[ET Trac] [Einstein Toolkit] #2112: move CCTK_MyHost and friends into flesh

[Einstein Toolkit]

#2112: move CCTK_MyHost and friends into flesh
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  Reporter:  rhaas        |       Owner:                     
      Type:  enhancement  |      Status:  new                
  Priority:  minor        |   Milestone:                     
 Component:  Cactus       |     Version:  development version
Resolution:               |    Keywords:  Carpet PUGH driver 
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Comment (by rhaas):

 I do not really want to make the drivers depend on Formaline, otherwise,
 yes Formaline would give me a nice hopefully unique ID for the run.

 I am absolutely behind not over-designing this. MPI_Comm_split_type is the
 best solution if available. The downside to it seems to be your comment
 that MPI3 is not supported by all supercomputers of interest to us :-(

 Most of the logic should be re-usable by all methods though since they all
 boil down to:

 * mark one rank per host as leader
 * choose a host-id based on the leader's rank relative to the other
 leaders
 * have the leaders pass the host ID to the other ranks on the host

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/2112#comment:14>
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