Re: [boost] [Intrusive]

Subject: Re: [boost] [Intrusive]
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2017-08-23 22:49:52

On 08/24/17 01:18, Soul Studios via Boost wrote:
>> object is referenced by another API. The only alternative to 
>> Boost.Intrusive is keeping a pointer to the object in a separate 
>> container, which is way too cumbersome. Second is when you want your 
>> object to be a member of multiple containers and you don't want or 
>> cannot copy it. 
> 
> Storing a vector of pointers is not only less cumbersome than injecting 
> structures into the original objects,

Having tried both, I will just have to disagree.

> it's less expensive.
> According to the Doom3 BFG technical note 
> (fabiensanglard.net/doom3_documentation/DOOM-3-BFG-Technical-Note.pdf)
> a vector of indexes to a separate vector(s) of objects is significantly 
> faster than an intrusive list. The same would be true for a vector of 
> pointers (but less so).
> This approach is also amenable to multiple containers sharing objects.

Whether that is faster or not depends on many factors, primarilly the 
use scenarios at hand. One can't make a general statement like that 
without specifics. One factor that could make a vector more efficient 
than a list is cache friendliness, but an intrusive list could exploit 
it as well if you manage the storage appropriately.