Re: [boost] interest in structure of arrays container?

Subject: Re: [boost] interest in structure of arrays container?
From: Larry Evans (cppljevans_at_[hidden])
Date: 2016-10-18 11:29:34

On 10/14/2016 09:43 PM, Michael Marcin wrote:
 > Structure of arrays is a pretty well known pattern for improving memory
 > density and enabling vectorization in high performance code. Also known
 > as parallel arrays[1].
 >
 > After hand-rolling yet another of these it occurred to me that you make
 > a reasonable first implementation with a simple alias template.
 >
 > template< typename... Ts >
 > using soa = std::tuple< std::vector<Ts>... >;
 >
 > example:
 > soa<int,float,std::string> data;
 >
 > This is decent start but has several issues including:
 >  * nothing to preserve the invariant keeping the arrays the same length
 >  * missing coalesced interface for vector methods (size, reserve, etc)
 >  * no iterator
 >  * wasted storage for duplicated allocators, capacities, sizes
 >  * sizeof...(Ts) allocations could be a single large block
 >
 > The work required to address these issues is not too great I think.

The purpose of item:

   * sizeof...(Ts) allocations could be a single large block

is to just require 1 heap allocation instead of N, where N
is the number of vectors in soa<T1,T2,...,TN>?

-regards,
Larry