Function _mi_page_queue_append

3rd/mimalloc-2.0.9/src/page-queue.c:297–332

Only called from `mi_heap_absorb`.

// Only called from `mi_heap_absorb`.
size_t _mi_page_queue_append(mi_heap_t* heap, mi_page_queue_t* pq, mi_page_queue_t* append) {
  mi_assert_internal(mi_heap_contains_queue(heap,pq));
  mi_assert_internal(pq->block_size == append->block_size);

  if (append->first==NULL) return 0;

  // set append pages to new heap and count
  size_t count = 0;
  for (mi_page_t* page = append->first; page != NULL; page = page->next) {
    // inline `mi_page_set_heap` to avoid wrong assertion during absorption;
    // in this case it is ok to be delayed freeing since both "to" and "from" heap are still alive.
    mi_atomic_store_release(&page->xheap, (uintptr_t)heap);
    // set the flag to delayed free (not overriding NEVER_DELAYED_FREE) which has as a
    // side effect that it spins until any DELAYED_FREEING is finished. This ensures
    // that after appending only the new heap will be used for delayed free operations.
    _mi_page_use_delayed_free(page, MI_USE_DELAYED_FREE, false);
    count++;
  }

  if (pq->last==NULL) {
    // take over afresh
    mi_assert_internal(pq->first==NULL);
    pq->first = append->first;
    pq->last = append->last;
    mi_heap_queue_first_update(heap, pq);
  }
  else {
    // append to end
    mi_assert_internal(pq->last!=NULL);
    mi_assert_internal(append->first!=NULL);
    pq->last->next = append->first;
    append->first->prev = pq->last;
    pq->last = append->last;
  }
  return count;
}