Re: [boost] [Container] interest in a flat_unordered_map

Subject: Re: [boost] [Container] interest in a flat_unordered_map
From: Treb Connell (trebconnell_at_[hidden])
Date: 2015-09-21 12:32:04

>
> I believe, much of the benefit depends on the nature of keys and
> values (e.g. ints vs. strings)? Is there a more detailed description
> of the tests and results, at different container sizes?
>
I'm planning to port this enough to be able to run the Boost.Container perf
tests.  After I do that I'll post numbers from there.  Wanted to get an
initial sense of interest before starting work.

> Can the iterator tradeoff be made a compile time option?
>
> One frequently used operation that generally amounts to iterating
> through elements is clear(). Do I understand correctly that its
> complexity can be O(N) where N>size()? I believe the same applies to
> range erase().
>
> Also, is size() constant time?
>
size() is constant time, which I pay for in memory and a bit of logic to
keep track of that.  clear() is O(N) where N is bucket_count, though no
work is done on buckets with no elements .