If the Heap size exceeds a certain limit, garbage collect till you are below it again

Heap GC Helper

(defun current-heap-size-megs (&key (spaces '(:static :dynamic :read-only))
                          &aux (total-mem 0) (total-cnt 0))
  (iter (for s in spaces)
    (iter (for (mem cnt type) in (sb-vm::type-breakdown s))
      (incf total-mem mem)
      (incf total-cnt cnt)))
  (values (ceiling (/ total-mem (expt 2 20)))
          total-cnt))

(defun gc-till-heap-available ( &key
                                (heap-size-max 500)
                                (sleep-time .01) (limit 5)
                                log?
                               &aux (cnt 0) megs)
  (iter
    (setf megs (current-heap-size-megs))
    (while (> megs heap-size-max))
    ;; while debugging I am going to turn this off, but
    ;; this seems to be the reason
    ;; (function-cache:clear-cache-all-function-caches)
    (incf cnt)
    (when (= limit 3)
      (adwolf-log.error "Had to clear all caches to free space so we can continue")
      (function-cache:clear-cache-all-function-caches))
    (unless (plusp (decf limit))
      (error "Couldnt collect enough garbage to continue full-validation loop"))
    (sb-ext:gc :full t)
    (sleep sleep-time))
  (when log?
    (adwolf-log.info "GC'ed ~A times resulting in a ~DM heap " cnt megs))
  (values cnt megs))