On 10/14/2016 11:32 PM, degski wrote:
On 15 October 2016 at 05:43, Michael Marcin <mike.marcin@gmail.com> wrote:
Does this already exist somewhere?
Take a look at Boost.DoubleEnded 1 <http://erenon.hu/double_ended/> and see whether boost::double_ended::batch_deque <http://erenon.hu/double_ended/double_ended/design_rationale.html#double_ended.design_rationale.batch_deque> fills all of your requirements.
Sorry I think I wasn't clear. Let me back up a bit and give some examples. Arrays of Structures is the normal programming model. Let's take a toy example, say I'm looking at some census data and have a structure that looks like: struct citizen_t { string first_name; string last_name; int salary; int age; }; Then the Array of Structures container would be: vector<citizen_t> aos_citizens; The Structure of Arrays version of the same data would look like: struct soa_citizens_t { vector<string> first_names; vector<string> last_names; vector<int> salary; vector<int> age; }; soa_citizens_t soa_citizens; Why does this matter? Let's say I want to calculate the average salary of 300 million citizens. The code is a simple iterative average and very simple. // Array of Structures int avg = 0; int t = 1; for ( auto & c : aos_citizens ) { avg += (c.salary - avg) / t; ++t; } // Structures of Arrays int avg = 0; int t = 1; for ( int salary : soa_citizens.salary ) { avg += (salary - avg) / t; ++t; } Run this under a simple benchmark: https://ideone.com/QNqKpD AoS 3.03523 seconds SoA 1.94902 seconds Both loops are doing the exact same work but the memory layout allows the second loop to run much faster.