common.HighPerformance.Memory
 
                 // init spare memory node
 
-                _spareMemory->Position = _basePtr;
+                _spareMemory->Position = (nuint)(ulong)_basePtr;
                 _spareMemory->SizeMask = _totalSize;
                 _spareMemory->NextLevel = 0;
                 _spareMemory->NextNear = 0;
@@ -119,7 +120,7 @@ namespace Nitload.Common.HighPerformance.Memory
                 node->PreviousNear = 0;
                 node->NextNear = 0;
 
-                node->Position = _basePtr;
+                node->Position = (nuint)(ulong)_basePtr;
                 node->SizeMask = 0;
                 node->State = AllocationState.SpareOrCollect;
                 node->PreviousLevel = 0;
@@ -405,11 +406,13 @@ namespace Nitload.Common.HighPerformance.Memory
             }
 
             public void Free(
-                        int handle,
+                        CacheLineMetadata* head,
                         int collectScanWindow = 4
             )
             {
-                CacheLineMetadata* head = MetadataAt(handle);
+                if (head < _spareMemory || head >= _spareMemory + MaxCacheLineCount) {
+                    throw new ArgumentOutOfRangeException(nameof(head), "Handle is out of range.");
+                }
                 short headIdx = (short)(_spareMemory - head);
                 uint size = head->SizeMask;
                 for (int i = 0; i < collectScanWindow; i++)
@@ -463,6 +466,27 @@ namespace Nitload.Common.HighPerformance.Memory
                 return;
             }
 
+            public void Free(
+                        ulong handle,
+                        int collectScanWindow = 4
+            )
+            {
+                if (handle < (ulong)_basePtr || handle >= (ulong)_basePtr + _totalSize) {
+                    throw new ArgumentOutOfRangeException(nameof(handle), "Handle is out of range.");
+                }
+                CacheLineMetadata* head = (CacheLineMetadata*)handle;
+                Free(head, collectScanWindow);
+            }
+
+            public void Free(
+                        int handle,
+                        int collectScanWindow = 4
+            )
+            {
+                CacheLineMetadata* head = MetadataAt(handle);
+                Free(head, collectScanWindow);
+            }
+
             public bool TryAlloc(
                         uint size,
                         out int h

src/Nitload.Common/HighPerformance/Memory/L4.cs

@@ -12,13 +12,16 @@ namespace Nitload.Common.HighPerformance.Memory
     public sealed unsafe partial class L4 : IDisposable
     {
 
+        private const int MaxActiveCacheLineCount = 8192;
+
         private const nuint PageSize = 4096;
         private const int PredictorRingCapacity = 256;
 
+        private readonly IL4Predictor[] _ring;
+
         private bool _disposed;
         private readonly int _bindedNuma;
         private readonly nuint _baseAddress;
-        private readonly IL4Predictor[] _ring;
         private SwissTable _addressMap;
         private TLSF _bufferAllocator;
 
@@ -76,6 +79,8 @@ namespace Nitload.Common.HighPerformance.Memory
             _bufferAllocator.Free(handle);
         }
 
+        internal partial int Predict();
+
         internal bool TryAllocate(
                       uint size,
                       out int handle
@@ -85,14 +90,15 @@ namespace Nitload.Common.HighPerformance.Memory
             return _bufferAllocator.TryAlloc(size, out handle);
         }
 
-        internal partial int Predict();
+        private static int GetPredictSlowPathCount(
-
+                           int bindedNuma
-        private static int GetPredictSlowPathCount(int bindedNuma)
+        )
         {
             foreach (NumaNode node in Numa.AllNumaNode)
             {
-                if (node.NumaNodeId == (uint)bindedNuma)
+                if (node.NumaNodeId == (uint)bindedNuma) {
                     return checked(node.LogicalCoreCount * 2);
+                }
             }
 
             throw new ArgumentOutOfRangeException(nameof(bindedNuma), "No topology information exists for the bound NUMA node.");

src/Nitload.Common/HighPerformance/Memory/L4Predictor.cs

@@ -22,6 +22,12 @@ namespace Nitload.Common.HighPerformance.Memory
             in Span<L4.AddressSource> RequiredBuffer
         );
 
+        void Prefetch(
+             L4.AddressSource RequiredBuffer,
+             nuint allocBuffer,
+             nuint bufferSize
+        );
+
     }
 
     public interface IL4Predictor<TMission> : IL4Predictor
@@ -32,5 +38,4 @@ namespace Nitload.Common.HighPerformance.Memory
         );
 
     }
-
 }