MulAvailable

StgSharp.Common/HighPerformance/Memory/SlabAllocator.SequencialConcurrent.cs

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+//-----------------------------------------------------------------------
+// -----------------------------------------------------------------------
+// file="SlabAllocator.SequencialConcurrent"
+// Project: StgSharp
+// AuthorGroup: Nitload
+// Copyright (c) Nitload. All rights reserved.
+//     
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+//     
+// -----------------------------------------------------------------------
+// -----------------------------------------------------------------------
+using StgSharp.Threading;
+
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using System.Threading;
+
+namespace StgSharp.HighPerformance.Memory
+{
+    public sealed unsafe class ConcurrentSequentialSlabAllocator<T> : SlabAllocator<T> where T: unmanaged
+    {
+
+        private T* _buffer;
+
+        private readonly BufferExpansionLock _lock = new();
+        private readonly ConcurrentBufferStack<nuint> _stack;
+        private readonly int _elementSize;
+        private nuint _highestAllocated;
+        private ulong _capacity;
+
+        public ConcurrentSequentialSlabAllocator(nuint initialCapacity)
+        {
+            _elementSize = Unsafe.SizeOf<T>();
+            _capacity = initialCapacity;
+            _highestAllocated = 0;
+
+            _buffer = (T*)NativeMemory.Alloc((nuint)_capacity * (nuint)_elementSize);
+            int initCount = _capacity switch
+            {
+                <= 4 => 4,
+                > 64 => 64,
+                _ => (int)_capacity / 4
+            };
+            Span<nuint> span = stackalloc nuint[initCount];
+            for (int i = 0; i < initCount; i++) {
+                span[i] = (nuint)i;
+            }
+            _stack = BufferStackBuilder.CreateConcurrent(span);
+            _highestAllocated += (nuint)initCount;
+        }
+
+        internal T* BasePointer
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get => _buffer;
+        }
+
+        public override nuint Allocate()
+        {
+            if (_stack.TryPop(out nuint index)) {
+                return index;
+            }
+            while (true)
+            {
+                index = Volatile.Read(ref _highestAllocated);
+                _lock.EnterMetaDataRead();
+                try
+                {
+                    if (index >= _capacity)
+                    {
+                        _lock.ExitMetaDataRead();
+                        _lock.EnterExpansionProcess();
+                        try
+                        {
+                            _capacity = Volatile.Read(ref _capacity) * 2;
+                            nuint newSize = (nuint)_capacity * (nuint)_elementSize;
+                            _lock.EnterBufferCopy();
+                            try
+                            {
+                                _buffer = (T*)NativeMemory.Realloc(_buffer, newSize);
+                            }
+                            finally
+                            {
+                                _lock.ExitBufferCopy();
+                            }
+                        }
+                        finally
+                        {
+                            _lock.ExitExpansionProcess();
+                        }
+                    }
+                    _ = Interlocked.Increment(ref Unsafe.As<nuint, ulong>(ref _highestAllocated));
+                    return index;
+                }
+                finally
+                {
+                    if (_lock.IsThreadReadingMetaData) {
+                        _lock.ExitMetaDataRead();
+                    }
+                }
+            }
+        }
+
+        public override void Dispose()
+        {
+            _stack.Dispose();
+            NativeMemory.Free(_buffer);
+            _lock.Dispose();
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public override void EnterBufferReading()
+        {
+            _lock.EnterBufferRead();
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public override void ExitBufferReading()
+        {
+            _lock.ExitBufferRead();
+        }
+
+        public override void Free(nuint index)
+        {
+            _stack.Push(index);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public override SlabAllocationHandle<T> ReadAllocation()
+        {
+            EnterBufferReading();
+            return new SlabAllocationHandle<T>(this, true);
+        }
+
+        ~ConcurrentSequentialSlabAllocator()
+        {
+            Dispose();
+        }
+
+    }
+}