8.37 ATOMIC_REF — Obtaining the value of a variable atomically


ATOMIC_DEFINE(ATOM, VALUE) atomically assigns the value of the variable ATOM to VALUE. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of ISO_FORTRAN_ENV’s STAT_STOPPED_IMAGE and if the remote image has failed, the value STAT_FAILED_IMAGE.


Fortran 2008 and later; with STAT, TS 18508 or later


Atomic subroutine



VALUEScalar of the same type as ATOM. If the kind is different, the value is converted to the kind of ATOM.
ATOMScalar coarray or coindexed variable of either integer type with ATOMIC_INT_KIND kind or logical type with ATOMIC_LOGICAL_KIND kind.
STAT(optional) Scalar default-kind integer variable.
program atomic
  use iso_fortran_env
  logical(atomic_logical_kind) :: atom[*]
  logical :: val
  call atomic_ref (atom, .false.)
  ! ...
  call atomic_ref (atom, val)
  if (val) then
    print *, "Obtained"
  end if
end program atomic
See also:

ATOMIC_DEFINE — Setting a variable atomically, ATOMIC_CAS — Atomic compare and swap, ISO_FORTRAN_ENV, ATOMIC_FETCH_ADD — Atomic ADD operation with prior fetch, ATOMIC_FETCH_AND — Atomic bitwise AND operation with prior fetch, ATOMIC_FETCH_OR — Atomic bitwise OR operation with prior fetch, ATOMIC_FETCH_XOR — Atomic bitwise XOR operation with prior fetch