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Re: Power of two rehash policy
- From: Jonathan Wakely <jwakely dot gcc at gmail dot com>
- To: Jason Arnold <jasonar81 at gmail dot com>
- Cc: gcc-help <gcc-help at gcc dot gnu dot org>
- Date: Wed, 15 Nov 2017 17:40:37 +0000
- Subject: Re: Power of two rehash policy
- Authentication-results: sourceware.org; auth=none
- References: <CAA8nznVbu0G21d8grkiZnS3WB95ZqW1QQZjvBG3Jf+sCCBK-Mg@mail.gmail.com>
On 15 November 2017 at 17:38, Jason Arnold wrote:
> The GCC7 notes says
>
> - A new power-of-two rehashing policy for use with the _Hashtable internals,
> thanks to François Dumont.
>
> What do I have to do to use this instead of the default prime rehash
> policy, for example with std::unordered_set/map?
You can't use it with unordered_map, because there's no way to change
the rehash policy. You'd need to use the _Hashtable type directly,
rather than via unordered_set.