Current subsurface breakage

[Linus Torvalds]

On Fri, Jan 2, 2015 at 6:43 PM, Linus Torvalds
<torvalds at linux-foundation.org> wrote:
>
> The *other* bug is apparently intentional, and annoying. The code to
> suppress saving temperatures for every sample has been broken. So
> saving the new dives changed all the old dives I had, and made the
> save much bigger.

Yes. Commit 6cf3787a0ed1 ("Remove code that zeroes out duplicate
oxygen sensor and temperature values") causes this.

I'm not at all understanding why that commit also touched the
temperature code. The commit message talks about )2 setpoints, but
then it screws with temperatures too.

Can we please either revert it? At least the temperature part?
Alternatively, somebody would make it not *save* those redundant
temperatures.. As it is, this changes the file format, and that's
always nasty because even if the redundant saving "only" wastes
diskspace and makes save/loading slower, a change like this *also*
screws up the whole "let's verify that subsurface doesn't screw up any
user data" when it rewrites all the files.

Looking at the XML (or git) diffs is a *very* powerful way to make
sure some subsurface change doesn't mistakenly bugger some actual
data. And clearly nobody did that with any existing files here.
Because that temperature change causes this for my dive save state:

[torvalds at i7 scuba]$ git show --stat
Author: Linus Torvalds <torvalds at linux-foundation.org>
Date:   Fri Jan 2 19:28:49 2015 -0800

    dive 552: Cliff (Bonaire)

    Uemis Zurich, Suunto Vyper Air, Suunto HelO2, Suunto EON Steel
    Created by subsurface 4.3-184-gcef150d7dcd7

 2009/08/29-MolokiniCrater/08-29-Sat-09:06:00/Divecomputer   |  152 ++++-----
 2009/08/29-MolokiniCrater/08-29-Sat-10:34:00/Divecomputer   |  170 +++++-----
 2009/08/29-MolokiniCrater/08-29-Sat-13:35:00/Divecomputer   |  220
++++++-------
...
 2014/10/07-Bonaire/11-Sat-14:13:57/Divecomputer-001         | 1206
+++++++++++++++++++++++++++++++++----------------------------------
 2014/10/07-Bonaire/11-Sat-14:13:57/Divecomputer-002         |  338
+++++++++----------
 2014/10/07-Bonaire/11-Sat-14:13:57/Divecomputer-003         |  336
+++++++++----------
 2014/10/07-Bonaire/11-Sat-14:13:57/Divecomputer-004         |  632
+++++++++++++++++------------------
 820 files changed, 223389 insertions(+), 223389 deletions(-)

ie the "diff" here is just under half a million lines.

                       Linus