373 lines
16 KiB
C#
373 lines
16 KiB
C#
using AOT;
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using System;
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using System.Threading;
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using Unity.Burst;
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using Unity.Collections.LowLevel.Unsafe;
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using Unity.Jobs.LowLevel.Unsafe;
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using Unity.Mathematics;
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namespace Unity.Collections
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{
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struct Spinner
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{
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int m_value;
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public void Lock()
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{
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while (0 != Interlocked.CompareExchange(ref m_value, 1, 0))
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{
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}
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Interlocked.MemoryBarrier();
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}
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public void Unlock()
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{
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Interlocked.MemoryBarrier();
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while (1 != Interlocked.CompareExchange(ref m_value, 0, 1))
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{
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}
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}
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}
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internal struct UnmanagedArray<T> : IDisposable where T : unmanaged
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{
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IntPtr m_pointer;
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int m_length;
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AllocatorManager.AllocatorHandle m_allocator;
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public UnmanagedArray(int length, AllocatorManager.AllocatorHandle allocator)
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{
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unsafe
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{
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m_pointer = (IntPtr)Memory.Unmanaged.Array.Allocate<T>(length, allocator);
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}
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m_length = length;
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m_allocator = allocator;
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}
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public void Dispose()
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{
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unsafe
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{
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Memory.Unmanaged.Free((T*)m_pointer, Allocator.Persistent);
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}
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}
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public unsafe T* GetUnsafePointer()
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{
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return (T*)m_pointer;
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}
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public ref T this[int index]
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{
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get { unsafe { return ref ((T*)m_pointer)[index]; } }
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}
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}
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/// <summary>
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/// An allocator that is fast like a linear allocator, is threadsafe, and automatically invalidates
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/// all allocations made from it, when "rewound" by the user.
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/// </summary>
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[BurstCompile]
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public struct RewindableAllocator : AllocatorManager.IAllocator
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{
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[BurstCompatible]
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internal unsafe struct MemoryBlock : IDisposable
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{
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public const int kMaximumAlignment = 16384; // can't align any coarser than this many bytes
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public byte* m_pointer; // pointer to contiguous memory
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public long m_bytes; // how many bytes of contiguous memory it points to
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public long m_current; // next byte to give out, when people "allocate" from this block
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public long m_allocations; // how many allocations have been made from this block, so far?
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public MemoryBlock(long bytes)
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{
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m_pointer = (byte*)Memory.Unmanaged.Allocate(bytes, kMaximumAlignment, Allocator.Persistent);
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m_bytes = bytes;
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m_current = 0;
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m_allocations = 0;
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}
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public void Rewind()
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{
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m_current = 0;
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m_allocations = 0;
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}
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public void Dispose()
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{
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Memory.Unmanaged.Free(m_pointer, Allocator.Persistent);
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m_pointer = null;
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m_bytes = 0;
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m_current = 0;
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m_allocations = 0;
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}
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public int TryAllocate(ref AllocatorManager.Block block)
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{
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// Make the alignment multiple of cacheline size
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var alignment = math.max(JobsUtility.CacheLineSize, block.Alignment);
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var extra = alignment != JobsUtility.CacheLineSize ? 1 : 0;
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var cachelineMask = JobsUtility.CacheLineSize - 1;
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if (extra == 1)
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{
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alignment = (alignment + cachelineMask) & ~cachelineMask;
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}
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// Adjust the size to be multiple of alignment, add extra alignment
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// to size if alignment is more than cacheline size
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var mask = alignment - 1L;
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var size = (block.Bytes + extra * alignment + mask) & ~mask;
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var readValue = Interlocked.Read(ref m_current);
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long oldReadValue;
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long writtenValue;
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long begin;
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do
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{
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writtenValue = readValue + size;
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begin = (readValue + mask) & ~mask;
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if (begin + block.Bytes > m_bytes)
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{
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return AllocatorManager.kErrorBufferOverflow;
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}
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oldReadValue = readValue;
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readValue = Interlocked.CompareExchange(ref m_current, writtenValue, oldReadValue);
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} while (readValue != oldReadValue);
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block.Range.Pointer = (IntPtr)(m_pointer + begin);
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block.AllocatedItems = block.Range.Items;
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Interlocked.Increment(ref m_allocations);
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return AllocatorManager.kErrorNone;
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}
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public bool Contains(IntPtr ptr)
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{
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unsafe
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{
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void* pointer = (void*)ptr;
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return (pointer >= m_pointer) && (pointer < m_pointer + m_current);
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}
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}
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};
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Spinner m_spinner;
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AllocatorManager.AllocatorHandle m_handle;
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UnmanagedArray<MemoryBlock> m_block;
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int m_best; // block we expect is best to allocate from next
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int m_last; // highest-index block that has memory to allocate from
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int m_used; // highest-index block that we actually allocated from, since last rewind
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bool m_enableBlockFree; // flag indicating if allocator enables individual block free
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/// <summary>
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/// Initializes the allocator. Must be called before first use.
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/// </summary>
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/// <param name="initialSizeInBytes">The initial capacity of the allocator, in bytes</param>
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public void Initialize(int initialSizeInBytes, bool enableBlockFree = false)
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{
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m_spinner = default;
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m_block = new UnmanagedArray<MemoryBlock>(64, Allocator.Persistent);
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m_block[0] = new MemoryBlock(initialSizeInBytes);
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m_last = m_used = m_best = 0;
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m_enableBlockFree = enableBlockFree;
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}
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/// <summary>
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/// Property to get and set enable block free flag, a flag indicating whether allocator enables individual block free.
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/// </summary>
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public bool EnableBlockFree
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{
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get => m_enableBlockFree;
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set => m_enableBlockFree = value;
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}
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/// <summary>
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/// Retrieves the number of memory blocks that the allocator has requested from the system.
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/// </summary>
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public int BlocksAllocated => (int)(m_last + 1);
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/// <summary>
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/// Retrieves the size of the initial memory block, as requested in the Initialize function.
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/// </summary>
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public int InitialSizeInBytes => (int)(m_block[0].m_bytes);
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/// <summary>
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/// Rewind the allocator; invalidate all allocations made from it, and potentially also free memory blocks
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/// it has allocated from the system.
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/// </summary>
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public void Rewind()
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{
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if (JobsUtility.IsExecutingJob)
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throw new InvalidOperationException("You cannot Rewind a RewindableAllocator from a Job.");
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m_handle.Rewind(); // bump the allocator handle version, invalidate all dependents
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while (m_last > m_used) // *delete* all blocks we didn't even allocate from this time around.
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m_block[m_last--].Dispose();
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while (m_used > 0) // simply *rewind* all blocks we used in this update, to avoid allocating again, every update.
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m_block[m_used--].Rewind();
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m_block[0].Rewind();
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m_best = 0;
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}
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/// <summary>
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/// Dispose the allocator. This must be called to free the memory blocks that were allocated from the system.
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/// </summary>
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public void Dispose()
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{
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if (JobsUtility.IsExecutingJob)
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throw new InvalidOperationException("You cannot Dispose a RewindableAllocator from a Job.");
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m_used = 0; // so that we delete all blocks in Rewind() on the next line
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Rewind();
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m_block[0].Dispose();
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m_block.Dispose();
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m_last = m_used = m_best = 0;
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}
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/// <summary>
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/// All allocators must implement this property, in order to be installed in the custom allocator table.
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/// </summary>
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[NotBurstCompatible]
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public AllocatorManager.TryFunction Function => Try;
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/// <summary>
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/// Try to allocate, free, or reallocate a block of memory. This is an internal function, and
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/// is not generally called by the user.
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/// </summary>
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/// <param name="block">The memory block to allocate, free, or reallocate</param>
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public int Try(ref AllocatorManager.Block block)
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{
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if (block.Range.Pointer == IntPtr.Zero)
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{
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// first, try to allocate from the block that succeeded last time, which we expect is likely to succeed again.
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var error = m_block[m_best].TryAllocate(ref block);
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if (error == AllocatorManager.kErrorNone)
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return error;
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// if that fails, check all the blocks to see if any of them have enough memory
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m_spinner.Lock();
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int best;
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for (best = 0; best <= m_last; ++best)
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{
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error = m_block[best].TryAllocate(ref block);
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if (error == AllocatorManager.kErrorNone)
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{
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m_used = best > m_used ? best : m_used;
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m_best = best;
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m_spinner.Unlock();
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return error;
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}
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}
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// if that fails, allocate another block that's guaranteed big enough, and allocate from it.
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var bytes = math.max(m_block[0].m_bytes << best, math.ceilpow2(block.Bytes)); // if user suddenly asks for 1GB, skip smaller sizes
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m_block[best] = new MemoryBlock(bytes);
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error = m_block[best].TryAllocate(ref block);
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m_best = best;
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m_used = best;
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m_last = best;
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m_spinner.Unlock();
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return error;
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}
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// To free memory, no-op unless allocator enables individual block to be freed
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if (block.Range.Items == 0)
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{
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if (m_enableBlockFree)
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{
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m_spinner.Lock();
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if (m_block[m_best].Contains(block.Range.Pointer))
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if (0 == Interlocked.Decrement(ref m_block[m_best].m_allocations))
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m_block[m_best].Rewind();
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m_spinner.Unlock();
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}
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return 0; // we could check to see if the pointer belongs to us, if we want to be strict about it.
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}
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return -1;
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}
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[BurstCompile]
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[MonoPInvokeCallback(typeof(AllocatorManager.TryFunction))]
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internal static int Try(IntPtr state, ref AllocatorManager.Block block)
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{
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unsafe { return ((RewindableAllocator*)state)->Try(ref block); }
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}
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/// <summary>
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/// Retrieve the AllocatorHandle associated with this allocator. The handle is used as an index into a
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/// global table, for times when a reference to the allocator object isn't available.
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/// </summary>
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/// <value>The AllocatorHandle retrieved.</value>
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public AllocatorManager.AllocatorHandle Handle { get { return m_handle; } set { m_handle = value; } }
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/// <summary>
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/// Retrieve the Allocator associated with this allocator.
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/// </summary>
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/// <value>The Allocator retrieved.</value>
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public Allocator ToAllocator { get { return m_handle.ToAllocator; } }
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/// <summary>
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/// Check whether this AllocatorHandle is a custom allocator.
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/// </summary>
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/// <value>True if this AllocatorHandle is a custom allocator.</value>
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public bool IsCustomAllocator { get { return m_handle.IsCustomAllocator; } }
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/// <summary>
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/// Allocate a NativeArray of type T from memory that is guaranteed to remain valid until the end of the
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/// next Update of this World. There is no need to Dispose the NativeArray so allocated. It is not possible
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/// to free the memory by Disposing it - it is automatically freed after the end of the next Update for this
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/// World.
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/// </summary>
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/// <typeparam name="T">The element type of the NativeArray to allocate.</typeparam>
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/// <param name="length">The length of the NativeArray to allocate, measured in elements.</param>
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/// <returns>The NativeArray allocated by this function.</returns>
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[BurstCompatible(GenericTypeArguments = new[] { typeof(int) })]
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public NativeArray<T> AllocateNativeArray<T>(int length) where T : struct
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{
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var container = new NativeArray<T>();
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unsafe
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{
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container.m_Buffer = this.AllocateStruct(default(T), length);
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}
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container.m_Length = length;
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container.m_AllocatorLabel = Allocator.None;
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#if ENABLE_UNITY_COLLECTIONS_CHECKS
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container.m_MinIndex = 0;
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container.m_MaxIndex = length - 1;
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container.m_Safety = CollectionHelper.CreateSafetyHandle(ToAllocator);
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#if REMOVE_DISPOSE_SENTINEL
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#else
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container.m_DisposeSentinel = null;
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#endif
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CollectionHelper.SetStaticSafetyId<NativeArray<T>>(ref container.m_Safety, ref NativeArrayExtensions.NativeArrayStaticId<T>.s_staticSafetyId.Data);
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Handle.AddSafetyHandle(container.m_Safety);
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#endif
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return container;
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}
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/// <summary>
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/// Allocate a NativeList of type T from memory that is guaranteed to remain valid until the end of the
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/// next Update of this World. There is no need to Dispose the NativeList so allocated. It is not possible
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/// to free the memory by Disposing it - it is automatically freed after the end of the next Update for this
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/// World. The NativeList must be initialized with its maximum capacity; if it were to dynamically resize,
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/// up to 1/2 of the total final capacity would be wasted, because the memory can't be dynamically freed.
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/// </summary>
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/// <typeparam name="T">The element type of the NativeList to allocate.</typeparam>
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/// <param name="capacity">The capacity of the NativeList to allocate, measured in elements.</param>
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/// <returns>The NativeList allocated by this function.</returns>
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[BurstCompatible(GenericTypeArguments = new[] { typeof(int) })]
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public NativeList<T> AllocateNativeList<T>(int capacity) where T : unmanaged
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{
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var container = new NativeList<T>();
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unsafe
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{
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container.m_ListData = this.Allocate(default(UnsafeList<T>), 1);
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container.m_ListData->Ptr = this.Allocate(default(T), capacity);
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container.m_ListData->m_capacity = capacity;
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container.m_ListData->m_length = 0;
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container.m_ListData->Allocator = Allocator.None;
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}
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container.m_DeprecatedAllocator = Allocator.None;
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#if ENABLE_UNITY_COLLECTIONS_CHECKS
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container.m_Safety = CollectionHelper.CreateSafetyHandle(ToAllocator);
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#if REMOVE_DISPOSE_SENTINEL
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#else
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container.m_DisposeSentinel = null;
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#endif
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CollectionHelper.SetStaticSafetyId<NativeList<T>>(ref container.m_Safety, ref NativeList<T>.s_staticSafetyId.Data);
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AtomicSafetyHandle.SetBumpSecondaryVersionOnScheduleWrite(container.m_Safety, true);
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Handle.AddSafetyHandle(container.m_Safety);
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#endif
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return container;
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}
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}
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}
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