linux-ext4 - Re: [RFC] Thing 1: Shardmap fox Ext4

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Message-ID: <3b4d380f-cb33-b0fb-2426-67109875ce77@phunq.net>
Date:   Sun, 8 Dec 2019 02:25:22 -0800
From:   Daniel Phillips <daniel@...nq.net>
To:     "Theodore Y. Ts'o" <tytso@....edu>
Cc:     linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Subject: Re: [RFC] Thing 1: Shardmap fox Ext4

On 2019-11-27 6:28 p.m., Theodore Y. Ts'o wrote:
> The use of C++ with templates is presumably one of the "less so"
> parts, and it was that which I had in mind when I said,
> "reimplementing from scratch".

The templates were removed without reimplementing from scratch:

   https://github.com/danielbot/Shardmap/blob/master/shardmap.h#L88
   https://github.com/danielbot/Shardmap/blob/master/shardmap.cc#L82

The duopack/tripack facility, central to Shardmap efficient scalability, are
now just ordinary C code that happens to be compiled by a C++ compiler. I
think the machine code should be identical to what the templates produced,
though I did not verify.

This was a strictly mechanical conversion, less error prone than
reimplementing from scratch I would think. I expect the rest of the
back conversions to be similarly mechanical.

Regards,

Daniel