This is the eighth part of the Custom memory allocation series. For your convenience you can find other parts in the table of contents in Part 1 — Allocating object on a stack
Today we are going to revisit an Unsafe list example using .NET Core. Since I use x64 edition, I need to adjust a code using pointers:
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public void Add ( T item )
{
_currentIndex ++;
unsafe
{
TypedReference reference = __makeref ( item ) ;
long * itemAddress = ( long *) ( *( long *) *( long *) &reference - 8);
for ( long i = 1 ; i < _elementSize ; ++i )
{
_storage [ _currentIndex* _elementSize + i ] = *itemAddress ;
itemAddress = itemAddress + 1 ;
}
reference = __makeref ( _storage ) ;
_storage [ _currentIndex* _elementSize ] = *( long *) *( long *) &reference + _currentIndex*_elementSize*8 + 32;
_elements [ _currentIndex ] = GetInternal ( _currentIndex ) ;
}
}
Changes are rather simple — one just needs to replace integers with longs and multiply all the offsets by two.
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class Poco
{
public long Field1 ;
public long Field2 ;
public long Field3 ;
public long Field4 ;
public long Field5 ;
public long Field6 ;
public long Field7 ;
public long Field8 ;
public long Field9 ;
public long Field10 ;
public long Field11 ;
public long Field12 ;
public long Field13 ;
public long Field14 ;
public long Field15 ;
public long Field16 ;
}
Here I just use long fields to make the code simpler. Of course one can detect the size of the object and work with integers as well.
Here are the results:
Unsafe list is still faster.
