[boost] Re: Direct vs. indirect shared_ptr

From: David Abrahams (abrahams_at_[hidden])
Date: 1998-12-07 09:50:44

Greg Colvin (gcolvin_at_[hidden]) wrote:

>Recall (as you may already) that both versions store the count on
>the heap:
>
>   "direct":
>               object <- shared_ptr -> count
>
>   "indirect":
>                         shared_ptr -> count -> object
>
>You understand this stuff better than I do, but I don't really see how
>the "indirect" version suffers compared to the "direct", though it might
>depend a lot on the memory manager.  Perhaps some decent memory managers
>would be a good addition to Boost.

In programs where the object being referred is used much more often than 
the count (that seems like the likliest scenario), the indirect version 
would often force the an additional cache line to be replaced just to get 
the actual pointer to the object.

--------------------------------------------------------------
David Abrahams * Mark of the Unicorn, Inc. * abrahams_at_[hidden]

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