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/GNU Fortran 7

9.99 EVENT_QUERY — Query whether a coarray event has occurred

Description:

EVENT_QUERY assignes the number of events to COUNT which have been posted to the EVENT variable and not yet been removed by calling EVENT WAIT. 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 and COUNT is assigned the value -1.

Standard:

TS 18508 or later

Class:

subroutine

Syntax:

CALL EVENT_QUERY (EVENT, COUNT [, STAT])

Arguments:
EVENT (intent(IN)) Scalar of type EVENT_TYPE, defined in ISO_FORTRAN_ENV; shall not be coindexed.
COUNT (intent(out))Scalar integer with at least the precision of default integer.
STAT (optional) Scalar default-kind integer variable.
Example:
program atomic
  use iso_fortran_env
  implicit none
  type(event_type) :: event_value_has_been_set[*]
  integer :: cnt
  if (this_image() == 1) then
    call event_query (event_value_has_been_set, cnt)
    if (cnt > 0) write(*,*) "Value has been set"
  elseif (this_image() == 2) then
    event post (event_value_has_been_set[1])
  end if
end program atomic

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https://gcc.gnu.org/onlinedocs/gcc-7.1.0/gfortran/EVENT_005fQUERY.html