nproc.cc

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//
// Copyright (C) 2012-2021 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
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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"
 
DEFUN (nproc, args, ,
       doc: /* -*- texinfo -*-
@deftypefn  {} {} nproc ()
@deftypefnx {} {} nproc (@var{query})
Return the current number of available processors.
 
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")
*/