Parallel Programming in Fortran 95 using OpenMP - People

4.2. Lock routines 61
subroutine OMP_set_lock(svar)
integer(kind = OMP_lock_kind), intent(inout) :: svar
end subroutine OMP_set_lock
subroutine OMP_set_nest_lock(nvar)
integer(kind = OMP_nest_lock_kind), intent(inout) :: nvar
end subroutine OMP_set_nest_lock
A simple lock will be available if it is unlocked, while a nestable lock is available if it
is unlocked or if it is already owned by the thread executing the subroutine. In the latter
case, the nesting counter of a nestable lock variable is incremented by one when it is set.
4.2.3 OMP unset lock and OMP unset nest lock
These subroutines provide the means of releasing the ownership of a lock. Their interface
declaration is:
subroutine OMP_unset_lock(svar)
integer(kind = OMP_lock_kind), intent(inout) :: svar
end subroutine OMP_unset_lock
subroutine OMP_unset_nest_lock(nvar)
integer(kind = OMP_nest_lock_kind), intent(inout) :: nvar
end subroutine OMP_unset_nest_lock
In the first case, a call to the subroutine releases the calling thread from the ownership
of the simple lock associated to the corresponding lock variable svar, while in the second
case the call to the subroutine decreases by one the nesting counter of nvar and only
releases the calling thread, if the counter reaches zero.
To call these subroutines only makes sense, if the calling thread owns the corresponding
lock; the behaviour is unspecified if the calling thread does not own the lock!
4.2.4 OMP test lock and OMP test nest lock
These functions attempt to set a lock in the same way as the subroutines OMP set lock and
OMP set nest lock do, but they do not force the calling thread to wait until the specified
lock is available. Their interface declarations are the following ones:
function OMP_test_lock(svar)
logical(kind = OMP_logical_kind) :: OMP_test_lock
integer(kind = OMP_lock_kind), intent(inout) :: svar
end function OMP_test_lock
function OMP_test_nest_lock(nvar)
integer(kind = OMP_integer_kind) :: OMP_test_nest_lock
integer(kind = OMP_nest_lock_kind), intent(inout) :: nvar
end function OMP_test_nest_lock