Adam
/
AyCode.Core
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Refactor small int optimization in IdentityMap 

Clarified and restricted the "small int" optimization path to tracking (serialization) only, not value storage. Made _useSmallInt a constant, removed unnecessary _smallValues initialization, and improved comments for clarity. Updated code to safely handle uninitialized _smallValues and documented that hash table is preferred for value storage.
This commit is contained in:
Loretta 2026-02-01 09:15:41 +01:00
parent c7f44906e7
commit 056a66d713
1 changed files with 46 additions and 61 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

107
AyCode.Core/Serializers/IdentityMap.cs
View File

@ -46,8 +46,9 @@ public interface IIdentityMap
/// <typeparam name="TId">The ID type (int, long, Guid, string)</typeparam>
public sealed class IdentityMap<TId> : IIdentityMap where TId : notnull
{
private bool _useSmallInt = false;
private const bool _useSmallInt = true;
// Small int optimization (TId = int only, 0-4095), 512 bytes (fits in L1 cache!)
private const int SmallBitmapSize = 64;
private const int SmallSize = 4096;
@ -55,10 +56,6 @@ public sealed class IdentityMap<TId> : IIdentityMap where TId : notnull
//private const int SmallBitmapSize = 1024;
//private const int SmallSize = SmallBitmapSize * 64;
// Small int optimization (TId = int only, 0-4095)
//private const int SmallSize = 4096;
//private const int SmallBitmapSize = SmallSize / 64; // 64 ulongs = 512 bytes (fits in L1 cache!)
// Slot for hash table entries (generation needed for hash table validity)
private struct HashSlot
{
@ -90,8 +87,7 @@ public sealed class IdentityMap<TId> : IIdentityMap where TId : notnull
public IdentityMap()
{
}
/// <summary>
/// Tries to add a key to tracking (serialization).
/// Returns true if first occurrence (key was added).
@ -311,16 +307,16 @@ public sealed class IdentityMap<TId> : IIdentityMap where TId : notnull
// NOTE: SmallInt path DISABLED for deserializer.
// The 512KB _smallValues sparse array causes cache misses.
// Hash table has better cache locality.
// // Small int fast path
// if (_useSmallInt && IsInt32)
// {
// var intKey = Unsafe.As<TId, int>(ref key);
// if ((uint)intKey < SmallSize)
// {
// return TryGetOrAddSmallInt(intKey, out existing);
// }
// }
//// Small int fast path
//if (_useSmallInt && IsInt32)
//{
// var intKey = Unsafe.As<TId, int>(ref key);
// if ((uint)intKey < SmallSize)
// {
// return TryGetOrAddSmallInt(intKey, out existing);
// }
//}
// Hash table path
if (!TryAddHash(key, out var slotIndex))
@ -335,19 +331,13 @@ public sealed class IdentityMap<TId> : IIdentityMap where TId : notnull
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private bool TryGetOrAddSmallInt(int key, out object? existing)
{
// Lazy init bitmap
// Lazy init bitmap only - NOT _smallValues!
// This method is for tracking (key seen?), not value storage.
if (_smallBitmap == null)
{
_smallBitmap = ArrayPool<ulong>.Shared.Rent(SmallBitmapSize);
Array.Clear(_smallBitmap, 0, SmallBitmapSize);
}
// Lazy init values array (only when needed for deserialization)
if (_smallValues == null)
{
_smallValues = ArrayPool<object?>.Shared.Rent(SmallSize);
Array.Clear(_smallValues, 0, SmallSize);
}
var wordIdx = key >> 6;
var bit = 1UL << (key & 63);
@ -355,14 +345,13 @@ public sealed class IdentityMap<TId> : IIdentityMap where TId : notnull
ref var word = ref _smallBitmap[wordIdx];
if ((word & bit) != 0)
{
// Bitmap says seen - value is valid
existing = _smallValues![key];
// Bitmap says seen - return stored value if any
existing = _smallValues?[key];
return false; // Already seen
}
// First occurrence - mark as seen
// First occurrence - mark as seen (don't touch _smallValues!)
word |= bit;
_smallValues![key] = null;
existing = null;
return true;
}
@ -378,16 +367,16 @@ public sealed class IdentityMap<TId> : IIdentityMap where TId : notnull
// The 512KB _smallValues sparse array causes cache misses.
// Hash table has better cache locality (only stores actual entries).
// Bitmap is only useful for tracking (serializer) - not for value storage.
// // Small int fast path
// if (_useSmallInt && IsInt32)
// {
// var intKey = Unsafe.As<TId, int>(ref key);
// if ((uint)intKey < SmallSize)
// {
// return TryGetOrAddSmallIntValue(intKey, newValue);
// }
// }
//// Small int fast path
//if (_useSmallInt && IsInt32)
//{
// var intKey = Unsafe.As<TId, int>(ref key);
// if ((uint)intKey < SmallSize)
// {
// return TryGetOrAddSmallIntValue(intKey, newValue);
// }
//}
// Hash table path
if (!TryAddHash(key, out var slotIndex))
@ -441,28 +430,24 @@ public sealed class IdentityMap<TId> : IIdentityMap where TId : notnull
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public bool TryGetValue(TId key, out object? value)
{
// NOTE: SmallInt path DISABLED for deserializer value lookup.
// The 512KB _smallValues sparse array causes cache misses.
// Hash table has better cache locality.
// // Small int fast path - bitmap check first (cache-friendly, 512 bytes)
// if (_useSmallInt && IsInt32)
// {
// var intKey = Unsafe.As<TId, int>(ref key);
// if ((uint)intKey < SmallSize && _smallBitmap != null)
// {
// var wordIdx = intKey >> 6;
// var bit = 1UL << (intKey & 63);
// if ((_smallBitmap[wordIdx] & bit) != 0)
// {
// // Bitmap says seen - value is valid
// value = _smallValues![intKey];
// return true;
// }
// value = null;
// return false;
// }
// }
//// Small int fast path - bitmap check first (cache-friendly, 512 bytes)
//if (_useSmallInt && IsInt32)
//{
// var intKey = Unsafe.As<TId, int>(ref key);
// if ((uint)intKey < SmallSize && _smallBitmap != null)
// {
// var wordIdx = intKey >> 6;
// var bit = 1UL << (intKey & 63);
// if ((_smallBitmap[wordIdx] & bit) != 0)
// {
// // Bitmap says seen - return value if exists
// value = _smallValues?[intKey];
// return value != null;
// }
// value = null;
// return false;
// }
//}
// Hash table path
if (_buckets == null)