[ET Trac] [Einstein Toolkit] #1239: AHFinderDirect uses incorrect origin_* upon recovery when horizon was never found before

[Einstein Toolkit]

#1239: AHFinderDirect uses incorrect origin_* upon recovery when horizon was never
found before
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  Reporter:  reisswig@…                  |       Owner:                
      Type:  defect                      |      Status:  new           
  Priority:  major                       |   Milestone:                
 Component:  EinsteinToolkit thorn       |     Version:                
Resolution:                              |    Keywords:  AHFinderDirect
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Comment (by rhaas):

 Three comments:
 * there is commented out code in the commit which might as well be not
 committed :-)
 * this code seems to pose the danger of ps.origin() never being called
 when both h_found_flag[horizon_number-1] == 0 and
 (ah_really_initial_find_flag[horizon_number-1] . Since before ps.origin()
 was always called, I wonder if this might cause it to remain initialized.
 * finally the code in the else branch uses horizon_number instead of
 horizon_number-1

 A general question: This seems to be an instance of a thorn that makes
 copies of Cactus' parameters (or quantities computed from them) and then
 checkpoints them. This seems to interfere badly with Cactus' ability to
 change parameter values on recovery. My question is if there is use in
 such thorns trying to emulate the logic in Cactus as to when to update
 values? I believe the login in Cactus goes something like this: at
 recovery the values for parameters are those stored in checkpoints unless
 it is explicitly set in the new parameter file and this setting differs
 from the one in the original parameter file used at checkpoint time in
 which case values from the new parameter file are used. Is this correct?
 Do we want to implement something similar in AHFinderDirect (I assume this
 to involve checking how often a parameter has been set at
 POST_RECOVER_VARIABLES time).

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/1239#comment:1>
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