Function mi_segment_span_free

3rd/mimalloc-2.0.9/src/segment.c:581–608

note: can be called on abandoned segments

// note: can be called on abandoned segments
static void mi_segment_span_free(mi_segment_t* segment, size_t slice_index, size_t slice_count, bool allow_decommit, mi_segments_tld_t* tld) {
  mi_assert_internal(slice_index < segment->slice_entries);
  mi_span_queue_t* sq = (segment->kind == MI_SEGMENT_HUGE || mi_segment_is_abandoned(segment) 
                          ? NULL : mi_span_queue_for(slice_count,tld));
  if (slice_count==0) slice_count = 1;
  mi_assert_internal(slice_index + slice_count - 1 < segment->slice_entries);

  // set first and last slice (the intermediates can be undetermined)
  mi_slice_t* slice = &segment->slices[slice_index];
  slice->slice_count = (uint32_t)slice_count;
  mi_assert_internal(slice->slice_count == slice_count); // no overflow?
  slice->slice_offset = 0;
  if (slice_count > 1) {
    mi_slice_t* last = &segment->slices[slice_index + slice_count - 1];
    last->slice_count = 0;
    last->slice_offset = (uint32_t)(sizeof(mi_page_t)*(slice_count - 1));
    last->xblock_size = 0;
  }

  // perhaps decommit
  if (allow_decommit) {
    mi_segment_perhaps_decommit(segment, mi_slice_start(slice), slice_count * MI_SEGMENT_SLICE_SIZE, tld->stats);
  }
  
  // and push it on the free page queue (if it was not a huge page)
  if (sq != NULL) mi_span_queue_push( sq, slice );
             else slice->xblock_size = 0; // mark huge page as free anyways
}

/*
// called from reclaim to add existing free spans