264 lines
9.8 KiB
C#
264 lines
9.8 KiB
C#
//-----------------------------------------------------------------------
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// -----------------------------------------------------------------------
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// file="HLSFAllocator.SegmentEntry"
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// Project: StgSharp
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// AuthorGroup: Nitload
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// Copyright (c) Nitload. All rights reserved.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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//
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// -----------------------------------------------------------------------
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// -----------------------------------------------------------------------
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using System;
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using System.Runtime.CompilerServices;
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using System.Runtime.InteropServices;
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namespace StgSharp.HighPerformance.Memory
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{
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public unsafe partial class HybridLayerSegregatedFitAllocator
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{
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/// <summary>
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/// check out if a bucket is within the same higher-level boundary as currentOffset
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/// </summary>
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/// <param name="currentOffset">
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///
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/// </param>
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/// <param name="target">
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///
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/// </param>
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/// <param name="level">
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///
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/// </param>
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/// <returns>
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///
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/// </returns>
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private bool AssertBackwardBoundary(ulong currentOffset, Entry* target, int level)
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{
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level = int.Min(level, MaxLevel);
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int nextLevelSize = levelSizeArray[level] * 4;
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ulong targetHead = target->Position - (ulong)m_Buffer;
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return (currentOffset / (ulong)nextLevelSize) == (targetHead / (ulong)nextLevelSize);
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}
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/// <summary>
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/// check out if a bucket is within the same higher-level boundary as currentOffset
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/// </summary>
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/// <param name="currentOffset">
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///
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/// </param>
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/// <param name="target">
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///
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/// </param>
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/// <param name="level">
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///
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/// </param>
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/// <returns>
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///
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/// </returns>
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private bool AssertForwardBoundary(ulong currentOffset, Entry* target, int level)
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{
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level = int.Min(level, MaxLevel);
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int nextLevelSize = levelSizeArray[level] * 4;
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ulong targetTail = target->Position - (ulong)m_Buffer + target->Size - 1;
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return (currentOffset / (ulong)nextLevelSize) == (targetTail / (ulong)nextLevelSize);
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}
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/// <summary>
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/// Determine segment index based on size and originLevel
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/// </summary>
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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private int DetermineSegmentIndex(uint size, int level)
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{
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level = int.Min(level, MaxLevel);
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return (int)(size - 1) / levelSizeArray[level];
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}
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/// <summary>
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/// Check if two Entries are adjacent in memory
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/// </summary>
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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private static bool IsAdjacentTo(Entry* current, Entry* other)
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{
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// Check if this immediately follows other
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return other->Position + other->Size == current->Position ||
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current->Position + current->Size == other->Position;
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}
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/// <summary>
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/// Used in Free operations, efficiently remove from buckets and merge adjacent blocks.
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/// Current Entry will serve as the final merged block. The Merge will be in lazy
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/// strategy.
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/// </summary>
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private void MergeAndRemoveFromBuckets(Entry* entry)
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{
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// TODO
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/*
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* 1.有限回收，最多向上收集2层（算上当前总共3层）
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* 2.单层内就可以通过前后链表遍历解决，很容易做到
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* 3.由于SLAB分配器内部包含快速复用路径，因而可以考虑直接进行Free掉被合并的Entry。复用成本很低（因为SLAB既没有Version也没有IEnumerable，所以不会有额外的操作计数损耗）
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* 4.后续提供HLSF.Collect全量整理API，从头遍历邻接块进行彻底的合并
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*/
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if (entry == null)
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{
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return;
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}
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Entry* result = entry;
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uint size = entry->Size;
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int originLevel = entry->Level;
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int segment = DetermineSegmentIndex(size, originLevel);
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// RemoveFromBucket(originLevel, segment, (BucketNode*)entry->Position);
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do
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{
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originLevel = entry->Level;
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while (true)
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{
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// backward merging - simplified to single attempt
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Entry* prev = entry->PreviousNear;
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// compute offset of current block and base position
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ulong currentOffset = entry->Position - (ulong)m_Buffer;
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if (prev != null &&
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prev != _spareMemory &&
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AssertBackwardBoundary(currentOffset, prev, originLevel) &&
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IsAdjacentTo(entry, prev) &&
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TryRemoveFromBucket(originLevel, DetermineSegmentIndex(prev->Size, originLevel), (BucketNode*)prev->Position))
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{
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// Merge
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entry->Position = prev->Position;
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entry->Size += prev->Size;
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RemoveFromPositionChain(prev);
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}
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// Update linked list
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/*
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Entry* prevPrev = prev->PreviousNear;
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if (prevPrev != null) {
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prevPrev->NextNear = entry;
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}
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entry->PreviousNear = prevPrev;
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/**/
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}
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while (true)
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{
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// forward merging - simplified to single attempt
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Entry* next = entry->NextNear;
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ulong currentOffset = entry->Position - (ulong)m_Buffer;
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if (next == null ||
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next == _spareMemory ||
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!AssertForwardBoundary(currentOffset, next, entry->Level) ||
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!IsAdjacentTo(entry, next) ||
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entry->Level != next->Level ||
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!TryRemoveFromBucket(originLevel, DetermineSegmentIndex(next->Size, originLevel), (BucketNode*)next->Position))
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{
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break;
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}
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// Update linked list
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/*
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Entry* nextNext = next->NextNear;
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if (nextNext != null) {
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nextNext->PreviousNear = entry;
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}
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entry->NextNear = nextNext;
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/**/
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// Merge
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entry->Size += next->Size;
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RemoveFromPositionChain(next);
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}
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entry->Level = GetLevelFromSize(entry->Size);
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} while (originLevel < entry->Level);
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}
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/// <summary>
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/// Remove node from position linked list
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/// </summary>
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private void RemoveFromPositionChain(Entry* entry)
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{
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Entry* prev = entry->PreviousNear;
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Entry* next = entry->NextNear;
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if (prev != null) {
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prev->NextNear = entry->NextNear;
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}
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if (next != null) {
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next->PreviousNear = entry->PreviousNear;
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}
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// Clear node pointers
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entry->NextNear = null;
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entry->PreviousNear = null;
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// Console.WriteLine("entry recycled.");
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_entries.Free((nuint)entry);
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}
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/// <summary>
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/// Entry structure - streamlined version (only position and state information) Stored in
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/// external SLAB
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/// </summary>
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[StructLayout(LayoutKind.Explicit, Size = 36)]
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internal struct Entry
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{
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[FieldOffset(8)] internal Entry* NextNear; // Position linked list: next pointer
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[FieldOffset(16)] internal Entry* PreviousNear; // Position linked list: previous pointer
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[FieldOffset(28)] internal int Level; // Level of the block in the allocator
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[FieldOffset(24)] internal uint Size; // Block size information
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[FieldOffset(32)] public EntryState State;
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[FieldOffset(0)] public nuint Position; // Memory block position
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}
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internal enum EntryState : uint
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{
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Spare,
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Empty,
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Allocated
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}
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#region Entry Operations
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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private static bool IsNullOrEmptyEntryIndex(ulong index)
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{
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return index == 0;
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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private static bool IsNullOrEmptyEntryIndex(Entry* entry)
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{
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return entry == null;
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}
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#endregion
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}
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}
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