nproc.cc

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// This file is part of Octave.
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#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif
 
#include "nproc-wrapper.h"
 
#include "defun.h"
#include "error.h"
 
OCTAVE_BEGIN_NAMESPACE(octave)
 
DEFUN (nproc, args, ,
       doc: /* -*- texinfo -*-
@deftypefn  {} {@var{n} =} nproc ()
@deftypefnx {} {@var{n} =} nproc (@var{query})
Return the current number of available (logical) processors.
 
This returns the number of logical processors.  For processors with
hyperthreading, this is larger than the number of physical cores.
 
If called with the optional argument @var{query}, modify how processors
are counted as follows:
 
@table @code
@item all
total number of processors.
 
@item current
processors available to the current process.
 
@item overridable
same as @code{current}, but overridable through the
@w{@env{OMP_NUM_THREADS}} environment variable.
@end table
@end deftypefn */)
{
  int nargin = args.length ();
 
  if (nargin > 1)
    print_usage ();
 
  octave_nproc_query query = OCTAVE_NPROC_CURRENT_OVERRIDABLE;
 
  if (nargin == 1)
    {
      std::string arg = args(0).string_value ();
 
      std::transform (arg.begin (), arg.end (), arg.begin (), tolower);
 
      if (arg == "all")
        query = OCTAVE_NPROC_ALL;
      else if (arg == "current")
        query = OCTAVE_NPROC_CURRENT;
      else if (arg == "overridable")
        query = OCTAVE_NPROC_CURRENT_OVERRIDABLE;
      else
        error ("nproc: invalid value for QUERY");
    }
 
  return ovl (octave_num_processors_wrapper (query));
}
 
/*
## Must always report at least 1 cpu available
%!assert (nproc () >= 1)
%!assert (nproc ("all") >= 1)
%!assert (nproc ("current") >= 1)
 
## Test that "overridable" is the default
%!assert (nproc ("overridable"), nproc ())
 
%!test
%! c = nproc ("current");
%! unwind_protect
%!   old_val = getenv ("OMP_NUM_THREADS");
%!   new_val = c + 1;
%!   setenv ("OMP_NUM_THREADS", num2str (new_val));
%!   assert (nproc ("overridable"), new_val);
%! unwind_protect_cleanup
%!   if (! isempty (old_val))
%!     setenv ("OMP_NUM_THREADS", old_val);
%!   else
%!     unsetenv ("OMP_NUM_THREADS");
%!   endif
%! end_unwind_protect
 
%!error nproc ("no_valid_option")
*/
 
OCTAVE_END_NAMESPACE(octave)