Implement Events

[bonachea]

These should basically just be a thin wrapper around integer atomics, ie:

type, public :: prif_event_type
  private
  integer(PRIF_ATOMIC_INT_KIND) :: value = 0
end type

! Everything below is UNTESTED PSEUDOCODE

module procedure prif_event_post(image_num, coarray_handle, offset, stat, errmsg, errmsg_alloc)
  call prif_sync_memory(stat, errmsg, errmsg_alloc)
  if (present(stat) && stat) return
  call prif_atomic_add(image_num, coarray_handle, offset, 1, stat)
  if (present(stat) && stat) ... ! set errmsg(_alloc) if present
end procedure 

module procedure prif_event_post_indirect(image_num, event_var_ptr, stat, errmsg, errmsg_alloc)
  ! same as above, but using prif_atomic_add_indirect
end procedure 

module procedure prif_event_query(event_var_ptr, count, stat)
  integer(PRIF_ATOMIC_INT_KIND) :: temp

  call prif_atomic_ref_int_indirect(this_image_world, event_var_ptr, temp, stat)
  if (!(present(stat) && stat)) count = temp
end procedure 

module procedure prif_event_wait(event_var_ptr, until_count, stat, errmsg, errmsg_alloc)
  integer(PRIF_ATOMIC_INT_KIND) :: until_int

  if (present(until_count)) until_int = max(until_count,1)
  else until_int = 1
  do 
     integer(PRIF_ATOMIC_INT_KIND) :: temp

     call prif_atomic_ref_int_indirect(this_image_world, event_var_ptr, temp, stat)
     if (present(stat) && stat) {
        ! set errmsg(_alloc) if present
        return
     }
     if (temp >= until_int) exit
  end do
  call prif_atomic_add_indirect(this_image_world, event_var_ptr, -until_int, stat)  
  if (present(stat) && stat) {
    ! set errmsg(_alloc) if present
    return
  }
  call prif_sync_memory(stat, errmsg, errmsg_alloc)
end procedure 

Where the atomic operations are themselves just thin wrappers around GASNet-EX atomics.