using AOT;
using System;
using System.Runtime.CompilerServices;
using System.Threading;
using UnityEngine.Assertions;
using Unity.Burst;
using Unity.Collections.LowLevel.Unsafe;
using Unity.Jobs.LowLevel.Unsafe;
using Unity.Mathematics;
namespace Unity.Collections
{
internal struct UnmanagedArray<T> : IDisposable where T : unmanaged
{
IntPtr m_pointer;
int m_length;
public int Length => 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]
{
[MethodImpl(MethodImplOptions.AggressiveInlining)]
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
{
internal struct Union
{
internal long m_long;
// Number of bits used to store current position in a block to give out memory.
// This limits the maximum block size to 1TB (2^40).
const int currentBits = 40;
// Offset of current position in m_long
const int currentOffset = 0;
// Number of bits used to store the allocation count in a block
const long currentMask = (1L << currentBits) - 1;
// Number of bits used to store allocation count in a block.
// This limits the maximum number of allocations per block to 16 millions (2^24)
const int allocCountBits = 24;
// Offset of allocation count in m_long
const int allocCountOffset = currentOffset + currentBits;
const long allocCountMask = (1L << allocCountBits) - 1;
// Current position in a block to give out memory
internal long m_current
{
[MethodImpl(MethodImplOptions.AggressiveInlining)]
get
{
return (m_long >> currentOffset) & currentMask;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
set
{
m_long &= ~(currentMask << currentOffset);
m_long |= (value & currentMask) << currentOffset;
}
}
// The number of allocations in a block
internal long m_allocCount
{
[MethodImpl(MethodImplOptions.AggressiveInlining)]
get
{
return (m_long >> allocCountOffset) & allocCountMask;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
set
{
m_long &= ~(allocCountMask << allocCountOffset);
m_long |= (value & allocCountMask) << allocCountOffset;
}
}
}
[GenerateTestsForBurstCompatibility]
internal unsafe struct MemoryBlock : IDisposable
{
// can't align any coarser than this many bytes
public const int kMaximumAlignment = 16384;
// pointer to contiguous memory
public byte* m_pointer;
// how many bytes of contiguous memory it points to
public long m_bytes;
// Union of current position to give out memory and allocation counts
public Union m_union;
public MemoryBlock(long bytes)
{
m_pointer = (byte*)Memory.Unmanaged.Allocate(bytes, kMaximumAlignment, Allocator.Persistent);
Assert.IsTrue(m_pointer != null, "Memory block allocation failed, system out of memory");
m_bytes = bytes;
m_union = default;
}
public void Rewind()
{
m_union = default;
}
public void Dispose()
{
Memory.Unmanaged.Free(m_pointer, Allocator.Persistent);
m_pointer = null;
m_bytes = 0;
m_union = default;
}
public bool Contains(IntPtr ptr)
{
unsafe
{
void* pointer = (void*)ptr;
return (pointer >= m_pointer) && (pointer < m_pointer + m_union.m_current);
}
}
};
// Log2 of Maximum memory block size. Cannot exceed MemoryBlock.Union.currentBits.
const int kLog2MaxMemoryBlockSize = 26;
// Maximum memory block size. Can exceed maximum memory block size if user requested more.
const long kMaxMemoryBlockSize = 1L << kLog2MaxMemoryBlockSize; // 64MB
/// Minimum memory block size, 128KB.
const long kMinMemoryBlockSize = 128 * 1024;
/// Maximum number of memory blocks.
const int kMaxNumBlocks = 64;
// Bit mask (bit 31) of the memory block busy flag indicating whether the block is busy rewinding.
const int kBlockBusyRewindMask = 0x1 << 31;
// Bit mask of the memory block busy flag indicating whether the block is busy allocating.
const int kBlockBusyAllocateMask = ~kBlockBusyRewindMask;
Spinner m_spinner;
AllocatorManager.AllocatorHandle m_handle;
UnmanagedArray<MemoryBlock> m_block;
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
byte m_enableBlockFree; // flag indicating if allocator enables individual block free
byte m_reachMaxBlockSize; // flag indicating if reach maximum block size
/// <summary>
/// Initializes the allocator. Must be called before first use.
/// </summary>
/// <param name="initialSizeInBytes">The initial capacity of the allocator, in bytes</param>
/// <param name="enableBlockFree">A flag indicating if allocator enables individual block free</param>
public void Initialize(int initialSizeInBytes, bool enableBlockFree = false)
{
m_spinner = default;
m_block = new UnmanagedArray<MemoryBlock>(kMaxNumBlocks, Allocator.Persistent);
// Initial block size should be larger than min block size
var blockSize = initialSizeInBytes > kMinMemoryBlockSize ? initialSizeInBytes : kMinMemoryBlockSize;
m_block[0] = new MemoryBlock(blockSize);
m_last = m_used = 0;
m_enableBlockFree = enableBlockFree ? (byte)1 : (byte)0;
m_reachMaxBlockSize = (initialSizeInBytes >= kMaxMemoryBlockSize) ? (byte)1 : (byte)0;
}
/// <summary>
/// Property to get and set enable block free flag, a flag indicating whether the allocator should enable individual block to be freed.
/// </summary>
public bool EnableBlockFree
{
get => m_enableBlockFree != 0;
set => m_enableBlockFree = value ? (byte)1 : (byte)0;
}
/// <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>
/// Retrieves the maximum memory block size.
/// </summary>
internal long MaxMemoryBlockSize => kMaxMemoryBlockSize;
/// <summary>
/// Retrieves the total bytes of the memory blocks allocated by this allocator.
/// </summary>
internal long BytesAllocated
{
get
{
long totalBytes = 0;
for(int i = 0; i <= m_last; i++)
{
totalBytes += m_block[i].m_bytes;
}
return totalBytes;
}
}
/// <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 = 0;
}
/// <summary>
/// All allocators must implement this property, in order to be installed in the custom allocator table.
/// </summary>
[ExcludeFromBurstCompatTesting("Uses managed delegate")]
public AllocatorManager.TryFunction Function => Try;
unsafe int TryAllocate(ref AllocatorManager.Block block, int startIndex, int lastIndex, long alignedSize, long alignmentMask)
{
for (int best = startIndex; best <= lastIndex; best++)
{
Union oldUnion;
Union readUnion = default;
long begin = 0;
bool skip = false;
readUnion.m_long = Interlocked.Read(ref m_block[best].m_union.m_long);
do
{
begin = (readUnion.m_current + alignmentMask) & ~alignmentMask;
if (begin + block.Bytes > m_block[best].m_bytes)
{
skip = true;
break;
}
oldUnion = readUnion;
Union newUnion = default;
newUnion.m_current = (begin + alignedSize) > m_block[best].m_bytes ? m_block[best].m_bytes : (begin + alignedSize);
newUnion.m_allocCount = readUnion.m_allocCount + 1;
readUnion.m_long = Interlocked.CompareExchange(ref m_block[best].m_union.m_long, newUnion.m_long, oldUnion.m_long);
} while (readUnion.m_long != oldUnion.m_long);
if(skip)
{
continue;
}
block.Range.Pointer = (IntPtr)(m_block[best].m_pointer + begin);
block.AllocatedItems = block.Range.Items;
Interlocked.MemoryBarrier();
int oldUsed;
int readUsed;
int newUsed;
readUsed = m_used;
do
{
oldUsed = readUsed;
newUsed = best > oldUsed ? best : oldUsed;
readUsed = Interlocked.CompareExchange(ref m_used, newUsed, oldUsed);
} while (newUsed != oldUsed);
return AllocatorManager.kErrorNone;
}
return AllocatorManager.kErrorBufferOverflow;
}
/// <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>
/// <returns>0 if successful. Otherwise, returns the error code from the allocator function.</returns>
public int Try(ref AllocatorManager.Block block)
{
if (block.Range.Pointer == IntPtr.Zero)
{
// 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;
// Check all the blocks to see if any of them have enough memory
var last = m_last;
int error = TryAllocate(ref block, 0, m_last, size, mask);
if (error == AllocatorManager.kErrorNone)
{
return error;
}
// If that fails, allocate another block that's guaranteed big enough, and allocate from it.
// Allocate twice as much as last time until it reaches MaxMemoryBlockSize, after that, increase
// the block size by MaxMemoryBlockSize.
m_spinner.Acquire();
// After getting the lock, we must try to allocate again, because if many threads waited at
// the lock, the first one allocates and when it unlocks, it's likely that there's space for the
// other threads' allocations in the first thread's block.
error = TryAllocate(ref block, last, m_last, size, mask);
if (error == AllocatorManager.kErrorNone)
{
m_spinner.Release();
return error;
}
long bytes;
if (m_reachMaxBlockSize == 0)
{
bytes = m_block[m_last].m_bytes << 1;
}
else
{
bytes = m_block[m_last].m_bytes + kMaxMemoryBlockSize;
}
// if user asks more, skip smaller sizes
bytes = math.max(bytes, size);
m_reachMaxBlockSize = (bytes >= kMaxMemoryBlockSize) ? (byte)1 : (byte)0;
m_block[m_last + 1] = new MemoryBlock(bytes);
Interlocked.Increment(ref m_last);
error = TryAllocate(ref block, m_last, m_last, size, mask);
m_spinner.Release();
return error;
}
// To free memory, no-op unless allocator enables individual block to be freed
if (block.Range.Items == 0)
{
if (m_enableBlockFree != 0)
{
for (int blockIndex = 0; blockIndex <= m_last; ++blockIndex)
{
if (m_block[blockIndex].Contains(block.Range.Pointer))
{
Union oldUnion;
Union readUnion = default;
readUnion.m_long = Interlocked.Read(ref m_block[blockIndex].m_union.m_long);
do
{
oldUnion = readUnion;
Union newUnion = readUnion;
newUnion.m_allocCount--;
if (newUnion.m_allocCount == 0)
{
newUnion.m_current = 0;
}
readUnion.m_long = Interlocked.CompareExchange(ref m_block[blockIndex].m_union.m_long, newUnion.m_long, oldUnion.m_long);
} while (readUnion.m_long != oldUnion.m_long);
}
}
}
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>
/// Check whether this allocator will automatically dispose allocations.
/// </summary>
/// <remarks>Allocations made by Rewindable allocator are automatically disposed.</remarks>
/// <value>Always true</value>
public bool IsAutoDispose { get { return true; } }
/// <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>
[GenerateTestsForBurstCompatibility(GenericTypeArguments = new[] { typeof(int) })]
public NativeArray<T> AllocateNativeArray<T>(int length) where T : unmanaged
{
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);
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>
[GenerateTestsForBurstCompatibility(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_length = 0;
container.m_ListData->m_capacity = capacity;
container.m_ListData->Allocator = Allocator.None;
}
#if ENABLE_UNITY_COLLECTIONS_CHECKS
container.m_Safety = CollectionHelper.CreateSafetyHandle(ToAllocator);
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;
}
}
}