Hello all,
Cactus's reduction interface provides two different set of reduction operations:
1. reduction of grid variables (grid functions, grid arrays) that are identified via their variable index
2. reduction of local arrays that are identifies using the local memory address
These two operations use different reduction operator handles returned by the CCTK_ReductionHandle (grid variables) and CCTK_ReductionArrayHandle (local arrays) functions, respectively.
In the past the numerical values returned by these functions often happened to be identical for identical string input (eg "maximum" might be handle number 1 in both functions).
This was, however, an accident due entirely to the order in which the individual operator names for each type of reduction were registered with Cactus.
As of Cactus commit 32def5eb "Cactus: use different handle ranges for old-style array and grid reductions"
https://bitbucket.org/cactuscode/cactus/commits/32def5eb2030151b15753e040470...
this is no longer the case and the numeric handle values intentionally differ.
This may make existing code that incorrectly used the handles to fail with errors reported about invalid operator handles or unknown operators (depending on the level return code checking done).
The common error case is that CCTK_ReductionHandle was used with CCTK_ReduceLocalScalar which must be fixed by using CCTK_ReductionArrayHandle.
Please see ticket #1001:
https://bitbucket.org/einsteintoolkit/tickets/issues/1001/distinguish-betwee...
for details.
Yours, Roland