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