[M3devel] FreeSlots/lookup slot locking

[Jay K]

Tony:

> Also, I am unconvinced that the current implementation of AssignSlot can ever
> be correct without the critical section. It requires atomic update of both
> the slots array pointer (with the new slots) *and* the array elements. This
> requires a proper CS instead of non-blocking synchronization.


 

I don't see it.

I could be wrong.

 

The writes are done within a critical section, to avoid racing with other writers.

 

Writes interact with readers in that:

 

            SUBARRAY (new_slots^, 0, n) := slots^;
finish writing to the array elements

MemoryBarrier

            slots := new_slots;


 

so readers don't see slots unless it has been fully initialized.

 

AssignSlots should also be able to be lock free via InterlockedCompareExchangePointer.

 

 

 - Jay

 
 		 	   		  
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